Merge remote-tracking branch 'origin/feat/8-bit-output' into dev

# Conflicts:
#	src/client/client_cli.c
#	src/client/client_send.c
#	src/shared/config.c
#	tests/test_client_cli.c
#	tests/test_config.c
#	tests/test_shared_utils.c

RSYNC_COMPAT.md

@@ -43,7 +43,7 @@ This document maps rsync's full feature set to FastSync's current implementation
 | `--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 | |
+| `--8-bit-output`, `-8` | Leave high-bit chars unescaped | ✅ Implemented | Applies to displayed paths and protocol debug output |
 | `--list-only` | List files instead of copying | ❌ Not Implemented | Removed because it had no effect |
 
 ## 3. File Selection

src/client/client_cli.c

@@ -156,6 +156,7 @@ static const OptionEntry OPTION_TABLE[] = {
     {"--inplace", NULL, OPT_FLAG, offsetof(Config, inplace)},
     {"--fsync", NULL, OPT_FLAG, offsetof(Config, use_fsync)},
     {"--checksum", NULL, OPT_FLAG, offsetof(Config, checksum)},
+    {"--8-bit-output", "-8", OPT_FLAG, offsetof(Config, eight_bit_output)},
 
     {"--source-dir", NULL, OPT_STRING, offsetof(Config, send_directory)},
     {"--dest-dir", NULL, OPT_STRING, offsetof(Config, receive_root_directory)},
@@ -214,6 +215,7 @@ static int apply_table_option(Config* config, const OptionEntry* entry, const ch
 int parse_args(Config* config, int argc, char* argv[], int* positional_args,
                int* positional_count) {
   bool verbose = false;
+  protocol_set_8_bit_output(config->eight_bit_output);
   for (int i = 1; i < argc; i++) {
     const OptionEntry* entry = find_table_option(argv[i]);
     if (entry) {
@@ -227,6 +229,8 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
       } else if (apply_table_option(config, entry, NULL) != 0) {
         return -1;
       }
+      if (entry->offset == offsetof(Config, eight_bit_output))
+        protocol_set_8_bit_output(true);
       continue;
     }
 
@@ -302,7 +306,10 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
       log_message(LOG_LEVEL_INFO, "Enabled Chunk Serialization");
     } else if (opt_is(argv[i], "--server-port", NULL) && i + 1 < argc) {
       if (!parse_positive_int(argv[++i], &config->server_port)) {
-        log_message(LOG_LEVEL_ERROR, "invalid --server-port value: %s", argv[i]);
+        char* escaped = output_escape(argv[i], false);
+        log_message(LOG_LEVEL_ERROR, "invalid --server-port value: %s",
+                    escaped ? escaped : "<allocation failed>");
+        free(escaped);
         return -1;
       }
       if (config->server_port > 65535) {
@@ -340,7 +347,10 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
       }
       FILE* lf = fopen(argv[++i], "a");
       if (!lf) {
-        log_message(LOG_LEVEL_ERROR, "could not open log file '%s': %s", argv[i], strerror(errno));
+        char* escaped = output_escape(argv[i], false);
+        log_message(LOG_LEVEL_ERROR, "could not open log file '%s': %s",
+                    escaped ? escaped : "<allocation failed>", strerror(errno));
+        free(escaped);
         return -1;
       }
       config->log_file = lf;
@@ -368,14 +378,18 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
         return -1;
       }
     } else if (argv[i][0] == '-') {
-      fprintf(stderr, "Unknown option: %s\n", argv[i]);
+      char* escaped = output_escape(argv[i], false);
+      fprintf(stderr, "Unknown option: %s\n", escaped ? escaped : "<allocation failed>");
+      free(escaped);
       print_usage();
       return -1;
     } else {
       if (*positional_count < 2)
         positional_args[(*positional_count)++] = i;
       else {
-        fprintf(stderr, "Unexpected argument: %s\n", argv[i]);
+        char* escaped = output_escape(argv[i], false);
+        fprintf(stderr, "Unexpected argument: %s\n", escaped ? escaped : "<allocation failed>");
+        free(escaped);
         print_usage();
         return -1;
       }
@@ -388,7 +402,10 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
 static int read_patterns_from_file(const char* filepath, char*** patterns, int* count) {
   FILE* fp = fopen(filepath, "r");
   if (!fp) {
-    log_message(LOG_LEVEL_ERROR, "could not open pattern file '%s': %s", filepath, strerror(errno));
+    char* escaped = output_escape(filepath, false);
+    log_message(LOG_LEVEL_ERROR, "could not open pattern file '%s': %s",
+                escaped ? escaped : "<allocation failed>", strerror(errno));
+    free(escaped);
     return -1;
   }
   char* line = NULL;

src/client/client_send.c

@@ -233,11 +233,18 @@ static int send_dry_run_manifest(const Config* config) {
   while ((chunk = directory_scanner_next(scanner)) != NULL) {
     for (int i = 0; i < chunk->element_count; i++) {
       if (!config->quiet) {
+        char* escaped_path = output_escape(chunk->items[i]->path, config->eight_bit_output);
+        if (!escaped_path) {
+          chunk_destroy(chunk);
+          directory_scanner_destroy(scanner);
+          return -1;
+        }
         if (config->human_readable)
-          printf("  %s (%s)\n", chunk->items[i]->path,
+          printf("  %s (%s)\n", escaped_path,
                  display_bytes(chunk->items[i]->data->size, true, size_buffer, sizeof(size_buffer)));
         else
-          printf("  %s (%zu bytes)\n", chunk->items[i]->path, chunk->items[i]->data->size);
+          printf("  %s (%zu bytes)\n", escaped_path, chunk->items[i]->data->size);
+        free(escaped_path);
       }
       total_bytes += chunk->items[i]->data->size;
       file_count++;

src/client/usage.c

@@ -21,6 +21,7 @@ void print_usage(void) {
   printf("  --remove-source-files  Remove regular source files after successful transfer\n");
   printf("  -p <port>           SSH port (default: 22)\n");
   printf("  --progress          Show transfer progress\n");
+  printf("  -8, --8-bit-output  Leave high-bit characters unescaped in output\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");

src/server/server.c

@@ -232,6 +232,7 @@ void handler(int file_descriptor) {
     protocol_session_unbind();
     return;
   }
+  protocol_set_8_bit_output(config->eight_bit_output);
   if (!authorized_root) {
     log_message(LOG_LEVEL_ERROR, "No server-side destination root configured");
     config_delete(config);
@@ -400,12 +401,17 @@ int main(int argc, char* argv[]) {
       char* end;
       long p = strtol(argv[++i], &end, 10);
       if (*end || p <= 0 || p > 65535) {
-        fprintf(stderr, "Error: invalid port '%s' (must be 1-65535)\n", argv[i]);
+        char* escaped = output_escape(argv[i], false);
+        fprintf(stderr, "Error: invalid port '%s' (must be 1-65535)\n",
+                escaped ? escaped : "<allocation failed>");
+        free(escaped);
         return 1;
       }
       port = (int)p;
     } else if (argv[i][0] == '-') {
-      fprintf(stderr, "Unknown option: %s\n", argv[i]);
+      char* escaped = output_escape(argv[i], false);
+      fprintf(stderr, "Unknown option: %s\n", escaped ? escaped : "<allocation failed>");
+      free(escaped);
       print_server_usage();
       return 1;
     }
@@ -415,7 +421,10 @@ int main(int argc, char* argv[]) {
   signal(SIGINT, cleanup);
   signal(SIGTERM, cleanup);
   if (!configure_authorization(destination_root)) {
-    fprintf(stderr, "Error: invalid destination root '%s'\n", destination_root);
+    char* escaped = output_escape(destination_root, false);
+    fprintf(stderr, "Error: invalid destination root '%s'\n",
+            escaped ? escaped : "<allocation failed>");
+    free(escaped);
     return 1;
   }
   if (stdio_mode) {

src/shared/config.c

@@ -69,6 +69,7 @@ static void config_set_defaults(Config* config) {
   config->debug_level = 0;
   config->list_only = false;
   config->human_readable = false;
+  config->eight_bit_output = false;
   config->update = false;
   config->inplace = false;
   config->use_fsync = false;
@@ -131,7 +132,7 @@ static bool validate_received_config(const Config* config) {
          valid_wire_bool(config->delete_excluded) && valid_wire_bool(config->delete_after) &&
          valid_wire_bool(config->relative) && valid_wire_bool(config->prune_empty_dirs) &&
          valid_wire_bool(config->partial) && valid_wire_bool(config->delete_before) &&
-         valid_wire_bool(config->checksum) &&
+         valid_wire_bool(config->checksum) && valid_wire_bool(config->eight_bit_output) &&
          (!config->use_compression ||
           (config->compression_level >= 1 && config->compression_level <= 22)) &&
          config->chunk_size > 0 && config->chunk_size <= MAX_CHUNK_SIZE &&
@@ -221,11 +222,13 @@ void config_delete(Config* config) {
  * helper call order in config_send and config_receive unchanged when adding
  * fields. */
 static bool send_core_fields(int fd, const Config* c) {
-  return send_str(fd, c->version) && send_str(fd, c->send_directory) &&
-         send_str(fd, c->receive_root_directory) && send_int(fd, c->save_to_disk) &&
-         send_int(fd, c->use_multithreading) && send_int(fd, c->use_chunk_serialization) &&
-         send_int(fd, c->use_compression) && send_int(fd, c->use_metadata) &&
-         send_int(fd, c->compression_level) &&
+  if (!send_str(fd, c->version) || !send_int(fd, c->eight_bit_output))
+    return false;
+  protocol_set_8_bit_output(c->eight_bit_output);
+  return send_str(fd, c->send_directory) && send_str(fd, c->receive_root_directory) &&
+         send_int(fd, c->save_to_disk) && send_int(fd, c->use_multithreading) &&
+         send_int(fd, c->use_chunk_serialization) && send_int(fd, c->use_compression) &&
+         send_int(fd, c->use_metadata) && send_int(fd, c->compression_level) &&
          send_n_data(fd, &c->chunk_size, sizeof(c->chunk_size)) && send_int(fd, c->use_sendfile);
 }
 
@@ -262,6 +265,9 @@ static bool send_resume_options(int fd, const Config* c) {
 
 static bool receive_core_fields(int fd, Config* c) {
   int value;
+  if (!receive_wire_bool(fd, &c->eight_bit_output))
+    return false;
+  protocol_set_8_bit_output(c->eight_bit_output);
   c->send_directory = receive_str(fd);
   c->receive_root_directory = receive_str(fd);
   if (!c->send_directory || !c->receive_root_directory)
@@ -362,8 +368,10 @@ Config* config_receive(int file_descriptor) {
   if (!config->version)
     goto error;
   if (strcmp(config->version, PROTOCOL_VERSION) != 0) {
-    fprintf(stderr, "Protocol version mismatch: client=%s, server=%s\n", config->version,
-            PROTOCOL_VERSION);
+    char* escaped_version = output_escape(config->version, false);
+    fprintf(stderr, "Protocol version mismatch: client=%s, server=%s\n",
+            escaped_version ? escaped_version : "<allocation failed>", PROTOCOL_VERSION);
+    free(escaped_version);
     send_status(file_descriptor, STATUS_ERROR);
     goto error;
   }
@@ -375,7 +383,10 @@ Config* config_receive(int file_descriptor) {
     goto error;
   if (config->compress_choice[0] != '\0' && strcmp(config->compress_choice, "zstd") != 0 &&
       strcmp(config->compress_choice, "none") != 0) {
-    fprintf(stderr, "Unsupported compression choice: %s\n", config->compress_choice);
+    char* escaped_choice = output_escape(config->compress_choice, config->eight_bit_output);
+    fprintf(stderr, "Unsupported compression choice: %s\n",
+            escaped_choice ? escaped_choice : "<allocation failed>");
+    free(escaped_choice);
     send_status(file_descriptor, STATUS_ERROR);
     goto error;
   }

src/shared/config.h

@@ -75,6 +75,7 @@ typedef struct Config {
   int debug_level;
   bool list_only;
   bool human_readable;
+  bool eight_bit_output;
 
   // Issue #127: Transfer modes
   bool update;

src/shared/file_receive.c

@@ -332,7 +332,10 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
   }
 
   if (has_path_traversal(check_path)) {
-    log_message(LOG_LEVEL_ERROR, "Path traversal detected: %s", check_path);
+    char* escaped_path = output_escape(check_path, log_get_8_bit_output());
+    log_message(LOG_LEVEL_ERROR, "Path traversal detected: %s",
+                escaped_path ? escaped_path : "<allocation failed>");
+    free(escaped_path);
     free(check_path);
     return NULL;
   }
@@ -479,7 +482,10 @@ File* file_receive(const Config* config, int file_descriptor) {
   if (path == NULL)
     return NULL;
   if (path[0] == '\0' || has_path_traversal(path)) {
-    log_message(LOG_LEVEL_ERROR, "Invalid received file path: %s", path);
+    char* escaped_path = output_escape(path, log_get_8_bit_output());
+    log_message(LOG_LEVEL_ERROR, "Invalid received file path: %s",
+                escaped_path ? escaped_path : "<allocation failed>");
+    free(escaped_path);
     free(path);
     return NULL;
   }

src/shared/log.c

@@ -8,6 +8,7 @@
 static const char* log_level_strings[] = {"DEBUG", "INFO", "WARN", "ERROR"};
 static LogLevel current_log_level = LOG_LEVEL_WARNING;
 static FILE* log_fp = NULL;
+static _Thread_local bool eight_bit_output;
 
 void set_log_level(LogLevel level) {
   current_log_level = level;
@@ -17,6 +18,14 @@ void log_set_file(FILE* fp) {
   log_fp = fp;
 }
 
+void log_set_8_bit_output(bool enabled) {
+  eight_bit_output = enabled;
+}
+
+bool log_get_8_bit_output(void) {
+  return eight_bit_output;
+}
+
 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,

src/shared/log.h

@@ -2,6 +2,7 @@
 #define LOG_H
 
 #include <stdio.h>
+#include <stdbool.h>
 
 typedef enum { LOG_LEVEL_DEBUG, LOG_LEVEL_INFO, LOG_LEVEL_WARNING, LOG_LEVEL_ERROR } LogLevel;
 
@@ -9,5 +10,7 @@ void log_message(LogLevel log_level, const char* message, ...);
 void log_perror(const char* context);
 void set_log_level(LogLevel level);
 void log_set_file(FILE* fp);
+void log_set_8_bit_output(bool enabled);
+bool log_get_8_bit_output(void);
 
 #endif

src/shared/metadata.c

@@ -2,6 +2,7 @@
 #include "file.h"
 #include "log.h"
 #include "protocol.h"
+#include "utils.h"
 #include <errno.h>
 #include <fcntl.h>
 #include <stdint.h>
@@ -183,8 +184,12 @@ void file_restore_metadata(const char* path, const FileMetadata* metadata) {
   if (metadata == NULL)
     return;
   mode_t safe_mode = metadata->mode & 0777 & ~(S_IWGRP | S_IWOTH);
-  if (chmod(path, safe_mode) != 0)
-    log_message(LOG_LEVEL_WARNING, "Failed to chmod %s: %s", path, strerror(errno));
+  if (chmod(path, safe_mode) != 0) {
+    char* escaped_path = output_escape(path, log_get_8_bit_output());
+    log_message(LOG_LEVEL_WARNING, "Failed to chmod %s: %s",
+                escaped_path ? escaped_path : "<allocation failed>", strerror(errno));
+    free(escaped_path);
+  }
   /* Never apply client-supplied ownership.  The descriptor API below is the
      receiver write path; retain this legacy API only for compatibility. */
   struct timespec times[2];
@@ -192,8 +197,12 @@ void file_restore_metadata(const char* path, const FileMetadata* metadata) {
   times[0].tv_nsec = UTIME_OMIT;
   times[1].tv_sec = metadata->mtime_sec;
   times[1].tv_nsec = metadata->mtime_nsec;
-  if (utimensat(AT_FDCWD, path, times, 0) != 0)
-    log_message(LOG_LEVEL_WARNING, "Failed to set timestamps on %s: %s", path, strerror(errno));
+  if (utimensat(AT_FDCWD, path, times, 0) != 0) {
+    char* escaped_path = output_escape(path, log_get_8_bit_output());
+    log_message(LOG_LEVEL_WARNING, "Failed to set timestamps on %s: %s",
+                escaped_path ? escaped_path : "<allocation failed>", strerror(errno));
+    free(escaped_path);
+  }
 }
 
 bool file_restore_metadata_fd(int fd, const FileMetadata* metadata) {

src/shared/protocol.c

@@ -1,5 +1,6 @@
 #include "protocol.h"
 #include "log.h"
+#include "utils.h"
 #include <errno.h>
 #include <limits.h>
 #include <openssl/ssl.h>
@@ -44,6 +45,7 @@ void io_set_fds(int read_fd, int write_fd) {
   legacy_io_session.read_fd = read_fd;
   legacy_io_session.write_fd = write_fd;
   legacy_io_session.ssl = NULL;
+  legacy_io_session.eight_bit_output = false;
   legacy_io_session.total_allocated_bytes = 0;
   protocol_session_set_bwlimit(&legacy_io_session, global_bwlimit());
 }
@@ -59,6 +61,7 @@ void protocol_session_init(ProtocolSession* session, int read_fd, int write_fd)
 
 void protocol_session_bind(ProtocolSession* session) {
   bound_session = session;
+  log_set_8_bit_output(session && session->eight_bit_output);
 }
 
 void protocol_session_unbind(void) {
@@ -103,6 +106,19 @@ void protocol_session_set_bwlimit(ProtocolSession* session, unsigned long long b
   session->bw_last_refill_nsec = now.tv_nsec;
 }
 
+void protocol_session_set_8_bit_output(ProtocolSession* session, bool enabled) {
+  if (!session)
+    return;
+  session->eight_bit_output = enabled;
+  if (session == bound_session)
+    log_set_8_bit_output(enabled);
+}
+
+void protocol_set_8_bit_output(bool enabled) {
+  ProtocolSession* session = bound_session ? bound_session : &legacy_io_session;
+  protocol_session_set_8_bit_output(session, enabled);
+}
+
 static void bw_throttle_session(ProtocolSession* session, size_t bytes_written) {
   if (session->bwlimit == 0)
     return;
@@ -328,7 +344,9 @@ bool protocol_send_str(ProtocolSession* session, const char* data) {
     return false;
   if (!protocol_send_n_data(session, data, size))
     return false;
-  log_message(LOG_LEVEL_DEBUG, "Send String: %s", data);
+  char* escaped = output_escape(data, session->eight_bit_output);
+  log_message(LOG_LEVEL_DEBUG, "Send String: %s", escaped ? escaped : "<allocation failed>");
+  free(escaped);
   return true;
 }
 
@@ -356,7 +374,9 @@ char* protocol_receive_str(ProtocolSession* session) {
   }
   data[size] = '\0';
   session->total_allocated_bytes += size + 1;
-  log_message(LOG_LEVEL_DEBUG, "Received String: %s", data);
+  char* escaped = output_escape(data, session->eight_bit_output);
+  log_message(LOG_LEVEL_DEBUG, "Received String: %s", escaped ? escaped : "<allocation failed>");
+  free(escaped);
   return data;
 }
 

src/shared/protocol.h

@@ -36,6 +36,7 @@ typedef struct ProtocolSession {
   long long bw_last_refill_sec;
   long bw_last_refill_nsec;
   unsigned long long total_allocated_bytes;
+  bool eight_bit_output;
 } ProtocolSession;
 
 typedef int Status;
@@ -65,6 +66,8 @@ void protocol_session_bind(ProtocolSession* session);
 void protocol_session_unbind(void);
 void protocol_session_set_ssl(ProtocolSession* session, SSL* ssl);
 void protocol_session_set_bwlimit(ProtocolSession* session, unsigned long long bytes_per_sec);
+void protocol_session_set_8_bit_output(ProtocolSession* session, bool enabled);
+void protocol_set_8_bit_output(bool enabled);
 bool protocol_send_n_data(ProtocolSession* session, const void* data, size_t data_size);
 bool protocol_receive_n_data(ProtocolSession* session, void* data, size_t data_size);
 bool protocol_send_str(ProtocolSession* session, const char* data);

src/shared/transport_ssh.c

@@ -71,7 +71,9 @@ static int parse_remote_dest(const char* dest, RemoteDest* r) {
 Client* client_connect_ssh(const char* destination, int port, const char* server_path) {
   RemoteDest r;
   if (parse_remote_dest(destination, &r) != 0) {
-    fprintf(stderr, "Invalid remote destination: %s\n", destination);
+    char* escaped = output_escape(destination, false);
+    fprintf(stderr, "Invalid remote destination: %s\n", escaped ? escaped : "<allocation failed>");
+    free(escaped);
     return NULL;
   }
 
@@ -169,8 +171,11 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
     close(sv[0]);
     waitpid(pid, NULL, 0);
     remote_dest_destroy(&r);
+    const char* path = server_path ? server_path : "fastsync-server";
+    char* escaped = output_escape(path, false);
     fprintf(stderr, "Error: could not launch '%s --stdio' on remote\n",
-            server_path ? server_path : "fastsync-server");
+            escaped ? escaped : "<allocation failed>");
+    free(escaped);
     return NULL;
   }
 

src/shared/transport_tcp.c

@@ -1,6 +1,7 @@
 #include "transport_tcp.h"
 #include "log.h"
 #include "protocol.h"
+#include "utils.h"
 #include <arpa/inet.h>
 #include <errno.h>
 #include <netdb.h>
@@ -190,7 +191,10 @@ bool tcp_connect_socket(Client* client, char* host, int 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));
+    char* escaped_host = output_escape(host, false);
+    fprintf(stderr, "Could not resolve host: %s (%s)\n",
+            escaped_host ? escaped_host : "<allocation failed>", gai_strerror(err));
+    free(escaped_host);
     return false;
   }
 

src/shared/transport_tls.c

@@ -2,6 +2,7 @@
 #include "log.h"
 #include "protocol.h"
 #include "transport_tcp.h"
+#include "utils.h"
 #include <arpa/inet.h>
 #include <openssl/err.h>
 #include <openssl/ssl.h>
@@ -65,13 +66,19 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
       return NULL;
     }
     if (SSL_CTX_use_certificate_file(ctx, cert, SSL_FILETYPE_PEM) <= 0) {
-      log_message(LOG_LEVEL_ERROR, "Failed to load certificate: %s", cert);
+      char* escaped = output_escape(cert, false);
+      log_message(LOG_LEVEL_ERROR, "Failed to load certificate: %s",
+                  escaped ? escaped : "<allocation failed>");
+      free(escaped);
       log_ssl_errors();
       SSL_CTX_free(ctx);
       return NULL;
     }
     if (SSL_CTX_use_PrivateKey_file(ctx, key, SSL_FILETYPE_PEM) <= 0) {
-      log_message(LOG_LEVEL_ERROR, "Failed to load private key: %s", key);
+      char* escaped = output_escape(key, false);
+      log_message(LOG_LEVEL_ERROR, "Failed to load private key: %s",
+                  escaped ? escaped : "<allocation failed>");
+      free(escaped);
       log_ssl_errors();
       SSL_CTX_free(ctx);
       return NULL;
@@ -85,7 +92,10 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
 
   if (ca_path) {
     if (!SSL_CTX_load_verify_locations(ctx, ca_path, NULL)) {
-      log_message(LOG_LEVEL_ERROR, "Failed to load CA: %s", ca_path);
+      char* escaped = output_escape(ca_path, false);
+      log_message(LOG_LEVEL_ERROR, "Failed to load CA: %s",
+                  escaped ? escaped : "<allocation failed>");
+      free(escaped);
       log_ssl_errors();
       SSL_CTX_free(ctx);
       return NULL;

src/shared/utils.c

@@ -1,6 +1,7 @@
 #include "utils.h"
 #include "array_list.h"
 #include "libgen.h"
+#include "log.h"
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -132,6 +133,32 @@ char* str_dup(const char* string) {
   return new_string;
 }
 
+char* output_escape(const char* string, bool eight_bit_output) {
+  if (!string)
+    return NULL;
+  size_t length = strlen(string);
+  if (length > (SIZE_MAX - 1) / 5)
+    return NULL;
+  char* escaped = malloc(length * 5 + 1);
+  if (!escaped)
+    return NULL;
+  size_t out = 0;
+  for (size_t i = 0; i < length; i++) {
+    unsigned char byte = (unsigned char)string[i];
+    if ((byte >= 32 && byte <= 126) || (eight_bit_output && byte >= 128)) {
+      escaped[out++] = (char)byte;
+    } else {
+      escaped[out++] = '\\';
+      escaped[out++] = '#';
+      escaped[out++] = (char)('0' + ((byte >> 6) & 7));
+      escaped[out++] = (char)('0' + ((byte >> 3) & 7));
+      escaped[out++] = (char)('0' + (byte & 7));
+    }
+  }
+  escaped[out] = '\0';
+  return escaped;
+}
+
 /* Match a glob pattern against a string. Supported wildcards:
  *   ?      matches any single character except '/'.
  *   *      matches any sequence of characters within one path component (no '/').
@@ -293,7 +320,9 @@ static bool delete_extras_fd(int dirfd, const char* rel_path, ArrayList* manifes
         } else {
           (*deleted_count)++;
         }
-        fprintf(stderr, "  Deleted: %s\n", child_rel);
+        char* escaped_path = output_escape(child_rel, log_get_8_bit_output());
+        fprintf(stderr, "  Deleted: %s\n", escaped_path ? escaped_path : "<allocation failed>");
+        free(escaped_path);
       }
     }
     free(child_rel);

src/shared/utils.h

@@ -7,6 +7,7 @@
 
 bool mkdir_r(const char* path);
 char* str_dup(const char* string);
+char* output_escape(const char* string, bool eight_bit_output);
 char* path_cat(const char* path1, const char* path2);
 bool glob_match(const char* pattern, const char* str);
 bool delete_extras(const char* dest_root, ArrayList* manifest);

tests/test_client_cli.c

@@ -397,6 +397,24 @@ static void test_parse_args_fsync() {
   config_delete(cfg);
 }
 
+static void test_parse_args_8_bit_output() {
+  Config* cfg = config_create();
+  char* long_argv[] = {"fastsync", "--8-bit-output", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  EXPECT_EQ_INT(parse_args(cfg, 4, long_argv, positional_args, &positional_count), 0);
+  EXPECT_TRUE(cfg->eight_bit_output);
+  config_delete(cfg);
+
+  cfg = config_create();
+  char* short_argv[] = {"fastsync", "-8", "/src", "/dst"};
+  positional_count = 0;
+  EXPECT_EQ_INT(parse_args(cfg, 4, short_argv, positional_args, &positional_count), 0);
+  EXPECT_TRUE(cfg->eight_bit_output);
+  config_delete(cfg);
+}
+
 void test_client_cli() {
   test_validate_config_required_paths();
   test_validate_config_incompatible_options();
@@ -423,4 +441,5 @@ void test_client_cli() {
   test_parse_args_human_readable();
   test_parse_args_archive();
   test_parse_args_fsync();
+  test_parse_args_8_bit_output();
 }

tests/test_config.c

@@ -127,6 +127,7 @@ static void test_config_send_receive() {
   send_cfg->use_fsync = true;
   send_cfg->compression_level = 5;
   send_cfg->chunk_size = 1024;
+  send_cfg->eight_bit_output = true;
 
   /* Use socketpair for bidirectional communication */
   int p[2];
@@ -163,6 +164,7 @@ static void test_config_send_receive() {
         ok = false;
       if (!recv_cfg->use_fsync)
         ok = false;
+      if (!recv_cfg->eight_bit_output)
     }
     config_delete(recv_cfg);
     close(p[0]);

tests/test_shared_utils.c

@@ -1,8 +1,27 @@
 #include "test_shared_utils.h"
 #include "utils.h"
+#include "protocol.h"
 #include "test_utils.h"
 #include <stdlib.h>
 #include <string.h>
+#include <threads.h>
+
+typedef struct {
+  bool eight_bit_output;
+  const char* expected;
+  int failed;
+} EscapeThreadArgs;
+
+static int escape_thread(void* arg) {
+  EscapeThreadArgs* args = arg;
+  for (int i = 0; i < 1000; i++) {
+    char* escaped = output_escape("x\xc3\xa9\n", args->eight_bit_output);
+    if (!escaped || strcmp(escaped, args->expected) != 0)
+      args->failed = 1;
+    free(escaped);
+  }
+  return 0;
+}
 
 void test_shared_utils() {
   char formatted[32];
@@ -14,6 +33,34 @@ void test_shared_utils() {
   EXPECT_EQ_STR(formatted, "1.5 MB");
   EXPECT_FALSE(format_human_bytes(1024, formatted, 4));
 
+  char high_bit[] = {'a', (char)0xc3, (char)0xa9, '\n', '\0'};
+  char* escaped = output_escape(high_bit, false);
+  EXPECT_EQ_STR(escaped, "a\\#303\\#251\\#012");
+  free(escaped);
+  escaped = output_escape(high_bit, true);
+  EXPECT_EQ_STR(escaped, "a\xc3\xa9\\#012");
+  free(escaped);
+
+  ProtocolSession safe_session;
+  ProtocolSession eight_bit_session;
+  protocol_session_init(&safe_session, -1, -1);
+  protocol_session_init(&eight_bit_session, -1, -1);
+  protocol_session_set_8_bit_output(&safe_session, false);
+  protocol_session_set_8_bit_output(&eight_bit_session, true);
+  EXPECT_FALSE(safe_session.eight_bit_output);
+  EXPECT_TRUE(eight_bit_session.eight_bit_output);
+
+  EscapeThreadArgs safe_args = {false, "x\\#303\\#251\\#012", 0};
+  EscapeThreadArgs eight_bit_args = {true, "x\xc3\xa9\\#012", 0};
+  thrd_t safe_thread;
+  thrd_t eight_bit_thread;
+  EXPECT_EQ_INT(thrd_create(&safe_thread, escape_thread, &safe_args), thrd_success);
+  EXPECT_EQ_INT(thrd_create(&eight_bit_thread, escape_thread, &eight_bit_args), thrd_success);
+  EXPECT_EQ_INT(thrd_join(safe_thread, NULL), thrd_success);
+  EXPECT_EQ_INT(thrd_join(eight_bit_thread, NULL), thrd_success);
+  EXPECT_FALSE(safe_args.failed);
+  EXPECT_FALSE(eight_bit_args.failed);
+
   // Test str_dup
   const char* dup_null = str_dup(NULL);
   EXPECT_NULL(dup_null);