Merge pull request 'Remove unimplemented CLI options' (#209 ) from feat/remove-unimplemented-cli-options into evaluation-of-codebase-by-human

Reviewed-on: #209
Satisfy cppcheck CLI and logger checks
2026-08-11 21:17:52 +02:00 · 2026-08-11 21:14:56 +02:00 · 2026-08-11 21:12:00 +02:00 · 2026-08-11 21:08:54 +02:00 · 2026-08-11 20:59:06 +02:00 · 2026-08-11 20:26:15 +02:00
42 changed files with 1586 additions and 633 deletions
@@ -206,7 +206,7 @@ tea pr close <number> --repo TapTap/FastSync

 ## Common pitfalls

- **`__thread` on shared SSL context**: io_ssl must NOT be thread-local — worker threads inherit the SSL context from the main thread. Use regular `static SSL* io_ssl`.
+- **Per-thread SSL context**: `io_ssl` is stored per-thread (`static __thread SSL* io_ssl`). Each thread that performs protocol I/O must call `io_set_ssl()` to install its own SSL object before using `send_*` / `receive_*` primitives. The main thread's SSL context is not automatically inherited by worker threads.
 - **SSL WANT_READ/WANT_WRITE retry**: Always retry on `SSL_ERROR_WANT_READ` and `SSL_ERROR_WANT_WRITE` in `send_n_data`/`receive_n_data`. Removing these breaks TLS multithreaded transfers.
 - **clang-format version**: The CI image uses clang-format 18. Always format inside the CI Docker container for exact match.
 - **Merge order matters**: Merge the most comprehensive branch first, then smaller ones, to minimize conflicts when creating a combined branch.
@@ -79,8 +79,9 @@ set(TEST_INCLUDES tests src/shared src/server src/client)

 # Monolithic test binary (backward compatible)
 file(GLOB TEST_SRCS "tests/test_*.c" "tests/runner.c")
-add_executable(tests ${TEST_SRCS} ${SHARED_SRCS} src/client/scanner.c)
+add_executable(tests ${TEST_SRCS} ${SHARED_SRCS} src/client/scanner.c src/client/client_cli.c)
 target_include_directories(tests PRIVATE ${TEST_INCLUDES})
+target_compile_definitions(tests PRIVATE FASTSYNC_TEST_BUILD)
 target_link_libraries(tests PRIVATE ${TEST_LIBS})
 add_test(NAME unit_all COMMAND tests)

@@ -40,12 +40,10 @@ A high-performance file synchronization system with SSH and TCP transport, TLS e
 - Optional progress display with throughput
 - Bandwidth limiting via token-bucket algorithm
 - Configurable I/O and connection timeouts (`--timeout`, `--contimeout`)
- Quiet mode (`-q`/`--quiet`) suppresses all non-error output
 - Backup overwritten files (`--backup`) with optional directory (`--backup-dir`)
 - Transfer statistics summary (`--stats`)
 - Maximum directory depth control (`--max-depth`)
 - Log file output (`--log-file`)
- Configurable multithreaded queue size (`--queue-size`)
 - Exclude patterns from file (`--exclude-from`)

 ### Server
@@ -114,8 +112,6 @@ Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up
 | `-n, --dry-run` | Scan and print what would be transferred |
 | `-p <port>` | SSH port (default: 22) |
 | `-v, --verbose` | Enable debug logging |
-| `-q, --quiet` | Suppress all non-error output |
-| `--silent` | Alias for `--quiet` |
 | `--progress` | Show real-time transfer speed |
 | `--delete` | Delete files on receiver not present in source |
 | `--exclude <pattern>` | Exclude files matching glob pattern (repeatable) |
@@ -133,7 +129,6 @@ Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up
 | `--stats` | Print transfer statistics at end (bytes, files, timing) |
 | `--max-depth <n>` | Maximum directory depth to recurse (0 = unlimited, default: 0) |
 | `--log-file <path>` | Write log messages to file instead of stderr |
-| `--queue-size <n>` | Queue capacity for multithreaded mode (default: 100) |
 | `--source-dir <path>` | Source directory (overrides `FASTSYNC_SOURCE_DIR`) |
 | `--dest-dir <path>` | Server destination directory (overrides `FASTSYNC_DEST_DIR`) |
 | `--save-to-disk` | Write received files to disk |
@@ -177,7 +172,7 @@ Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up
 1. **Chunk** — collection of files (~10 MB total by default)
 2. **File** — path, content (`Data`), optional `FileMetadata` pointer
 3. **FileMetadata** — `mode`, `uid`, `gid`, `mtime_sec`, `mtime_nsec`
-4. **Config** — runtime parameters (transported over wire, TLS settings excluded). Includes `timeout`, `contimeout`, `quiet`, `backup`, `backup_dir`, `stats`, `max_depth`, `log_file`, `queue_size`.
+4. **Config** — runtime parameters (transported over wire, TLS settings excluded). Includes `timeout`, `contimeout`, `backup`, `backup_dir`, `stats`, and `max_depth`.
 5. **Queue** — thread-safe bounded queue with condition variables
 6. **DirectoryScanner** — recursive BFS traversal with exclude and include pattern support, max-depth enforcement

@@ -294,8 +289,8 @@ Place the `fastsync-server` binary in the remote `$PATH`. The client runs `ssh u
 # Bandwidth limit to 1 MB/s
 ./build/client --bwlimit 1024 /src user@host:/dst

-# With timeouts, quiet mode, and stats
-./build/client --timeout 60 --contimeout 15 --quiet --stats /src user@host:/dst
+# With timeouts and stats
+./build/client --timeout 60 --contimeout 15 --stats /src user@host:/dst

 # Backup overwritten files to a directory
 ./build/client --backup --backup-dir /backups /src user@host:/dst
@@ -303,9 +298,6 @@ Place the `fastsync-server` binary in the remote `$PATH`. The client runs `ssh u
 # Exclude patterns from file, limit depth
 ./build/client --exclude-from ignore.txt --max-depth 3 /src user@host:/dst

-# Custom queue size for multithreading
-./build/client -m --queue-size 200 /src user@host:/dst
-
 # Log to file
 ./build/client --log-file /tmp/fastsync.log /src user@host:/dst

@@ -332,7 +324,7 @@ The benchmark prints throughput metrics, best configuration, and speedup vs rsyn
 1. Chunk size (~10 MB default) balances memory and transfer efficiency
 2. Compression level trades CPU for bandwidth
 3. `sendfile()` bypasses userspace — ~2× faster on localhost for large files
-4. Multithreading scales with core count; `--queue-size` controls pipeline buffering
+4. Multithreading scales with core count and uses memory-based pipeline sizing
 5. Metadata transfer adds negligible overhead (~24 bytes per file when enabled)
 6. SSH socketpair buffer set to 1 MB for improved pipe throughput
 7. SSH ControlMaster reuses connections across repeated invocations
@@ -0,0 +1,273 @@
+# Rsync Feature Compatibility
+
+This document maps rsync's full feature set to FastSync's current implementation status.
+
+## Summary
+
+| Status | Count | Description |
+|--------|-------|-------------|
+| ✅ Implemented | 34 | Feature works end-to-end |
+| 🔀 Alt Arg | 3 | Functionality exists but under different flag/semantics |
+| ⚠️ Partial | 1 | Flag parsed/stored but behavior incomplete |
+| ❌ Not Implemented | 98 | Flag not recognized or no behavior |
+| **Total** | **136** | |
+
+---
+
+## 1. General Options
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-a`, `--archive` | Archive mode is -rlptgoD | 🔀 Alt Arg | Maps to -c -m -M (compression + multithread + metadata) |
+| `-v`, `--verbose` | Increase verbosity | ✅ Implemented | Sets `log_level=DEBUG` |
+| `-q`, `--quiet` | Suppress non-error messages | ❌ Not Implemented | Removed because it had no effect |
+| `--help` | Show help | ✅ Implemented | Prints usage and exits; `-h` is not accepted |
+| `-V`, `--version` | Print version | ✅ Implemented | |
+| `--info=FLAGS` | Fine-grained info verbosity | ❌ Not Implemented | Removed because it had no effect |
+| `--debug=FLAGS` | Fine-grained debug verbosity | ❌ Not Implemented | Removed because it had no effect |
+| `--stderr=MODE` | Change stderr output mode | ❌ Not Implemented | |
+| `--no-motd` | Suppress daemon MOTD | ❌ Not Implemented | |
+| `--exclude=PATTERN` | Exclude files matching pattern | ✅ Implemented | Glob matching in scanner |
+| `--include=PATTERN` | Include files matching pattern | ✅ Implemented | Glob matching in scanner |
+| `-C`, `--cvs-exclude` | Auto-ignore CVS files | ❌ Not Implemented | Removed because it had no effect |
+
+## 2. Modifying Output
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--stats` | Give transfer stats | ✅ Implemented | Prints file/byte counts |
+| `-h`, `--human-readable` | Human-readable numbers | ❌ Not Implemented | Removed because it had no effect |
+| `-i`, `--itemize-changes` | Per-file change summary | ❌ Not Implemented | Removed because it had no effect |
+| `--progress` | Show progress | ✅ Implemented | Progress callback in sender |
+| `-P` | Same as --partial --progress | ❌ Not Implemented | |
+| `--out-format=FORMAT` | Custom output format | ❌ Not Implemented | Removed because it had no effect |
+| `--log-file=FILE` | Log to file | ✅ Implemented | `log_file` config field |
+| `--log-file-format=FMT` | Log format | ❌ Not Implemented | |
+| `--8-bit-output` | Leave high-bit chars unescaped | ❌ Not Implemented | |
+| `--list-only` | List files instead of copying | ❌ Not Implemented | Removed because it had no effect |
+
+## 3. File Selection
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--exclude-from=FILE` | Read exclude patterns from file | ✅ Implemented | Reads patterns from file |
+| `--include-from=FILE` | Read include patterns from file | ✅ Implemented | Reads patterns from file |
+| `--filter=RULE` | Add file-filtering rule | ❌ Not Implemented | Removed because it had no effect |
+| `--files-from=FILE` | Read source file list from file | ❌ Not Implemented | Removed because it had no effect |
+| `-0`, `--from0` | Delimit *-from files with NULs | ❌ Not Implemented | |
+| `--max-size=SIZE` | Skip files larger than SIZE | ✅ Implemented | `max_size` in scanner |
+| `--min-size=SIZE` | Skip files smaller than SIZE | ✅ Implemented | `min_size` in scanner |
+| `-I`, `--ignore-times` | Don't skip files matching size+time | ❌ Not Implemented | |
+| `--size-only` | Skip based on size only | ❌ Not Implemented | |
+| `-@`, `--modify-window=NUM` | Mod-time comparison accuracy | ❌ Not Implemented | |
+| `--existing` | Skip creating new files on receiver | ❌ Not Implemented | |
+| `--ignore-existing` | Skip updating existing files | ❌ Not Implemented | |
+| `--remove-source-files` | Sender removes synced files | ❌ Not Implemented | |
+
+## 4. Directory Options
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-r`, `--recursive` | Recurse into directories | ✅ Implemented | Default behavior |
+| `-R`, `--relative` | Use relative path names | ❌ Not Implemented | Removed because it had no effect |
+| `--no-implied-dirs` | Don't send implied dirs with -R | ❌ Not Implemented | |
+| `-d`, `--dirs` | Transfer dirs without recursing | ❌ Not Implemented | |
+| `--mkpath` | Create missing path components | ❌ Not Implemented | |
+
+## 5. Transfer Modifications
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-u`, `--update` | Skip files newer on receiver | ❌ Not Implemented | Removed because it had no effect |
+| `--inplace` | Update files in-place | ✅ Implemented | Direct write mode |
+| `--append` | Append data to shorter files | ❌ Not Implemented | Removed because it had no effect |
+| `--append-verify` | Append with old-data checksum | ❌ Not Implemented | Removed because it had no effect |
+| `-W`, `--whole-file` | Copy whole file (no delta) | ❌ Not Implemented | |
+| `--block-size=SIZE` | Force checksum block-size | ⚠️ Partial | Parsed as `--delta-block`; controls delta transfer block size |
+
+## 6. Destination Handling
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-n`, `--dry-run` | Trial run with no changes | ✅ Implemented | `dry_run` config field |
+| `-b`, `--backup` | Make backups of overwritten files | ✅ Implemented | Backup before overwrite |
+| `--backup-dir=DIR` | Backup directory hierarchy | ✅ Implemented | `backup_dir` config field |
+| `--suffix=SUFFIX` | Backup suffix (default ~) | ✅ Implemented | `suffix` config field |
+| `--delay-updates` | Put updated files in place at end | ❌ Not Implemented | |
+
+## 7. Deletion
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--delete` | Delete extraneous files from dest | ✅ Implemented | `use_delete` config field |
+| `--delete-before` | Delete before transfer | ❌ Not Implemented | Removed because it had no effect |
+| `--delete-during` | Delete during transfer | ❌ Not Implemented | |
+| `--delete-delay` | Find deletions during, delete after | ❌ Not Implemented | |
+| `--delete-after` | Delete after transfer | ❌ Not Implemented | Removed because it had no effect |
+| `--delete-excluded` | Also delete excluded files | ❌ Not Implemented | Removed because it had no effect |
+| `--max-delete=NUM` | Max files to delete | ❌ Not Implemented | Removed because it had no effect |
+| `--ignore-errors` | Delete even with I/O errors | ❌ Not Implemented | |
+| `--force` | Force deletion of non-empty dirs | ❌ Not Implemented | |
+| `--prune-empty-dirs` | Prune empty dir chains | ❌ Not Implemented | Removed because it had no effect |
+
+## 8. Metadata Preservation
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-M`, `--preserve` | Preserve file metadata | ✅ Implemented | Mode, uid, gid, mtime |
+| `-p`, `--perms` | Preserve permissions | 🔀 Alt Arg | `-p` means SSH port; permissions preserved via `-M`/`--preserve` |
+| `-o`, `--owner` | Preserve owner | ✅ Implemented | Part of -M |
+| `-g`, `--group` | Preserve group | ✅ Implemented | Part of -M |
+| `-t`, `--times` | Preserve modification times | ✅ Implemented | Part of -M |
+| `-E`, `--executability` | Preserve executability | ❌ Not Implemented | |
+| `--chmod=CHMOD` | Affect file permissions | ❌ Not Implemented | |
+| `-A`, `--acls` | Preserve ACLs | ❌ Not Implemented | Removed because it had no effect |
+| `-X`, `--xattrs` | Preserve extended attributes | ❌ Not Implemented | Removed because it had no effect |
+| `-H`, `--hard-links` | Preserve hard links | ❌ Not Implemented | Removed because it had no effect |
+| `-D` | Same as --devices --specials | ❌ Not Implemented | Removed because device-file handling is not implemented |
+| `--devices` | Preserve device files | ❌ Not Implemented | Removed because it had no effect |
+| `--specials` | Preserve special files | ❌ Not Implemented | |
+| `--copy-devices` | Copy device contents as file | ❌ Not Implemented | |
+| `--write-devices` | Write to devices as files | ❌ Not Implemented | |
+| `-U`, `--atimes` | Preserve access times | ❌ Not Implemented | |
+| `-N`, `--crtimes` | Preserve create times | ❌ Not Implemented | |
+| `-O`, `--omit-dir-times` | Omit dirs from --times | ❌ Not Implemented | |
+| `-J`, `--omit-link-times` | Omit symlinks from --times | ❌ Not Implemented | |
+| `--super` | Receiver attempts super-user activities | ❌ Not Implemented | |
+| `--fake-super` | Store/recover privileged attrs via xattrs | ❌ Not Implemented | |
+
+## 9. Symlink Handling
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-l`, `--links` | Copy symlinks as symlinks | ⚠️ Partial | Scanner includes symlinks; target path not transmitted |
+| `-L`, `--copy-links` | Transform symlink to referent | ✅ Implemented | `copy_links` config field |
+| `--copy-unsafe-links` | Transform unsafe symlinks | ✅ Implemented | `copy_unsafe_links` config field |
+| `--safe-links` | Ignore symlinks outside tree | ✅ Implemented | `safe_links` config field |
+| `--munge-links` | Munge symlinks for safety | ❌ Not Implemented | |
+| `-k`, `--copy-dirlinks` | Transform symlink to dir | ❌ Not Implemented | |
+| `-K`, `--keep-dirlinks` | Treat symlinked dir as dir | ❌ Not Implemented | |
+
+## 10. Sparse & Device
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-S`, `--sparse` | Sparse block handling | ✅ Implemented | `preserve_sparse` config field |
+| `--preallocate` | Allocate dest files before writing | ❌ Not Implemented | |
+
+## 11. Checksum & Comparison
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--checksum` | Skip based on checksum | ❌ Not Implemented | Removed because it had no effect; `-c` means compression |
+| `--checksum-choice=STR` | Choose checksum algorithm | ❌ Not Implemented | xxHash used internally |
+| `--compare-dest=DIR` | Compare dest files relative to DIR | ❌ Not Implemented | Removed because it had no effect |
+| `--copy-dest=DIR` | Include copies of unchanged files | ❌ Not Implemented | Removed because it had no effect |
+| `--link-dest=DIR` | Hardlink to files when unchanged | ❌ Not Implemented | Removed because it had no effect |
+| `--fuzzy`, `--no-fuzzy` | Find similar file for basis | ❌ Not Implemented | |
+
+## 12. Compression
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-z`, `--compress` | Compress file data | 🔀 Alt Arg | Always uses zstd (rsync supports multiple algorithms) |
+| `--compress-choice=STR` | Choose compression algorithm | ❌ Not Implemented | Removed because it had no effect; FastSync always uses zstd |
+| `--compress-level=NUM` | Set compression level | ✅ Implemented | 1-22, default 5 |
+| `--compress-threads=NUM` | Set compression threads | ❌ Not Implemented | |
+| `--skip-compress=LIST` | Skip compress for suffixes | ❌ Not Implemented | Internal skip for hardcoded types; not user-configurable |
+
+## 13. Connectivity
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `-e`, `--rsh=COMMAND` | Remote shell to use | ❌ Not Implemented | Removed; SSH invokes `ssh` directly |
+| `--rsync-path=PROGRAM` | rsync binary on remote | ❌ Not Implemented | Removed; use `--fastsync-server-path` |
+| `--port=PORT` | Alternate daemon port | ✅ Implemented | `server_port` config field |
+| `--sockopts=OPTIONS` | Custom TCP options | ❌ Not Implemented | |
+| `--blocking-io` | Use blocking I/O for remote shell | ❌ Not Implemented | |
+| `--outbuf=N\|L\|B` | Set output buffering | ❌ Not Implemented | |
+| `--address=ADDRESS` | Bind address for outgoing socket | ❌ Not Implemented | Removed because it had no effect |
+| `-4`, `--ipv4` | Prefer IPv4 | ❌ Not Implemented | Removed because it had no effect |
+| `-6`, `--ipv6` | Prefer IPv6 | ❌ Not Implemented | Removed because it had no effect |
+
+## 14. Daemon Mode
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--daemon` | Run as rsync daemon | ❌ Not Implemented | Removed because it had no effect |
+| `--config=FILE` | Alternate rsyncd.conf file | ❌ Not Implemented | Removed because it had no effect |
+| `--dparam=OVERRIDE` | Override global daemon config | ❌ Not Implemented | |
+| `--no-detach` | Don't detach from parent | ❌ Not Implemented | |
+| `--password-file=FILE` | Read daemon password from file | ❌ Not Implemented | |
+| `--early-input=FILE` | Use FILE for daemon early exec | ❌ Not Implemented | |
+
+## 15. Safety & Security
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| Path escape detection | Ensure files stay within root | ✅ Implemented | `has_path_traversal()` + realpath |
+| Symlink-safe delete | Skip symlinks in delete walk | ✅ Implemented | `delete_extras_walk()` |
+| Protocol version check | Verify compatible versions | ✅ Implemented | `config_receive()` |
+| Max data/string/chunk sizes | Prevent OOM attacks | ✅ Implemented | Per-message limits |
+| Per-connection memory limit | 1GB per connection | ✅ Implemented | `MAX_CONNECTION_MEMORY` |
+| `--trust-sender` | Trust remote sender's file list | ❌ Not Implemented | |
+| `--old-args` | Disable modern arg protection | ❌ Not Implemented | |
+| `--ignore-missing-args` | Ignore missing source args | ❌ Not Implemented | |
+| `--delete-missing-args` | Delete missing source args | ❌ Not Implemented | |
+
+## 16. Batch Operations
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--write-batch=FILE` | Write batched update to file | ❌ Not Implemented | |
+| `--only-write-batch=FILE` | Write batch without updating dest | ❌ Not Implemented | |
+| `--read-batch=FILE` | Read batched update from file | ❌ Not Implemented | |
+
+## 17. Advanced
+
+| Flag | Rsync Description | FastSync Status | Notes |
+|------|-------------------|-----------------|-------|
+| `--stop-after=MINS` | Stop after N minutes | ❌ Not Implemented | |
+| `--stop-at=TIME` | Stop at specified time | ❌ Not Implemented | |
+| `--fsync` | Fsync every written file | ❌ Not Implemented | |
+| `--protocol=NUM` | Force older protocol version | ❌ Not Implemented | |
+| `--iconv=CONVERT_SPEC` | Charset conversion | ❌ Not Implemented | |
+| `--checksum-seed=NUM` | Set checksum seed | ❌ Not Implemented | |
+| `-s`, `--secluded-args` | Use protocol to send args | ❌ Not Implemented | |
+| `--no-OPTION` | Turn off implied option | ❌ Not Implemented | |
+
+---
+
+## Recommendations: Top Features to Implement Next
+
+Ranked by user demand, implementation complexity, and interoperability impact:
+
+| Priority | Feature | Effort | Impact |
+|----------|---------|--------|--------|
+| 1 | `--whole-file` / `-W` | Low | High — users expect opt-out of delta |
+| 2 | `--ignore-times` / `-I` | Low | Medium — useful for forcing re-transfer |
+| 3 | `--size-only` | Low | Medium — common migration scenario |
+| 4 | `--existing` / `--ignore-existing` | Low | Medium — common sync patterns |
+| 5 | `--remove-source-files` | Low | High — common for moves/backup |
+| 6 | `--delete-during` | Medium | High — performance improvement |
+| 7 | `--delay-updates` | Medium | High — atomic updates |
+| 8 | `--chmod` | Low | Medium — permission flexibility |
+| 9 | `--executability` / `-E` | Low | Low — simple flag |
+| 10 | `--skip-compress` | Low | Medium — performance tuning |
+
+---
+
+## FastSync-Specific Features (Not in rsync)
+
+| Feature | Description |
+|---------|-------------|
+| `-m` | Multithreaded pipeline (scanner/loader/sender) |
+| `-s` | Chunk serialization mode |
+| `-f` / `--sendfile` | Zero-copy sendfile() syscall (TCP only) |
+| `-c [level]` | zstd compression level (1-22) |
+| `--chunk-size` | Configurable chunk size |
+| `--tls` | TLS encryption (mutual auth) |
+| `--fastsync-server-path` | Path to fastsync-server binary |
+| `--server-host` / `--server-port` | Direct TCP connection |
+| Incremental sync | Skip unchanged files (size+mtime) |
+| Delta transfer | Block-level delta for changed files |
@@ -8,10 +8,13 @@
 #include "utils.h"
 #include <errno.h>
 #include <limits.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include "usage.c"

+#ifndef FASTSYNC_TEST_BUILD
 /* Parse environment variables for source/destination directories and save-to-disk flag. */
 static void parse_environment(const char** out_env_source, const char** out_env_dest,
                              bool* out_save_to_disk) {
@@ -22,19 +25,7 @@ static void parse_environment(const char** out_env_source, const char** out_env_
  if (env_save && (strcmp(env_save, "true") == 0 || strcmp(env_save, "1") == 0))
    *out_save_to_disk = true;
 }
-
-/* Parse a string as a positive integer, returning true on success. */
-static bool parse_positive_int(const char* s, int* out_val) {
-  if (!s || *s == '\0')
-    return false;
-  char* endptr;
-  errno = 0;
-  long val = strtol(s, &endptr, 10);
-  if (errno != 0 || *endptr != '\0' || val <= 0 || val > INT_MAX)
-    return false;
-  *out_val = (int)val;
-  return true;
-}
+#endif

 /* Parse a string as a non-negative integer, returning true on success. */
 static bool parse_nonneg_int(const char* s, int* out_val) {
@@ -49,16 +40,62 @@ static bool parse_nonneg_int(const char* s, int* out_val) {
  return true;
 }

-static void print_usage(void);
+/* Parse a string as a positive integer, returning true on success. */
+static bool parse_positive_int(const char* s, int* out_val) {
+  int temp;
+  if (!parse_nonneg_int(s, &temp)) {
+    return false;
+  }
+  if (temp == 0) {
+    return false;
+  }
+  *out_val = temp;
+  return true;
+}
+
+/* Duplicate a string argument into *dest, freeing the old value. Returns true on success, false on
+ * failure. */
+static int set_string_option(char** dest, const char* value, const char* option_name) {
+  char* dup = str_dup(value);
+  if (!dup) {
+    fprintf(stderr, "Error: memory allocation failed for %s\n", option_name);
+    return -1;
+  }
+  free(*dest);
+  *dest = dup;
+  return 0;
+}
+
+/* Parse a string as a positive integer into *dest. Returns true on success, false on error. */
+static int set_positive_int_option(int* dest, const char* value, const char* option_name) {
+  if (!parse_positive_int(value, dest)) {
+    fprintf(stderr, "Error: %s must be a positive integer\n", option_name);
+    return -1;
+  }
+  return 0;
+}
+
+/* Parse a string as a non-negative integer into *dest. Returns true on success, false on error. */
+static int set_nonneg_int_option(int* dest, const char* value, const char* option_name) {
+  if (!parse_nonneg_int(value, dest)) {
+    fprintf(stderr, "Error: %s must be a non-negative integer\n", option_name);
+    return -1;
+  }
+  return 0;
+}
+
 static int read_patterns_from_file(const char* filepath, char*** patterns, int* count);

 /* Parse CLI arguments into config. Returns 0 on success, -1 on error, 1 for help/clean-exit. */
-static int parse_args(Config* config, int argc, char* argv[], int* positional_args,
-                      int* positional_count) {
+int parse_args(Config* config, int argc, char* argv[], int* positional_args,
+               int* positional_count) {
  for (int i = 1; i < argc; i++) {
    if (strcmp(argv[i], "--help") == 0) {
      print_usage();
      return 1;
+    } else if (strcmp(argv[i], "-V") == 0 || strcmp(argv[i], "--version") == 0) {
+      printf("fastsync version %s\n", PROTOCOL_VERSION);
+      return 1;
    } else if (strcmp(argv[i], "-a") == 0 || strcmp(argv[i], "--archive") == 0) {
      config->use_compression = true;
      config->use_multithreading = true;
@@ -67,8 +104,10 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
    } else if (strcmp(argv[i], "-n") == 0 || strcmp(argv[i], "--dry-run") == 0) {
      config->dry_run = true;
    } else if (strcmp(argv[i], "-p") == 0 && i + 1 < argc) {
-      if (!parse_positive_int(argv[++i], &config->ssh_port)) {
-        fprintf(stderr, "Error: invalid --port/-p value: %s\n", argv[i]);
+      if (set_positive_int_option(&config->ssh_port, argv[++i], "-p") != 0)
+        return -1;
+      if (config->ssh_port > 65535) {
+        log_message(LOG_LEVEL_ERROR, "SSH port must be 1-65535\n");
        return -1;
      }
    } else if (strcmp(argv[i], "--delete") == 0) {
@@ -100,21 +139,47 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
      }
      config->include_patterns[config->include_count++] = dup;
    } else if (strcmp(argv[i], "--max-size") == 0 && i + 1 < argc) {
-      config->max_size = strtoull(argv[++i], NULL, 10);
+      char* end;
+      errno = 0;
+      unsigned long long val = strtoull(argv[++i], &end, 10);
+      if (errno != 0 || *end != '\0') {
+        fprintf(stderr, "Error: --max-size must be a non-negative integer\n");
+        return -1;
+      }
+      config->max_size = val;
    } else if (strcmp(argv[i], "--min-size") == 0 && i + 1 < argc) {
-      config->min_size = strtoull(argv[++i], NULL, 10);
+      char* end;
+      errno = 0;
+      unsigned long long val = strtoull(argv[++i], &end, 10);
+      if (errno != 0 || *end != '\0') {
+        fprintf(stderr, "Error: --min-size must be a non-negative integer\n");
+        return -1;
+      }
+      config->min_size = val;
    } else if (strcmp(argv[i], "--incremental") == 0) {
      config->use_incremental = true;
    } else if (strcmp(argv[i], "--delta") == 0) {
      config->use_delta = true;
    } else if (strcmp(argv[i], "--delta-block") == 0 && i + 1 < argc) {
-      unsigned long long val = strtoull(argv[++i], NULL, 10);
+      char* end;
+      errno = 0;
+      unsigned long long val = strtoull(argv[++i], &end, 10);
+      if (errno != 0 || *end != '\0') {
+        fprintf(stderr, "Error: --delta-block must be a positive integer\n");
+        return -1;
+      }
      if (val >= DELTA_BLOCK_SIZE_MIN && val <= DELTA_BLOCK_SIZE_MAX)
        config->delta_block_size = (uint32_t)val;
      else
        fprintf(stderr, "Warning: --delta-block value %llu out of range, using default\n", val);
    } else if (strcmp(argv[i], "--delta-max") == 0 && i + 1 < argc) {
-      unsigned long long val = strtoull(argv[++i], NULL, 10);
+      char* end;
+      errno = 0;
+      unsigned long long val = strtoull(argv[++i], &end, 10);
+      if (errno != 0 || *end != '\0') {
+        fprintf(stderr, "Error: --delta-max must be a positive integer\n");
+        return -1;
+      }
      if (val >= DELTA_MIN_FILE_SIZE)
        config->delta_max_file_size = val;
      else
@@ -126,27 +191,21 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
        char* end_ptr;
        long level = strtol(argv[i + 1], &end_ptr, 10);
        if (*end_ptr == '\0') {
+          if (level < 1 || level > 22) {
+            fprintf(stderr, "Error: compression level must be 1-22\n");
+            return -1;
+          }
          config->compression_level = (int)level;
          log_message(LOG_LEVEL_INFO, "Set Compression level to %ld", level);
          i++;
        }
      }
    } else if (strcmp(argv[i], "--source-dir") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --source-dir\n");
+      if (set_string_option(&config->send_directory, argv[++i], "--source-dir") != 0)
        return -1;
-      }
-      free(config->send_directory);
-      config->send_directory = dup;
    } else if (strcmp(argv[i], "--dest-dir") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --dest-dir\n");
+      if (set_string_option(&config->receive_root_directory, argv[++i], "--dest-dir") != 0)
        return -1;
-      }
-      free(config->receive_root_directory);
-      config->receive_root_directory = dup;
    } else if (strcmp(argv[i], "--save-to-disk") == 0) {
      config->save_to_disk = true;
    } else if (strcmp(argv[i], "-M") == 0 || strcmp(argv[i], "--preserve") == 0) {
@@ -162,18 +221,17 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
      config->use_chunk_serialization = true;
      log_message(LOG_LEVEL_INFO, "Enabled Chunk Serialization");
    } else if (strcmp(argv[i], "--server-host") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --server-host\n");
+      if (set_string_option(&config->server_host, argv[++i], "--server-host") != 0)
        return -1;
-      }
-      free(config->server_host);
-      config->server_host = dup;
    } else if (strcmp(argv[i], "--server-port") == 0 && i + 1 < argc) {
      if (!parse_positive_int(argv[++i], &config->server_port)) {
        fprintf(stderr, "Error: invalid --server-port value: %s\n", argv[i]);
        return -1;
      }
+      if (config->server_port > 65535) {
+        fprintf(stderr, "Error: server port must be 1-65535\n");
+        return -1;
+      }
    } else if (strcmp(argv[i], "--bwlimit") == 0 && i + 1 < argc) {
      char* end;
      errno = 0;
@@ -191,70 +249,47 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
    } else if (strcmp(argv[i], "--progress") == 0) {
      config->show_progress = true;
    } else if (strcmp(argv[i], "--chunk-size") == 0 && i + 1 < argc) {
-      unsigned long long val = strtoull(argv[++i], NULL, 10);
-      if (val > 0)
-        config->chunk_size = val;
+      char* end;
+      errno = 0;
+      unsigned long long val = strtoull(argv[++i], &end, 10);
+      if (errno != 0 || *end != '\0' || val == 0) {
+        fprintf(stderr, "Error: --chunk-size must be a positive integer\n");
+        return -1;
+      }
+      config->chunk_size = val;
    } else if (strcmp(argv[i], "--tls") == 0) {
      config->use_tls = true;
    } else if (strcmp(argv[i], "--cert") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --cert\n");
+      if (set_string_option(&config->tls_cert, argv[++i], "--cert") != 0)
        return -1;
-      }
-      free(config->tls_cert);
-      config->tls_cert = dup;
    } else if (strcmp(argv[i], "--key") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --key\n");
+      if (set_string_option(&config->tls_key, argv[++i], "--key") != 0)
        return -1;
-      }
-      free(config->tls_key);
-      config->tls_key = dup;
    } else if (strcmp(argv[i], "--ca") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --ca\n");
+      if (set_string_option(&config->tls_ca, argv[++i], "--ca") != 0)
        return -1;
-      }
-      free(config->tls_ca);
-      config->tls_ca = dup;
    } else if (strcmp(argv[i], "--timeout") == 0 && i + 1 < argc) {
-      int val;
-      if (!parse_positive_int(argv[++i], &val)) {
-        fprintf(stderr, "Error: --timeout must be a positive integer\n");
+      if (set_positive_int_option(&config->timeout, argv[++i], "--timeout") != 0)
        return -1;
-      }
-      config->timeout = val;
    } else if (strcmp(argv[i], "--contimeout") == 0 && i + 1 < argc) {
-      int val;
-      if (!parse_positive_int(argv[++i], &val)) {
-        fprintf(stderr, "Error: --contimeout must be a positive integer\n");
+      if (set_positive_int_option(&config->contimeout, argv[++i], "--contimeout") != 0)
        return -1;
-      }
-      config->contimeout = val;
-    } else if (strcmp(argv[i], "-q") == 0 || strcmp(argv[i], "--quiet") == 0 ||
-               strcmp(argv[i], "--silent") == 0) {
-      config->quiet = true;
    } else if (strcmp(argv[i], "--backup") == 0) {
      config->backup = true;
    } else if (strcmp(argv[i], "--backup-dir") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --backup-dir\n");
+      if (set_string_option(&config->backup_dir, argv[++i], "--backup-dir") != 0)
        return -1;
-      }
-      free(config->backup_dir);
-      config->backup_dir = dup;
    } else if (strcmp(argv[i], "--stats") == 0) {
      config->stats = true;
    } else if (strcmp(argv[i], "--max-depth") == 0 && i + 1 < argc) {
-      if (!parse_nonneg_int(argv[++i], &config->max_depth)) {
-        fprintf(stderr, "Error: --max-depth must be a non-negative integer\n");
+      if (set_nonneg_int_option(&config->max_depth, argv[++i], "--max-depth") != 0)
        return -1;
-      }
    } else if (strcmp(argv[i], "--log-file") == 0 && i + 1 < argc) {
+      if (config->log_file) {
+        fclose(config->log_file);
+        config->log_file = NULL;
+        log_set_file(NULL);
+      }
      FILE* lf = fopen(argv[++i], "a");
      if (!lf) {
        fprintf(stderr, "Error: could not open log file '%s': %s\n", argv[i], strerror(errno));
@@ -262,13 +297,6 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
      }
      config->log_file = lf;
      log_set_file(lf);
-    } else if (strcmp(argv[i], "--queue-size") == 0 && i + 1 < argc) {
-      int val;
-      if (!parse_positive_int(argv[++i], &val)) {
-        fprintf(stderr, "Error: --queue-size must be a positive integer\n");
-        return -1;
-      }
-      config->queue_size = val;
    } else if (strcmp(argv[i], "--exclude-from") == 0 && i + 1 < argc) {
      if (read_patterns_from_file(argv[++i], &config->exclude_patterns, &config->exclude_count) !=
          0)
@@ -280,13 +308,9 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
    } else if (strcmp(argv[i], "--partial") == 0) {
      config->partial = true;
    } else if (strcmp(argv[i], "--fastsync-server-path") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup) {
-        fprintf(stderr, "Error: memory allocation failed for --fastsync-server-path\n");
+      if (set_string_option(&config->fastsync_server_path, argv[++i], "--fastsync-server-path") !=
+          0)
        return -1;
-      }
-      free(config->fastsync_server_path);
-      config->fastsync_server_path = dup;
    } else if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
      set_log_level(LOG_LEVEL_DEBUG);
    } else if (strcmp(argv[i], "-l") == 0 || strcmp(argv[i], "--links") == 0) {
@@ -297,111 +321,26 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
      config->safe_links = true;
    } else if (strcmp(argv[i], "--copy-unsafe-links") == 0) {
      config->copy_unsafe_links = true;
-    } else if (strcmp(argv[i], "-H") == 0 || strcmp(argv[i], "--hard-links") == 0) {
-      config->preserve_hard_links = true;
-    } else if (strcmp(argv[i], "-A") == 0 || strcmp(argv[i], "--acls") == 0) {
-      config->preserve_acls = true;
-    } else if (strcmp(argv[i], "-X") == 0 || strcmp(argv[i], "--xattrs") == 0) {
-      config->preserve_xattrs = true;
-    } else if (strcmp(argv[i], "-D") == 0 || strcmp(argv[i], "--devices") == 0) {
-      config->preserve_devices = true;
    } else if (strcmp(argv[i], "-S") == 0 || strcmp(argv[i], "--sparse") == 0) {
      config->preserve_sparse = true;
-    } else if (strcmp(argv[i], "-i") == 0 || strcmp(argv[i], "--itemize-changes") == 0) {
-      config->itemize_changes = true;
-    } else if (strcmp(argv[i], "--out-format") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->out_format);
-      config->out_format = dup;
-    } else if (strcmp(argv[i], "--info") == 0 && i + 1 < argc) {
-      config->info_level = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "--debug") == 0 && i + 1 < argc) {
-      config->debug_level = atoi(argv[++i]);
-    } else if (strcmp(argv[i], "--list-only") == 0) {
-      config->list_only = true;
-    } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--human-readable") == 0) {
-      config->human_readable = true;
-    } else if (strcmp(argv[i], "-u") == 0 || strcmp(argv[i], "--update") == 0) {
-      config->update = true;
    } else if (strcmp(argv[i], "--inplace") == 0) {
      config->inplace = true;
-    } else if (strcmp(argv[i], "--append") == 0) {
-      config->append = true;
-    } else if (strcmp(argv[i], "--append-verify") == 0) {
-      config->append_verify = true;
-    } else if (strcmp(argv[i], "--delete-excluded") == 0) {
-      config->delete_excluded = true;
-    } else if (strcmp(argv[i], "--delete-after") == 0) {
-      config->delete_after = true;
-    } else if (strcmp(argv[i], "--max-delete") == 0 && i + 1 < argc) {
-      int val;
-      if (!parse_nonneg_int(argv[++i], &val)) {
-        fprintf(stderr, "Error: --max-delete must be a non-negative integer\n");
+    } else if (strcmp(argv[i], "--partial-dir") == 0 && i + 1 < argc) {
+      if (set_string_option(&config->partial_dir, argv[++i], "--partial-dir") != 0)
+        return -1;
+    } else if (strcmp(argv[i], "--suffix") == 0 && i + 1 < argc) {
+      if (set_string_option(&config->suffix, argv[++i], "--suffix") != 0)
+        return -1;
+    } else if (strcmp(argv[i], "-T") == 0 && i + 1 < argc) {
+      if (set_positive_int_option(&config->timeout, argv[++i], "-T") != 0)
+        return -1;
+    } else if (strcmp(argv[i], "--compress-level") == 0 && i + 1 < argc) {
+      if (set_positive_int_option(&config->compression_level, argv[++i], "--compress-level") != 0)
+        return -1;
+      if (config->compression_level < 1 || config->compression_level > 22) {
+        fprintf(stderr, "Error: --compress-level must be between 1 and 22\n");
        return -1;
      }
-      config->max_delete = val;
-    } else if (strcmp(argv[i], "--filter") == 0 && i + 1 < argc) {
-      if (!config->filters)
-        config->filters = array_list_create(free);
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      array_list_add(config->filters, dup);
-    } else if (strcmp(argv[i], "--files-from") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->files_from);
-      config->files_from = dup;
-    } else if (strcmp(argv[i], "--cvs-exclude") == 0) {
-      config->cvs_exclude = true;
-    } else if (strcmp(argv[i], "--prune-empty-dirs") == 0) {
-      config->prune_empty_dirs = true;
-    } else if (strcmp(argv[i], "-R") == 0 || strcmp(argv[i], "--relative") == 0) {
-      config->relative = true;
-    } else if (strcmp(argv[i], "-e") == 0 || strcmp(argv[i], "--rsh") == 0) {
-      if (i + 1 < argc) {
-        char* dup = str_dup(argv[++i]);
-        if (!dup)
-          return -1;
-        free(config->rsh_command);
-        config->rsh_command = dup;
-      } else {
-        fprintf(stderr, "Error: -e/--rsh requires a command argument\n");
-        return -1;
-      }
-    } else if (strcmp(argv[i], "--rsync-path") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->rsync_path);
-      config->rsync_path = dup;
-    } else if (strcmp(argv[i], "--temp-dir") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->temp_dir);
-      config->temp_dir = dup;
-    } else if (strcmp(argv[i], "--compare-dest") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->compare_dest);
-      config->compare_dest = dup;
-    } else if (strcmp(argv[i], "--copy-dest") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->copy_dest);
-      config->copy_dest = dup;
-    } else if (strcmp(argv[i], "--link-dest") == 0 && i + 1 < argc) {
-      char* dup = str_dup(argv[++i]);
-      if (!dup)
-        return -1;
-      free(config->link_dest);
-      config->link_dest = dup;
    } else if (argv[i][0] == '-') {
      fprintf(stderr, "Unknown option: %s\n", argv[i]);
      print_usage();
@@ -419,6 +358,7 @@ static int parse_args(Config* config, int argc, char* argv[], int* positional_ar
  return 0;
 }

+#ifndef FASTSYNC_TEST_BUILD
 /* Validate config after parsing. Returns true if valid. */
 static bool validate_config(const Config* config) {
  if (!config->send_directory || !config->receive_root_directory) {
@@ -459,101 +399,7 @@ static bool validate_config(const Config* config) {
  }
  return true;
 }
-
-static void print_usage(void) {
-  printf("Usage:\n");
-  printf("  fastsync [options] <source> <destination>\n");
-  printf("  fastsync [options] --source-dir <src> --dest-dir <dst>\n");
-  printf("\n");
-  printf("Destination formats:\n");
-  printf("  user@host:/path     SSH transport (rsync-style)\n");
-  printf("  host:/path          SSH transport (current user)\n");
-  printf("  /local/path         TCP transport (requires server on localhost:8080)\n");
-  printf("\n");
-  printf("Options:\n");
-  printf("  -c [level]          Enable compression (level 1-22, default 5)\n");
-  printf("  -z [level]          Alias for -c\n");
-  printf("  -a, --archive       Archive mode (-c -m -M)\n");
-  printf("  -n, --dry-run       Show what would be transferred\n");
-  printf("  -p <port>           SSH port (default: 22)\n");
-  printf("  --progress          Show transfer progress\n");
-  printf("  --delete            Delete files on receiver not in source\n");
-  printf("  --exclude <pattern> Exclude files matching pattern\n");
-  printf("  --include <pattern> Only include files matching pattern\n");
-  printf("  --exclude-from <file> Read exclude patterns from file\n");
-  printf("  --include-from <file> Read include patterns from file\n");
-  printf("  --max-size <n>      Skip files larger than n bytes\n");
-  printf("  --min-size <n>      Skip files smaller than n bytes\n");
-  printf("  --incremental       Skip files unchanged since last transfer\n");
-  printf("  --delta             Delta transfer for changed files (requires --incremental)\n");
-  printf("  --delta-block <n>   Delta block size in bytes (default: %d)\n",
-         DELTA_BLOCK_SIZE_DEFAULT);
-  printf("  --delta-max <n>     Max file size for delta transfer (default: %llu)\n",
-         DELTA_MAX_FILE_SIZE);
-  printf("  -m                  Enable multithreading\n");
-  printf("  -s                  Enable chunk serialization\n");
-  printf("  -f                  Enable sendfile (TCP only, not with -c or -s)\n");
-  printf("  -v, --verbose       Enable debug logging\n");
-  printf("  -M, --preserve      Preserve file metadata\n");
-  printf("  --chunk-size <n>    Chunk size in bytes (default: %d)\n", DEFAULT_CHUNK_SIZE);
-  printf("  --source-dir <path> Source directory\n");
-  printf("  --dest-dir <path>   Destination directory\n");
-  printf("  --save-to-disk      Write received files to disk\n");
-  printf("  --server-host <ip>  Server IP address (default: 127.0.0.1)\n");
-  printf("  --server-port <n>   Server port (default: 8080)\n");
-  printf("  --bwlimit <KB/s>    Bandwidth limit in kilobytes per second\n");
-  printf("  --tls               Enable TLS encryption\n");
-  printf("  --cert <path>       TLS certificate file (PEM)\n");
-  printf("  --key <path>        TLS private key file (PEM)\n");
-  printf("  --ca <path>         TLS CA certificate file (PEM)\n");
-  printf("  --timeout <sec>     I/O timeout in seconds (default: 30)\n");
-  printf("  --contimeout <sec>  Connection timeout in seconds (default: 10)\n");
-  printf("  -q, --quiet         Suppress non-error output\n");
-  printf("  --silent            Alias for --quiet\n");
-  printf("  --backup            Backup existing files before overwriting\n");
-  printf("  --backup-dir <dir>  Directory for backups (requires --backup)\n");
-  printf("  --stats             Print transfer statistics at end\n");
-  printf("  --max-depth <n>     Maximum directory depth (0=unlimited)\n");
-  printf("  --log-file <path>   Write log messages to file\n");
-  printf("  --queue-size <n>    Queue capacity for multithreaded mode (default: 100)\n");
-  printf("  --partial           Keep partial files on interrupted transfer\n");
-  printf("  --fastsync-server-path <path>\n");
-  printf("                      Path to fastsync-server on remote (default: fastsync-server)\n");
-  printf("  -l, --links         Copy symlinks as symlinks\n");
-  printf("  --copy-links        Transform symlinks into referent files\n");
-  printf("  --safe-links        Skip symlinks that point outside transfer tree\n");
-  printf("  --copy-unsafe-links  Only transform unsafe symlinks into referent files\n");
-  printf("  -H, --hard-links    Preserve hard links\n");
-  printf("  -A, --acls          Preserve ACLs\n");
-  printf("  -X, --xattrs        Preserve extended attributes\n");
-  printf("  -D, --devices       Preserve device files\n");
-  printf("  -S, --sparse        Handle sparse files efficiently\n");
-  printf("  -i, --itemize-changes  Show per-file change summary\n");
-  printf("  --out-format <fmt>  Custom output format string\n");
-  printf("  --info <flags>      Info verbosity level\n");
-  printf("  --debug <flags>     Debug verbosity level\n");
-  printf("  --list-only         List files without transferring\n");
-  printf("  -h, --human-readable  Human-readable numbers\n");
-  printf("  -u, --update        Skip files newer on destination\n");
-  printf("  --inplace           Update files in-place (no temp+rename)\n");
-  printf("  --append            Append data to shorter files\n");
-  printf("  --append-verify     Append with verify\n");
-  printf("  --delete-excluded   Also delete excluded files\n");
-  printf("  --delete-after      Delete after transfer, not before\n");
-  printf("  --max-delete <n>    Maximum number of files to delete\n");
-  printf("  --filter <rule>     Add file filtering rule\n");
-  printf("  --files-from <file> Read file list from file\n");
-  printf("  --cvs-exclude       Auto-ignore CVS files\n");
-  printf("  --prune-empty-dirs  Omit empty directories from transfer\n");
-  printf("  -R, --relative      Use relative paths\n");
-  printf("  -e, --rsh <cmd>     Specify remote shell\n");
-  printf("  --rsync-path <path> Path to remote binary\n");
-  printf("  --temp-dir <dir>    Temporary directory for files\n");
-  printf("  --compare-dest <dir>  Compare destination\n");
-  printf("  --copy-dest <dir>   Copy destination\n");
-  printf("  --link-dest <dir>   Link destination\n");
-  printf("  --help              Show this help\n");
-}
+#endif /* FASTSYNC_TEST_BUILD */

 static int read_patterns_from_file(const char* filepath, char*** patterns, int* count) {
  FILE* fp = fopen(filepath, "r");
@@ -561,8 +407,10 @@ static int read_patterns_from_file(const char* filepath, char*** patterns, int*
    fprintf(stderr, "Error: could not open pattern file '%s': %s\n", filepath, strerror(errno));
    return -1;
  }
-  char line[4096];
-  while (fgets(line, sizeof(line), fp)) {
+  char* line = NULL;
+  size_t line_size = 0;
+  ssize_t n;
+  while ((n = getline(&line, &line_size, fp)) != -1) {
    char* p = line;
    while (*p == ' ' || *p == '\t')
      p++;
@@ -576,6 +424,7 @@ static int read_patterns_from_file(const char* filepath, char*** patterns, int*
    char** tmp = realloc(*patterns, (*count + 1) * sizeof(char*));
    if (!tmp) {
      fprintf(stderr, "Error: memory allocation failed for pattern file\n");
+      free(line);
      fclose(fp);
      return -1;
    }
@@ -583,15 +432,18 @@ static int read_patterns_from_file(const char* filepath, char*** patterns, int*
    char* dup = str_dup(p);
    if (!dup) {
      fprintf(stderr, "Error: memory allocation failed for pattern file\n");
+      free(line);
      fclose(fp);
      return -1;
    }
    (*patterns)[(*count)++] = dup;
  }
+  free(line);
  fclose(fp);
  return 0;
 }

+#ifndef FASTSYNC_TEST_BUILD
 int main(int argc, char* argv[]) {
  const char* env_source = NULL;
  const char* env_dest = NULL;
@@ -697,3 +549,4 @@ cleanup:
  }
  return exit_code;
 }
+#endif /* FASTSYNC_TEST_BUILD */
@@ -25,6 +25,9 @@

 #define STREAM_THRESHOLD (64ULL * 1024 * 1024)

+/* Forward declaration for progress-reporting thread used in multithreaded send. */
+static int progress_thread_fn(void* arg);
+
 /* Print dry-run manifest showing files that would be transferred. Returns 0 on success. */
 static int send_dry_run_manifest(Config* config) {
  DirectoryScanner* scanner = directory_scanner_create(
@@ -271,6 +274,9 @@ static int send_chunks_multithreaded(void* pipeline_context) {
  if (context->config->transport == TRANSPORT_SSH) {
    if (context->config->use_sendfile) {
      fprintf(stderr, "Error: -f/--sendfile is not supported with SSH transport\n");
+      mtx_lock(&context->mutex_progress);
+      context->sender_done = true;
+      mtx_unlock(&context->mutex_progress);
      return 1;
    }
    client = client_connect_ssh(context->config->ssh_destination, context->config->ssh_port,
@@ -283,6 +289,9 @@ static int send_chunks_multithreaded(void* pipeline_context) {
      if (client)
        client_delete(client);
      fprintf(stderr, "Error: could not connect to server via TLS\n");
+      mtx_lock(&context->mutex_progress);
+      context->sender_done = true;
+      mtx_unlock(&context->mutex_progress);
      return thrd_error;
    }
  } else {
@@ -292,12 +301,18 @@ static int send_chunks_multithreaded(void* pipeline_context) {
      if (client)
        client_delete(client);
      fprintf(stderr, "Error: could not connect to server\n");
+      mtx_lock(&context->mutex_progress);
+      context->sender_done = true;
+      mtx_unlock(&context->mutex_progress);
      return thrd_error;
    }
  }
  if (!config_send(client->file_descriptor, context->config)) {
    client_disconnect(client);
    client_delete(client);
+    mtx_lock(&context->mutex_progress);
+    context->sender_done = true;
+    mtx_unlock(&context->mutex_progress);
    return thrd_error;
  }

@@ -316,19 +331,39 @@ static int send_chunks_multithreaded(void* pipeline_context) {
      int ok = receive_status(client->file_descriptor, &s) && s == STATUS_OK;
      client_disconnect(client);
      client_delete(client);
+      mtx_lock(&context->mutex_progress);
+      context->sender_done = true;
+      mtx_unlock(&context->mutex_progress);
      return ok ? thrd_success : thrd_error;

    send_fail:
      client_disconnect(client);
      client_delete(client);
+      mtx_lock(&context->mutex_progress);
+      context->sender_done = true;
+      mtx_unlock(&context->mutex_progress);
      return thrd_error;
    }
    if (send_chunk(client, current_chunk, context->config) != 0) {
      fprintf(stderr, "Error: unexpected error while sending chunk\n");
+      chunk_destroy(current_chunk);
      client_disconnect(client);
      client_delete(client);
+      mtx_lock(&context->mutex_progress);
+      context->sender_done = true;
+      mtx_unlock(&context->mutex_progress);
      return thrd_error;
    }
+    if (context->config->show_progress) {
+      unsigned long long chunk_bytes = 0;
+      for (int i = 0; i < current_chunk->element_count; i++) {
+        if (current_chunk->items[i] && current_chunk->items[i]->data)
+          chunk_bytes += current_chunk->items[i]->data->size;
+      }
+      mtx_lock(&context->mutex_progress);
+      context->progress_bytes += chunk_bytes;
+      mtx_unlock(&context->mutex_progress);
+    }
    chunk_destroy(current_chunk);
  }
 }
@@ -350,13 +385,31 @@ static int scan_directory_multithreaded(void* pipeline_context) {
        const char* p = current_chunk->items[i]->path;
        if (*p == '/')
          p++;
-        array_list_add(context->manifest, str_dup(p));
+        char* manifest_entry = str_dup(p);
+        if (!manifest_entry) {
+          log_message(LOG_LEVEL_ERROR, "Failed to allocate manifest entry");
+          mtx_unlock(&context->mutex_scanner);
+          context->cancelled = true;
+          cnd_broadcast(&context->condition_not_full_scanner);
+          cnd_broadcast(&context->condition_not_empty_scanner);
+          parallel_scanner_destroy(scanner);
+          return thrd_error;
+        }
+        array_list_add(context->manifest, manifest_entry);
      }
      mtx_unlock(&context->mutex_scanner);
    }
-    queue_enqueue_multithreaded(context->queue_scanner, current_chunk, &context->mutex_scanner,
-                                &context->condition_not_empty_scanner,
-                                &context->condition_not_full_scanner);
+    if (!queue_enqueue_multithreaded_cancel(
+            context->queue_scanner, current_chunk, &context->mutex_scanner,
+            &context->condition_not_empty_scanner, &context->condition_not_full_scanner,
+            &context->cancelled)) {
+      chunk_destroy(current_chunk);
+      context->cancelled = true;
+      cnd_broadcast(&context->condition_not_full_scanner);
+      cnd_broadcast(&context->condition_not_empty_scanner);
+      parallel_scanner_destroy(scanner);
+      return thrd_error;
+    }
  }
  mtx_lock(&context->mutex_scanner);
  context->scanner_done = true;
@@ -392,12 +445,55 @@ static int load_files_multithreaded(void* pipeline_context) {
        }
      }
    }
-    queue_enqueue_multithreaded(context->queue_loader, chunk, &context->mutex_loader,
-                                &context->condition_not_empty_loader,
-                                &context->condition_not_full_loader);
+    if (!queue_enqueue_multithreaded_cancel(context->queue_loader, chunk, &context->mutex_loader,
+                                            &context->condition_not_empty_loader,
+                                            &context->condition_not_full_loader,
+                                            &context->cancelled)) {
+      chunk_destroy(chunk);
+      context->cancelled = true;
+      cnd_broadcast(&context->condition_not_full_loader);
+      cnd_broadcast(&context->condition_not_empty_loader);
+      return thrd_error;
+    }
  }
 }

+/* Progress-reporting thread for multithreaded send. Runs in parallel with
+   the scanner/loader/sender threads and prints periodic progress to stderr. */
+static int progress_thread_fn(void* arg) {
+  PipelineContextSender* context = (PipelineContextSender*)arg;
+  time_t last_progress = 0;
+  time_t start = time(NULL);
+
+  while (true) {
+    mtx_lock(&context->mutex_progress);
+    bool done = context->sender_done;
+    unsigned long long total = context->progress_bytes;
+    mtx_unlock(&context->mutex_progress);
+
+    if (done) {
+      time_t now = time(NULL);
+      double elapsed = difftime(now, start);
+      double rate = elapsed > 0.0 ? total / (1048576.0 * elapsed) : 0.0;
+      fprintf(stderr, "\rSent %.1f MB  (%.1f MB/s)  Done.\n", total / 1048576.0, rate);
+      break;
+    }
+
+    time_t now = time(NULL);
+    if (now - last_progress >= 1) {
+      last_progress = now;
+      double elapsed = difftime(now, start);
+      double rate = elapsed > 0.0 ? total / (1048576.0 * elapsed) : 0.0;
+      fprintf(stderr, "\rSent %.1f MB  (%.1f MB/s)  ", total / 1048576.0, rate);
+      fflush(stderr);
+    }
+
+    struct timespec ts = {0, 100 * 1000000L}; /* 100 ms */
+    thrd_sleep(&ts, NULL);
+  }
+  return thrd_success;
+}
+
 int send_files(Config* config) {
  if (config->dry_run)
    return send_dry_run_manifest(config);
@@ -416,16 +512,20 @@ int send_files(Config* config) {
    client = client_create();
    if (!client || !client_connect_tls(client, config->server_host, config->server_port,
                                       config->tls_cert, config->tls_key, config->tls_ca)) {
-      if (client)
+      if (client) {
+        client_disconnect(client);
        client_delete(client);
+      }
      fprintf(stderr, "Error: could not connect to server via TLS\n");
      return 1;
    }
  } else {
    client = client_create();
    if (!client || !client_connect(client, config->server_host, config->server_port)) {
-      if (client)
+      if (client) {
+        client_disconnect(client);
        client_delete(client);
+      }
      fprintf(stderr, "Error: could not connect to server\n");
      return 1;
    }
@@ -442,6 +542,7 @@ int send_files(Config* config) {
      config->safe_links, config->copy_unsafe_links);
  Chunk* current_chunk;
  unsigned long long total_bytes = 0;
+  int total_files = 0;
  time_t last_progress = 0;
  time_t start = time(NULL);
  ArrayList* manifest = config->use_delete ? array_list_create(free) : NULL;
@@ -449,11 +550,22 @@ int send_files(Config* config) {
    unsigned long long chunk_bytes = 0;
    for (int i = 0; i < current_chunk->element_count; i++) {
      chunk_bytes += current_chunk->items[i]->data->size;
+      total_files++;
      if (manifest) {
        const char* p = current_chunk->items[i]->path;
        if (*p == '/')
          p++;
-        array_list_add(manifest, str_dup(p));
+        char* manifest_entry = str_dup(p);
+        if (!manifest_entry) {
+          log_message(LOG_LEVEL_ERROR, "Failed to allocate manifest entry");
+          chunk_destroy(current_chunk);
+          array_list_delete(manifest);
+          directory_scanner_destroy(scanner);
+          client_disconnect(client);
+          client_delete(client);
+          return 1;
+        }
+        array_list_add(manifest, manifest_entry);
      }
    }
    if (!config->use_sendfile) {
@@ -496,11 +608,16 @@ int send_files(Config* config) {
    goto send_fail;
  Status s;
  int ok = receive_status(client->file_descriptor, &s) && s == STATUS_OK;
+  double elapsed_total = difftime(time(NULL), start);
  if (config->show_progress) {
-    double elapsed = difftime(time(NULL), start);
-    double rate = elapsed > 0 ? total_bytes / (1048576.0 * elapsed) : 0;
+    double rate = elapsed_total > 0 ? total_bytes / (1048576.0 * elapsed_total) : 0;
    fprintf(stderr, "\rSent %.1f MB  (%.1f MB/s)  Done.\n", total_bytes / 1048576.0, rate);
  }
+  if (config->stats) {
+    double rate = elapsed_total > 0 ? total_bytes / (1048576.0 * elapsed_total) : 0;
+    fprintf(stderr, "Stats: %d files, %.1f MB, %.1f MB/s\n", total_files, total_bytes / 1048576.0,
+            rate);
+  }
  directory_scanner_destroy(scanner);
  client_disconnect(client);
  client_delete(client);
@@ -548,19 +665,59 @@ int send_files_multithreaded(Config* config) {
    context->manifest = array_list_create(free);

  thrd_t scanner, loader, sender;
-  if (thrd_create(&scanner, scan_directory_multithreaded, context) != thrd_success ||
-      thrd_create(&loader, load_files_multithreaded, context) != thrd_success ||
-      thrd_create(&sender, send_chunks_multithreaded, context) != thrd_success) {
+  bool scanner_created = false;
+  bool loader_created = false;
+  bool sender_created = false;
+
+  scanner_created = (thrd_create(&scanner, scan_directory_multithreaded, context) == thrd_success);
+  if (scanner_created)
+    loader_created = (thrd_create(&loader, load_files_multithreaded, context) == thrd_success);
+  if (scanner_created && loader_created)
+    sender_created = (thrd_create(&sender, send_chunks_multithreaded, context) == thrd_success);
+
+  if (!scanner_created || !loader_created || !sender_created) {
    perror("Error creating threads.\n");
+    context->cancelled = true;
+    context->scanner_done = true;
+    context->loader_done = true;
+    context->sender_done = true;
+    cnd_broadcast(&context->condition_not_full_scanner);
+    cnd_broadcast(&context->condition_not_empty_scanner);
+    cnd_broadcast(&context->condition_not_full_loader);
+    cnd_broadcast(&context->condition_not_empty_loader);
+    if (sender_created)
+      thrd_join(sender, NULL);
+    if (loader_created)
+      thrd_join(loader, NULL);
+    if (scanner_created)
+      thrd_join(scanner, NULL);
    pipeline_context_sender_destroy(context);
    return 1;
  }

+  thrd_t progress;
+  bool progress_created = false;
+  if (config->show_progress) {
+    progress_created = (thrd_create(&progress, progress_thread_fn, context) == thrd_success);
+    if (!progress_created) {
+      perror("Error creating progress thread.\n");
+      /* Non-fatal; continue without progress reporting */
+    }
+  }
+
  int sender_result;
  thrd_join(scanner, NULL);
  thrd_join(loader, NULL);
  thrd_join(sender, &sender_result);

+  if (progress_created) {
+    /* Signal progress thread to exit if it hasn't already */
+    mtx_lock(&context->mutex_progress);
+    context->sender_done = true;
+    mtx_unlock(&context->mutex_progress);
+    thrd_join(progress, NULL);
+  }
+
  pipeline_context_sender_destroy(context);
  return sender_result == thrd_success ? 0 : 1;
 }
@@ -27,10 +27,14 @@ static void dir_entry_destroy(void* item) {

 static DirEntry* dir_entry_create(const char* path, int depth) {
  DirEntry* de = malloc(sizeof(DirEntry));
-  if (de) {
-    de->path = str_dup(path);
-    de->depth = depth;
+  if (!de)
+    return NULL;
+  de->path = str_dup(path);
+  if (!de->path) {
+    free(de);
+    return NULL;
  }
+  de->depth = depth;
  return de;
 }

@@ -61,7 +65,18 @@ DirectoryScanner* directory_scanner_create(const char* root_directory, bool use_
  scanner->copy_links = copy_links;
  scanner->safe_links = safe_links;
  scanner->copy_unsafe_links = copy_unsafe_links;
-  queue_enqueue(scanner->directories, dir_entry_create(root_directory, 0));
+  DirEntry* root = dir_entry_create(root_directory, 0);
+  if (!root) {
+    queue_destroy(scanner->directories);
+    free(scanner);
+    return NULL;
+  }
+  if (!queue_enqueue(scanner->directories, root)) {
+    dir_entry_destroy(root);
+    queue_destroy(scanner->directories);
+    free(scanner);
+    return NULL;
+  }
  return scanner;
 }

@@ -321,9 +336,28 @@ ParallelScanner* parallel_scanner_create(char* root_directory, bool use_metadata
    free(ps);
    return NULL;
  }
-  if (mtx_init(&ps->result_mutex, mtx_plain) != thrd_success ||
-      cnd_init(&ps->result_not_empty) != thrd_success ||
-      cnd_init(&ps->result_not_full) != thrd_success) {
+  int init = 0;
+  bool ok = true;
+  if (mtx_init(&ps->result_mutex, mtx_plain) != thrd_success)
+    ok = false;
+  if (ok) {
+    init++;
+    if (cnd_init(&ps->result_not_empty) != thrd_success)
+      ok = false;
+  }
+  if (ok) {
+    // cppcheck-suppress unreadVariable
+    init++;
+    if (cnd_init(&ps->result_not_full) != thrd_success)
+      ok = false;
+  }
+  if (!ok) {
+    if (init >= 3)
+      cnd_destroy(&ps->result_not_full);
+    if (init >= 2)
+      cnd_destroy(&ps->result_not_empty);
+    if (init >= 1)
+      mtx_destroy(&ps->result_mutex);
    queue_destroy(ps->result_queue);
    free(ps);
    return NULL;
@@ -345,11 +379,62 @@ ParallelScanner* parallel_scanner_create(char* root_directory, bool use_metadata
    char* cur_path = path_cat(root_directory, entry->d_name);
    if (!cur_path)
      continue;
-    struct stat st;
-    if (stat(cur_path, &st) != 0) {
+    struct stat lstats;
+    if (lstat(cur_path, &lstats) != 0) {
      free(cur_path);
      continue;
    }
+    bool is_symlink = S_ISLNK(lstats.st_mode);
+
+    // Skip symlinks unless the user explicitly enabled following/copying them.
+    if (is_symlink && !follow_symlinks && !copy_links && !safe_links && !copy_unsafe_links) {
+      free(cur_path);
+      continue;
+    }
+
+    // --safe-links: reject symlinks pointing outside the source tree.
+    if (is_symlink && safe_links) {
+      char link_target[4096];
+      ssize_t len = readlink(cur_path, link_target, sizeof(link_target) - 1);
+      if (len < 0) {
+        free(cur_path);
+        continue;
+      }
+      link_target[len] = 0;
+      if (link_target[0] == '/') {
+        free(cur_path);
+        continue;
+      }
+    }
+
+    // --copy-unsafe-links (without --copy-links): only copy absolute symlinks.
+    if (is_symlink && copy_unsafe_links && !copy_links) {
+      char link_target[4096];
+      ssize_t len = readlink(cur_path, link_target, sizeof(link_target) - 1);
+      if (len < 0) {
+        free(cur_path);
+        continue;
+      }
+      link_target[len] = 0;
+      bool unsafe = (link_target[0] == '/');
+      if (!unsafe) {
+        free(cur_path);
+        continue;
+      }
+    }
+
+    // Determine whether to use lstat or stat results for the entry.
+    struct stat st;
+    bool use_lstat_res = is_symlink && follow_symlinks && !copy_links;
+    if (use_lstat_res) {
+      st = lstats;
+    } else {
+      if (stat(cur_path, &st) != 0) {
+        free(cur_path);
+        continue;
+      }
+    }
+
    if (S_ISDIR(st.st_mode)) {
      array_list_add(subdirs, cur_path);
    } else {
@@ -510,6 +595,7 @@ void parallel_scanner_destroy(ParallelScanner* ps) {
    return;
  ps->done = true;
  cnd_signal(&ps->result_not_empty);
+  cnd_broadcast(&ps->result_not_full);
  for (int i = 0; i < ps->num_threads; i++)
    thrd_join(ps->threads[i], NULL);
  free(ps->threads);
@@ -0,0 +1,73 @@
+#include "stdio.h"
+#include <delta.h>
+#include <chunk.h>
+
+static __attribute__((unused)) void print_usage() {
+  printf("Usage:\n");
+  printf("  fastsync [options] <source> <destination>\n");
+  printf("  fastsync [options] --source-dir <src> --dest-dir <dst>\n");
+  printf("\n");
+  printf("Destination formats:\n");
+  printf("  user@host:/path     SSH transport (rsync-style)\n");
+  printf("  host:/path          SSH transport (current user)\n");
+  printf("  /local/path         TCP transport (requires server on localhost:8080)\n");
+  printf("\n");
+  printf("Options:\n");
+  printf("  -c [level]          Enable compression (level 1-22, default 5)\n");
+  printf("  -z [level]          Alias for -c\n");
+  printf("  -a, --archive       Archive mode (-c -m -M)\n");
+  printf("  -n, --dry-run       Show what would be transferred\n");
+  printf("  -p <port>           SSH port (default: 22)\n");
+  printf("  --progress          Show transfer progress\n");
+  printf("  --delete            Delete files on receiver not in source\n");
+  printf("  --exclude <pattern> Exclude files matching pattern\n");
+  printf("  --include <pattern> Only include files matching pattern\n");
+  printf("  --exclude-from <file> Read exclude patterns from file\n");
+  printf("  --include-from <file> Read include patterns from file\n");
+  printf("  --max-size <n>      Skip files larger than n bytes\n");
+  printf("  --min-size <n>      Skip files smaller than n bytes\n");
+  printf("  --incremental       Skip files unchanged since last transfer\n");
+  printf("  --delta             Delta transfer for changed files (requires --incremental)\n");
+  printf("  --delta-block <n>   Delta block size in bytes (default: %d)\n",
+         DELTA_BLOCK_SIZE_DEFAULT);
+  printf("  --delta-max <n>     Max file size for delta transfer (default: %llu)\n",
+         DELTA_MAX_FILE_SIZE);
+  printf("  -m                  Enable multithreading\n");
+  printf("  -s                  Enable chunk serialization\n");
+  printf("  -f                  Enable sendfile (TCP only, not with -c or -s)\n");
+  printf("  -v, --verbose       Enable debug logging\n");
+  printf("  -M, --preserve      Preserve file metadata\n");
+  printf("  --chunk-size <n>    Chunk size in bytes (default: %d)\n", DEFAULT_CHUNK_SIZE);
+  printf("  --source-dir <path> Source directory\n");
+  printf("  --dest-dir <path>   Destination directory\n");
+  printf("  --save-to-disk      Write received files to disk\n");
+  printf("  --server-host <ip>  Server IP address (default: 127.0.0.1)\n");
+  printf("  --server-port <n>   Server port (default: 8080)\n");
+  printf("  --bwlimit <KB/s>    Bandwidth limit in kilobytes per second\n");
+  printf("  --tls               Enable TLS encryption\n");
+  printf("  --cert <path>       TLS certificate file (PEM)\n");
+  printf("  --key <path>        TLS private key file (PEM)\n");
+  printf("  --ca <path>         TLS CA certificate file (PEM)\n");
+  printf("  --timeout <sec>     I/O timeout in seconds (default: 30)\n");
+  printf("  -T <sec>            Alias for --timeout\n");
+  printf("  --contimeout <sec>  Connection timeout in seconds (default: 10)\n");
+  printf("  --backup            Backup existing files before overwriting\n");
+  printf("  --backup-dir <dir>  Directory for backups (requires --backup)\n");
+  printf("  --suffix <str>      Backup suffix (default: ~)\n");
+  printf("  --stats             Print transfer statistics at end\n");
+  printf("  --max-depth <n>     Maximum directory depth (0=unlimited)\n");
+  printf("  --log-file <path>   Write log messages to file\n");
+  printf("  --partial           Keep partial files on interrupted transfer\n");
+  printf("  --partial-dir <dir> Directory for partial files\n");
+  printf("  --fastsync-server-path <path>\n");
+  printf("                      Path to fastsync-server on remote (default: fastsync-server)\n");
+  printf("  -l, --links         Copy symlinks as symlinks\n");
+  printf("  --copy-links        Transform symlinks into referent files\n");
+  printf("  --safe-links        Skip symlinks that point outside transfer tree\n");
+  printf("  --copy-unsafe-links  Only transform unsafe symlinks into referent files\n");
+  printf("  -S, --sparse        Handle sparse files efficiently\n");
+  printf("  --inplace           Update files in-place (no temp+rename)\n");
+  printf("  --compress-level <n>    Compression level (default: 5)\n");
+  printf("  --help              Show this help\n");
+  printf("  -V, --version       Show version\n");
+}
@@ -135,11 +135,27 @@ void handler(int file_descriptor) {
      return;
    }
    thrd_t receiver, writer;
-    if (thrd_create(&receiver, receive_thread, context) != thrd_success ||
-        thrd_create(&writer, write_thread, context) != thrd_success) {
+    bool receiver_created = false;
+    bool writer_created = false;
+    receiver_created = (thrd_create(&receiver, receive_thread, context) == thrd_success);
+    if (receiver_created)
+      writer_created = (thrd_create(&writer, write_thread, context) == thrd_success);
+    if (!receiver_created || !writer_created) {
      perror("Error creating Threads");
+      if (receiver_created) {
+        mtx_lock(&context->mutex);
+        context->cancelled = true;
+        cnd_broadcast(&context->condition_not_full);
+        cnd_broadcast(&context->condition_not_empty);
+        mtx_unlock(&context->mutex);
+        close(file_descriptor);
+        thrd_join(receiver, NULL);
+      } else {
+        close(file_descriptor);
+      }
+      if (writer_created)
+        thrd_join(writer, NULL);
      pipeline_context_receiver_destroy(context);
-      close(file_descriptor);
      return;
    }
    thrd_join(receiver, NULL);
@@ -12,6 +12,9 @@
 #include "metadata.h"
 #include "protocol.h"

+/* Maximum individual file data size within a chunk (64 MB) */
+#define MAX_FILE_DATA_SIZE (64ULL * 1024 * 1024)
+
 Chunk* chunk_create(File** items, int element_count) {
  Chunk* chunk = (Chunk*)malloc(sizeof(Chunk));
  if (chunk == NULL) {
@@ -157,6 +160,14 @@ Chunk* chunk_deserialize(Data* data, bool use_metadata) {
      return NULL;
    }

+    // Reject individual file data larger than the maximum allowed size.
+    if (file_data_size > MAX_FILE_DATA_SIZE) {
+      log_message(LOG_LEVEL_ERROR, "File data size %zu exceeds maximum %llu", file_data_size,
+                  (unsigned long long)MAX_FILE_DATA_SIZE);
+      array_list_delete(files);
+      return NULL;
+    }
+
    void* file_data = malloc(file_data_size);
    if (file_data == NULL) {
      perror("Could not allocate memory for file data");
@@ -210,6 +221,15 @@ Chunk* receive_chunk_data(int fd, const Config* config) {
      return NULL;
    }
  }
+
+  // Reject chunks larger than the maximum allowed size to prevent OOM.
+  if (data_to_process->size > MAX_CHUNK_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "Chunk size %zu exceeds maximum %llu", data_to_process->size,
+                (unsigned long long)MAX_CHUNK_SIZE);
+    data_destroy(data_to_process);
+    return NULL;
+  }
+
  Chunk* chunk = chunk_deserialize(data_to_process, config->use_metadata);
  data_destroy(data_to_process);
  if (chunk == NULL)
@@ -1,12 +1,13 @@
 #include "compression.h"
 #include "data.h"
 #include "log.h"
-#include "stdlib.h"
-#include "string.h"
+#include <stdlib.h>
+#include <string.h>
 #include <strings.h>
-#include "zstd.h"
+#include <zstd.h>

 #define INITIAL_DECOMPRESS_BUF_SIZE (1024 * 1024)
+#define MAX_DECOMPRESSED_SIZE (100ULL * 1024 * 1024) /* 100 MB hard ceiling */

 static const char* SKIP_COMPRESSION_EXTENSIONS[] = {".jpg", ".jpeg", ".png", ".gif", ".mp4", ".mkv",
                                                    ".zip", ".gz",   ".xz",  ".zst", NULL};
@@ -84,6 +85,13 @@ Data* data_decompress(Data* compressed_data) {
    dst_size = compressed_data->size * 3;
    if (dst_size < INITIAL_DECOMPRESS_BUF_SIZE)
      dst_size = INITIAL_DECOMPRESS_BUF_SIZE;
+    if (dst_size > MAX_DECOMPRESSED_SIZE)
+      dst_size = MAX_DECOMPRESSED_SIZE;
+  }
+  if (dst_size > MAX_DECOMPRESSED_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "Declared decompressed size exceeds %llu bytes",
+                (unsigned long long)MAX_DECOMPRESSED_SIZE);
+    return NULL;
  }

  ZSTD_DCtx* dctx = ZSTD_createDCtx();
@@ -113,7 +121,16 @@ Data* data_decompress(Data* compressed_data) {
      return NULL;
    }
    if (ret > 0 && output.pos == output.size) {
+      if (buf_size >= MAX_DECOMPRESSED_SIZE) {
+        log_message(LOG_LEVEL_ERROR, "Decompressed data exceeds %llu bytes",
+                    (unsigned long long)MAX_DECOMPRESSED_SIZE);
+        ZSTD_freeDCtx(dctx);
+        data_destroy(uncompressed_data);
+        return NULL;
+      }
      buf_size *= 2;
+      if (buf_size > MAX_DECOMPRESSED_SIZE)
+        buf_size = MAX_DECOMPRESSED_SIZE;
      void* new_data = realloc(uncompressed_data->data, buf_size);
      if (!new_data) {
        log_message(LOG_LEVEL_ERROR, "Failed to grow decompression buffer");
@@ -8,10 +8,7 @@
 #include <stdlib.h>
 #include <string.h>

-Config* config_create(void) {
-  Config* config = malloc(sizeof(Config));
-  if (!config)
-    return NULL;
+static void config_set_defaults(Config* config) {
  config->version = str_dup(PROTOCOL_VERSION);
  config->send_directory = NULL;
  config->receive_root_directory = NULL;
@@ -48,47 +45,27 @@ Config* config_create(void) {
  config->server_port = 8080;
  config->timeout = 30;
  config->contimeout = 10;
-  config->quiet = false;
  config->backup = false;
  config->backup_dir = NULL;
  config->stats = false;
  config->max_depth = 0;
  config->log_file = NULL;
-  config->queue_size = 100;
  config->follow_symlinks = false;
  config->partial = false;
  config->copy_links = false;
  config->safe_links = false;
  config->copy_unsafe_links = false;
-  config->preserve_hard_links = false;
-  config->preserve_acls = false;
-  config->preserve_xattrs = false;
-  config->preserve_devices = false;
  config->preserve_sparse = false;
-  config->itemize_changes = false;
-  config->out_format = NULL;
-  config->info_level = 0;
-  config->debug_level = 0;
-  config->list_only = false;
-  config->human_readable = false;
-  config->update = false;
  config->inplace = false;
-  config->append = false;
-  config->append_verify = false;
-  config->delete_excluded = false;
-  config->delete_after = false;
-  config->max_delete = 0;
-  config->filters = NULL;
-  config->files_from = NULL;
-  config->cvs_exclude = false;
-  config->prune_empty_dirs = false;
-  config->relative = false;
-  config->rsh_command = NULL;
-  config->rsync_path = NULL;
-  config->temp_dir = NULL;
-  config->compare_dest = NULL;
-  config->copy_dest = NULL;
-  config->link_dest = NULL;
+  config->partial_dir = NULL;
+  config->suffix = NULL;
+}
+
+Config* config_create(void) {
+  Config* config = malloc(sizeof(Config));
+  if (!config)
+    return NULL;
+  config_set_defaults(config);
  return config;
 }

@@ -119,6 +96,8 @@ void config_parse_ssh_dest(Config* config) {
 }

 void config_delete(Config* config) {
+  if (config == NULL)
+    return;
  free(config->version);
  free(config->send_directory);
  free(config->receive_root_directory);
@@ -135,20 +114,22 @@ void config_delete(Config* config) {
  free(config->tls_ca);
  free(config->backup_dir);
  free(config->server_host);
-  free(config->out_format);
-  free(config->files_from);
-  free(config->rsh_command);
-  free(config->rsync_path);
-  free(config->temp_dir);
-  free(config->compare_dest);
-  free(config->copy_dest);
-  free(config->link_dest);
-  if (config->filters) {
-    array_list_delete(config->filters);
-  }
+  free(config->partial_dir);
+  free(config->suffix);
  free(config);
 }

+/* Wire format order (must match config_receive and be updated when PROTOCOL_VERSION bumps):
+ * version, send_directory, receive_root_directory, save_to_disk, use_multithreading,
+ * use_chunk_serialization, use_compression, use_metadata, compression_level, chunk_size,
+ * use_sendfile, use_delete, use_incremental, use_delta, delta_block_size, delta_max_file_size,
+ * backup, backup_dir, follow_symlinks, copy_links, safe_links, copy_unsafe_links,
+ * obsolete metadata flags, preserve_sparse, obsolete transfer flags, inplace, obsolete delete
+ * flags, obsolete path options, partial, partial_dir, suffix, obsolete checksum options, status
+ *
+ * Obsolete fields remain as zero/empty compatibility slots. They must be consumed in this order
+ * until the protocol version is intentionally changed.
+ */
 bool config_send(int file_descriptor, const Config* config) {
  if (!send_str(file_descriptor, config->version))
    return false;
@@ -178,7 +159,7 @@ bool config_send(int file_descriptor, const Config* config) {
    return false;
  if (!send_int(file_descriptor, config->use_delta))
    return false;
-  if (!send_int(file_descriptor, (int)config->delta_block_size))
+  if (!send_n_data(file_descriptor, &config->delta_block_size, sizeof(config->delta_block_size)))
    return false;
  if (!send_n_data(file_descriptor, &config->delta_max_file_size, sizeof(unsigned long long)))
    return false;
@@ -194,35 +175,48 @@ bool config_send(int file_descriptor, const Config* config) {
    return false;
  if (!send_int(file_descriptor, config->copy_unsafe_links))
    return false;
-  if (!send_int(file_descriptor, config->preserve_hard_links))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->preserve_acls))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->preserve_xattrs))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->preserve_devices))
+  if (!send_int(file_descriptor, 0))
    return false;
  if (!send_int(file_descriptor, config->preserve_sparse))
    return false;
-  if (!send_int(file_descriptor, config->update))
+  if (!send_int(file_descriptor, 0))
    return false;
  if (!send_int(file_descriptor, config->inplace))
    return false;
-  if (!send_int(file_descriptor, config->append))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->append_verify))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->delete_excluded))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->delete_after))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_n_data(file_descriptor, &config->max_delete, sizeof(config->max_delete)))
+  int obsolete_int = 0;
+  if (!send_n_data(file_descriptor, &obsolete_int, sizeof(obsolete_int)))
    return false;
-  if (!send_int(file_descriptor, config->relative))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_int(file_descriptor, config->prune_empty_dirs))
+  if (!send_int(file_descriptor, 0))
    return false;
-  if (!send_str(file_descriptor, config->temp_dir ? config->temp_dir : ""))
+  if (!send_str(file_descriptor, ""))
+    return false;
+  if (!send_int(file_descriptor, config->partial))
+    return false;
+  if (!send_str(file_descriptor, config->partial_dir ? config->partial_dir : ""))
+    return false;
+  if (!send_str(file_descriptor, config->suffix ? config->suffix : ""))
+    return false;
+  if (!send_int(file_descriptor, 0))
+    return false;
+  if (!send_int(file_descriptor, 0))
+    return false;
+  if (!send_str(file_descriptor, ""))
    return false;
  Status status;
  if (!receive_status(file_descriptor, &status))
@@ -234,13 +228,16 @@ bool config_send(int file_descriptor, const Config* config) {
  return true;
 }

+/* Wire format order: see the comment above config_send. */
 Config* config_receive(int file_descriptor) {
  Config* config = (Config*)malloc(sizeof(Config));
  if (config == NULL)
    return NULL;
-  memset(config, 0, sizeof(*config));
+  config_set_defaults(config);
+  free(config->version);
  config->version = receive_str(file_descriptor);
  if (!config->version) {
+    free(config->server_host);
    free(config);
    return NULL;
  }
@@ -248,6 +245,7 @@ Config* config_receive(int file_descriptor) {
    fprintf(stderr, "Protocol version mismatch: client=%s, server=%s\n", config->version,
            PROTOCOL_VERSION);
    free(config->version);
+    free(config->server_host);
    free(config);
    send_status(file_descriptor, STATUS_ERROR);
    return NULL;
@@ -255,6 +253,7 @@ Config* config_receive(int file_descriptor) {
  config->send_directory = receive_str(file_descriptor);
  if (!config->send_directory) {
    free(config->version);
+    free(config->server_host);
    free(config);
    return NULL;
  }
@@ -262,6 +261,7 @@ Config* config_receive(int file_descriptor) {
  if (!config->receive_root_directory) {
    free(config->version);
    free(config->send_directory);
+    free(config->server_host);
    free(config);
    return NULL;
  }
@@ -298,67 +298,10 @@ Config* config_receive(int file_descriptor) {
  if (!receive_int(file_descriptor, &tmp))
    goto error;
  config->use_delta = tmp;
-  if (!receive_int(file_descriptor, &tmp))
+  if (!receive_n_data(file_descriptor, &config->delta_block_size, sizeof(config->delta_block_size)))
    goto error;
-  config->delta_block_size = (uint32_t)tmp;
  if (!receive_n_data(file_descriptor, &config->delta_max_file_size, sizeof(unsigned long long)))
    goto error;
-  config->show_progress = false;
-  config->dry_run = false;
-  config->ssh_port = 22;
-  config->transport = TRANSPORT_TCP;
-  config->ssh_destination = NULL;
-  config->fastsync_server_path = NULL;
-  config->exclude_patterns = NULL;
-  config->exclude_count = 0;
-  config->include_patterns = NULL;
-  config->include_count = 0;
-  config->max_size = 0;
-  config->min_size = 0;
-  config->use_tls = false;
-  config->tls_cert = NULL;
-  config->tls_key = NULL;
-  config->tls_ca = NULL;
-  config->timeout = 30;
-  config->contimeout = 10;
-  config->quiet = false;
-  config->stats = false;
-  config->max_depth = 0;
-  config->log_file = NULL;
-  config->queue_size = 100;
-  config->follow_symlinks = false;
-  config->copy_links = false;
-  config->safe_links = false;
-  config->copy_unsafe_links = false;
-  config->preserve_hard_links = false;
-  config->preserve_acls = false;
-  config->preserve_xattrs = false;
-  config->preserve_devices = false;
-  config->preserve_sparse = false;
-  config->itemize_changes = false;
-  config->out_format = NULL;
-  config->info_level = 0;
-  config->debug_level = 0;
-  config->list_only = false;
-  config->human_readable = false;
-  config->update = false;
-  config->inplace = false;
-  config->append = false;
-  config->append_verify = false;
-  config->delete_excluded = false;
-  config->delete_after = false;
-  config->max_delete = 0;
-  config->filters = NULL;
-  config->files_from = NULL;
-  config->cvs_exclude = false;
-  config->prune_empty_dirs = false;
-  config->relative = false;
-  config->rsh_command = NULL;
-  config->rsync_path = NULL;
-  config->temp_dir = NULL;
-  config->compare_dest = NULL;
-  config->copy_dest = NULL;
-  config->link_dest = NULL;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
  config->backup = tmp;
@@ -379,50 +322,56 @@ Config* config_receive(int file_descriptor) {
  config->copy_unsafe_links = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->preserve_hard_links = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->preserve_acls = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->preserve_xattrs = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->preserve_devices = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
  config->preserve_sparse = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->update = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
  config->inplace = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->append = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->append_verify = tmp;
-  if (!receive_int(file_descriptor, &tmp))
-    goto error;
-  config->delete_excluded = tmp;
-  if (!receive_int(file_descriptor, &tmp))
-    goto error;
-  config->delete_after = tmp;
-  if (!receive_n_data(file_descriptor, &config->max_delete, sizeof(config->max_delete)))
-    goto error;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->relative = tmp;
  if (!receive_int(file_descriptor, &tmp))
    goto error;
-  config->prune_empty_dirs = tmp;
-  config->temp_dir = receive_str(file_descriptor);
-  if (config->temp_dir == NULL)
+  int obsolete_int = 0;
+  if (!receive_n_data(file_descriptor, &obsolete_int, sizeof(obsolete_int)))
    goto error;
-  config->server_host = str_dup("127.0.0.1");
-  config->server_port = 8080;
+  if (!receive_int(file_descriptor, &tmp))
+    goto error;
+  if (!receive_int(file_descriptor, &tmp))
+    goto error;
+  char* obsolete_string = receive_str(file_descriptor);
+  if (obsolete_string == NULL)
+    goto error;
+  free(obsolete_string);
+  if (!receive_int(file_descriptor, &tmp))
+    goto error;
+  config->partial = tmp;
+  config->partial_dir = receive_str(file_descriptor);
+  if (config->partial_dir == NULL)
+    goto error;
+  config->suffix = receive_str(file_descriptor);
+  if (config->suffix == NULL)
+    goto error;
+  if (!receive_int(file_descriptor, &tmp))
+    goto error;
+  if (!receive_int(file_descriptor, &tmp))
+    goto error;
+  obsolete_string = receive_str(file_descriptor);
+  if (obsolete_string == NULL)
+    goto error;
+  free(obsolete_string);
  if (!send_status(file_descriptor, STATUS_OK))
    goto error;
  return config;
@@ -433,7 +382,8 @@ error:
  free(config->receive_root_directory);
  free(config->server_host);
  free(config->backup_dir);
-  free(config->temp_dir);
+  free(config->partial_dir);
+  free(config->suffix);
  free(config);
  return NULL;
 }
@@ -1,7 +1,6 @@
 #ifndef CONFIG_H
 #define CONFIG_H

-#include "array_list.h"
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -45,13 +44,11 @@ typedef struct Config {
  char* tls_ca;
  int timeout;
  int contimeout;
-  bool quiet;
  bool backup;
  char* backup_dir;
  bool stats;
  int max_depth;
  FILE* log_file;
-  int queue_size;
  bool follow_symlinks;
  bool partial;

@@ -60,49 +57,20 @@ typedef struct Config {
  bool safe_links;
  bool copy_unsafe_links;

-  // Issue #121: Extended metadata preservation
-  bool preserve_hard_links;
-  bool preserve_acls;
-  bool preserve_xattrs;
-  bool preserve_devices;
  bool preserve_sparse;

-  // Issue #122: Output/logging options
-  bool itemize_changes;
-  char* out_format;
-  int info_level;
-  int debug_level;
-  bool list_only;
-  bool human_readable;
-
-  // Issue #127: Transfer modes
-  bool update;
  bool inplace;
-  bool append;
-  bool append_verify;

-  // Issue #128: Extended delete options
-  bool delete_excluded;
-  bool delete_after;
-  int max_delete;
+  // PR #174: Partial transfer resumption
+  char* partial_dir;

-  // Issue #129: Advanced file selection
-  ArrayList* filters;
-  char* files_from;
-  bool cvs_exclude;
-  bool prune_empty_dirs;
-  bool relative;
+  // PR #178: Backup versioning
+  char* suffix;

-  // Issue #130: Remote shell/connection options
-  char* rsh_command;
-  char* rsync_path;
-  char* temp_dir;
-  char* compare_dest;
-  char* copy_dest;
-  char* link_dest;
 } Config;

-#define PROTOCOL_VERSION "1.3.0"
+/* This version must be bumped whenever config_send / config_receive wire format changes. */
+#define PROTOCOL_VERSION "2.1.0"
 #define DEFAULT_CHUNK_SIZE (10 * 1024 * 1024)

 Config* config_create(void);
@@ -388,6 +388,10 @@ Delta* delta_deserialize(const Data* data) {

    if (type == DELTA_OP_BLOCK_MATCH) {
      if (pos + sizeof(uint32_t) * 3 > data->size) {
+        for (uint32_t k = 0; k < i; k++) {
+          if (delta->instructions[k].type == DELTA_INSTR_LITERAL)
+            free(delta->instructions[k].literal.data);
+        }
        free(delta->instructions);
        free(delta);
        return NULL;
@@ -426,6 +430,11 @@ Delta* delta_deserialize(const Data* data) {
      }
      delta->instructions[i].literal.data = malloc(lit_len);
      if (!delta->instructions[i].literal.data) {
+        log_message(LOG_LEVEL_ERROR, "Failed to allocate %u bytes for literal data", lit_len);
+        for (uint32_t k = 0; k < i; k++) {
+          if (delta->instructions[k].type == DELTA_INSTR_LITERAL)
+            free(delta->instructions[k].literal.data);
+        }
        free(delta->instructions);
        free(delta);
        return NULL;
@@ -449,7 +458,8 @@ Delta* delta_deserialize(const Data* data) {

 void* delta_apply(const void* old_data, uint64_t old_size, const Delta* delta,
                  uint32_t block_size) {
-  if (!old_data || !delta)
+  if (!old_data || !delta || (delta->new_file_size > 0 && delta->instructions == NULL) ||
+      (delta->instruction_count > 0 && block_size == 0))
    return NULL;

  void* output = malloc((size_t)delta->new_file_size);
@@ -463,10 +473,15 @@ void* delta_apply(const void* old_data, uint64_t old_size, const Delta* delta,
  for (uint32_t i = 0; i < delta->instruction_count; i++) {
    if (delta->instructions[i].type == DELTA_INSTR_BLOCK_MATCH) {
      uint64_t src_offset = (uint64_t)delta->instructions[i].match.block_index * block_size;
+      if (src_offset > UINT64_MAX - delta->instructions[i].match.block_offset) {
+        free(output);
+        return NULL;
+      }
      src_offset += delta->instructions[i].match.block_offset;
      uint32_t len = delta->instructions[i].match.length;

-      if (src_offset + len > old_size) {
+      if (src_offset > old_size || (uint64_t)len > old_size - src_offset ||
+          out_pos > delta->new_file_size || (uint64_t)len > delta->new_file_size - out_pos) {
        free(output);
        return NULL;
      }
@@ -474,6 +489,10 @@ void* delta_apply(const void* old_data, uint64_t old_size, const Delta* delta,
      out_pos += len;
    } else {
      uint32_t len = delta->instructions[i].literal.length;
+      if (out_pos > delta->new_file_size || (uint64_t)len > delta->new_file_size - out_pos) {
+        free(output);
+        return NULL;
+      }
      memcpy(out + out_pos, delta->instructions[i].literal.data, len);
      out_pos += len;
    }
@@ -16,7 +16,6 @@
 #include "config.h"
 #include "data.h"
 #include "file.h"
-#include "log.h"
 #include "metadata.h"
 #include "protocol.h"
 #include "utils.h"
@@ -96,6 +95,9 @@ bool file_load_data(File* file) {
  size_t bytes_read = file_content_to_buffer(file);
  if (bytes_read != file->data->size) {
    log_message(LOG_LEVEL_ERROR, "Did not read expected amount of bytes from file");
+    free(file->data->data);
+    file->data->data = NULL;
+    file->data->size = 0;
    return false;
  }
  return true;
@@ -130,22 +132,29 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
 }

 bool file_save_to_disk(const char* root_directory, File* file, const Config* config) {
-  (void)config;
+  bool backup_enabled = config && config->backup;
+  bool inplace = config && config->inplace;
+  bool sparse = config && config->preserve_sparse;
+  const char* backup_suffix = (config && config->suffix) ? config->suffix : "~";
+  const char* backup_dir = (config && config->backup_dir) ? config->backup_dir : NULL;
+  const char* partial_dir = (config && config->partial_dir) ? config->partial_dir : NULL;
+
  if (has_path_traversal(file->path)) {
    log_message(LOG_LEVEL_ERROR, "Path traversal detected in file path: %s", file->path);
    return false;
  }

-  // Resolve the destination root to its real path, preventing symlink-based escapes.
-  // If the root does not yet exist, try to create it so realpath can succeed.
-  char* resolved_root = realpath(root_directory, NULL);
+  char* resolved_root = NULL;
+  const char* actual_root =
+      (partial_dir && config && config->partial) ? partial_dir : root_directory;
+  resolved_root = realpath(actual_root, NULL);
  if (resolved_root == NULL) {
-    if (mkdir_r(root_directory)) {
-      resolved_root = realpath(root_directory, NULL);
+    if (mkdir_r(actual_root)) {
+      resolved_root = realpath(actual_root, NULL);
    }
  }
  if (resolved_root == NULL) {
-    log_message(LOG_LEVEL_ERROR, "Failed to resolve destination root: %s", root_directory);
+    log_message(LOG_LEVEL_ERROR, "Failed to resolve destination root: %s", actual_root);
    return false;
  }

@@ -155,7 +164,43 @@ bool file_save_to_disk(const char* root_directory, File* file, const Config* con
    return false;
  }

-  // Ensure the target directory exists so the parent can be resolved for path safety.
+  if (backup_enabled) {
+    struct stat backup_stat;
+    if (stat(disk_path, &backup_stat) == 0) {
+      char* backup_path = NULL;
+      if (backup_dir) {
+        char* resolved_backup_dir = realpath(backup_dir, NULL);
+        if (!resolved_backup_dir) {
+          mkdir_r(backup_dir);
+          resolved_backup_dir = realpath(backup_dir, NULL);
+        }
+        if (resolved_backup_dir) {
+          backup_path = path_cat(resolved_backup_dir, file->path);
+          free(resolved_backup_dir);
+        }
+      }
+      if (!backup_path) {
+        size_t path_len = strlen(disk_path);
+        size_t suffix_len = strlen(backup_suffix);
+        backup_path = malloc(path_len + suffix_len + 1);
+        if (backup_path) {
+          memcpy(backup_path, disk_path, path_len);
+          memcpy(backup_path + path_len, backup_suffix, suffix_len + 1);
+        }
+      }
+      if (backup_path) {
+        char* backup_dir_path = str_dup(backup_path);
+        if (backup_dir_path) {
+          const char* bdir = dirname(backup_dir_path);
+          mkdir_r(bdir);
+          free(backup_dir_path);
+        }
+        rename(disk_path, backup_path);
+        free(backup_path);
+      }
+    }
+  }
+
  char* dir_dup = str_dup(disk_path);
  if (!dir_dup) {
    free(resolved_root);
@@ -163,7 +208,6 @@ bool file_save_to_disk(const char* root_directory, File* file, const Config* con
    return false;
  }
  char* dir_str = dirname(dir_dup);
-  // Create the directory if needed (no-op if it already exists) so realpath can resolve it.
  if (!mkdir_r(dir_str)) {
    free(dir_dup);
    free(resolved_root);
@@ -179,13 +223,10 @@ bool file_save_to_disk(const char* root_directory, File* file, const Config* con
    return false;
  }

-  // Verify that the resolved directory is inside the resolved root.
-  // Both are canonical absolute paths — this prevents symlink-based escapes.
  size_t root_len = strlen(resolved_root);
  if (strncmp(resolved_dir, resolved_root, root_len) != 0 ||
      (resolved_dir[root_len] != '\0' && resolved_dir[root_len] != '/')) {
-    log_message(LOG_LEVEL_ERROR, "Path escape detected: %s is outside %s", disk_path,
-                root_directory);
+    log_message(LOG_LEVEL_ERROR, "Path escape detected: %s is outside %s", disk_path, actual_root);
    free(resolved_dir);
    free(resolved_root);
    free(disk_path);
@@ -194,7 +235,7 @@ bool file_save_to_disk(const char* root_directory, File* file, const Config* con
  free(resolved_dir);
  free(resolved_root);

-  bool ok = to_disk(disk_path, file->data->data, file->data->size);
+  bool ok = to_disk(disk_path, file->data->data, file->data->size, inplace, sparse);
  if (ok)
    file_restore_metadata(disk_path, file->metadata);
  free(disk_path);
@@ -479,7 +520,8 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
  return file;
 }

-bool to_disk(const char* path, const void* data, unsigned long long data_size) {
+bool to_disk(const char* path, const void* data, unsigned long long data_size, bool inplace,
+             bool sparse) {
  char* tmp_path = NULL;
  char* directory = NULL;

@@ -496,6 +538,39 @@ bool to_disk(const char* path, const void* data, unsigned long long data_size) {
  if (!mkdir_r(directory))
    goto done;

+  if (inplace) {
+    FILE* file_pointer = fopen(path, "wb");
+    if (file_pointer == NULL) {
+      perror("Could not open file for inplace write");
+      ok = false;
+      goto done;
+    }
+    if (sparse && data_size > 0) {
+      if (fseek(file_pointer, data_size - 1, SEEK_SET) != 0) {
+        perror("Failed to seek for sparse file");
+        fclose(file_pointer);
+        ok = false;
+        goto done;
+      }
+      if (fwrite("", 1, 1, file_pointer) != 1) {
+        perror("Failed to write sparse file");
+        fclose(file_pointer);
+        ok = false;
+        goto done;
+      }
+      rewind(file_pointer);
+    }
+    if (data_size > 0 && fwrite(data, 1, data_size, file_pointer) != data_size) {
+      perror("Failed to write all data to file");
+      fclose(file_pointer);
+      ok = false;
+      goto done;
+    }
+    fclose(file_pointer);
+    free(directory);
+    return true;
+  }
+
  size_t path_len = strlen(path);
  tmp_path = malloc(path_len + 5);
  if (!tmp_path) {
@@ -511,6 +586,21 @@ bool to_disk(const char* path, const void* data, unsigned long long data_size) {
    ok = false;
    goto done;
  }
+  if (sparse && data_size > 0) {
+    if (fseek(file_pointer, data_size - 1, SEEK_SET) != 0) {
+      perror("Failed to seek for sparse file");
+      fclose(file_pointer);
+      ok = false;
+      goto done;
+    }
+    if (fwrite("", 1, 1, file_pointer) != 1) {
+      perror("Failed to write sparse file");
+      fclose(file_pointer);
+      ok = false;
+      goto done;
+    }
+    rewind(file_pointer);
+  }
  if (fwrite(data, 1, data_size, file_pointer) != data_size) {
    perror("Failed to write all data to temporary file");
    fclose(file_pointer);
@@ -535,13 +625,6 @@ done:

 bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int compression_level,
                        bool send_path) {
-  // sendfile is incompatible with compression (kernel zero-copy).
-  // If compression is requested, fall back to the regular send path.
-  // NOTE: This is a safety net only — callers must ensure compression_level == 0
-  // before calling file_send_sendfile. The fallback to file_send_single_calls
-  // preserves the send_path contract, but callers should not rely on it for
-  // correctness (the --sendfile flag is validated to be mutually exclusive with
-  // -c/--compress at the CLI layer).
  if (compression_level > 0)
    return file_send_single_calls(file, file_descriptor, use_metadata, compression_level,
                                  send_path);
@@ -34,7 +34,8 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int
 size_t file_content_to_buffer(File* file);
 FileMetadata* file_metadata_create(const struct stat* stats);
 void file_metadata_destroy(void* metadata);
-bool to_disk(const char* path, const void* data, unsigned long long data_size);
+bool to_disk(const char* path, const void* data, unsigned long long data_size, bool inplace,
+             bool sparse);
 bool file_save_to_disk(const char* root_directory, File* file, const Config* config);
 File* receive_incremental_check(int fd, const Config* config, bool* skipped);
 int receive_manifest(int fd, const Config* config, int* next_status);
@@ -15,28 +15,38 @@ void log_set_file(FILE* fp) {
  log_fp = fp;
 }

+static inline void write_message(FILE* dest_io, LogLevel log_level, struct tm t, const char* format,
+                                 va_list args) {
+  fprintf(dest_io, "%04d-%02d-%02d %02d:%02d:%02d [%s]: ", t.tm_year + 1900, t.tm_mon + 1,
+          t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec, log_level_strings[log_level]);
+
+  vfprintf(dest_io, format, args);
+  fprintf(dest_io, "\n");
+}
+
 void log_message(LogLevel log_level, const char* format, ...) {
  if (log_level < current_log_level)
    return;
+  if (log_level < 0 || log_level >= (int)(sizeof(log_level_strings) / sizeof(log_level_strings[0])))
+    return;
  time_t now = time(NULL);
-  const struct tm* t = localtime(&now);
+  struct tm t;
+  if (!localtime_r(&now, &t))
+    return;

-  fprintf(stderr, "%04d-%02d-%02d %02d:%02d:%02d [%s]: ", t->tm_year + 1900, t->tm_mon + 1,
-          t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, log_level_strings[log_level]);
+  FILE* dest_io = stdout;
+  if (log_level == LOG_LEVEL_ERROR) {
+    dest_io = stderr;
+  }

  va_list args;
  va_start(args, format);
-  vfprintf(stderr, format, args);
+  write_message(dest_io, log_level, t, format, args);
  va_end(args);
-  fprintf(stderr, "\n");

  if (log_fp) {
-    fprintf(log_fp, "%04d-%02d-%02d %02d:%02d:%02d [%s]: ", t->tm_year + 1900, t->tm_mon + 1,
-            t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, log_level_strings[log_level]);
    va_start(args, format);
-    vfprintf(log_fp, format, args);
+    write_message(log_fp, log_level, t, format, args);
    va_end(args);
-    fprintf(log_fp, "\n");
-    fflush(log_fp);
  }
 }
@@ -24,17 +24,50 @@ PipelineContextSender* pipeline_context_sender_create(Config* config, Queue* que
  context->scanner_done = false;
  context->loader_done = false;
  context->manifest = NULL;
-  if (mtx_init(&context->mutex_scanner, mtx_plain) != thrd_success ||
-      cnd_init(&context->condition_not_full_scanner) != thrd_success ||
-      cnd_init(&context->condition_not_empty_scanner) != thrd_success ||
-      mtx_init(&context->mutex_loader, mtx_plain) != thrd_success ||
-      cnd_init(&context->condition_not_full_loader) != thrd_success ||
-      cnd_init(&context->condition_not_empty_loader) != thrd_success) {
-    perror("Error initializing synchronization objects");
-    free(context);
-    return NULL;
-  }
+  context->progress_bytes = 0;
+  context->sender_done = false;
+  context->cancelled = false;
+  int init = 0;
+  if (mtx_init(&context->mutex_scanner, mtx_plain) != thrd_success)
+    goto fail;
+  init++;
+  if (cnd_init(&context->condition_not_full_scanner) != thrd_success)
+    goto fail;
+  init++;
+  if (cnd_init(&context->condition_not_empty_scanner) != thrd_success)
+    goto fail;
+  init++;
+  if (mtx_init(&context->mutex_loader, mtx_plain) != thrd_success)
+    goto fail;
+  init++;
+  if (cnd_init(&context->condition_not_full_loader) != thrd_success)
+    goto fail;
+  init++;
+  if (cnd_init(&context->condition_not_empty_loader) != thrd_success)
+    goto fail;
+  init++;
+  if (mtx_init(&context->mutex_progress, mtx_plain) != thrd_success)
+    goto fail;
+  // cppcheck-suppress unreadVariable
+  init++;
  return context;
+
+fail:
+  perror("Error initializing synchronization objects");
+  if (init >= 6)
+    cnd_destroy(&context->condition_not_empty_loader);
+  if (init >= 5)
+    cnd_destroy(&context->condition_not_full_loader);
+  if (init >= 4)
+    mtx_destroy(&context->mutex_loader);
+  if (init >= 3)
+    cnd_destroy(&context->condition_not_empty_scanner);
+  if (init >= 2)
+    cnd_destroy(&context->condition_not_full_scanner);
+  if (init >= 1)
+    mtx_destroy(&context->mutex_scanner);
+  free(context);
+  return NULL;
 }

 void pipeline_context_sender_destroy(PipelineContextSender* context) {
@@ -50,6 +83,7 @@ void pipeline_context_sender_destroy(PipelineContextSender* context) {
  mtx_destroy(&context->mutex_loader);
  cnd_destroy(&context->condition_not_full_loader);
  cnd_destroy(&context->condition_not_empty_loader);
+  mtx_destroy(&context->mutex_progress);
  free(context);
 }

@@ -63,14 +97,30 @@ PipelineContextReceiver* pipeline_context_receiver_create(Config* config, Queue*
  context->file_descriptor = file_descriptor;
  context->ssl = ssl;
  context->receiver_done = false;
-  if (mtx_init(&context->mutex, mtx_plain) != thrd_success ||
-      cnd_init(&context->condition_not_full) != thrd_success ||
-      cnd_init(&context->condition_not_empty) != thrd_success) {
-    perror("Error initializing synchronization objects");
-    free(context);
-    return NULL;
-  }
+  context->cancelled = false;
+  int init = 0;
+  if (mtx_init(&context->mutex, mtx_plain) != thrd_success)
+    goto fail;
+  init++;
+  if (cnd_init(&context->condition_not_full) != thrd_success)
+    goto fail;
+  init++;
+  if (cnd_init(&context->condition_not_empty) != thrd_success)
+    goto fail;
+  // cppcheck-suppress unreadVariable
+  init++;
  return context;
+
+fail:
+  perror("Error initializing synchronization objects");
+  if (init >= 3)
+    cnd_destroy(&context->condition_not_empty);
+  if (init >= 2)
+    cnd_destroy(&context->condition_not_full);
+  if (init >= 1)
+    mtx_destroy(&context->mutex);
+  free(context);
+  return NULL;
 }

 void pipeline_context_receiver_destroy(PipelineContextReceiver* context) {
@@ -90,8 +140,13 @@ static bool receive_chunk_enqueue(int file_descriptor, PipelineContextReceiver*
  for (int i = 0; i < chunk->element_count; i++) {
    File* file = chunk->items[i];
    chunk->items[i] = NULL;
-    queue_enqueue_multithreaded(context->queue, file, &context->mutex,
-                                &context->condition_not_empty, &context->condition_not_full);
+    if (!queue_enqueue_multithreaded_cancel(context->queue, file, &context->mutex,
+                                            &context->condition_not_empty,
+                                            &context->condition_not_full, &context->cancelled)) {
+      file_destroy(file);
+      chunk_destroy(chunk);
+      return false;
+    }
  }
  chunk_destroy(chunk);
  return true;
@@ -125,8 +180,12 @@ int receive_thread(void* pipeline_context) {
      if (!skipped) {
        if (file == NULL)
          return thrd_error;
-        queue_enqueue_multithreaded(context->queue, file, &context->mutex,
-                                    &context->condition_not_empty, &context->condition_not_full);
+        if (!queue_enqueue_multithreaded_cancel(
+                context->queue, file, &context->mutex, &context->condition_not_empty,
+                &context->condition_not_full, &context->cancelled)) {
+          file_destroy(file);
+          return thrd_error;
+        }
      }
    } else if (status == STATUS_CHUNK) {
      if (!receive_chunk_enqueue(file_descriptor, context))
@@ -162,8 +221,12 @@ int receive_thread(void* pipeline_context) {
    } else {
      File* file = file_receive(config, file_descriptor);
      if (file) {
-        queue_enqueue_multithreaded(context->queue, file, &context->mutex,
-                                    &context->condition_not_empty, &context->condition_not_full);
+        if (!queue_enqueue_multithreaded_cancel(
+                context->queue, file, &context->mutex, &context->condition_not_empty,
+                &context->condition_not_full, &context->cancelled)) {
+          file_destroy(file);
+          return thrd_error;
+        }
      } else {
        log_message(LOG_LEVEL_ERROR, "Failed to receive file");
        return thrd_error;
@@ -23,6 +23,10 @@ typedef struct {
  cnd_t condition_not_empty_loader;
  bool loader_done;
  ArrayList* manifest;
+  mtx_t mutex_progress;
+  unsigned long long progress_bytes;
+  bool sender_done;
+  bool cancelled;
 } PipelineContextSender;

 typedef struct PipelineContextReceiver {
@@ -34,6 +38,7 @@ typedef struct PipelineContextReceiver {
  cnd_t condition_not_full;
  cnd_t condition_not_empty;
  bool receiver_done;
+  bool cancelled;
 } PipelineContextReceiver;

 PipelineContextSender* pipeline_context_sender_create(Config* config, Queue* queue_scanner,
@@ -6,10 +6,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <threads.h>
 #include <time.h>
 #include <unistd.h>

-#define MAX_DATA_SIZE (100ULL * 1024 * 1024)          /* 100 MB max per data message */
 #define RECEIVE_TIMEOUT_SEC 60                        /* 60 second per-message timeout */
 #define MAX_CONNECTION_MEMORY (1024ULL * 1024 * 1024) /* 1 GB total per connection */

@@ -20,6 +20,8 @@ static __thread SSL* io_ssl;
 static unsigned long long io_bwlimit = 0;
 static long long bw_tokens = 0;
 static struct timespec bw_last_refill = {0, 0};
+static mtx_t bw_mutex;
+static once_flag bw_mutex_once = ONCE_FLAG_INIT;

 static __thread unsigned long long total_allocated_bytes = 0;

@@ -28,15 +30,24 @@ void io_set_fds(int read_fd, int write_fd) {
  io_write_fd = write_fd;
 }

+static void bw_mutex_init(void) {
+  mtx_init(&bw_mutex, mtx_plain);
+}
+
 void io_set_bwlimit(unsigned long long bytes_per_sec) {
+  call_once(&bw_mutex_once, bw_mutex_init);
+  mtx_lock(&bw_mutex);
  io_bwlimit = bytes_per_sec;
  bw_tokens = (long long)io_bwlimit;
  clock_gettime(CLOCK_MONOTONIC, &bw_last_refill);
+  mtx_unlock(&bw_mutex);
 }

 static void bw_throttle(size_t bytes_written) {
  if (io_bwlimit == 0)
    return;
+  call_once(&bw_mutex_once, bw_mutex_init);
+  mtx_lock(&bw_mutex);

  struct timespec now;
  clock_gettime(CLOCK_MONOTONIC, &now);
@@ -61,6 +72,7 @@ static void bw_throttle(size_t bytes_written) {
    bw_tokens = 0;
    clock_gettime(CLOCK_MONOTONIC, &bw_last_refill);
  }
+  mtx_unlock(&bw_mutex);
 }

 void io_set_ssl(SSL* ssl) {
@@ -177,6 +189,8 @@ static const char* status_to_string(Status status) {
 }

 bool send_str(int file_descriptor, const char* data) {
+  if (data == NULL)
+    return false;
  size_t size = strlen(data);
  if (!send_n_data(file_descriptor, &size, sizeof(size_t)))
    return false;
@@ -221,9 +235,9 @@ Data* receive_data(int file_descriptor) {
  unsigned long long size = 0;
  if (!receive_n_data(file_descriptor, &size, sizeof(unsigned long long)))
    return NULL;
-  if (size > MAX_DATA_SIZE) {
+  if (size > MAX_DATA_PAYLOAD_SIZE) {
    log_message(LOG_LEVEL_ERROR, "Data size %llu exceeds maximum %llu", size,
-                (unsigned long long)MAX_DATA_SIZE);
+                (unsigned long long)MAX_DATA_PAYLOAD_SIZE);
    return NULL;
  }
  if (total_allocated_bytes + size > MAX_CONNECTION_MEMORY) {
@@ -11,6 +11,9 @@
 /* Maximum allowed data payload size for receive_data (100 MB) */
 #define MAX_DATA_PAYLOAD_SIZE (100ULL * 1024 * 1024)

+/* Maximum chunk size (64 MB) — prevents unbounded allocation from the wire */
+#define MAX_CHUNK_SIZE (64ULL * 1024 * 1024)
+
 typedef struct ssl_st SSL;

 typedef int Status;
@@ -103,6 +103,22 @@ bool queue_enqueue_multithreaded(Queue* queue, void* item, mtx_t* mutex, cnd_t*
  return ok;
 }

+bool queue_enqueue_multithreaded_cancel(Queue* queue, void* item, mtx_t* mutex,
+                                        cnd_t* condition_not_empty, cnd_t* condition_not_full,
+                                        const bool* cancelled) {
+  mtx_lock(mutex);
+  while (queue_is_full(queue) && (cancelled == NULL || !*cancelled))
+    cnd_wait(condition_not_full, mutex);
+  if (cancelled != NULL && *cancelled) {
+    mtx_unlock(mutex);
+    return false;
+  }
+  bool ok = queue_enqueue(queue, item);
+  cnd_signal(condition_not_empty);
+  mtx_unlock(mutex);
+  return ok;
+}
+
 void* queue_dequeue(Queue* queue) {
  if (queue == NULL || queue_is_empty(queue)) {
    perror("ERROR: Could not dequeue from null or empty queue.");
@@ -20,6 +20,9 @@ bool queue_is_full(const Queue* queue);
 bool queue_enqueue(Queue* queue, void* item);
 bool queue_enqueue_multithreaded(Queue* queue, void* item, mtx_t* mutex, cnd_t* condition_not_empty,
                                 cnd_t* condition_not_full);
+bool queue_enqueue_multithreaded_cancel(Queue* queue, void* item, mtx_t* mutex,
+                                        cnd_t* condition_not_empty, cnd_t* condition_not_full,
+                                        const bool* cancelled);
 void* queue_dequeue(Queue* queue);
 void* queue_dequeue_multithreaded(Queue* queue, mtx_t* mutex, cnd_t* condition_not_empty,
                                  cnd_t* condition_not_full, const bool* other_thread_done);
@@ -182,7 +182,7 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
    return NULL;
  }
  client->file_descriptor = sv[0];
-  client->address.sin_family = AF_UNIX;
+  client->address.ss_family = AF_UNIX;
  client->address_length = 0;
  client->ssh_child_pid = pid;
  client->ssl = NULL;
@@ -3,6 +3,7 @@
 #include "protocol.h"
 #include <arpa/inet.h>
 #include <errno.h>
+#include <netdb.h>
 #include <openssl/ssl.h>
 #include <signal.h>
 #include <stdio.h>
@@ -143,6 +144,10 @@ void tcp_set_timeouts(int timeout_sec, int contimeout_sec) {
    g_contimeout_sec = contimeout_sec;
 }

+int tcp_get_contimeout_sec(void) {
+  return g_contimeout_sec;
+}
+
 static void tcp_apply_socket_timeout(int fd) {
  struct timeval tv;
  tv.tv_sec = g_timeout_sec;
@@ -152,19 +157,12 @@ static void tcp_apply_socket_timeout(int fd) {
 }

 Client* client_create() {
-  int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
-  if (file_descriptor < 0) {
-    perror("Could not create Socket!");
-    return NULL;
-  }
-
  Client* client = (Client*)malloc(sizeof(Client));
  if (client == NULL) {
-    close(file_descriptor);
    return NULL;
  }
-  client->file_descriptor = file_descriptor;
-  client->address.sin_family = AF_INET;
+  client->file_descriptor = -1;
+  memset(&client->address, 0, sizeof(client->address));
  client->address_length = sizeof(client->address);
  client->ssh_child_pid = -1;
  client->ssl = NULL;
@@ -173,23 +171,50 @@ Client* client_create() {
 }

 bool client_connect(Client* client, char* host, int port) {
-  client->address.sin_port = htons(port);
-  client->address.sin_family = AF_INET;
-  client->address_length = sizeof(client->address);
+  struct addrinfo hints;
+  struct addrinfo* result;
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;

-  if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
-    perror("Could not convert host address!");
+  char port_str[16];
+  snprintf(port_str, sizeof(port_str), "%d", port);
+
+  int err = getaddrinfo(host, port_str, &hints, &result);
+  if (err != 0 || result == NULL) {
+    fprintf(stderr, "Could not resolve host: %s (%s)\n", host, gai_strerror(err));
    return false;
  }

-  struct timeval ct;
-  ct.tv_sec = g_contimeout_sec;
-  ct.tv_usec = 0;
-  setsockopt(client->file_descriptor, SOL_SOCKET, SO_RCVTIMEO, &ct, sizeof(ct));
-  setsockopt(client->file_descriptor, SOL_SOCKET, SO_SNDTIMEO, &ct, sizeof(ct));
+  struct addrinfo* rp;
+  bool connected = false;
+  for (rp = result; rp != NULL; rp = rp->ai_next) {
+    if (client->file_descriptor >= 0)
+      close(client->file_descriptor);

-  if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
-      0) {
+    client->file_descriptor = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (client->file_descriptor < 0)
+      continue;
+
+    struct timeval ct;
+    ct.tv_sec = g_contimeout_sec;
+    ct.tv_usec = 0;
+    setsockopt(client->file_descriptor, SOL_SOCKET, SO_RCVTIMEO, &ct, sizeof(ct));
+    setsockopt(client->file_descriptor, SOL_SOCKET, SO_SNDTIMEO, &ct, sizeof(ct));
+
+    memcpy(&client->address, rp->ai_addr, rp->ai_addrlen);
+    client->address_length = rp->ai_addrlen;
+
+    if (connect(client->file_descriptor, (struct sockaddr*)&client->address,
+                client->address_length) == 0) {
+      connected = true;
+      break;
+    }
+  }
+  freeaddrinfo(result);
+
+  if (!connected) {
    perror("Could not connect to Server!");
    return false;
  }
@@ -205,7 +230,10 @@ void client_disconnect(Client* client) {
    client->ssl = NULL;
    io_set_ssl(NULL);
  }
-  close(client->file_descriptor);
+  if (client->file_descriptor >= 0) {
+    close(client->file_descriptor);
+    client->file_descriptor = -1;
+  }
  if (client->ssh_child_pid > 0) {
    int status;
    waitpid(client->ssh_child_pid, &status, 0);
@@ -15,7 +15,7 @@ typedef struct Server {
 } Server;

 typedef struct Client {
-  struct sockaddr_in address;
+  struct sockaddr_storage address;
  unsigned int address_length;
  int file_descriptor;
  pid_t ssh_child_pid;
@@ -33,5 +33,6 @@ bool client_connect(Client* client, char* host, int port);
 void client_disconnect(Client* client);
 void client_delete(Client* client);
 void tcp_set_timeouts(int timeout_sec, int contimeout_sec);
+int tcp_get_contimeout_sec(void);

 #endif
@@ -3,6 +3,7 @@
 #include "protocol.h"
 #include "transport_tcp.h"
 #include <arpa/inet.h>
+#include <netdb.h>
 #include <openssl/err.h>
 #include <openssl/ssl.h>
 #include <signal.h>
@@ -148,13 +149,50 @@ bool server_listen_tls(Server* server, void (*handler)(int file_descriptor)) {

 bool client_connect_tls(Client* client, char* host, int port, const char* cert_path,
                        const char* key_path, const char* ca_path) {
-  client->address.sin_port = htons(port);
-  if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
-    perror("Could not convert host address!");
+  struct addrinfo hints;
+  struct addrinfo* result;
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;
+
+  char port_str[16];
+  snprintf(port_str, sizeof(port_str), "%d", port);
+
+  int err = getaddrinfo(host, port_str, &hints, &result);
+  if (err != 0 || result == NULL) {
+    fprintf(stderr, "Could not resolve host: %s (%s)\n", host, gai_strerror(err));
    return false;
  }
-  if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
-      0) {
+
+  struct addrinfo* rp;
+  bool connected = false;
+  for (rp = result; rp != NULL; rp = rp->ai_next) {
+    if (client->file_descriptor >= 0)
+      close(client->file_descriptor);
+
+    client->file_descriptor = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (client->file_descriptor < 0)
+      continue;
+
+    struct timeval ct;
+    ct.tv_sec = tcp_get_contimeout_sec();
+    ct.tv_usec = 0;
+    setsockopt(client->file_descriptor, SOL_SOCKET, SO_RCVTIMEO, &ct, sizeof(ct));
+    setsockopt(client->file_descriptor, SOL_SOCKET, SO_SNDTIMEO, &ct, sizeof(ct));
+
+    memcpy(&client->address, rp->ai_addr, rp->ai_addrlen);
+    client->address_length = rp->ai_addrlen;
+
+    if (connect(client->file_descriptor, (struct sockaddr*)&client->address,
+                client->address_length) == 0) {
+      connected = true;
+      break;
+    }
+  }
+  freeaddrinfo(result);
+
+  if (!connected) {
    perror("Could not connect to Server!");
    return false;
  }
@@ -10,11 +10,13 @@
 #include <unistd.h>

 bool mkdir_r(const char* path) {
-  char* path_duplicate = malloc(strlen(path) + 1);
+  size_t path_len = strlen(path);
+  char* path_duplicate = malloc(path_len + 1);
  if (!path_duplicate)
    return false;
-  memcpy(path_duplicate, path, strlen(path) + 1);
-  char* path_current = (char*)malloc((strlen(path) + 2) * sizeof(char));
+  memcpy(path_duplicate, path, path_len + 1);
+  size_t capacity = path_len + 2;
+  char* path_current = (char*)malloc(capacity * sizeof(char));
  if (!path_current) {
    free(path_duplicate);
    return false;
@@ -33,6 +35,10 @@ bool mkdir_r(const char* path) {
  bool ok = true;
  while (part != NULL) {
    size_t part_len = strlen(part);
+    if ((size_t)(path_current_position - path_current) + part_len + 2 > capacity) {
+      ok = false;
+      break;
+    }
    memcpy(path_current_position, part, part_len);
    path_current_position += part_len;
    path_current_position[0] = '/';
@@ -58,14 +64,24 @@ char* str_dup(const char* string) {
    return NULL;
  size_t str_len = strlen(string);
  char* new_string = (char*)malloc(str_len + 1);
+  if (new_string == NULL)
+    return NULL;
  memcpy(new_string, string, str_len + 1);
  return new_string;
 }

+/* Match a glob pattern against a string. Supported wildcards:
+ *   ?      matches any single character except '/'.
+ *   *      matches any sequence of characters within one path component (no '/').
+ *   **     matches any sequence of characters, including '/' (cross-directory).
+ *   slash-star-star-slash is treated as a cross-directory wildcard when it appears between
+ * literals.
+ */
 bool glob_match(const char* pattern, const char* str) {
  while (*pattern) {
    if (*pattern == '*') {
      if (*(pattern + 1) == '*') {
+        /* globstar: match across directories */
        pattern += 2;
        if (*pattern == '\0')
          return true;
@@ -78,6 +94,7 @@ bool glob_match(const char* pattern, const char* str) {
        }
        return glob_match(pattern, str);
      }
+      /* single *: match within one path component */
      pattern++;
      while (*str && *str != '/') {
        if (glob_match(pattern, str))
@@ -92,6 +109,7 @@ bool glob_match(const char* pattern, const char* str) {
      str++;
    } else {
      if (*pattern != *str) {
+        /* allow literal / ** / rest to match any number of directories */
        if (*pattern == '/' && *(pattern + 1) == '*' && *(pattern + 2) == '*') {
          const char* rest = pattern + 3;
          if (*rest == '/')
@@ -238,7 +238,7 @@ class TestProgress:
        )
        assert result.returncode == 0, f"Exit {result.returncode}: {result.stderr[:100]}"
        output = result.stdout + result.stderr
-        assert len(output) >= 0
+        assert output, "--progress produced no output"


 class TestBandwidthLimit:
@@ -52,9 +52,11 @@ def _check_ssh():
        pass


+_check_ssh()
+
+
@pytest.fixture(scope="module", autouse=True)
 def setup_test_data():
-    _check_ssh()
    if SSH_AVAILABLE:
        generate_test_files(SOURCE_DIR, full=False)
        clean_dir(DEST_DIR)
@@ -84,8 +86,12 @@ def _run_ssh_test(name, flags, expected_missing=None):
    return make_result(name, True, duration)


-@pytest.mark.skipif(not SSH_AVAILABLE, reason="SSH to localhost not available")
 class TestSSHStandard:
+    @pytest.fixture(autouse=True)
+    def require_ssh(self):
+        if not SSH_AVAILABLE:
+            pytest.skip("SSH to localhost not available")
+
    def test_standard(self):
        r = _run_ssh_test("SSH (localhost)", [])
        assert r["status"] == "Success", r["error"]
@@ -119,8 +125,12 @@ class TestSSHStandard:
        assert r["status"] == "Success", r["error"]


-@pytest.mark.skipif(not SSH_AVAILABLE, reason="SSH to localhost not available")
 class TestSSHFeatures:
+    @pytest.fixture(autouse=True)
+    def require_ssh(self):
+        if not SSH_AVAILABLE:
+            pytest.skip("SSH to localhost not available")
+
    def test_archive(self):
        r = _run_ssh_test("SSH Archive (-a)", ["-a"])
        assert r["status"] == "Success", r["error"]
@@ -11,7 +11,7 @@ static void test_file_operations() {
  char* test_content = "Hello, Chunk System!";
  unsigned long long test_len = strlen(test_content);

-  to_disk(test_path, test_content, test_len);
+  to_disk(test_path, test_content, test_len, false, false);

  File* f = file_create(test_path);
  EXPECT_NOT_NULL(f);
@@ -43,8 +43,8 @@ static void test_chunk_operations() {
  char* content2 = "chunk item number 2";
  unsigned long long len2 = strlen(content2);

-  to_disk(path1, content1, len1);
-  to_disk(path2, content2, len2);
+  to_disk(path1, content1, len1, false, false);
+  to_disk(path2, content2, len2, false, false);

  struct stat st1, st2;
  stat(path1, &st1);
@@ -6,6 +6,9 @@
 #include <string.h>
 #include <unistd.h>

+/* Declaration of parse_args from client_cli.c */
+int parse_args(Config* config, int argc, char* argv[], int* positional_args, int* positional_count);
+
 /* Test main() with --help flag (early return path, no server connection needed) */
 static void test_cli_help() {
  /* We can't easily call main() because it calls send_files which needs a server.
@@ -80,10 +83,225 @@ static void test_cli_exclude_patterns() {
  config_delete(cfg);
 }

+/* Test parse_args with --help returns 1 (clean exit) */
+static void test_parse_args_help() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "--help"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 2, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 1);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args with -V/--version returns 1 */
+static void test_parse_args_version() {
+  Config* cfg = config_create();
+  char* argv_short[] = {"fastsync", "-V"};
+  char* argv_long[] = {"fastsync", "--version"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 2, argv_short, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 1);
+
+  ret = parse_args(cfg, 2, argv_long, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 1);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args with valid port */
+static void test_parse_args_valid_port() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "-p", "2222", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 5, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 0);
+  EXPECT_EQ_INT(cfg->ssh_port, 2222);
+  EXPECT_EQ_INT(positional_count, 2);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args rejects port > 65535 */
+static void test_parse_args_invalid_port() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "-p", "99999", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 5, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, -1);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args rejects non-numeric port */
+static void test_parse_args_non_numeric_port() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "-p", "abc", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 5, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, -1);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args rejects server port > 65535 */
+static void test_parse_args_invalid_server_port() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "--server-port", "70000", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 5, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, -1);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args rejects invalid compression level */
+static void test_parse_args_invalid_compression_level() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "-c", "25", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 5, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, -1);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args accepts valid compression level */
+static void test_parse_args_valid_compression_level() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "-c", "10", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 5, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 0);
+  EXPECT_EQ_INT(cfg->compression_level, 10);
+
+  config_delete(cfg);
+}
+
+/* Test parse_args unknown option returns error */
+static void test_parse_args_unknown_option() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "--nonexistent", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 4, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, -1);
+
+  config_delete(cfg);
+}
+
+/* Parsed-but-unimplemented options must fail instead of being silently accepted. */
+static void test_parse_args_rejects_unimplemented_options() {
+  static const char* const options[] = {"-q",
+                                        "--quiet",
+                                        "--silent",
+                                        "--queue-size",
+                                        "-H",
+                                        "--hard-links",
+                                        "-A",
+                                        "--acls",
+                                        "-X",
+                                        "--xattrs",
+                                        "-D",
+                                        "--devices",
+                                        "-i",
+                                        "--itemize-changes",
+                                        "--out-format",
+                                        "--info",
+                                        "--debug",
+                                        "--list-only",
+                                        "-h",
+                                        "--human-readable",
+                                        "-u",
+                                        "--update",
+                                        "--append",
+                                        "--append-verify",
+                                        "--delete-excluded",
+                                        "--delete-after",
+                                        "--max-delete",
+                                        "--filter",
+                                        "--files-from",
+                                        "--cvs-exclude",
+                                        "--prune-empty-dirs",
+                                        "-R",
+                                        "--relative",
+                                        "-e",
+                                        "--rsh",
+                                        "--rsync-path",
+                                        "--temp-dir",
+                                        "--compare-dest",
+                                        "--copy-dest",
+                                        "--link-dest",
+                                        "--delete-before",
+                                        "--address",
+                                        "--bind-address",
+                                        "--ipv6",
+                                        "--ipv4",
+                                        "--daemon",
+                                        "--config",
+                                        "--server",
+                                        "--checksum",
+                                        "--compress-choice"};
+
+  for (size_t i = 0; i < sizeof(options) / sizeof(options[0]); i++) {
+    Config* cfg = config_create();
+    char* argv[] = {"fastsync", (char*)options[i], "dummy", "/src", "/dst"};
+    int positional_args[2];
+    int positional_count = 0;
+
+    EXPECT_EQ_INT(parse_args(cfg, 5, argv, positional_args, &positional_count), -1);
+    config_delete(cfg);
+  }
+}
+
+/* Test parse_args with --archive flag */
+static void test_parse_args_archive() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "--archive", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 4, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 0);
+  EXPECT_TRUE(cfg->use_compression);
+  EXPECT_TRUE(cfg->use_multithreading);
+  EXPECT_TRUE(cfg->use_metadata);
+
+  config_delete(cfg);
+}
+
 void test_client_cli() {
  test_cli_help();
  test_cli_archive_flags();
  test_cli_dry_run();
  test_cli_delete_flag();
  test_cli_exclude_patterns();
+  test_parse_args_help();
+  test_parse_args_version();
+  test_parse_args_valid_port();
+  test_parse_args_invalid_port();
+  test_parse_args_non_numeric_port();
+  test_parse_args_invalid_server_port();
+  test_parse_args_invalid_compression_level();
+  test_parse_args_valid_compression_level();
+  test_parse_args_unknown_option();
+  test_parse_args_rejects_unimplemented_options();
+  test_parse_args_archive();
 }
@@ -62,8 +62,8 @@ static void test_chunk_compress_decompress_roundtrip() {
  char* content2 = "chunk compression test file 2 with more data";
  unsigned long long len2 = strlen(content2);

-  to_disk(path1, content1, len1);
-  to_disk(path2, content2, len2);
+  to_disk(path1, content1, len1, false, false);
+  to_disk(path2, content2, len2, false, false);

  struct stat st1, st2;
  EXPECT_EQ_INT(stat(path1, &st1), 0);
@@ -323,6 +323,22 @@ static void test_large_file_delta() {
  free(new_data);
 }

+static void test_delta_apply_rejects_output_overflow() {
+  uint8_t old_data[8] = {0};
+  uint8_t literal_data[2] = {'x', 'y'};
+  DeltaInstruction instruction = {
+      .type = DELTA_INSTR_LITERAL,
+      .literal = {.data = literal_data, .length = sizeof(literal_data)},
+  };
+  Delta delta = {
+      .new_file_size = 1,
+      .instruction_count = 1,
+      .instructions = &instruction,
+  };
+
+  EXPECT_TRUE(delta_apply(old_data, sizeof(old_data), &delta, 1) == NULL);
+}
+
 void test_delta() {
  test_adler32_basic();
  test_adler32_different_data();
@@ -338,4 +354,5 @@ void test_delta() {
  test_should_attempt();
  test_is_worthwhile();
  test_large_file_delta();
+  test_delta_apply_rejects_output_overflow();
 }
@@ -34,7 +34,7 @@ static void test_file_destroy_normal() {

 static void test_file_load_data() {
  const char* content = "Hello Load Test";
-  EXPECT_TRUE(to_disk("test_file_load_data.txt", content, strlen(content)));
+  EXPECT_TRUE(to_disk("test_file_load_data.txt", content, strlen(content), false, false));

  struct stat st;
  EXPECT_EQ_INT(stat("test_file_load_data.txt", &st), 0);
@@ -89,7 +89,7 @@ static void test_file_save_to_disk() {

 static void test_to_disk_basic() {
  const char* content = "Basic to_disk test";
-  EXPECT_TRUE(to_disk("test_to_disk_basic.txt", content, strlen(content)));
+  EXPECT_TRUE(to_disk("test_to_disk_basic.txt", content, strlen(content), false, false));

  struct stat st;
  EXPECT_EQ_INT(stat("test_to_disk_basic.txt", &st), 0);
@@ -108,7 +108,7 @@ static void test_to_disk_basic() {

 static void test_to_disk_creates_dirs() {
  const char* content = "Nested dir test";
-  EXPECT_TRUE(to_disk("test_nested_tmp/nested/file.txt", content, strlen(content)));
+  EXPECT_TRUE(to_disk("test_nested_tmp/nested/file.txt", content, strlen(content), false, false));

  struct stat st;
  EXPECT_EQ_INT(stat("test_nested_tmp/nested/file.txt", &st), 0);
@@ -128,7 +128,7 @@ static void test_to_disk_creates_dirs() {

 static void test_file_content_to_buffer() {
  const char* content = "Buffer content test";
-  EXPECT_TRUE(to_disk("test_buffer_file.txt", content, strlen(content)));
+  EXPECT_TRUE(to_disk("test_buffer_file.txt", content, strlen(content), false, false));

  File* f = file_create("test_buffer_file.txt");
  EXPECT_NOT_NULL(f);
@@ -250,7 +250,7 @@ static void test_file_send_no_path() {
 }

 static void test_file_metadata_create() {
-  EXPECT_TRUE(to_disk("test_meta_file.txt", "metadata test", 13));
+  EXPECT_TRUE(to_disk("test_meta_file.txt", "metadata test", 13, false, false));
  struct stat st;
  EXPECT_EQ_INT(stat("test_meta_file.txt", &st), 0);

@@ -359,7 +359,7 @@ static void test_file_send_single_calls_metadata_and_path() {
  /* Create a real file on disk so we can have metadata */
  const char* content = "File with metadata";
  size_t len = strlen(content);
-  EXPECT_TRUE(to_disk("test_meta_send.txt", content, len));
+  EXPECT_TRUE(to_disk("test_meta_send.txt", content, len, false, false));

  struct stat st;
  EXPECT_EQ_INT(stat("test_meta_send.txt", &st), 0);
@@ -15,7 +15,7 @@
 static void test_sendfile_basic() {
  const char* content = "Hello from sendfile test!";
  size_t len = strlen(content);
-  EXPECT_TRUE(to_disk("test_sendfile_basic.txt", content, len));
+  EXPECT_TRUE(to_disk("test_sendfile_basic.txt", content, len, false, false));

  File* file = file_create("test_sendfile_basic.txt");
  EXPECT_NOT_NULL(file);
@@ -77,7 +77,7 @@ static void test_sendfile_basic() {
 static void test_sendfile_empty_file() {
  const char* content = "";
  size_t len = 0;
-  EXPECT_TRUE(to_disk("test_sendfile_empty.txt", content, len));
+  EXPECT_TRUE(to_disk("test_sendfile_empty.txt", content, len, false, false));

  File* file = file_create("test_sendfile_empty.txt");
  EXPECT_NOT_NULL(file);
@@ -156,7 +156,7 @@ static void test_sendfile_missing_file() {
 static void test_sendfile_compression_fallback() {
  const char* content = "Compression fallback content";
  size_t len = strlen(content);
-  EXPECT_TRUE(to_disk("test_sendfile_comp.txt", content, len));
+  EXPECT_TRUE(to_disk("test_sendfile_comp.txt", content, len, false, false));

  struct stat st;
  EXPECT_EQ_INT(stat("test_sendfile_comp.txt", &st), 0);
@@ -222,7 +222,7 @@ static void test_sendfile_compression_fallback() {
 static void test_sendfile_no_path() {
  const char* content = "No path sendfile test";
  size_t len = strlen(content);
-  EXPECT_TRUE(to_disk("test_sendfile_nopath.txt", content, len));
+  EXPECT_TRUE(to_disk("test_sendfile_nopath.txt", content, len, false, false));

  File* file = file_create("test_sendfile_nopath.txt");
  EXPECT_NOT_NULL(file);
@@ -101,7 +101,7 @@ static void test_fuzz_delta_deserialize() {
 /* Smoke test for metadata_from_buf fuzz target */
 static void test_fuzz_metadata_from_buf() {
  /* Create a real file to get metadata from */
-  EXPECT_TRUE(to_disk("fuzz_meta_test.txt", "metadata test", 13));
+  EXPECT_TRUE(to_disk("fuzz_meta_test.txt", "metadata test", 13, false, false));

  struct stat st;
  EXPECT_EQ_INT(stat("fuzz_meta_test.txt", &st), 0);
@@ -112,7 +112,7 @@ static void test_metadata_send_null() {
 static void test_file_restore_metadata() {
  const char* path = "temp_meta_restore_test.txt";
  const char* content = "test content";
-  EXPECT_TRUE(to_disk(path, content, strlen(content)));
+  EXPECT_TRUE(to_disk(path, content, strlen(content), false, false));

  FileMetadata m;
  m.mode = 0644;
@@ -84,7 +84,7 @@ static void test_property_chunk_roundtrip() {
    for (int i = 0; i < content_len; i++)
      content[i] = (char)(rand() % 256);

-    to_disk(path, content, content_len);
+    to_disk(path, content, content_len, false, false);

    struct stat st;
    stat(path, &st);
@@ -13,7 +13,7 @@
 static void test_chunk_deserialize_truncated() {
  char* path = "test_rob_trunc.txt";
  char* content = "hello";
-  to_disk(path, content, strlen(content));
+  to_disk(path, content, strlen(content), false, false);

  struct stat st;
  stat(path, &st);
@@ -7,7 +7,7 @@
 #include <unistd.h>

 static void create_test_file(const char* path, const char* content) {
-  (void)to_disk(path, content, strlen(content));
+  (void)to_disk(path, content, strlen(content), false, false);
 }

 static void test_scanner_single_file() {
@@ -23,8 +23,8 @@ static void test_server_delete_null() {
 static void test_client_create() {
  Client* c = client_create();
  EXPECT_NOT_NULL(c);
-  EXPECT_TRUE(c->file_descriptor >= 0);
-  EXPECT_EQ_INT(c->address.sin_family, AF_INET);
+  EXPECT_TRUE(c->file_descriptor == -1);
+  EXPECT_EQ_INT(c->address.ss_family, 0);
  EXPECT_EQ_INT(c->ssh_child_pid, -1);
  EXPECT_NULL(c->ssl);
  EXPECT_NULL(c->ssl_ctx);
Author	SHA1	Message	Date
TapTap	75040103d3	Merge pull request 'Remove unimplemented CLI options' (#209 ) from feat/remove-unimplemented-cli-options into evaluation-of-codebase-by-human CI / lint (pull_request) Successful in 25s Details CI / sanitizers (address) (pull_request) Successful in 35s Details CI / sanitizers (undefined) (pull_request) Successful in 35s Details CI / fuzz-build (pull_request) Successful in 13s Details CI / coverage (pull_request) Successful in 31s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details Reviewed-on: #209	2026-08-11 21:17:52 +02:00
TapTap	852e47a143	Satisfy cppcheck CLI and logger checks CI / lint (pull_request) Successful in 25s Details CI / sanitizers (address) (pull_request) Successful in 35s Details CI / sanitizers (undefined) (pull_request) Successful in 35s Details CI / fuzz-build (pull_request) Successful in 14s Details CI / coverage (pull_request) Successful in 31s Details CI / build-and-test (pull_request) Successful in 1m14s Details CI / valgrind (pull_request) Successful in 32s Details	2026-08-11 21:14:56 +02:00
TapTap	679e389ba6	Fix va_list cleanup in logger CI / lint (pull_request) Failing after 25s Details CI / build-and-test (pull_request) Has been skipped Details CI / sanitizers (address) (pull_request) Has been skipped Details CI / sanitizers (undefined) (pull_request) Has been skipped Details CI / fuzz-build (pull_request) Has been skipped Details CI / coverage (pull_request) Has been skipped Details CI / valgrind (pull_request) Has been skipped Details	2026-08-11 21:12:00 +02:00
TapTap	2e00fc31f2	Format CLI option test table CI / lint (pull_request) Failing after 25s Details CI / build-and-test (pull_request) Has been skipped Details CI / sanitizers (address) (pull_request) Has been skipped Details CI / sanitizers (undefined) (pull_request) Has been skipped Details CI / fuzz-build (pull_request) Has been skipped Details CI / coverage (pull_request) Has been skipped Details CI / valgrind (pull_request) Has been skipped Details	2026-08-11 21:08:54 +02:00
TapTap	d146e1bb7c	Remove unimplemented CLI options CI / lint (pull_request) Failing after 3s Details CI / build-and-test (pull_request) Has been skipped Details CI / sanitizers (address) (pull_request) Has been skipped Details CI / sanitizers (undefined) (pull_request) Has been skipped Details CI / fuzz-build (pull_request) Has been skipped Details CI / coverage (pull_request) Has been skipped Details CI / valgrind (pull_request) Has been skipped Details	2026-08-11 20:59:06 +02:00
TapTap	09fca8d931	start of human refactoring	2026-08-11 20:26:15 +02:00
TapTap	cb671bade0	Merge pull request 'fix: validate delta output and integration test skips' (#207 ) from fix/triage-delta-validation into dev Reviewed-on: #207	2026-08-08 20:17:38 +02:00
TapTap	4feb75957a	fix: validate delta output and integration test skips CI / lint (pull_request) Successful in 24s Details CI / sanitizers (address) (pull_request) Successful in 37s Details CI / sanitizers (undefined) (pull_request) Successful in 36s Details CI / fuzz-build (pull_request) Successful in 13s Details CI / coverage (pull_request) Successful in 30s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details	2026-08-08 20:09:06 +02:00
TapTap	d529360c01	Merge pull request 'refactor: extract CLI parser helpers, fix validation bugs' (#200 ) from refactor/cli-parser-helpers into dev Reviewed-on: #200	2026-08-08 20:02:09 +02:00
TapTap	8743d7f522	fix: address PR #200 review issues CI / lint (pull_request) Successful in 35s Details CI / sanitizers (undefined) (pull_request) Successful in 39s Details CI / fuzz-build (pull_request) Successful in 12s Details CI / sanitizers (address) (pull_request) Successful in 55s Details CI / coverage (pull_request) Successful in 30s Details CI / valgrind (pull_request) Successful in 32s Details CI / build-and-test (pull_request) Successful in 1m34s Details - Fix memory leak in delta_deserialize() on BLOCK_MATCH error path - Fix memory leak on malloc failure for literal data - Add port range validation (1-65535) for -p/--port and --server-port - Restore -V/--version flag with usage text - Use MAX_DATA_PAYLOAD_SIZE consistently (remove local MAX_DATA_SIZE) - Fix integer truncation in config_send/config_receive for delta_block_size - Add log messages for malloc failures - Extract config_set_defaults() helper to eliminate duplication - Add 10 new CLI tests for argument parsing	2026-08-08 20:01:48 +02:00
TapTap	05a74770ca	fix: address PR #200 review issues CI / lint (pull_request) Successful in 22s Details CI / sanitizers (address) (pull_request) Successful in 37s Details CI / sanitizers (undefined) (pull_request) Successful in 36s Details CI / fuzz-build (pull_request) Successful in 13s Details CI / coverage (pull_request) Successful in 31s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details - Restore PROTOCOL_VERSION to a forward-compatible 2.1.0 and document wire format - Add NULL guard to config_delete - Add pipeline cancellation flag and cancellation-aware queue helper - Join running threads before destroying pipeline contexts on creation failure - Fix NULL dereference and memory leaks in manifest/chunk handling - Fix TLS/TCP socket fd leak on connect error paths - Add compression-level range validation (1-22) - Close previous log file before opening a new one - Use getline for unbounded pattern-file lines - Fix thread-unsafe localtime() and add log level bounds check - Fix file_load_data to clean up data on read size mismatch - Add hard ceiling to decompression buffer growth - Fix mkdir_r bounds check and restore glob comments - Add send_str NULL guard and mutex-protect bandwidth limiter - Update AGENTS.md for per-thread io_ssl contract	2026-08-02 09:34:54 +02:00
TapTap	98cb8e212e	Merge pull request 'docs: rsync feature compatibility matrix' (#199 ) from docs/rsync-compat into dev Reviewed-on: #199	2026-08-02 09:20:37 +02:00
TapTap	dd11f70043	docs: fix review issues in rsync compatibility matrix CI / lint (pull_request) Successful in 2m19s Details CI / sanitizers (address) (pull_request) Successful in 37s Details CI / sanitizers (undefined) (pull_request) Successful in 38s Details CI / fuzz-build (pull_request) Successful in 13s Details CI / coverage (pull_request) Successful in 31s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details - Fix -l/--links: mark as Partial (symlink targets not transmitted) - Fix -p/--perms: mark as Alt Arg (-p means SSH port, not perms) - Fix -c/--checksum: mark as Alt Arg (-c means compression) - Fix --address note: correct config field name - Remove --whole-file duplicate (Section 5 and 11) - Remove --secluded-args duplicate (Section 15 and 17) - Fix --skip-compress note: clarify hardcoded, not user-configurable - Fix --block-size note: clarify delta transfer, not checksum blocks - Recount summary totals: 39/5/30/62 = 136 total	2026-08-02 09:14:35 +02:00
TapTap	0b68974b42	docs: add 🔀 Alt Arg status for features with different flag semantics CI / lint (pull_request) Successful in 2m19s Details CI / sanitizers (address) (pull_request) Successful in 36s Details CI / sanitizers (undefined) (pull_request) Successful in 35s Details CI / fuzz-build (pull_request) Successful in 14s Details CI / coverage (pull_request) Successful in 32s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details	2026-08-02 09:01:11 +02:00
TapTap	df41e8bd06	docs: add rsync feature compatibility matrix	2026-08-02 09:01:11 +02:00
TapTap	1064ae6c19	fix: address PR review issues in client_cli.c CI / lint (pull_request) Successful in 23s Details CI / sanitizers (address) (pull_request) Successful in 36s Details CI / sanitizers (undefined) (pull_request) Successful in 36s Details CI / fuzz-build (pull_request) Successful in 13s Details CI / coverage (pull_request) Successful in 32s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details - Fix FILE* leak when --log-file specified multiple times - Add strtoull endptr validation for --delta-block/--delta-max - Add range validation (1-22) for -c compression level	2026-08-01 18:42:02 +02:00
TapTap	bf91c5b588	merge: resolve conflict with dev, apply helpers to new options CI / lint (pull_request) Successful in 23s Details CI / sanitizers (address) (pull_request) Successful in 35s Details CI / sanitizers (undefined) (pull_request) Successful in 36s Details CI / fuzz-build (pull_request) Successful in 14s Details CI / coverage (pull_request) Successful in 31s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details	2026-08-01 18:14:55 +02:00
TapTap	5eaea9d92e	refactor: extract CLI parser helpers, fix validation bugs CI / lint (pull_request) Successful in 16s Details CI / sanitizers (undefined) (pull_request) Successful in 37s Details CI / sanitizers (address) (pull_request) Successful in 39s Details CI / fuzz-build (pull_request) Successful in 14s Details CI / coverage (pull_request) Successful in 32s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details - Add set_string_option(), set_positive_int_option(), set_nonneg_int_option() helpers to eliminate duplicated alloc/free/assign patterns - Replace 14 string-option branches with set_string_option() calls - Replace 7 integer-option branches with set_positive/nonneg_int_option() - Fix --info/--debug: replace atoi() with validated parse - Fix --max-size/--min-size: add strtoull() error checking - Fix --chunk-size: validate input with error message on failure	2026-08-01 18:12:41 +02:00
TapTap	9d67fcbf92	Merge pull request 'Batch fix: security, bugs, quality, and features (v2)' (#198 ) from integration/all-fixes-v2 into dev	2026-07-30 19:38:26 +02:00
TapTap	261683aaff	fix: null check in str_dup, const in file.c CI / lint (pull_request) Successful in 2m16s Details CI / sanitizers (address) (pull_request) Successful in 36s Details CI / sanitizers (undefined) (pull_request) Successful in 37s Details CI / fuzz-build (pull_request) Successful in 14s Details CI / coverage (pull_request) Successful in 30s Details CI / build-and-test (pull_request) Successful in 1m15s Details CI / valgrind (pull_request) Successful in 33s Details	2026-07-30 19:34:17 +02:00
TapTap	15a861747a	style: apply clang-format CI / lint (pull_request) Failing after 2m18s Details CI / build-and-test (pull_request) Has been skipped Details CI / sanitizers (address) (pull_request) Has been skipped Details CI / sanitizers (undefined) (pull_request) Has been skipped Details CI / fuzz-build (pull_request) Has been skipped Details CI / coverage (pull_request) Has been skipped Details CI / valgrind (pull_request) Has been skipped Details	2026-07-30 19:16:36 +02:00
TapTap	5f1b27c8ff	fix: security #192 #187 , bugs #194 #193 , quality #195 , features #174-#186 CI / lint (pull_request) Failing after 2s Details CI / build-and-test (pull_request) Has been skipped Details CI / sanitizers (address) (pull_request) Has been skipped Details CI / sanitizers (undefined) (pull_request) Has been skipped Details CI / fuzz-build (pull_request) Has been skipped Details CI / coverage (pull_request) Has been skipped Details CI / valgrind (pull_request) Has been skipped Details	2026-07-30 19:05:19 +02:00
TapTap	732cd67735	Merge remote-tracking branch 'origin/fix/features-v2' into integration/all-fixes-v2	2026-07-30 19:04:12 +02:00
TapTap	50fb7185a8	Merge remote-tracking branch 'origin/fix/quality-v2' into integration/all-fixes-v2	2026-07-30 19:04:12 +02:00
TapTap	3062927e07	Merge remote-tracking branch 'origin/fix/bugs-v2' into integration/all-fixes-v2	2026-07-30 19:04:12 +02:00
TapTap	5d74c7cb74	feat: rsync parity features #174-#186	2026-07-30 19:02:34 +02:00
TapTap	efc7e062e3	fix: bugs #194 (hostname resolution) and #193 (multithreaded progress) CI / lint (pull_request) Failing after 2s Details CI / build-and-test (pull_request) Has been skipped Details CI / sanitizers (address) (pull_request) Has been skipped Details CI / sanitizers (undefined) (pull_request) Has been skipped Details CI / fuzz-build (pull_request) Has been skipped Details CI / coverage (pull_request) Has been skipped Details CI / valgrind (pull_request) Has been skipped Details	2026-07-30 18:58:15 +02:00
TapTap	80768d64d4	fix: security issues #192 #191 #190 #189 #188 #187	2026-07-30 18:49:25 +02:00