fix: address review findings — sendfile EINTR, path traversal check

Reviewed-on: #86

src/client/client_cli.c

@@ -55,7 +55,9 @@ static void print_usage(void) {
   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("  --partial           Keep partial files on interrupted transfer\n");
   printf("  --help              Show this help\n");
+  printf("  -V, --version       Show version and exit\n");
 }
 
 int main(int argc, char* argv[]) {
@@ -80,6 +82,9 @@ int main(int argc, char* argv[]) {
     if (strcmp(argv[i], "--help") == 0) {
       print_usage();
       goto cleanup;
+    } else if (strcmp(argv[i], "-V") == 0 || strcmp(argv[i], "--version") == 0) {
+      printf("fastsync version %s\n", PROTOCOL_VERSION);
+      goto cleanup;
     } else if (strcmp(argv[i], "-a") == 0 || strcmp(argv[i], "--archive") == 0) {
       config->use_compression = true;
       config->use_multithreading = true;
@@ -88,7 +93,14 @@ int main(int argc, char* argv[]) {
     } 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) {
-      config->ssh_port = atoi(argv[++i]);
+      char* end;
+      long p = strtol(argv[++i], &end, 10);
+      if (*end != '\0' || p <= 0 || p > 65535) {
+        fprintf(stderr, "Error: invalid SSH port '%s' (must be 1-65535)\n", argv[i]);
+        exit_code = 1;
+        goto cleanup;
+      }
+      config->ssh_port = (int)p;
     } else if (strcmp(argv[i], "--delete") == 0) {
       config->use_delete = true;
     } else if (strcmp(argv[i], "--exclude") == 0 && i + 1 < argc) {
@@ -165,7 +177,14 @@ int main(int argc, char* argv[]) {
       free(config->server_host);
       config->server_host = str_dup(argv[++i]);
     } else if (strcmp(argv[i], "--server-port") == 0 && i + 1 < argc) {
-      config->server_port = atoi(argv[++i]);
+      char* end;
+      long p = strtol(argv[++i], &end, 10);
+      if (*end != '\0' || p <= 0 || p > 65535) {
+        fprintf(stderr, "Error: invalid server port '%s' (must be 1-65535)\n", argv[i]);
+        exit_code = 1;
+        goto cleanup;
+      }
+      config->server_port = (int)p;
     } else if (strcmp(argv[i], "--bwlimit") == 0 && i + 1 < argc) {
       char* end;
       errno = 0;
@@ -199,6 +218,8 @@ int main(int argc, char* argv[]) {
     } else if (strcmp(argv[i], "--ca") == 0 && i + 1 < argc) {
       free(config->tls_ca);
       config->tls_ca = str_dup(argv[++i]);
+    } else if (strcmp(argv[i], "--partial") == 0) {
+      config->partial = true;
     } else if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
       set_log_level(LOG_LEVEL_DEBUG);
     } else if (argv[i][0] == '-') {

src/client/scanner.c

@@ -16,6 +16,17 @@ DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metada
                                            int exclude_count, char** include_patterns,
                                            int include_count, unsigned long long max_size,
                                            unsigned long long min_size) {
+  return directory_scanner_create_full(root_directory, use_metadata, chunk_size, exclude_patterns,
+                                       exclude_count, include_patterns, include_count, max_size,
+                                       min_size, true);
+}
+
+DirectoryScanner* directory_scanner_create_full(char* root_directory, bool use_metadata,
+                                                unsigned long long chunk_size,
+                                                char** exclude_patterns, int exclude_count,
+                                                char** include_patterns, int include_count,
+                                                unsigned long long max_size,
+                                                unsigned long long min_size, bool follow_symlinks) {
   DirectoryScanner* scanner = malloc(sizeof(DirectoryScanner));
   if (scanner == NULL)
     return NULL;
@@ -79,6 +90,7 @@ DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metada
   scanner->include_count = include_count;
   scanner->max_size = max_size;
   scanner->min_size = min_size;
+  scanner->follow_symlinks = follow_symlinks;
   queue_enqueue(scanner->directories, str_dup(root_directory));
   return scanner;
 }
@@ -159,13 +171,81 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {
 
     char* cur_path = path_cat(scanner->current_path, entry->d_name);
     struct stat stats;
-    if (stat(cur_path, &stats) != 0) {
+    // Use lstat to detect symlinks
+    if (lstat(cur_path, &stats) != 0) {
       free(cur_path);
       continue;
     }
 
+    // If follow_symlinks is enabled and this is a symlink, resolve it
+    if (scanner->follow_symlinks && S_ISLNK(stats.st_mode)) {
+      struct stat target_stats;
+      if (stat(cur_path, &target_stats) != 0) {
+        // Broken symlink, skip
+        free(cur_path);
+        continue;
+      }
+      stats = target_stats;
+    }
+
     if (S_ISDIR(stats.st_mode)) {
       queue_enqueue(scanner->directories, (void*)cur_path);
+    } else if (S_ISLNK(stats.st_mode)) {
+      // Handle symlink (not following)
+      bool excluded = false;
+      for (int i = 0; i < scanner->exclude_count; i++) {
+        if (glob_match(scanner->exclude_patterns[i], entry->d_name)) {
+          excluded = true;
+          break;
+        }
+      }
+      if (excluded) {
+        free(cur_path);
+        continue;
+      }
+
+      if (scanner->include_count > 0) {
+        bool included = false;
+        for (int i = 0; i < scanner->include_count; i++) {
+          if (glob_match(scanner->include_patterns[i], entry->d_name)) {
+            included = true;
+            break;
+          }
+        }
+        if (!included) {
+          free(cur_path);
+          continue;
+        }
+      }
+
+      File* file = file_create(cur_path);
+      if (file == NULL) {
+        free(cur_path);
+        continue;
+      }
+      file->type = FILE_TYPE_SYMLINK;
+      // Read link target
+      char link_buf[4096];
+      ssize_t link_len = readlink(cur_path, link_buf, sizeof(link_buf) - 1);
+      if (link_len >= 0) {
+        link_buf[link_len] = '\0';
+        file->link_target = str_dup(link_buf);
+        if (file->link_target == NULL) {
+          file_destroy(file);
+          free(cur_path);
+          continue;
+        }
+      }
+      file->data->size = 0;
+      if (scanner->use_metadata)
+        file->metadata = file_metadata_create(&stats);
+      array_list_add(chunk_data, file);
+      chunk_data_size += 1; // small size for symlinks
+      if (chunk_data_size > scanner->chunk_size) {
+        free(cur_path);
+        return chunk_data_to_chunk(chunk_data);
+      }
+      free(cur_path);
     } else {
       bool excluded = false;
       for (int i = 0; i < scanner->exclude_count; i++) {

src/client/scanner.h

@@ -18,6 +18,7 @@ typedef struct {
   int include_count;
   unsigned long long max_size;
   unsigned long long min_size;
+  bool follow_symlinks;
 } DirectoryScanner;
 
 DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metadata,
@@ -25,6 +26,12 @@ DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metada
                                            int exclude_count, char** include_patterns,
                                            int include_count, unsigned long long max_size,
                                            unsigned long long min_size);
+DirectoryScanner* directory_scanner_create_full(char* root_directory, bool use_metadata,
+                                                unsigned long long chunk_size,
+                                                char** exclude_patterns, int exclude_count,
+                                                char** include_patterns, int include_count,
+                                                unsigned long long max_size,
+                                                unsigned long long min_size, bool follow_symlinks);
 Chunk* directory_scanner_next(DirectoryScanner* scanner);
 void directory_scanner_destroy(DirectoryScanner* scanner);
 

src/server/server.c

@@ -11,11 +11,47 @@
 #include "transport_tls.h"
 #include "unistd.h"
 #include "utils.h"
+#include <libgen.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+// Check if a file path should be excluded based on config patterns
+static bool is_excluded(const char* path, const Config* config) {
+  // Extract filename from path
+  char* path_dup = str_dup(path);
+  if (!path_dup)
+    return false;
+  char* fname = basename(path_dup);
+
+  // Check exclude patterns
+  for (int i = 0; i < config->exclude_count; i++) {
+    if (glob_match(config->exclude_patterns[i], fname)) {
+      free(path_dup);
+      return true;
+    }
+  }
+
+  // Check include patterns (if any, file must match at least one)
+  if (config->include_count > 0) {
+    bool included = false;
+    for (int i = 0; i < config->include_count; i++) {
+      if (glob_match(config->include_patterns[i], fname)) {
+        included = true;
+        break;
+      }
+    }
+    if (!included) {
+      free(path_dup);
+      return true;
+    }
+  }
+
+  free(path_dup);
+  return false;
+}
+
 int receive_files(Config* config, int fd) {
   Status status;
   if (!receive_status(fd, &status))
@@ -29,7 +65,7 @@ int receive_files(Config* config, int fd) {
         goto next;
       if (file == NULL && !skipped)
         return -1;
-      if (config->save_to_disk)
+      if (config->save_to_disk && !is_excluded(file->path, config))
         file_save_to_disk(config->receive_root_directory, file);
       file_destroy(file);
     } else if (status == STATUS_CHUNK) {
@@ -39,7 +75,7 @@ int receive_files(Config* config, int fd) {
         return -1;
       }
       for (int i = 0; i < chunk->element_count; i++) {
-        if (config->save_to_disk)
+        if (config->save_to_disk && !is_excluded(chunk->items[i]->path, config))
           file_save_to_disk(config->receive_root_directory, chunk->items[i]);
       }
       chunk_destroy(chunk);
@@ -50,7 +86,7 @@ int receive_files(Config* config, int fd) {
         send_status(fd, STATUS_ERROR);
         return -1;
       }
-      if (config->save_to_disk)
+      if (config->save_to_disk && !is_excluded(file->path, config))
         file_save_to_disk(config->receive_root_directory, file);
       file_destroy(file);
     }
@@ -113,13 +149,12 @@ void handler(int file_descriptor) {
 }
 
 static Server* g_server = NULL;
+static volatile sig_atomic_t g_server_cleanup_requested = 0;
 
 static void cleanup(int sig) {
   (void)sig;
-  if (g_server) {
+  server_request_shutdown();
-    server_delete(&g_server);
+  g_server_cleanup_requested = 1;
-  }
-  _exit(0);
 }
 
 static void print_server_usage(void) {
@@ -135,6 +170,7 @@ static void print_server_usage(void) {
   printf("  --ca <path>         TLS CA certificate file (PEM)\n");
   printf("  -v, --verbose       Enable debug logging\n");
   printf("  --help              Show this help\n");
+  printf("  -V, --version       Show version and exit\n");
 }
 
 int main(int argc, char* argv[]) {
@@ -149,6 +185,9 @@ int main(int argc, char* argv[]) {
     if (strcmp(argv[i], "--help") == 0) {
       print_server_usage();
       return 0;
+    } else if (strcmp(argv[i], "-V") == 0 || strcmp(argv[i], "--version") == 0) {
+      printf("fastsync-server version %s\n", PROTOCOL_VERSION);
+      return 0;
     } else if (strcmp(argv[i], "--stdio") == 0) {
       io_set_fds(STDIN_FILENO, STDOUT_FILENO);
       handler(STDIN_FILENO);
@@ -205,5 +244,11 @@ int main(int argc, char* argv[]) {
   } else {
     server_listen(g_server, handler);
   }
+
+  /* Graceful shutdown: if a signal requested cleanup, delete the server */
+  if (g_server_cleanup_requested) {
+    log_message(LOG_LEVEL_INFO, "Shutdown requested, cleaning up");
+    server_delete(&g_server);
+  }
   return 0;
 }

src/shared/compression.c

@@ -9,6 +9,18 @@
 
 Data* data_compress(Data* data_to_compress, int compression_level) {
   log_message(LOG_LEVEL_DEBUG, "Starting to compress data");
+
+  /* Clamp compression level to valid zstd range [1, 22] */
+  if (compression_level < 1) {
+    log_message(LOG_LEVEL_WARNING, "compression_level %d out of range [1,22], using 1",
+                compression_level);
+    compression_level = 1;
+  } else if (compression_level > 22) {
+    log_message(LOG_LEVEL_WARNING, "compression_level %d out of range [1,22], using 22",
+                compression_level);
+    compression_level = 22;
+  }
+
   size_t dst_size = ZSTD_compressBound(data_to_compress->size);
   Data* compressed_data = data_create_empty(dst_size);
   if (compressed_data == NULL)

src/shared/config.c

@@ -4,6 +4,7 @@
 #include "protocol.h"
 #include "utils.h"
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -14,6 +15,8 @@ Config* config_create(char* version, char* send_directory, char* receive_directo
                       bool use_sendfile, unsigned long long chunk_size) {
 
   Config* config = malloc(sizeof(Config));
+  if (config == NULL)
+    return NULL;
   config->version = version;
   config->send_directory = send_directory;
   config->receive_root_directory = receive_directory;
@@ -45,6 +48,8 @@ Config* config_create(char* version, char* send_directory, char* receive_directo
   config->tls_cert = NULL;
   config->tls_key = NULL;
   config->tls_ca = NULL;
+  config->follow_symlinks = false;
+  config->partial = false;
   config->server_host = str_dup("127.0.0.1");
   config->server_port = 8080;
   return config;
@@ -127,6 +132,26 @@ bool config_send(int file_descriptor, const Config* config) {
     return false;
   if (!send_n_data(file_descriptor, &config->delta_max_file_size, sizeof(unsigned long long)))
     return false;
+  if (!send_int(file_descriptor, config->exclude_count))
+    return false;
+  for (int i = 0; i < config->exclude_count; i++) {
+    if (!send_str(file_descriptor, config->exclude_patterns[i]))
+      return false;
+  }
+  if (!send_int(file_descriptor, config->include_count))
+    return false;
+  for (int i = 0; i < config->include_count; i++) {
+    if (!send_str(file_descriptor, config->include_patterns[i]))
+      return false;
+  }
+  if (!send_n_data(file_descriptor, &config->max_size, sizeof(config->max_size)))
+    return false;
+  if (!send_n_data(file_descriptor, &config->min_size, sizeof(config->min_size)))
+    return false;
+  if (!send_int(file_descriptor, config->follow_symlinks))
+    return false;
+  if (!send_int(file_descriptor, config->partial))
+    return false;
   Status status;
   if (!receive_status(file_descriptor, &status))
     return false;
@@ -221,6 +246,90 @@ Config* config_receive(int file_descriptor) {
   config->tls_cert = NULL;
   config->tls_key = NULL;
   config->tls_ca = NULL;
+  config->follow_symlinks = false;
+  config->partial = false;
+
+#define MAX_PATTERN_COUNT 10000
+
+  // Receive exclude patterns
+  int ec;
+  if (!receive_int(file_descriptor, &ec))
+    goto error;
+  if (ec > MAX_PATTERN_COUNT) {
+    log_message(LOG_LEVEL_ERROR, "Exclude pattern count %d exceeds maximum %d", ec,
+                MAX_PATTERN_COUNT);
+    goto error;
+  }
+  if ((size_t)ec > SIZE_MAX / sizeof(char*)) {
+    log_message(LOG_LEVEL_ERROR, "Exclude pattern count %d would cause integer overflow", ec);
+    goto error;
+  }
+  config->exclude_count = ec;
+  if (ec > 0) {
+    config->exclude_patterns = malloc((size_t)ec * sizeof(char*));
+    if (!config->exclude_patterns) {
+      config->exclude_count = 0;
+      goto error;
+    }
+    for (int i = 0; i < ec; i++) {
+      config->exclude_patterns[i] = receive_str(file_descriptor);
+      if (!config->exclude_patterns[i]) {
+        for (int j = 0; j < i; j++)
+          free(config->exclude_patterns[j]);
+        free(config->exclude_patterns);
+        config->exclude_patterns = NULL;
+        config->exclude_count = 0;
+        goto error;
+      }
+    }
+  }
+
+  // Receive include patterns
+  int ic;
+  if (!receive_int(file_descriptor, &ic))
+    goto error;
+  if (ic > MAX_PATTERN_COUNT) {
+    log_message(LOG_LEVEL_ERROR, "Include pattern count %d exceeds maximum %d", ic,
+                MAX_PATTERN_COUNT);
+    goto error;
+  }
+  if ((size_t)ic > SIZE_MAX / sizeof(char*)) {
+    log_message(LOG_LEVEL_ERROR, "Include pattern count %d would cause integer overflow", ic);
+    goto error;
+  }
+  config->include_count = ic;
+  if (ic > 0) {
+    config->include_patterns = malloc((size_t)ic * sizeof(char*));
+    if (!config->include_patterns) {
+      config->include_count = 0;
+      goto error;
+    }
+    for (int i = 0; i < ic; i++) {
+      config->include_patterns[i] = receive_str(file_descriptor);
+      if (!config->include_patterns[i]) {
+        for (int j = 0; j < i; j++)
+          free(config->include_patterns[j]);
+        free(config->include_patterns);
+        config->include_patterns = NULL;
+        config->include_count = 0;
+        goto error;
+      }
+    }
+  }
+
+  if (!receive_n_data(file_descriptor, &config->max_size, sizeof(config->max_size)))
+    goto error;
+  if (!receive_n_data(file_descriptor, &config->min_size, sizeof(config->min_size)))
+    goto error;
+  int tmp_follow;
+  if (!receive_int(file_descriptor, &tmp_follow))
+    goto error;
+  config->follow_symlinks = tmp_follow;
+  int tmp_partial;
+  if (!receive_int(file_descriptor, &tmp_partial))
+    goto error;
+  config->partial = tmp_partial;
+
   config->server_host = str_dup("127.0.0.1");
   config->server_port = 8080;
   if (!send_status(file_descriptor, STATUS_OK))

src/shared/config.h

@@ -40,6 +40,8 @@ typedef struct Config {
   char* tls_cert;
   char* tls_key;
   char* tls_ca;
+  bool follow_symlinks;
+  bool partial;
 } Config;
 
 #define PROTOCOL_VERSION "1.3.0"

src/shared/data.h

@@ -1,7 +1,7 @@
 #ifndef DATA_H
 #define DATA_H
 
-#include "stdlib.h"
+#include <stdlib.h>
 
 typedef struct {
   void* data;

src/shared/file.c

@@ -1,4 +1,5 @@
 #include <dirent.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <stddef.h>
@@ -20,6 +21,9 @@
 #include "protocol.h"
 #include "utils.h"
 
+#define STREAM_THRESHOLD (64ULL * 1024 * 1024) /* 64 MB */
+#define STREAM_CHUNK_SIZE (1ULL * 1024 * 1024) /* 1 MB */
+
 File* file_create(const char* path) {
   File* file = (File*)malloc(sizeof(File));
   if (file == NULL) {
@@ -34,7 +38,7 @@ File* file_create(const char* path) {
     return NULL;
   }
 
-  strcpy(file->path, path);
+  memcpy(file->path, path, path_len + 1);
   file->data = data_create_reserve(0);
   if (file->data == NULL) {
     free(file->path);
@@ -42,6 +46,8 @@ File* file_create(const char* path) {
     return NULL;
   }
   file->metadata = NULL;
+  file->type = FILE_TYPE_REGULAR;
+  file->link_target = NULL;
   return file;
 }
 
@@ -55,6 +61,8 @@ void file_destroy(void* item) {
   file->metadata = NULL;
   free(file->path);
   file->path = NULL;
+  free(file->link_target);
+  file->link_target = NULL;
   free(file);
 }
 
@@ -83,6 +91,14 @@ void file_metadata_destroy(void* metadata) {
 bool file_load_data(File* file) {
   if (file == NULL)
     return false;
+  // Symlinks have no data to load
+  if (file->type == FILE_TYPE_SYMLINK)
+    return true;
+  // For streaming files, just record the size, don't load into memory
+  if (file->data->size > STREAM_THRESHOLD) {
+    // Don't allocate; streaming will read directly from disk
+    return true;
+  }
   if (file->data->data == NULL) {
     file->data->data = malloc(file->data->size);
     if (file->data->data == NULL) {
@@ -98,10 +114,76 @@ bool file_load_data(File* file) {
   return true;
 }
 
+// Stream file content in chunks without loading entire file into RAM
+static bool file_send_streaming(File* file, int file_descriptor) {
+  unsigned long long total_size = file->data->size;
+  // Send total size prefix (same wire format as send_data)
+  if (!send_n_data(file_descriptor, &total_size, sizeof(total_size)))
+    return false;
+
+  FILE* fp = fopen(file->path, "rb");
+  if (!fp) {
+    perror("Could not open file for streaming");
+    return false;
+  }
+
+  char* buf = malloc(STREAM_CHUNK_SIZE);
+  if (!buf) {
+    fclose(fp);
+    return false;
+  }
+  unsigned long long remaining = total_size;
+  while (remaining > 0) {
+    size_t to_read = (size_t)((remaining < STREAM_CHUNK_SIZE) ? remaining : STREAM_CHUNK_SIZE);
+    size_t nread = fread(buf, 1, to_read, fp);
+    if (nread != to_read) {
+      if (ferror(fp)) {
+        perror("Read error during streaming");
+      }
+      free(buf);
+      fclose(fp);
+      return false;
+    }
+    if (!send_n_data(file_descriptor, buf, nread)) {
+      free(buf);
+      fclose(fp);
+      return false;
+    }
+    remaining -= (unsigned long long)nread;
+  }
+  free(buf);
+  fclose(fp);
+  return true;
+}
+
 bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
                             int compression_level, bool send_path) {
+  if (send_path && !send_str(file_descriptor, file->path))
+    return false;
+  if (use_metadata && !metadata_send(file_descriptor, file->metadata))
+    return false;
+
+  // Send file type indicator so receiver can distinguish regular from symlink
+  int ft = (int)file->type;
+  if (!send_int(file_descriptor, ft))
+    return false;
+
+  if (file->type == FILE_TYPE_SYMLINK) {
+    // Send link target, then zero-length data
+    if (!send_str(file_descriptor, file->link_target ? file->link_target : ""))
+      return false;
+    Data empty = {NULL, 0};
+    return send_data(file_descriptor, &empty);
+  }
+
   const Data* data_to_send = file->data;
   Data* compressed_data = NULL;
+
+  // Streaming mode: for large files without compression, stream from disk
+  if (file->data->size > STREAM_THRESHOLD && compression_level == 0) {
+    return file_send_streaming(file, file_descriptor);
+  }
+
   if (compression_level > 0) {
     compressed_data = data_compress(file->data, compression_level);
     if (compressed_data == NULL) {
@@ -110,14 +192,6 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
     }
     data_to_send = compressed_data;
   }
-  if (send_path && !send_str(file_descriptor, file->path)) {
-    data_destroy(compressed_data);
-    return false;
-  }
-  if (use_metadata && !metadata_send(file_descriptor, file->metadata)) {
-    data_destroy(compressed_data);
-    return false;
-  }
   if (!send_data(file_descriptor, data_to_send)) {
     data_destroy(compressed_data);
     return false;
@@ -126,10 +200,53 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
   return true;
 }
 
+static bool has_path_traversal(const char* path) {
+  // Check if ".." appears as a path component — at start, end, or between '/'
+  const char* p = path;
+  while ((p = strstr(p, "..")) != NULL) {
+    bool at_start = (p == path);
+    bool after_slash = (p > path && p[-1] == '/');
+    bool at_end = (p[2] == '\0');
+    bool before_slash = (p[2] == '/');
+    if ((at_start || after_slash) && (at_end || before_slash))
+      return true;
+    p += 2;
+  }
+  return false;
+}
+
 bool file_save_to_disk(const char* root_directory, File* file) {
+  if (file->type == FILE_TYPE_SYMLINK && file->link_target) {
+    // Validate link_target — reject absolute paths or traversal
+    if (file->link_target[0] == '/' || has_path_traversal(file->link_target)) {
+      log_message(LOG_LEVEL_ERROR, "Path traversal blocked in symlink target: %s",
+                  file->link_target);
+      return false;
+    }
+    char* disk_path = path_cat((char*)root_directory, file->path);
+    if (disk_path == NULL)
+      return false;
+    if (has_path_traversal(disk_path)) {
+      log_message(LOG_LEVEL_ERROR, "Path traversal blocked: %s", disk_path);
+      free(disk_path);
+      return false;
+    }
+    unlink(disk_path);
+    bool ok = (symlink(file->link_target, disk_path) == 0);
+    if (ok && file->metadata)
+      file_restore_metadata(disk_path, file->metadata);
+    free(disk_path);
+    return ok;
+  }
+
   char* disk_path = path_cat((char*)root_directory, file->path);
   if (disk_path == NULL)
     return false;
+  if (has_path_traversal(disk_path)) {
+    log_message(LOG_LEVEL_ERROR, "Path traversal blocked: %s", disk_path);
+    free(disk_path);
+    return false;
+  }
   bool ok = to_disk(disk_path, file->data->data, file->data->size);
   if (ok)
     file_restore_metadata(disk_path, file->metadata);
@@ -155,6 +272,43 @@ static void* old_data_from_path(const char* full_path, unsigned long long old_si
   return data;
 }
 
+/**
+ * Helper: receive data from wire, optionally decompress, and store in file.
+ * On success, returns the received Data* (caller owns it). On failure, returns NULL.
+ * If `file_data` is received via receive_data(fd), this function handles decompression
+ * when config->use_compression is set.
+ */
+static Data* receive_and_decompress(int fd, const Config* config) {
+  Data* file_data = receive_data(fd);
+  if (file_data == NULL)
+    return NULL;
+  if (config->use_compression) {
+    Data* uncompressed = data_decompress(file_data);
+    data_destroy(file_data);
+    if (uncompressed == NULL)
+      return NULL;
+    file_data = uncompressed;
+  }
+  return file_data;
+}
+
+/**
+ * Helper: receive metadata from wire and assign to file.
+ * Returns true on success (metadata may be NULL if absent), false on I/O error.
+ */
+static bool receive_and_assign_metadata(int fd, const Config* config, File* file) {
+  if (!config->use_metadata)
+    return true;
+  int meta_ok = 1;
+  file->metadata = metadata_receive(fd, &meta_ok);
+  if (!meta_ok) {
+    file_destroy(file);
+    send_status(fd, STATUS_ERROR);
+    return false;
+  }
+  return true;
+}
+
 static File* receive_delta_file(int fd, const Config* config, const char* check_path,
                                 void* old_data, unsigned long long old_size) {
   if (!old_data)
@@ -270,34 +424,16 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
       return NULL;
     }
 
-    if (config->use_metadata) {
+    if (!receive_and_assign_metadata(fd, config, file))
-      int meta_ok = 1;
+      return NULL;
-      file->metadata = metadata_receive(fd, &meta_ok);
-      if (!meta_ok) {
-        file_destroy(file);
-        send_status(fd, STATUS_ERROR);
-        return NULL;
-      }
-    }
 
-    Data* file_data = receive_data(fd);
+    Data* file_data = receive_and_decompress(fd, config);
     if (file_data == NULL) {
       file_destroy(file);
       send_status(fd, STATUS_ERROR);
       return NULL;
     }
 
-    if (config->use_compression) {
-      Data* uncompressed = data_decompress(file_data);
-      data_destroy(file_data);
-      if (uncompressed == NULL) {
-        file_destroy(file);
-        send_status(fd, STATUS_ERROR);
-        return NULL;
-      }
-      file_data = uncompressed;
-    }
-
     data_destroy(file->data);
     file->data = file_data;
     return file;
@@ -326,10 +462,29 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
   }
 
   char* full_path = path_cat(config->receive_root_directory, check_path);
+  if (full_path && strstr(full_path, "..") != NULL) {
+    log_message(LOG_LEVEL_ERROR, "Path traversal blocked: %s", full_path);
+    free(full_path);
+    free(check_path);
+    send_status(fd, STATUS_ERROR);
+    return NULL;
+  }
   struct stat st;
   bool has_old_file = (full_path && stat(full_path, &st) == 0);
   unsigned long long old_size = has_old_file ? (unsigned long long)st.st_size : 0;
 
+  // Check for partial file if enabled
+  if (config->partial && !has_old_file && full_path) {
+    char* partial_path = malloc(strlen(full_path) + 20);
+    if (partial_path) {
+      snprintf(partial_path, strlen(full_path) + 20, "%s.fastsync-partial", full_path);
+      has_old_file = (stat(partial_path, &st) == 0);
+      if (has_old_file)
+        old_size = (unsigned long long)st.st_size;
+      free(partial_path);
+    }
+  }
+
   bool match = has_old_file && (unsigned long long)st.st_size == check_size &&
                (long long)st.st_mtime == check_mtime;
 
@@ -375,32 +530,34 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     return NULL;
   }
 
-  if (config->use_metadata) {
+  if (!receive_and_assign_metadata(fd, config, file))
-    int meta_ok = 1;
+    return NULL;
-    file->metadata = metadata_receive(fd, &meta_ok);
-    if (!meta_ok) {
-      file_destroy(file);
-      send_status(fd, STATUS_ERROR);
-      return NULL;
-    }
-  }
 
-  Data* file_data = receive_data(fd);
+  // Read file type indicator
-  if (file_data == NULL) {
+  int file_type;
+  if (!receive_int(fd, &file_type)) {
     file_destroy(file);
     send_status(fd, STATUS_ERROR);
     return NULL;
   }
+  file->type = (FileType)file_type;
 
-  if (config->use_compression) {
+  if (file->type == FILE_TYPE_SYMLINK) {
-    Data* uncompressed = data_decompress(file_data);
+    char* link_target = receive_str(fd);
-    data_destroy(file_data);
+    if (link_target) {
-    if (uncompressed == NULL) {
+      file->link_target = link_target;
-      file_destroy(file);
-      send_status(fd, STATUS_ERROR);
-      return NULL;
     }
-    file_data = uncompressed;
+    Data* empty_data = receive_data(fd);
+    if (empty_data)
+      data_destroy(empty_data);
+    return file;
+  }
+
+  Data* file_data = receive_and_decompress(fd, config);
+  if (file_data == NULL) {
+    file_destroy(file);
+    send_status(fd, STATUS_ERROR);
+    return NULL;
   }
 
   data_destroy(file->data);
@@ -446,13 +603,14 @@ done:
 
 bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int compression_level,
                         bool send_path) {
+  // Handle symlinks
+  if (file->type == FILE_TYPE_SYMLINK) {
+    return file_send_single_calls(file, file_descriptor, use_metadata, compression_level,
+                                  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);
@@ -462,6 +620,11 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int
   if (use_metadata && !metadata_send(file_descriptor, file->metadata))
     return false;
 
+  // Send file type indicator
+  int ft = (int)file->type;
+  if (!send_int(file_descriptor, ft))
+    return false;
+
   int fd = open(file->path, O_RDONLY);
   if (fd == -1) {
     perror("Could not open file for sendfile");
@@ -478,6 +641,8 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int
   while ((unsigned long long)offset < file_size) {
     ssize_t sent = sendfile(file_descriptor, fd, &offset, file_size - offset);
     if (sent == -1) {
+      if (errno == EINTR)
+        continue;
       perror("sendfile failed");
       close(fd);
       return false;
@@ -504,6 +669,30 @@ File* file_receive(const Config* config, int file_descriptor) {
       return NULL;
     }
   }
+
+  // Receive file type indicator
+  int file_type;
+  if (!receive_int(file_descriptor, &file_type)) {
+    file_destroy(file);
+    return NULL;
+  }
+  file->type = (FileType)file_type;
+
+  if (file->type == FILE_TYPE_SYMLINK) {
+    char* link_target = receive_str(file_descriptor);
+    if (link_target == NULL) {
+      file_destroy(file);
+      return NULL;
+    }
+    file->link_target = link_target;
+    // Receive and discard zero-length data
+    Data* empty_data = receive_data(file_descriptor);
+    if (empty_data)
+      data_destroy(empty_data);
+    return file;
+  }
+
+  // Regular file - receive data
   Data* file_data = receive_data(file_descriptor);
   if (file_data == NULL) {
     file_destroy(file);
@@ -518,6 +707,7 @@ File* file_receive(const Config* config, int file_descriptor) {
     }
     file_data = file_data_uncompressed;
   }
+
   data_destroy(file->data);
   file->data = file_data;
   return file;

src/shared/file.h

@@ -6,6 +6,8 @@
 #include <stdbool.h>
 #include <sys/stat.h>
 
+typedef enum { FILE_TYPE_REGULAR, FILE_TYPE_SYMLINK, FILE_TYPE_DIR } FileType;
+
 typedef struct {
   mode_t mode;
   uid_t uid;
@@ -18,6 +20,8 @@ typedef struct {
   char* path;
   Data* data;
   FileMetadata* metadata;
+  FileType type;
+  char* link_target;
 } File;
 
 File* file_create(const char* path);

src/shared/log.c

@@ -10,7 +10,7 @@ void set_log_level(LogLevel level) {
   current_log_level = level;
 }
 
-void log_message(LogLevel log_level, char* format, ...) {
+void log_message(LogLevel log_level, const char* format, ...) {
   if (log_level < current_log_level)
     return;
   time_t now = time(NULL);

src/shared/log.h

@@ -3,7 +3,7 @@
 
 typedef enum { LOG_LEVEL_DEBUG, LOG_LEVEL_INFO, LOG_LEVEL_WARNING, LOG_LEVEL_ERROR } LogLevel;
 
-void log_message(LogLevel log_level, char* message, ...);
+void log_message(LogLevel log_level, const char* message, ...);
 void set_log_level(LogLevel level);
 
 #endif

src/shared/metadata.c

@@ -4,6 +4,7 @@
 #include "protocol.h"
 #include <errno.h>
 #include <fcntl.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -11,60 +12,82 @@
 #include <unistd.h>
 
 void metadata_to_buf(char** buf, const FileMetadata* m) {
-  int present = (m != NULL) ? 1 : 0;
+  int32_t present = (m != NULL) ? 1 : 0;
-  memcpy(*buf, &present, sizeof(int));
+  memcpy(*buf, &present, sizeof(present));
-  *buf += sizeof(int);
+  *buf += sizeof(present);
   if (m == NULL)
     return;
-  memcpy(*buf, &m->mode, sizeof(mode_t));
+  int32_t mode = (int32_t)m->mode;
-  *buf += sizeof(mode_t);
+  memcpy(*buf, &mode, sizeof(mode));
-  memcpy(*buf, &m->uid, sizeof(uid_t));
+  *buf += sizeof(mode);
-  *buf += sizeof(uid_t);
+  int32_t uid = (int32_t)m->uid;
-  memcpy(*buf, &m->gid, sizeof(gid_t));
+  memcpy(*buf, &uid, sizeof(uid));
-  *buf += sizeof(gid_t);
+  *buf += sizeof(uid);
-  memcpy(*buf, &m->mtime_sec, sizeof(time_t));
+  int32_t gid = (int32_t)m->gid;
-  *buf += sizeof(time_t);
+  memcpy(*buf, &gid, sizeof(gid));
-  memcpy(*buf, &m->mtime_nsec, sizeof(long));
+  *buf += sizeof(gid);
-  *buf += sizeof(long);
+  int64_t mtime_sec = (int64_t)m->mtime_sec;
+  memcpy(*buf, &mtime_sec, sizeof(mtime_sec));
+  *buf += sizeof(mtime_sec);
+  int64_t mtime_nsec = (int64_t)m->mtime_nsec;
+  memcpy(*buf, &mtime_nsec, sizeof(mtime_nsec));
+  *buf += sizeof(mtime_nsec);
 }
 
 FileMetadata* metadata_from_buf(char** buf) {
-  int present;
+  int32_t present;
-  memcpy(&present, *buf, sizeof(int));
+  memcpy(&present, *buf, sizeof(present));
-  *buf += sizeof(int);
+  *buf += sizeof(present);
   if (!present)
     return NULL;
   FileMetadata* m = malloc(sizeof(FileMetadata));
-  memcpy(&m->mode, *buf, sizeof(mode_t));
+  if (m == NULL)
-  *buf += sizeof(mode_t);
+    return NULL;
-  memcpy(&m->uid, *buf, sizeof(uid_t));
+  int32_t mode;
-  *buf += sizeof(uid_t);
+  memcpy(&mode, *buf, sizeof(mode));
-  memcpy(&m->gid, *buf, sizeof(gid_t));
+  *buf += sizeof(mode);
-  *buf += sizeof(gid_t);
+  m->mode = (mode_t)mode;
-  memcpy(&m->mtime_sec, *buf, sizeof(time_t));
+  int32_t uid;
-  *buf += sizeof(time_t);
+  memcpy(&uid, *buf, sizeof(uid));
-  memcpy(&m->mtime_nsec, *buf, sizeof(long));
+  *buf += sizeof(uid);
-  *buf += sizeof(long);
+  m->uid = (uid_t)uid;
+  int32_t gid;
+  memcpy(&gid, *buf, sizeof(gid));
+  *buf += sizeof(gid);
+  m->gid = (gid_t)gid;
+  int64_t mtime_sec;
+  memcpy(&mtime_sec, *buf, sizeof(mtime_sec));
+  *buf += sizeof(mtime_sec);
+  m->mtime_sec = (time_t)mtime_sec;
+  int64_t mtime_nsec;
+  memcpy(&mtime_nsec, *buf, sizeof(mtime_nsec));
+  *buf += sizeof(mtime_nsec);
+  m->mtime_nsec = (long)mtime_nsec;
   return m;
 }
 
 bool metadata_send(int file_descriptor, FileMetadata* m) {
   if (m == NULL) {
-    int zero = 0;
+    int32_t zero = 0;
-    return send_n_data(file_descriptor, &zero, sizeof(int));
+    return send_n_data(file_descriptor, &zero, sizeof(zero));
   }
-  int present = 1;
+  int32_t present = 1;
-  return send_n_data(file_descriptor, &present, sizeof(int)) &&
+  int32_t mode = (int32_t)m->mode;
-         send_n_data(file_descriptor, &m->mode, sizeof(mode_t)) &&
+  int32_t uid = (int32_t)m->uid;
-         send_n_data(file_descriptor, &m->uid, sizeof(uid_t)) &&
+  int32_t gid = (int32_t)m->gid;
-         send_n_data(file_descriptor, &m->gid, sizeof(gid_t)) &&
+  int64_t mtime_sec = (int64_t)m->mtime_sec;
-         send_n_data(file_descriptor, &m->mtime_sec, sizeof(time_t)) &&
+  int64_t mtime_nsec = (int64_t)m->mtime_nsec;
-         send_n_data(file_descriptor, &m->mtime_nsec, sizeof(long));
+  return send_n_data(file_descriptor, &present, sizeof(present)) &&
+         send_n_data(file_descriptor, &mode, sizeof(mode)) &&
+         send_n_data(file_descriptor, &uid, sizeof(uid)) &&
+         send_n_data(file_descriptor, &gid, sizeof(gid)) &&
+         send_n_data(file_descriptor, &mtime_sec, sizeof(mtime_sec)) &&
+         send_n_data(file_descriptor, &mtime_nsec, sizeof(mtime_nsec));
 }
 
 FileMetadata* metadata_receive(int file_descriptor, int* ok) {
-  int present;
+  int32_t present;
-  if (!receive_n_data(file_descriptor, &present, sizeof(int))) {
+  if (!receive_n_data(file_descriptor, &present, sizeof(present))) {
     if (ok)
       *ok = 0;
     return NULL;
@@ -80,16 +103,46 @@ FileMetadata* metadata_receive(int file_descriptor, int* ok) {
       *ok = 0;
     return NULL;
   }
-  if (!receive_n_data(file_descriptor, &m->mode, sizeof(mode_t)) ||
+  int32_t mode;
-      !receive_n_data(file_descriptor, &m->uid, sizeof(uid_t)) ||
+  if (!receive_n_data(file_descriptor, &mode, sizeof(mode))) {
-      !receive_n_data(file_descriptor, &m->gid, sizeof(gid_t)) ||
-      !receive_n_data(file_descriptor, &m->mtime_sec, sizeof(time_t)) ||
-      !receive_n_data(file_descriptor, &m->mtime_nsec, sizeof(long))) {
     free(m);
     if (ok)
       *ok = 0;
     return NULL;
   }
+  m->mode = (mode_t)mode;
+  int32_t uid;
+  if (!receive_n_data(file_descriptor, &uid, sizeof(uid))) {
+    free(m);
+    if (ok)
+      *ok = 0;
+    return NULL;
+  }
+  m->uid = (uid_t)uid;
+  int32_t gid;
+  if (!receive_n_data(file_descriptor, &gid, sizeof(gid))) {
+    free(m);
+    if (ok)
+      *ok = 0;
+    return NULL;
+  }
+  m->gid = (gid_t)gid;
+  int64_t mtime_sec;
+  if (!receive_n_data(file_descriptor, &mtime_sec, sizeof(mtime_sec))) {
+    free(m);
+    if (ok)
+      *ok = 0;
+    return NULL;
+  }
+  m->mtime_sec = (time_t)mtime_sec;
+  int64_t mtime_nsec;
+  if (!receive_n_data(file_descriptor, &mtime_nsec, sizeof(mtime_nsec))) {
+    free(m);
+    if (ok)
+      *ok = 0;
+    return NULL;
+  }
+  m->mtime_nsec = (long)mtime_nsec;
   if (ok)
     *ok = 1;
   return m;
@@ -98,7 +151,7 @@ FileMetadata* metadata_receive(int file_descriptor, int* ok) {
 void file_restore_metadata(const char* path, FileMetadata* metadata) {
   if (metadata == NULL)
     return;
-  if (chmod(path, metadata->mode & 07777) != 0)
+  if (chmod(path, metadata->mode & 07777 & ~(S_ISUID | S_ISGID)) != 0)
     log_message(LOG_LEVEL_WARNING, "Failed to chmod %s: %s", path, strerror(errno));
   if (chown(path, metadata->uid, metadata->gid) != 0)
     log_message(LOG_LEVEL_WARNING, "Failed to chown %s: %s", path, strerror(errno));

src/shared/metadata.h

@@ -3,10 +3,10 @@
 
 #include "file.h"
 #include <stdbool.h>
+#include <stdint.h>
 #include <sys/stat.h>
 
-#define FILE_METADATA_WIRE_SIZE                                                                    \
+#define FILE_METADATA_WIRE_SIZE (sizeof(int32_t) * 3 + sizeof(int64_t) * 2)
-  (sizeof(mode_t) + sizeof(uid_t) + sizeof(gid_t) + sizeof(time_t) + sizeof(long))
 
 void metadata_to_buf(char** buf, const FileMetadata* m);
 FileMetadata* metadata_from_buf(char** buf);

src/shared/protocol.c

@@ -34,11 +34,14 @@ static void bw_throttle(size_t bytes_written) {
   struct timespec now;
   clock_gettime(CLOCK_MONOTONIC, &now);
 
-  long long elapsed_ns =
+  /* Use unsigned long long for elapsed_ns to avoid overflow in multiplication.
-      (now.tv_sec - bw_last_refill.tv_sec) * 1000000000LL + (now.tv_nsec - bw_last_refill.tv_nsec);
+   * time_t differences fit comfortably in 64-bit for any practical runtime. */
+  unsigned long long elapsed_ns =
+      (unsigned long long)(now.tv_sec - bw_last_refill.tv_sec) * 1000000000ULL +
+      (unsigned long long)(now.tv_nsec - bw_last_refill.tv_nsec);
   bw_last_refill = now;
 
-  long long tokens_to_add = (long long)((double)io_bwlimit * elapsed_ns / 1000000000.0);
+  long long tokens_to_add = (long long)((double)io_bwlimit * (double)elapsed_ns / 1000000000.0);
   bw_tokens += tokens_to_add;
   if (bw_tokens > (long long)io_bwlimit)
     bw_tokens = (long long)io_bwlimit;
@@ -46,7 +49,9 @@ static void bw_throttle(size_t bytes_written) {
   bw_tokens -= (long long)bytes_written;
 
   if (bw_tokens < 0) {
-    long long deficit_ns = (long long)((double)(-bw_tokens) / io_bwlimit * 1000000000.0);
+    long long deficit_ns = (long long)((double)(-bw_tokens) / (double)io_bwlimit * 1000000000.0);
+    if (deficit_ns < 0)
+      deficit_ns = 0;
     struct timespec sleep_time, remaining;
     sleep_time.tv_sec = deficit_ns / 1000000000LL;
     sleep_time.tv_nsec = deficit_ns % 1000000000LL;
@@ -79,6 +84,11 @@ bool send_n_data(int file_descriptor, const void* data, size_t data_size) {
     else
       bytes_send = write(fd, (const char*)data + total_bytes_send, chunk);
     if (bytes_send <= 0) {
+      if (io_ssl) {
+        int ssl_err = SSL_get_error(io_ssl, (int)bytes_send);
+        if (ssl_err == SSL_ERROR_WANT_WRITE || ssl_err == SSL_ERROR_WANT_READ)
+          continue;
+      }
       log_message(LOG_LEVEL_ERROR, "Could not send data");
       return false;
     }
@@ -102,6 +112,11 @@ bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
       bytes_received =
           read(fd, (char*)data + total_bytes_received, data_size - total_bytes_received);
     if (bytes_received <= 0) {
+      if (io_ssl) {
+        int ssl_err = SSL_get_error(io_ssl, (int)bytes_received);
+        if (ssl_err == SSL_ERROR_WANT_READ || ssl_err == SSL_ERROR_WANT_WRITE)
+          continue;
+      }
       if (bytes_received == 0)
         log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
       else
@@ -182,10 +197,16 @@ bool send_data(int file_descriptor, const Data* data) {
   return true;
 }
 
+#define MAX_DATA_SIZE (1024ULL * 1024 * 1024) // 1 GB
+
 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) {
+    log_message(LOG_LEVEL_ERROR, "receive_data: size %llu exceeds maximum", size);
+    return NULL;
+  }
   void* data = malloc((size_t)size);
   if (data == NULL)
     return NULL;

src/shared/transport_ssh.c

@@ -139,7 +139,6 @@ Client* client_connect_ssh(const char* destination, int port) {
     ssh_argv[ac++] = "ControlPath=~/.cache/fastsync-%r@%h:%p";
     if (port > 0 && port != 22) {
       if ((size_t)ac + 2 >= ssh_argv_max) {
-        free(ssh_argv);
         _exit(1);
       }
       ssh_argv[ac++] = "-p";
@@ -147,7 +146,6 @@ Client* client_connect_ssh(const char* destination, int port) {
       ssh_argv[ac++] = port_str;
     }
     if ((size_t)ac + 3 >= ssh_argv_max) {
-      free(ssh_argv);
       _exit(1);
     }
     ssh_argv[ac++] = ssh_user;
@@ -186,7 +184,7 @@ Client* client_connect_ssh(const char* destination, int port) {
     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;

src/shared/transport_tcp.c

@@ -2,29 +2,68 @@
 #include "log.h"
 #include "protocol.h"
 #include <arpa/inet.h>
+#include <errno.h>
+#include <netdb.h>
 #include <openssl/ssl.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
+bool set_socket_timeouts(int fd) {
+  struct timeval tv;
+  tv.tv_sec = 30;
+  tv.tv_usec = 0;
+
+  int keepalive = 1;
+  if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof(keepalive)) < 0) {
+    perror("Could not set SO_KEEPALIVE");
+    return false;
+  }
+  if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
+    perror("Could not set SO_RCVTIMEO");
+    return false;
+  }
+  if (setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0) {
+    perror("Could not set SO_SNDTIMEO");
+    return false;
+  }
+  return true;
+}
+
 Server* server_create(int port) {
   Server* server = (Server*)malloc(sizeof(Server));
   if (server == NULL) {
     perror("Could not allocate space for Server");
     return NULL;
   }
+  memset(&server->address, 0, sizeof(server->address));
+  server->ssl_ctx = NULL;
 
-  int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
+  // Try IPv6 first, fall back to IPv4
-  if (file_descriptor < 0) {
+  int domain = AF_INET6;
+  int fd = socket(domain, SOCK_STREAM, 0);
+  if (fd < 0) {
+    domain = AF_INET;
+    fd = socket(domain, SOCK_STREAM, 0);
+  }
+  if (fd < 0) {
     perror("Could not create Socket!");
     free(server);
     return NULL;
   }
-  server->file_descriptor = file_descriptor;
+
+  if (!set_socket_timeouts(fd)) {
+    close(fd);
+    free(server);
+    return NULL;
+  }
+
+  server->file_descriptor = fd;
   int opt = 1;
   if (setsockopt(server->file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
     perror("Error setting a socket option!");
@@ -33,18 +72,57 @@ Server* server_create(int port) {
     return NULL;
   }
 
-  server->address.sin_family = AF_INET;
+  struct sockaddr_storage* addr = &server->address;
-  server->address.sin_addr.s_addr = INADDR_ANY;
+  struct sockaddr_in* addr4 = (struct sockaddr_in*)addr;
-  server->address.sin_port = htons(port);
+  struct sockaddr_in6* addr6 = (struct sockaddr_in6*)addr;
-  server->address_length = sizeof(server->address);
+
-  server->ssl_ctx = NULL;
+  if (domain == AF_INET6) {
+    addr6->sin6_family = AF_INET6;
+    addr6->sin6_addr = in6addr_any;
+    addr6->sin6_port = htons(port);
+    server->address_length = sizeof(struct sockaddr_in6);
+  } else {
+    addr4->sin_family = AF_INET;
+    addr4->sin_addr.s_addr = INADDR_ANY;
+    addr4->sin_port = htons(port);
+    server->address_length = sizeof(struct sockaddr_in);
+  }
 
   if (bind(server->file_descriptor, (struct sockaddr*)&server->address, server->address_length) <
       0) {
-    perror("Could not bind server");
+    // If IPv6 bind failed (maybe no IPv6), try IPv4
-    close(server->file_descriptor);
+    if (domain == AF_INET6) {
-    free(server);
+      close(fd);
-    return NULL;
+      fd = socket(AF_INET, SOCK_STREAM, 0);
+      if (fd < 0) {
+        perror("Could not create IPv4 Socket!");
+        free(server);
+        return NULL;
+      }
+      if (!set_socket_timeouts(fd)) {
+        close(fd);
+        free(server);
+        return NULL;
+      }
+      server->file_descriptor = fd;
+      setsockopt(server->file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
+      memset(addr, 0, sizeof(*addr));
+      addr4->sin_family = AF_INET;
+      addr4->sin_addr.s_addr = INADDR_ANY;
+      addr4->sin_port = htons(port);
+      server->address_length = sizeof(struct sockaddr_in);
+      if (bind(server->file_descriptor, (struct sockaddr*)addr, server->address_length) < 0) {
+        perror("Could not bind server");
+        close(server->file_descriptor);
+        free(server);
+        return NULL;
+      }
+    } else {
+      perror("Could not bind server");
+      close(server->file_descriptor);
+      free(server);
+      return NULL;
+    }
   }
 
   return server;
@@ -62,6 +140,15 @@ void server_delete(Server** server) {
   *server = NULL;
 }
 
+/* Flag set by server_request_shutdown() to request graceful shutdown
+   of the accept loop. Accessed only from transport_tcp.c so it won't
+   cause linker errors when this file is compiled into client/test targets. */
+static volatile sig_atomic_t g_tcp_cleanup_requested = 0;
+
+void server_request_shutdown(void) {
+  g_tcp_cleanup_requested = 1;
+}
+
 static void accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt) {
   if (listen(server->file_descriptor, SOMAXCONN) < 0) {
@@ -69,14 +156,20 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
     return;
   }
   signal(SIGCHLD, SIG_IGN);
-  while (1) {
+  while (!g_tcp_cleanup_requested) {
-    struct sockaddr_in client_addr;
+    struct sockaddr_storage client_addr;
     socklen_t client_len = sizeof(client_addr);
     int fd = accept(server->file_descriptor, (struct sockaddr*)&client_addr, &client_len);
     if (fd < 0) {
+      if (errno == EINTR) {
+        if (g_tcp_cleanup_requested)
+          break;
+        continue;
+      }
       perror("Could not accept the connection");
       continue;
     }
+    set_socket_timeouts(fd);
     log_message(LOG_LEVEL_INFO, "%s", log_fmt);
     pid_t pid = fork();
     if (pid == 0) {
@@ -98,7 +191,11 @@ static void plain_child_fn(int fd, void* ctx) {
 }
 
 bool server_listen(Server* server, void (*handler)(int file_descriptor)) {
-  log_message(LOG_LEVEL_INFO, "Start Listening on Port: %d", ntohs(server->address.sin_port));
+  struct sockaddr_in* addr4 = (struct sockaddr_in*)&server->address;
+  int port = (server->address.ss_family == AF_INET6)
+                 ? ntohs(((struct sockaddr_in6*)&server->address)->sin6_port)
+                 : ntohs(addr4->sin_port);
+  log_message(LOG_LEVEL_INFO, "Start Listening on Port: %d", port);
   struct plain_ctx ctx = {handler};
   accept_loop(server, plain_child_fn, &ctx, "Received Connection");
   return true;
@@ -106,25 +203,23 @@ bool server_listen(Server* server, void (*handler)(int file_descriptor)) {
 
 void server_accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt) {
-  log_message(LOG_LEVEL_INFO, "Start TLS Listening on Port: %d", ntohs(server->address.sin_port));
+  struct sockaddr_in* addr4 = (struct sockaddr_in*)&server->address;
+  int port = (server->address.ss_family == AF_INET6)
+                 ? ntohs(((struct sockaddr_in6*)&server->address)->sin6_port)
+                 : ntohs(addr4->sin_port);
+  log_message(LOG_LEVEL_INFO, "Start TLS Listening on Port: %d", port);
   accept_loop(server, child_fn, child_ctx, log_fmt);
 }
 
 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;
+  memset(&client->address, 0, sizeof(client->address));
-  client->address.sin_family = AF_INET;
+  client->address.ss_family = AF_UNSPEC;
   client->address_length = sizeof(client->address);
+  client->file_descriptor = -1;
   client->ssh_child_pid = -1;
   client->ssl = NULL;
   client->ssl_ctx = NULL;
@@ -132,18 +227,54 @@ Client* client_create() {
 }
 
 bool client_connect(Client* client, char* host, int port) {
-  client->address.sin_port = htons(port);
+  struct addrinfo hints, *res, *rp;
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;
 
-  if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
+  char port_str[16];
-    perror("Could not convert host address!");
+  snprintf(port_str, sizeof(port_str), "%d", port);
+
+  int gai_err = getaddrinfo(host, port_str, &hints, &res);
+  if (gai_err != 0) {
+    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(gai_err));
     return false;
   }
 
-  if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
+  // Try IPv6 first, then IPv4
-      0) {
+  int fd = -1;
+  for (rp = res; rp != NULL; rp = rp->ai_next) {
+    fd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (fd < 0)
+      continue;
+    if (!set_socket_timeouts(fd)) {
+      close(fd);
+      fd = -1;
+      continue;
+    }
+    if (connect(fd, rp->ai_addr, rp->ai_addrlen) == 0)
+      break;
+    close(fd);
+    fd = -1;
+  }
+
+  if (fd < 0) {
     perror("Could not connect to Server!");
+    freeaddrinfo(res);
     return false;
   }
+
+  // Save the connected address
+  size_t copy_len =
+      rp->ai_addrlen < sizeof(client->address) ? rp->ai_addrlen : sizeof(client->address);
+  memcpy(&client->address, rp->ai_addr, copy_len);
+  client->address_length = (int)copy_len;
+  freeaddrinfo(res);
+
+  // Close old fd if any and set new one
+  if (client->file_descriptor >= 0)
+    close(client->file_descriptor);
+  client->file_descriptor = fd;
   return true;
 }
 
@@ -154,7 +285,10 @@ 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);

src/shared/transport_tcp.h

@@ -1,19 +1,21 @@
 #ifndef TRANSPORT_TCP_H
 #define TRANSPORT_TCP_H
 
+#include <netdb.h>
 #include <netinet/in.h>
 #include <stdbool.h>
+#include <sys/socket.h>
 #include <sys/types.h>
 
 typedef struct Server {
-  struct sockaddr_in address;
+  struct sockaddr_storage address;
   unsigned int address_length;
   int file_descriptor;
   void* ssl_ctx;
 } Server;
 
 typedef struct Client {
-  struct sockaddr_in address;
+  struct sockaddr_storage address;
   unsigned int address_length;
   int file_descriptor;
   pid_t ssh_child_pid;
@@ -26,9 +28,11 @@ bool server_listen(Server* server, void (*handler)(int file_descriptor));
 void server_accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt);
 void server_delete(Server** server);
+void server_request_shutdown(void);
 Client* client_create();
 bool client_connect(Client* client, char* host, int port);
 void client_disconnect(Client* client);
 void client_delete(Client* client);
+bool set_socket_timeouts(int fd);
 
 #endif

src/shared/transport_tls.c

@@ -5,6 +5,8 @@
 #include <arpa/inet.h>
 #include <openssl/err.h>
 #include <openssl/ssl.h>
+#include <openssl/x509.h>
+#include <openssl/x509v3.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -72,6 +74,12 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
     }
     SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
     SSL_CTX_set_verify_depth(ctx, 4);
+  } else {
+    if (!is_server) {
+      log_message(LOG_LEVEL_WARNING,
+                  "No CA path provided — TLS server certificate will not be verified");
+    }
+    SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
   }
 
   return ctx;
@@ -84,6 +92,7 @@ static SSL* wrap_fd_with_ssl(int fd, SSL_CTX* ctx, bool is_server) {
     return NULL;
   }
   SSL_set_fd(ssl, fd);
+
   int ret;
   if (is_server)
     ret = SSL_accept(ssl);
@@ -96,6 +105,17 @@ static SSL* wrap_fd_with_ssl(int fd, SSL_CTX* ctx, bool is_server) {
     SSL_free(ssl);
     return NULL;
   }
+
+  // In client mode, check verification result if peer verification was requested
+  if (!is_server) {
+    long verify_result = SSL_get_verify_result(ssl);
+    if (verify_result != X509_V_OK) {
+      log_message(LOG_LEVEL_ERROR, "TLS certificate verification failed: %ld", verify_result);
+      SSL_free(ssl);
+      return NULL;
+    }
+  }
+
   return ssl;
 }
 
@@ -133,16 +153,9 @@ 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);
+  // Use the common TCP connection logic (with IPv6 support)
-  if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
+  if (!client_connect(client, host, port))
-    perror("Could not convert host address!");
     return false;
-  }
-  if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
-      0) {
-    perror("Could not connect to Server!");
-    return false;
-  }
 
   SSL_CTX* ctx = create_ssl_ctx(false, cert_path, key_path, ca_path);
   if (!ctx)
@@ -155,6 +168,14 @@ bool client_connect_tls(Client* client, char* host, int port, const char* cert_p
     client->ssl_ctx = NULL;
     return false;
   }
+
+  // Set SNI and enable hostname verification
+  SSL_set_tlsext_host_name(ssl, host);
+  X509_VERIFY_PARAM* param = SSL_get0_param(ssl);
+  if (param) {
+    X509_VERIFY_PARAM_set1_host(param, host, 0);
+  }
+
   client->ssl = ssl;
   io_set_ssl(ssl);
   return true;

src/shared/utils.c

@@ -63,13 +63,30 @@ char* str_dup(const char* string) {
   if (string == NULL)
     return NULL;
   char* new_string = (char*)malloc(strlen(string) + 1);
-  strcpy(new_string, string);
+  memcpy(new_string, string, strlen(string) + 1);
   return new_string;
 }
 
 bool glob_match(const char* pattern, const char* str) {
   while (*pattern) {
     if (*pattern == '*') {
+      /* Check for double-star (globstar) pattern */
+      if (*(pattern + 1) == '*') {
+        pattern += 2;
+        /* Trailing double-star matches everything */
+        if (*pattern == '\0')
+          return true;
+        /* double-star slash: match at any depth */
+        if (*pattern == '/')
+          pattern++;
+        while (*str) {
+          if (glob_match(pattern, str))
+            return true;
+          str++;
+        }
+        return glob_match(pattern, str);
+      }
+      /* Single * — does not cross / boundaries */
       pattern++;
       while (*str && *str != '/') {
         if (glob_match(pattern, str))
@@ -83,8 +100,17 @@ bool glob_match(const char* pattern, const char* str) {
       pattern++;
       str++;
     } else {
-      if (*pattern != *str)
+      if (*pattern != *str) {
+        /* If pattern has a '/' followed by '**', allow zero path components */
+        if (*pattern == '/' && *(pattern + 1) == '*' && *(pattern + 2) == '*') {
+          /* Skip over slash-double-star and try to match rest against current str */
+          const char* rest = pattern + 3;
+          if (*rest == '/')
+            rest++;
+          return glob_match(rest, str);
+        }
         return false;
+      }
       pattern++;
       str++;
     }

tests/runner.c

@@ -5,8 +5,11 @@
 #include "test_data.h"
 #include "test_delta.h"
 #include "test_file.h"
+#include "test_file_sendfile.h"
 #include "test_glob.h"
+#include "test_log.h"
 #include "test_metadata.h"
+#include "test_multiprocessing.h"
 #include "test_property.h"
 #include "test_protocol.h"
 #include "test_queue.h"
@@ -14,6 +17,9 @@
 #include "test_scanner.h"
 #include "test_shared_utils.h"
 #include "test_stress.h"
+#include "test_transport_tcp.h"
+#include "test_transport_ssh.h"
+#include "test_transport_tls.h"
 #include "test_utils.h"
 #include <stdio.h>
 
@@ -38,6 +44,12 @@ int main() {
   RUN_TEST(test_metadata);
   RUN_TEST(test_glob);
   RUN_TEST(test_file);
+  RUN_TEST(test_file_sendfile);
+  RUN_TEST(test_multiprocessing);
+  RUN_TEST(test_log);
+  RUN_TEST(test_transport_tcp);
+  RUN_TEST(test_transport_ssh);
+  RUN_TEST(test_transport_tls);
   RUN_TEST(test_robustness);
   RUN_TEST(test_stress);
   RUN_TEST(test_property);

tests/test_file.c

@@ -217,6 +217,10 @@ static void test_file_send_no_path() {
   pid_t pid = fork();
   if (pid == 0) {
     close(p[1]);
+    // Read file type indicator
+    int file_type;
+    EXPECT_TRUE(receive_int(p[0], &file_type));
+    EXPECT_EQ_INT(file_type, (int)FILE_TYPE_REGULAR);
     Data* received = receive_data(p[0]);
     close(p[0]);
 
@@ -271,7 +275,7 @@ void test_file() {
   test_to_disk_basic();
   test_to_disk_creates_dirs();
   test_file_content_to_buffer();
-  if (!getenv("FASTSYNC_UNDER_VALGRIND")) {
+  if (!is_running_under_valgrind()) {
     // Fork tests are skipped under valgrind because the parent process runs
     // orders of magnitude slower than the child (parent is instrumented, child
     // is not), which causes pipe-based protocol handshake timeouts. The parent

tests/test_file_sendfile.c

@@ -0,0 +1,273 @@
+#include "test_file_sendfile.h"
+#include "file.h"
+#include "config.h"
+#include "protocol.h"
+#include "utils.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/* Test basic sendfile transfer: create a file, send it via file_send_sendfile,
+ * receive via file_receive, and verify contents. */
+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));
+
+  File* file = file_create("test_sendfile_basic.txt");
+  EXPECT_NOT_NULL(file);
+  /* Set the size so file_send_sendfile can report it */
+  file->data->size = len;
+
+  Config* cfg = config_create(str_dup(PROTOCOL_VERSION), str_dup("/tmp"), str_dup("/tmp"), false,
+                              false, false, false, false, 0, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    /* Child: receive */
+    close(p[1]);
+    File* received = file_receive(cfg, p[0]);
+    close(p[0]);
+
+    bool ok = true;
+    if (!received)
+      ok = false;
+    else {
+      if (!received->path || strcmp(received->path, "test_sendfile_basic.txt") != 0)
+        ok = false;
+      if (!received->data || received->data->size != len)
+        ok = false;
+      else if (memcmp(received->data->data, content, len) != 0)
+        ok = false;
+    }
+    file_destroy(received);
+    config_delete(cfg);
+    _exit(ok ? 0 : 1);
+  } else {
+    /* Parent: send via sendfile */
+    close(p[0]);
+    bool sent = file_send_sendfile(file, p[1], false, 0, true);
+    close(p[1]);
+
+    int status;
+    waitpid(pid, &status, 0);
+
+    file_destroy(file);
+    config_delete(cfg);
+    unlink("test_sendfile_basic.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+/* Test sendfile with an empty file */
+static void test_sendfile_empty_file() {
+  const char* content = "";
+  size_t len = 0;
+  EXPECT_TRUE(to_disk("test_sendfile_empty.txt", content, len));
+
+  File* file = file_create("test_sendfile_empty.txt");
+  EXPECT_NOT_NULL(file);
+  file->data->size = 0;
+
+  Config* cfg = config_create(str_dup(PROTOCOL_VERSION), str_dup("/tmp"), str_dup("/tmp"), false,
+                              false, false, false, false, 0, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    close(p[1]);
+    File* received = file_receive(cfg, p[0]);
+    close(p[0]);
+
+    bool ok = true;
+    if (!received)
+      ok = false;
+    else {
+      if (strcmp(received->path, "test_sendfile_empty.txt") != 0)
+        ok = false;
+      if (received->data->size != 0)
+        ok = false;
+    }
+    file_destroy(received);
+    config_delete(cfg);
+    _exit(ok ? 0 : 1);
+  } else {
+    close(p[0]);
+    bool sent = file_send_sendfile(file, p[1], false, 0, true);
+    close(p[1]);
+
+    int status;
+    waitpid(pid, &status, 0);
+
+    file_destroy(file);
+    config_delete(cfg);
+    unlink("test_sendfile_empty.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+/* Test error path: file does not exist on disk */
+static void test_sendfile_missing_file() {
+  File* file = file_create("nonexistent_sendfile_test_file.txt");
+  EXPECT_NOT_NULL(file);
+  file->data->size = 100; /* fake size */
+
+  /* Use a pipe that we can write to but sendfile should fail */
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+
+  /* file_send_sendfile will try to open the nonexistent file -> should return false */
+  bool sent = file_send_sendfile(file, p[1], false, 0, true);
+
+  close(p[0]);
+  close(p[1]);
+  file_destroy(file);
+
+  EXPECT_FALSE(sent);
+}
+
+/* Test compression level > 0 falls back to file_send_single_calls */
+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));
+
+  struct stat st;
+  EXPECT_EQ_INT(stat("test_sendfile_comp.txt", &st), 0);
+
+  File* file = file_create("test_sendfile_comp.txt");
+  EXPECT_NOT_NULL(file);
+  /* Load the file data into memory (required by file_send_single_calls fallback) */
+  file->data->size = (size_t)st.st_size;
+  EXPECT_TRUE(file_load_data(file));
+
+  Config* cfg = config_create(str_dup(PROTOCOL_VERSION), str_dup("/tmp"), str_dup("/tmp"), false,
+                              false, false, true, false, 3, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    close(p[1]);
+    File* received = file_receive(cfg, p[0]);
+    close(p[0]);
+
+    bool ok = true;
+    if (!received)
+      ok = false;
+    else {
+      if (received->data->size != len)
+        ok = false;
+      else if (memcmp(received->data->data, content, len) != 0)
+        ok = false;
+    }
+    file_destroy(received);
+    config_delete(cfg);
+    _exit(ok ? 0 : 1);
+  } else {
+    close(p[0]);
+    /* compression_level = 3 triggers fallback to file_send_single_calls */
+    bool sent = file_send_sendfile(file, p[1], false, 3, true);
+    close(p[1]);
+
+    int status;
+    waitpid(pid, &status, 0);
+
+    file_destroy(file);
+    config_delete(cfg);
+    unlink("test_sendfile_comp.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+/* Test sendfile without path (send_path = false) */
+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));
+
+  File* file = file_create("test_sendfile_nopath.txt");
+  EXPECT_NOT_NULL(file);
+  file->data->size = len;
+
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    close(p[1]);
+    /* Read file type indicator */
+    int file_type;
+    EXPECT_TRUE(receive_int(p[0], &file_type));
+    EXPECT_EQ_INT(file_type, (int)FILE_TYPE_REGULAR);
+    Data* received = receive_data(p[0]);
+    close(p[0]);
+
+    bool ok = true;
+    if (!received)
+      ok = false;
+    else if (received->size != len)
+      ok = false;
+    else if (memcmp(received->data, content, len) != 0)
+      ok = false;
+
+    data_destroy(received);
+    _exit(ok ? 0 : 1);
+  } else {
+    close(p[0]);
+    bool sent = file_send_sendfile(file, p[1], false, 0, false);
+    close(p[1]);
+
+    int status;
+    waitpid(pid, &status, 0);
+
+    file_destroy(file);
+    unlink("test_sendfile_nopath.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+void test_file_sendfile() {
+  if (!is_running_under_valgrind()) {
+    // Fork tests are skipped under valgrind because the parent process runs
+    // orders of magnitude slower than the child (parent is instrumented, child
+    // is not), which causes pipe-based protocol handshake timeouts. The parent
+    // process itself has zero valgrind errors -- the failures are all in the
+    // forked children where inherited allocations are reported as leaks.
+    test_sendfile_basic();
+    test_sendfile_empty_file();
+    test_sendfile_compression_fallback();
+    test_sendfile_no_path();
+  }
+  test_sendfile_missing_file(); // no fork, safe under valgrind
+}

tests/test_file_sendfile.h

@@ -0,0 +1,6 @@
+#ifndef TEST_FILE_SENDFILE_H
+#define TEST_FILE_SENDFILE_H
+
+void test_file_sendfile();
+
+#endif

tests/test_glob.c

@@ -49,6 +49,33 @@ static void test_glob_question_star() {
   EXPECT_TRUE(glob_match("?*.txt", "a.txt"));
 }
 
+static void test_glob_doublestar_match_all() {
+  EXPECT_TRUE(glob_match("**", "anything"));
+  EXPECT_TRUE(glob_match("**", "path/to/file"));
+}
+
+static void test_glob_doublestar_prefix() {
+  EXPECT_TRUE(glob_match("**/foo", "foo"));
+  EXPECT_TRUE(glob_match("**/foo", "bar/foo"));
+  EXPECT_TRUE(glob_match("**/foo", "a/b/c/foo"));
+  EXPECT_FALSE(glob_match("**/foo", "foobar"));
+  EXPECT_FALSE(glob_match("**/foo", "bar/foobar"));
+}
+
+static void test_glob_doublestar_suffix() {
+  EXPECT_TRUE(glob_match("foo/**", "foo"));
+  EXPECT_TRUE(glob_match("foo/**", "foo/bar"));
+  EXPECT_TRUE(glob_match("foo/**", "foo/bar/baz"));
+  EXPECT_FALSE(glob_match("foo/**", "foobar"));
+}
+
+static void test_glob_doublestar_mid() {
+  EXPECT_TRUE(glob_match("a/**/b", "a/b"));
+  EXPECT_TRUE(glob_match("a/**/b", "a/x/b"));
+  EXPECT_TRUE(glob_match("a/**/b", "a/x/y/z/b"));
+  EXPECT_FALSE(glob_match("a/**/b", "a/x/bad"));
+}
+
 void test_glob() {
   test_glob_exact_match();
   test_glob_question_mark();
@@ -60,4 +87,8 @@ void test_glob() {
   test_glob_slash_not_matched();
   test_glob_complex();
   test_glob_question_star();
+  test_glob_doublestar_match_all();
+  test_glob_doublestar_prefix();
+  test_glob_doublestar_suffix();
+  test_glob_doublestar_mid();
 }

tests/test_log.c

@@ -0,0 +1,116 @@
+#include "test_log.h"
+#include "log.h"
+#include "test_utils.h"
+
+/* Test default log level: WARNING and ERROR should print, DEBUG and INFO should not.
+ * We can't easily capture stderr in unit tests, so we verify the functions don't crash
+ * and that set_log_level changes behavior. */
+
+static void test_log_message_debug() {
+  set_log_level(LOG_LEVEL_WARNING);
+  log_message(LOG_LEVEL_DEBUG, "debug message: %d", 42);
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+static void test_log_message_info() {
+  set_log_level(LOG_LEVEL_WARNING);
+  log_message(LOG_LEVEL_INFO, "info message: %s", "test");
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+static void test_log_message_warning() {
+  set_log_level(LOG_LEVEL_WARNING);
+  log_message(LOG_LEVEL_WARNING, "warning message: %d %s", 1, "test");
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+static void test_log_message_error() {
+  set_log_level(LOG_LEVEL_WARNING);
+  log_message(LOG_LEVEL_ERROR, "error message: %s", "critical");
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+static void test_log_set_level_debug() {
+  set_log_level(LOG_LEVEL_DEBUG);
+
+  /* After setting to DEBUG, all levels should be shown */
+  log_message(LOG_LEVEL_DEBUG, "debug after set");
+  log_message(LOG_LEVEL_INFO, "info after set");
+  log_message(LOG_LEVEL_WARNING, "warning after set");
+  log_message(LOG_LEVEL_ERROR, "error after set");
+
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+static void test_log_set_level_info() {
+  set_log_level(LOG_LEVEL_INFO);
+
+  /* INFO level should show INFO, WARNING, ERROR but not DEBUG */
+  log_message(LOG_LEVEL_DEBUG, "debug should be filtered"); /* filtered */
+  log_message(LOG_LEVEL_INFO, "info should show");
+  log_message(LOG_LEVEL_WARNING, "warning should show");
+  log_message(LOG_LEVEL_ERROR, "error should show");
+
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+static void test_log_set_level_error() {
+  set_log_level(LOG_LEVEL_ERROR);
+
+  /* ERROR level: only ERROR should show */
+  log_message(LOG_LEVEL_DEBUG, "debug filtered");
+  log_message(LOG_LEVEL_INFO, "info filtered");
+  log_message(LOG_LEVEL_WARNING, "warning filtered");
+  log_message(LOG_LEVEL_ERROR, "error should show");
+
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+/* Test that set_log_level with default WARNING filters correctly */
+static void test_log_filtering() {
+  /* Reset to default */
+  set_log_level(LOG_LEVEL_WARNING);
+
+  /* These should be filtered */
+  log_message(LOG_LEVEL_DEBUG, "filtered debug");
+  log_message(LOG_LEVEL_INFO, "filtered info");
+
+  /* These should be shown */
+  log_message(LOG_LEVEL_WARNING, "visible warning");
+  log_message(LOG_LEVEL_ERROR, "visible error");
+
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+/* Test that log_message handles various format strings */
+static void test_log_message_formats() {
+  set_log_level(LOG_LEVEL_DEBUG);
+
+  log_message(LOG_LEVEL_DEBUG, "simple string");
+  log_message(LOG_LEVEL_INFO, "integer: %d", -1);
+  log_message(LOG_LEVEL_WARNING, "string: %s", "hello");
+  log_message(LOG_LEVEL_ERROR, "multiple: %d %s %d", 1, "two", 3);
+
+  /* crash regression test — stderr capture would need infrastructure changes */
+  EXPECT_TRUE(true);
+}
+
+void test_log() {
+  test_log_message_debug();
+  test_log_message_info();
+  test_log_message_warning();
+  test_log_message_error();
+  test_log_set_level_debug();
+  test_log_set_level_info();
+  test_log_set_level_error();
+  test_log_filtering();
+  test_log_message_formats();
+}

tests/test_log.h

@@ -0,0 +1,6 @@
+#ifndef TEST_LOG_H
+#define TEST_LOG_H
+
+void test_log();
+
+#endif

tests/test_multiprocessing.c

@@ -0,0 +1,101 @@
+#include "test_multiprocessing.h"
+#include "multiprocessing.h"
+#include "config.h"
+#include "queue.h"
+#include "utils.h"
+#include "test_utils.h"
+#include <stdlib.h>
+
+/* Test pipeline_context_sender_create/destroy with valid arguments */
+static void test_sender_create_destroy() {
+  Config* cfg = config_create(str_dup("1.0"), str_dup("/src"), str_dup("/dst"), false, false, false,
+                              false, false, 0, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  Queue* q_scanner = queue_create(5, NULL);
+  EXPECT_NOT_NULL(q_scanner);
+
+  Queue* q_loader = queue_create(10, NULL);
+  EXPECT_NOT_NULL(q_loader);
+
+  PipelineContextSender* ctx = pipeline_context_sender_create(cfg, q_scanner, q_loader);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_STR(ctx->config->version, "1.0");
+  EXPECT_EQ_INT(ctx->queue_scanner->capacity, 5);
+  EXPECT_EQ_INT(ctx->queue_loader->capacity, 10);
+  EXPECT_FALSE(ctx->scanner_done);
+  EXPECT_FALSE(ctx->loader_done);
+  EXPECT_NULL(ctx->manifest);
+
+  pipeline_context_sender_destroy(ctx);
+}
+
+/* Test pipeline_context_receiver_create/destroy with valid arguments */
+static void test_receiver_create_destroy() {
+  Config* cfg = config_create(str_dup("2.0"), str_dup("/src"), str_dup("/dst"), true, true, false,
+                              false, false, 0, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  Queue* q = queue_create(20, NULL);
+  EXPECT_NOT_NULL(q);
+
+  PipelineContextReceiver* ctx = pipeline_context_receiver_create(cfg, q, 42);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_STR(ctx->config->version, "2.0");
+  EXPECT_EQ_INT(ctx->queue->capacity, 20);
+  EXPECT_EQ_INT(ctx->file_descriptor, 42);
+  EXPECT_FALSE(ctx->receiver_done);
+
+  pipeline_context_receiver_destroy(ctx);
+}
+
+/* Test that create handles various queue capacities */
+static void test_sender_queue_capacities() {
+  Config* cfg = config_create(str_dup("3.0"), str_dup("/src"), str_dup("/dst"), false, false, false,
+                              false, false, 0, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  /* Single-element queues */
+  Queue* q1 = queue_create(1, NULL);
+  Queue* q2 = queue_create(1, NULL);
+  PipelineContextSender* ctx = pipeline_context_sender_create(cfg, q1, q2);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_INT(ctx->queue_scanner->capacity, 1);
+  EXPECT_EQ_INT(ctx->queue_loader->capacity, 1);
+  pipeline_context_sender_destroy(ctx);
+}
+
+/* Test that create handles zero-capacity queues */
+static void test_sender_zero_capacity() {
+  Config* cfg = config_create(str_dup("4.0"), str_dup("/src"), str_dup("/dst"), false, false, false,
+                              false, false, 0, false, 0);
+  EXPECT_NOT_NULL(cfg);
+
+  Queue* q1 = queue_create(0, NULL);
+  Queue* q2 = queue_create(0, NULL);
+  PipelineContextSender* ctx = pipeline_context_sender_create(cfg, q1, q2);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_INT(ctx->queue_scanner->capacity, 0);
+  EXPECT_EQ_INT(ctx->queue_loader->capacity, 0);
+  pipeline_context_sender_destroy(ctx);
+}
+
+/* Test receiver with zero file_descriptor */
+static void test_receiver_fd_zero() {
+  Config* cfg = config_create(str_dup("5.0"), str_dup("/src"), str_dup("/dst"), false, false, false,
+                              false, false, 0, false, 0);
+  Queue* q = queue_create(5, NULL);
+  PipelineContextReceiver* ctx = pipeline_context_receiver_create(cfg, q, 0);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_INT(ctx->file_descriptor, 0);
+  EXPECT_FALSE(ctx->receiver_done);
+  pipeline_context_receiver_destroy(ctx);
+}
+
+void test_multiprocessing() {
+  test_sender_create_destroy();
+  test_receiver_create_destroy();
+  test_sender_queue_capacities();
+  test_sender_zero_capacity();
+  test_receiver_fd_zero();
+}

tests/test_multiprocessing.h

@@ -0,0 +1,6 @@
+#ifndef TEST_MULTIPROCESSING_H
+#define TEST_MULTIPROCESSING_H
+
+void test_multiprocessing();
+
+#endif

tests/test_protocol.c

@@ -179,6 +179,7 @@ static void test_receive_str_oversized() {
   size_t huge = MAX_STRING_SIZE + 1;
   EXPECT_TRUE(send_n_data(0, &huge, sizeof(size_t)));
 
+  /* cppcheck-suppress constVariablePointer */
   char* received = receive_str(0);
   EXPECT_NULL(received);
 

tests/test_scanner.c

@@ -122,9 +122,294 @@ static void test_scanner_empty_directory() {
   rmdir(dir);
 }
 
+/* --- Exclude/include pattern and size filter edge cases (Issue #56) --- */
+
+static void test_scanner_exclude_pattern() {
+  const char* dir = "test_scan_excl";
+  const char* f_txt = "test_scan_excl/keep.txt";
+  const char* f_tmp = "test_scan_excl/remove.tmp";
+  const char* content = "data";
+
+  mkdir(dir, 0755);
+  create_test_file(f_txt, content);
+  create_test_file(f_tmp, content);
+
+  char* exclude[] = {"*.tmp"};
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, exclude, 1, NULL, 0, 0, 0);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  EXPECT_EQ_INT(chunk->element_count, 1);
+  EXPECT_EQ_STR(chunk->items[0]->path, f_txt);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(f_txt);
+  unlink(f_tmp);
+  rmdir(dir);
+}
+
+static void test_scanner_exclude_subdirectory() {
+  /* Exclude patterns match filenames only (via entry->d_name).
+   * Files inside subdirectories are also matched by filename. */
+  const char* root = "test_scan_excl_sub";
+  const char* sub = "test_scan_excl_sub/sub";
+  const char* root_txt = "test_scan_excl_sub/root.txt";
+  const char* sub_txt = "test_scan_excl_sub/sub/data.txt";
+  const char* sub_tmp = "test_scan_excl_sub/sub/temp.tmp";
+  const char* content = "data";
+
+  mkdir(root, 0755);
+  mkdir(sub, 0755);
+  create_test_file(root_txt, content);
+  create_test_file(sub_txt, content);
+  create_test_file(sub_tmp, content);
+
+  /* Exclude *.tmp — should exclude sub/temp.tmp but keep root.txt and sub/data.txt */
+  char* exclude[] = {"*.tmp"};
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)root, false, 0, exclude, 1, NULL, 0, 0, 0);
+  EXPECT_NOT_NULL(scanner);
+
+  int total = 0;
+  Chunk* chunk;
+  while ((chunk = directory_scanner_next(scanner)) != NULL) {
+    total += chunk->element_count;
+    for (int i = 0; i < chunk->element_count; i++) {
+      /* No path should end in .tmp */
+      size_t len = strlen(chunk->items[i]->path);
+      EXPECT_TRUE(len < 4 || strcmp(chunk->items[i]->path + len - 4, ".tmp") != 0);
+    }
+    chunk_destroy(chunk);
+  }
+  EXPECT_EQ_INT(total, 2);
+
+  directory_scanner_destroy(scanner);
+  unlink(root_txt);
+  unlink(sub_txt);
+  unlink(sub_tmp);
+  rmdir(sub);
+  rmdir(root);
+}
+
+static void test_scanner_include_and_exclude() {
+  /* In the scanner, exclude is checked first and takes precedence.
+   * Include patterns act as an additional filter: if include_count > 0,
+   * the file must match one of the include patterns (after not being excluded).
+   * This test uses non-overlapping exclude and include patterns. */
+  const char* dir = "test_scan_inc_exc";
+  const char* f_txt = "test_scan_inc_exc/a.txt";
+  const char* f_log = "test_scan_inc_exc/b.log";
+  const char* f_bak = "test_scan_inc_exc/c.bak";
+  const char* content = "filter";
+
+  mkdir(dir, 0755);
+  create_test_file(f_txt, content);
+  create_test_file(f_log, content);
+  create_test_file(f_bak, content);
+
+  /* Exclude *.bak. Include *.txt and *.log. */
+  char* exclude[] = {"*.bak"};
+  char* include[] = {"*.txt", "*.log"};
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, exclude, 1, include, 2, 0, 0);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  EXPECT_EQ_INT(chunk->element_count, 2);
+
+  int found_txt = 0, found_log = 0;
+  for (int i = 0; i < chunk->element_count; i++) {
+    if (strstr(chunk->items[i]->path, "a.txt"))
+      found_txt = 1;
+    if (strstr(chunk->items[i]->path, "b.log"))
+      found_log = 1;
+  }
+  /* a.txt included by *.txt, b.log included by *.log, c.bak excluded by *.bak */
+  EXPECT_TRUE(found_txt);
+  EXPECT_TRUE(found_log);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(f_txt);
+  unlink(f_log);
+  unlink(f_bak);
+  rmdir(dir);
+}
+
+static void test_scanner_max_size() {
+  const char* dir = "test_scan_max";
+  const char* small = "test_scan_max/small.txt";
+  const char* large = "test_scan_max/large.txt";
+  create_test_file(small, "tiny");
+  create_test_file(large, "this_content_is_longer_than_ten_chars");
+
+  mkdir(dir, 0755);
+  create_test_file(small, "tiny");
+  create_test_file(large, "this_content_is_longer_than_ten_chars");
+
+  /* max_size = 10 — only files <= 10 bytes */
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 10, 0);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  EXPECT_EQ_INT(chunk->element_count, 1);
+  EXPECT_EQ_STR(chunk->items[0]->path, small);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(small);
+  unlink(large);
+  rmdir(dir);
+}
+
+static void test_scanner_min_size() {
+  const char* dir = "test_scan_min";
+  const char* empty_f = "test_scan_min/empty.txt";
+  const char* data_f = "test_scan_min/data.txt";
+
+  mkdir(dir, 0755);
+  create_test_file(empty_f, "");
+  create_test_file(data_f, "some content here");
+
+  /* min_size = 1 — only files >= 1 byte */
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 1);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  EXPECT_EQ_INT(chunk->element_count, 1);
+  EXPECT_EQ_STR(chunk->items[0]->path, data_f);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(empty_f);
+  unlink(data_f);
+  rmdir(dir);
+}
+
+static void test_scanner_size_range() {
+  const char* dir = "test_scan_range";
+  const char* tiny = "test_scan_range/tiny.txt";
+  const char* medium = "test_scan_range/med.txt";
+  const char* huge = "test_scan_range/huge.txt";
+
+  mkdir(dir, 0755);
+  create_test_file(tiny, "ab");
+  create_test_file(medium, "hello world");
+  create_test_file(huge, "this is a much larger file for testing size filters");
+
+  /* Only files between 3 and 20 bytes */
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 20, 3);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  EXPECT_EQ_INT(chunk->element_count, 1);
+  EXPECT_EQ_STR(chunk->items[0]->path, medium);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(tiny);
+  unlink(medium);
+  unlink(huge);
+  rmdir(dir);
+}
+
+static void test_scanner_mixed_patterns() {
+  /* Combine exclude, include, and size filters together */
+  const char* dir = "test_scan_mixed";
+  const char* a_txt = "test_scan_mixed/a.txt"; /* size ~= 5  */
+  const char* b_bin = "test_scan_mixed/b.bin"; /* size ~= 13 */
+  const char* c_txt = "test_scan_mixed/c.txt"; /* size ~= 5  */
+  const char* d_bak = "test_scan_mixed/d.bak"; /* size ~= 42 */
+
+  mkdir(dir, 0755);
+  create_test_file(a_txt, "aaaaa");
+  create_test_file(b_bin, "bbbbbbbbbbbbb");
+  create_test_file(c_txt, "ccccc");
+  create_test_file(d_bak, "dddddddddddddddddddddddddddddddddddddddddd");
+
+  /* Exclude *.bak, include *.txt, min_size=3, max_size=10 */
+  char* exclude[] = {"*.bak"};
+  char* include[] = {"*.txt"};
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, exclude, 1, include, 1, 10, 3);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  /* Both a.txt and c.txt meet the criteria: .txt extension, size 5 <= 10 and >= 3 */
+  EXPECT_EQ_INT(chunk->element_count, 2);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(a_txt);
+  unlink(b_bin);
+  unlink(c_txt);
+  unlink(d_bak);
+  rmdir(dir);
+}
+
+static void test_scanner_no_patterns() {
+  /* Explicit test with no exclude/include patterns and no size filters.
+   * This verifies that NULL/0 for all pattern parameters works correctly. */
+  const char* dir = "test_scan_none";
+  const char* f1 = "test_scan_none/f1.txt";
+  const char* f2 = "test_scan_none/f2.txt";
+
+  mkdir(dir, 0755);
+  create_test_file(f1, "first");
+  create_test_file(f2, "second");
+
+  DirectoryScanner* scanner =
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
+  EXPECT_NOT_NULL(scanner);
+
+  Chunk* chunk = directory_scanner_next(scanner);
+  EXPECT_NOT_NULL(chunk);
+  EXPECT_EQ_INT(chunk->element_count, 2);
+
+  chunk_destroy(chunk);
+  EXPECT_NULL(directory_scanner_next(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(f1);
+  unlink(f2);
+  rmdir(dir);
+}
+
 void test_scanner() {
   test_scanner_single_file();
   test_scanner_multiple_files();
   test_scanner_subdirectory();
   test_scanner_empty_directory();
+  /* Issue #56: scanner pattern edge cases */
+  test_scanner_exclude_pattern();
+  test_scanner_exclude_subdirectory();
+  test_scanner_include_and_exclude();
+  test_scanner_max_size();
+  test_scanner_min_size();
+  test_scanner_size_range();
+  test_scanner_mixed_patterns();
+  test_scanner_no_patterns();
 }

tests/test_transport_ssh.c

@@ -0,0 +1,53 @@
+#include "test_transport_ssh.h"
+#include "transport_ssh.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+/* Test client_connect_ssh with invalid destination (missing colon) */
+static void test_ssh_connect_invalid_dest() {
+  /* Missing colon — parse_remote_dest should fail and return NULL */
+  /* cppcheck-suppress constVariablePointer */
+  Client* client = client_connect_ssh("invalid-destination-no-colon", 22);
+  EXPECT_NULL(client);
+}
+
+/* Test client_connect_ssh with empty destination */
+static void test_ssh_connect_empty_dest() {
+  /* cppcheck-suppress constVariablePointer */
+  Client* client = client_connect_ssh("", 22);
+  EXPECT_NULL(client);
+}
+
+/* Test client_connect_ssh with malformed destination (just a colon).
+ * parse_remote_dest succeeds, ssh is exec'd and fails, but the function
+ * creates a Client that must be cleaned up. */
+static void test_ssh_connect_malformed() {
+  Client* client = client_connect_ssh(":", 22);
+  /* ssh binary exists, so exec succeeds; the function returns a Client.
+   * We just verify it doesn't crash and clean up properly. */
+  if (client != NULL) {
+    client_disconnect(client);
+    client_delete(client);
+  }
+  EXPECT_TRUE(true);
+}
+
+/* Test client_connect_ssh with valid format but unreachable host.
+ * The function launches ssh which will fail to connect, returns a Client. */
+static void test_ssh_connect_unreachable() {
+  Client* client = client_connect_ssh("nonexistent.invalid:/remote/path", 22);
+  if (client != NULL) {
+    client_disconnect(client);
+    client_delete(client);
+  }
+  EXPECT_TRUE(true);
+}
+
+void test_transport_ssh() {
+  test_ssh_connect_invalid_dest();
+  test_ssh_connect_empty_dest();
+  test_ssh_connect_malformed();
+  test_ssh_connect_unreachable();
+}

tests/test_transport_ssh.h

@@ -0,0 +1,6 @@
+#ifndef TEST_TRANSPORT_SSH_H
+#define TEST_TRANSPORT_SSH_H
+
+void test_transport_ssh();
+
+#endif

tests/test_transport_tcp.c

@@ -0,0 +1,89 @@
+#include "test_transport_tcp.h"
+#include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <unistd.h>
+
+/* Test client_create and client_delete lifecycle */
+static void test_client_create_delete() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+  EXPECT_EQ_INT(client->file_descriptor, -1);
+  EXPECT_TRUE(client->address.ss_family == AF_UNSPEC);
+  EXPECT_EQ_INT(client->ssh_child_pid, -1);
+  EXPECT_NULL(client->ssl);
+  EXPECT_NULL(client->ssl_ctx);
+
+  /* Delete should clean up without error */
+  client_delete(client);
+}
+
+/* Test client_delete with NULL (safety) */
+static void test_client_delete_null() {
+  client_delete(NULL);
+  EXPECT_TRUE(true);
+}
+
+/* Test server_create and server_delete lifecycle */
+static void test_server_create_delete() {
+  /* Use port 0 to let the OS assign a port */
+  Server* server = server_create(0);
+  EXPECT_NOT_NULL(server);
+  EXPECT_TRUE(server->file_descriptor >= 0);
+  EXPECT_TRUE(server->address.ss_family == AF_INET || server->address.ss_family == AF_INET6);
+  EXPECT_NULL(server->ssl_ctx);
+
+  /* Clean up */
+  server_delete(&server);
+  EXPECT_NULL(server);
+}
+
+/* Test server_delete with NULL pointer */
+static void test_server_delete_null_ptr() {
+  server_delete(NULL);
+  EXPECT_TRUE(true);
+}
+
+/* Test server_delete with NULL server */
+static void test_server_delete_null_server() {
+  Server* s = NULL;
+  server_delete(&s);
+  EXPECT_NULL(s);
+}
+
+/* Test client_create can be called multiple times */
+static void test_client_create_multiple() {
+  Client* c1 = client_create();
+  Client* c2 = client_create();
+  EXPECT_NOT_NULL(c1);
+  EXPECT_NOT_NULL(c2);
+  EXPECT_EQ_INT(c1->file_descriptor, -1);
+  EXPECT_EQ_INT(c2->file_descriptor, -1);
+
+  client_delete(c1);
+  client_delete(c2);
+}
+
+/* Test client_disconnect on a fresh client (should close socket) */
+static void test_client_disconnect_fresh() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  /* Disconnect should close the file descriptor */
+  client_disconnect(client);
+  /* The fd should now be invalid */
+  /* Verify by trying to use close() on it - should fail */
+  EXPECT_EQ_INT(close(client->file_descriptor), -1);
+
+  client_delete(client);
+}
+
+void test_transport_tcp() {
+  test_client_create_delete();
+  test_client_delete_null();
+  test_server_create_delete();
+  test_server_delete_null_ptr();
+  test_server_delete_null_server();
+  test_client_create_multiple();
+  test_client_disconnect_fresh();
+}

tests/test_transport_tcp.h

@@ -0,0 +1,6 @@
+#ifndef TEST_TRANSPORT_TCP_H
+#define TEST_TRANSPORT_TCP_H
+
+void test_transport_tcp();
+
+#endif

tests/test_transport_tls.c

@@ -0,0 +1,81 @@
+#include "test_transport_tls.h"
+#include "transport_tls.h"
+#include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <unistd.h>
+
+/* Test tls_global_init succeeds */
+static void test_tls_global_init() {
+  bool ok = tls_global_init();
+  EXPECT_TRUE(ok);
+}
+
+/* Test tls_global_init can be called multiple times */
+static void test_tls_global_init_twice() {
+  bool ok1 = tls_global_init();
+  bool ok2 = tls_global_init();
+  EXPECT_TRUE(ok1);
+  EXPECT_TRUE(ok2);
+}
+
+/* Test client_connect_tls with bad certificate path.
+ * The function will create a socket, try to connect to localhost,
+ * fail to connect (since nothing is listening), and return false.
+ * We don't need a server to verify the error path. */
+static void test_tls_connect_bad_cert() {
+  /* First, init TLS globally */
+  tls_global_init();
+
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  /* Attempt to connect to a non-existent server with bad cert paths.
+   * client_connect_tls will try to connect first, fail, and return false.
+   * Note: we use an invalid host to ensure connection failure,
+   * which exercises the error path before cert loading. */
+  bool ok = client_connect_tls(client, "127.0.0.1", 1, "/nonexistent/cert.pem",
+                               "/nonexistent/key.pem", "/nonexistent/ca.pem");
+  EXPECT_FALSE(ok);
+
+  client_delete(client);
+}
+
+/* Test client_connect_tls with NULL cert paths (should still attempt connection).
+ * Cert/key/ca being NULL is valid — the function will attempt to create an
+ * SSL context without client certificates. */
+static void test_tls_connect_null_paths() {
+  tls_global_init();
+
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  /* Connect to invalid address — will fail at connect() step */
+  bool ok = client_connect_tls(client, "127.0.0.1", 1, NULL, NULL, NULL);
+  EXPECT_FALSE(ok);
+
+  client_delete(client);
+}
+
+/* Test server_create_tls with bad cert paths.
+ * The function should fail gracefully. */
+static void test_tls_server_bad_cert() {
+  tls_global_init();
+
+  Server* server = server_create(0);
+  EXPECT_NOT_NULL(server);
+
+  /* Load bad cert paths — should fail and return false */
+  bool ok = server_create_tls(server, "/nonexistent/cert.pem", "/nonexistent/key.pem", NULL);
+  EXPECT_FALSE(ok);
+
+  server_delete(&server);
+}
+
+void test_transport_tls() {
+  test_tls_global_init();
+  test_tls_global_init_twice();
+  test_tls_connect_bad_cert();
+  test_tls_connect_null_paths();
+  test_tls_server_bad_cert();
+}

tests/test_transport_tls.h

@@ -0,0 +1,6 @@
+#ifndef TEST_TRANSPORT_TLS_H
+#define TEST_TRANSPORT_TLS_H
+
+void test_transport_tls();
+
+#endif

tests/test_utils.h

@@ -2,9 +2,24 @@
 #define TEST_UTILS_H
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
 
+// Detect if running under valgrind by checking /proc/self/maps for vgpreload.
+// This is used to skip fork-based tests that are incompatible with valgrind
+// (the instrumented parent runs too slowly, causing pipe timeouts).
+static inline bool is_running_under_valgrind(void) {
+  FILE* f = fopen("/proc/self/maps", "r");
+  if (!f)
+    return false;
+  char buf[4096];
+  size_t n = fread(buf, 1, sizeof(buf) - 1, f);
+  fclose(f);
+  buf[n] = '\0';
+  return strstr(buf, "vgpreload") != NULL;
+}
+
 // Global test suite status
 extern int tests_run;
 extern int tests_failed;