fix: const qualifier for scanner root_directory parameter

.gitignore

@@ -5,3 +5,4 @@ __pycache__/
 build-asan
 coverage.info
 build-*/
+build3/

src/client/client_cli.c

@@ -3,6 +3,7 @@
 #include "delta.h"
 #include "log.h"
 #include "protocol.h"
+#include "transport_tcp.h"
 #include "transport_tls.h"
 #include "utils.h"
 #include <errno.h>
@@ -31,6 +32,8 @@ static void print_usage(void) {
   printf("  --delete            Delete files on receiver not in source\n");
   printf("  --exclude <pattern> Exclude files matching pattern\n");
   printf("  --include <pattern> Only include files matching pattern\n");
+  printf("  --exclude-from <file> Read exclude patterns from file\n");
+  printf("  --include-from <file> Read include patterns from file\n");
   printf("  --max-size <n>      Skip files larger than n bytes\n");
   printf("  --min-size <n>      Skip files smaller than n bytes\n");
   printf("  --incremental       Skip files unchanged since last transfer\n");
@@ -55,9 +58,50 @@ 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("  --timeout <sec>     I/O timeout in seconds (default: 30)\n");
+  printf("  --contimeout <sec>  Connection timeout in seconds (default: 10)\n");
+  printf("  -q, --quiet         Suppress non-error output\n");
+  printf("  --silent            Alias for --quiet\n");
+  printf("  --backup            Backup existing files before overwriting\n");
+  printf("  --backup-dir <dir>  Directory for backups (requires --backup)\n");
+  printf("  --stats             Print transfer statistics at end\n");
+  printf("  --max-depth <n>     Maximum directory depth (0=unlimited)\n");
+  printf("  --log-file <path>   Write log messages to file\n");
+  printf("  --queue-size <n>    Queue capacity for multithreaded mode (default: 100)\n");
   printf("  --help              Show this help\n");
 }
 
+static int read_patterns_from_file(const char* filepath, char*** patterns, int* count) {
+  FILE* fp = fopen(filepath, "r");
+  if (!fp) {
+    fprintf(stderr, "Error: could not open pattern file '%s': %s\n", filepath, strerror(errno));
+    return -1;
+  }
+  char line[4096];
+  while (fgets(line, sizeof(line), fp)) {
+    char* p = line;
+    while (*p == ' ' || *p == '\t')
+      p++;
+    if (*p == '#' || *p == '\n' || *p == '\0')
+      continue;
+    size_t len = strlen(p);
+    while (len > 0 && (p[len - 1] == '\n' || p[len - 1] == '\r'))
+      p[--len] = '\0';
+    if (len == 0)
+      continue;
+    char** tmp = realloc(*patterns, (*count + 1) * sizeof(char*));
+    if (!tmp) {
+      fprintf(stderr, "Error: memory allocation failed for pattern file\n");
+      fclose(fp);
+      return -1;
+    }
+    *patterns = tmp;
+    (*patterns)[(*count)++] = str_dup(p);
+  }
+  fclose(fp);
+  return 0;
+}
+
 int main(int argc, char* argv[]) {
   const char* env_source = getenv("FASTSYNC_SOURCE_DIR");
   const char* env_dest = getenv("FASTSYNC_DEST_DIR");
@@ -199,6 +243,64 @@ 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], "--timeout") == 0 && i + 1 < argc) {
+      config->timeout = atoi(argv[++i]);
+      if (config->timeout <= 0) {
+        fprintf(stderr, "Error: --timeout must be a positive integer\n");
+        exit_code = 1;
+        goto cleanup;
+      }
+    } else if (strcmp(argv[i], "--contimeout") == 0 && i + 1 < argc) {
+      config->contimeout = atoi(argv[++i]);
+      if (config->contimeout <= 0) {
+        fprintf(stderr, "Error: --contimeout must be a positive integer\n");
+        exit_code = 1;
+        goto cleanup;
+      }
+    } else if (strcmp(argv[i], "-q") == 0 || strcmp(argv[i], "--quiet") == 0 ||
+               strcmp(argv[i], "--silent") == 0) {
+      config->quiet = true;
+    } else if (strcmp(argv[i], "--backup") == 0) {
+      config->backup = true;
+    } else if (strcmp(argv[i], "--backup-dir") == 0 && i + 1 < argc) {
+      config->backup_dir = str_dup(argv[++i]);
+    } else if (strcmp(argv[i], "--stats") == 0) {
+      config->stats = true;
+    } else if (strcmp(argv[i], "--max-depth") == 0 && i + 1 < argc) {
+      config->max_depth = atoi(argv[++i]);
+      if (config->max_depth < 0) {
+        fprintf(stderr, "Error: --max-depth must be a non-negative integer\n");
+        exit_code = 1;
+        goto cleanup;
+      }
+    } else if (strcmp(argv[i], "--log-file") == 0 && i + 1 < argc) {
+      FILE* lf = fopen(argv[++i], "a");
+      if (!lf) {
+        fprintf(stderr, "Error: could not open log file '%s': %s\n", argv[i], strerror(errno));
+        exit_code = 1;
+        goto cleanup;
+      }
+      config->log_file = lf;
+      log_set_file(lf);
+    } else if (strcmp(argv[i], "--queue-size") == 0 && i + 1 < argc) {
+      config->queue_size = atoi(argv[++i]);
+      if (config->queue_size <= 0) {
+        fprintf(stderr, "Error: --queue-size must be a positive integer\n");
+        exit_code = 1;
+        goto cleanup;
+      }
+    } else if (strcmp(argv[i], "--exclude-from") == 0 && i + 1 < argc) {
+      if (read_patterns_from_file(argv[++i], &config->exclude_patterns, &config->exclude_count) !=
+          0) {
+        exit_code = 1;
+        goto cleanup;
+      }
+    } else if (strcmp(argv[i], "--include-from") == 0 && i + 1 < argc) {
+      if (read_patterns_from_file(argv[++i], &config->include_patterns, &config->include_count) !=
+          0) {
+        exit_code = 1;
+        goto cleanup;
+      }
     } else if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
       set_log_level(LOG_LEVEL_DEBUG);
     } else if (argv[i][0] == '-') {
@@ -297,6 +399,8 @@ int main(int argc, char* argv[]) {
     tls_global_init();
   }
 
+  tcp_set_timeouts(config->timeout, config->contimeout);
+
   if (config->use_multithreading) {
     config_owned_by_pipeline = true;
     exit_code = send_files_multithreaded(config);
@@ -305,6 +409,8 @@ int main(int argc, char* argv[]) {
   }
 
 cleanup:
+  if (config->log_file)
+    fclose(config->log_file);
   if (!config_owned_by_pipeline)
     config_delete(config);
   return exit_code;

src/client/client_send.c

@@ -16,14 +16,22 @@
 #include "transport_ssh.h"
 #include "transport_tls.h"
 #include "utils.h"
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <threads.h>
 #include <time.h>
-#include <unistd.h>
 
-#define STREAM_THRESHOLD (64ULL * 1024 * 1024)
+static volatile sig_atomic_t g_abort_requested = 0;
+static int g_abort_fd = -1;
+
+static void handle_sigint(int sig) {
+  (void)sig;
+  g_abort_requested = 1;
+}
+
+#define KEEPALIVE_INTERVAL 30
 
 static int incremental_check(Client* client, File* file, DeltaSignature** out_sig) {
   *out_sig = NULL;
@@ -99,6 +107,35 @@ static int send_delta(Client* client, File* file, DeltaSignature* sig, Config* c
   return ok ? 0 : -1;
 }
 
+static bool batch_incremental_check(Client* client, ArrayList* files) {
+  if (!send_status(client->file_descriptor, STATUS_CHECK_BATCH))
+    return false;
+  if (!send_int(client->file_descriptor, files->size))
+    return false;
+  for (int i = 0; i < files->size; i++) {
+    File* file = (File*)files->items[i];
+    if (!send_str(client->file_descriptor, file->path))
+      return false;
+    unsigned long long fsize = file->data ? file->data->size : 0;
+    long long mtime = file->metadata ? file->metadata->mtime_sec : 0;
+    if (!send_n_data(client->file_descriptor, &fsize, sizeof(fsize)))
+      return false;
+    if (!send_n_data(client->file_descriptor, &mtime, sizeof(mtime)))
+      return false;
+  }
+  for (int i = 0; i < files->size; i++) {
+    Status s;
+    if (!receive_status(client->file_descriptor, &s))
+      return false;
+    File* file = (File*)files->items[i];
+    if (s == STATUS_OK)
+      file->skip = true;
+    else if (s == STATUS_ERROR)
+      return false;
+  }
+  return true;
+}
+
 typedef bool (*file_send_fn)(File*, int, bool, int, bool);
 
 // Send a single file directly (non-incremental path).
@@ -121,6 +158,9 @@ static int send_single_file(Client* client, File* file, Config* config, bool use
                             bool use_sendfile) {
   int compression_level = config->use_compression ? config->compression_level : 0;
 
+  if (file->skip)
+    return 1;
+
   if (!use_incremental) {
     if (use_sendfile) {
       return send_file_direct_sendfile(file, client->file_descriptor, config->use_metadata) ? 0
@@ -211,13 +251,10 @@ int send_chunk(Client* client, Chunk* chunk, Config* config) {
     return 0;
   }
 
+  bool use_sendfile = config->use_sendfile && !config->use_compression;
   for (int i = 0; i < chunk->element_count; i++) {
-    File* f = chunk->items[i];
+    int rc =
-    if (f == NULL)
+        send_single_file(client, chunk->items[i], config, config->use_incremental, use_sendfile);
-      continue;
-    bool stream = f->data->data == NULL && f->data->size > 0;
-    bool use_sendfile = (config->use_sendfile && !config->use_compression) || stream;
-    int rc = send_single_file(client, f, config, config->use_incremental, use_sendfile);
     if (rc == 1)
       continue;
     if (rc < 0)
@@ -261,7 +298,30 @@ static int send_chunks_multithreaded(void* pipeline_context) {
     return thrd_error;
   }
 
+  g_abort_fd = client->file_descriptor;
+  time_t last_activity = time(NULL);
   while (true) {
+    if (g_abort_requested) {
+      send_status(client->file_descriptor, STATUS_ABORT);
+      client_disconnect(client);
+      client_delete(client);
+      return thrd_error;
+    }
+    time_t now = time(NULL);
+    if (now - last_activity >= KEEPALIVE_INTERVAL) {
+      if (!send_status(client->file_descriptor, STATUS_KEEPALIVE)) {
+        client_disconnect(client);
+        client_delete(client);
+        return thrd_error;
+      }
+      Status s;
+      if (!receive_status(client->file_descriptor, &s)) {
+        client_disconnect(client);
+        client_delete(client);
+        return thrd_error;
+      }
+      last_activity = now;
+    }
     Chunk* current_chunk = queue_dequeue_multithreaded(
         context->queue_loader, &context->mutex_loader, &context->condition_not_empty_loader,
         &context->condition_not_full_loader, &context->loader_done);
@@ -301,14 +361,16 @@ static int send_chunks_multithreaded(void* pipeline_context) {
 
 static int scan_directory_multithreaded(void* pipeline_context) {
   PipelineContextSender* context = (PipelineContextSender*)pipeline_context;
-  ParallelScanner* scanner = parallel_scanner_create(
+  mtx_lock(&context->mutex_scanner);
+  DirectoryScanner* scanner = directory_scanner_create(
       context->config->send_directory, context->config->use_metadata, context->config->chunk_size,
       context->config->exclude_patterns, context->config->exclude_count,
       context->config->include_patterns, context->config->include_count, context->config->max_size,
-      context->config->min_size, 4);
+      context->config->min_size, context->config->max_depth);
+  mtx_unlock(&context->mutex_scanner);
 
   Chunk* current_chunk;
-  while ((current_chunk = parallel_scanner_next(scanner)) != NULL) {
+  while ((current_chunk = directory_scanner_next(scanner)) != NULL) {
     if (context->config->use_delete) {
       mtx_lock(&context->mutex_scanner);
       for (int i = 0; i < current_chunk->element_count; i++) {
@@ -328,7 +390,7 @@ static int scan_directory_multithreaded(void* pipeline_context) {
   cnd_signal(&context->condition_not_empty_scanner);
   mtx_unlock(&context->mutex_scanner);
 
-  parallel_scanner_destroy(scanner);
+  directory_scanner_destroy(scanner);
   return thrd_success;
 }
 
@@ -347,12 +409,9 @@ static int load_files_multithreaded(void* pipeline_context) {
     }
     if (!context->config->use_sendfile) {
       for (int i = 0; i < chunk->element_count; i++) {
-        File* f = chunk->items[i];
+        if (!file_load_data(chunk->items[i])) {
-        if (f->data->size > STREAM_THRESHOLD)
-          continue;
-        if (!file_load_data(f)) {
           log_message(LOG_LEVEL_ERROR, "Failed to load file data, skipping");
-          file_destroy(f);
+          file_destroy(chunk->items[i]);
           chunk->items[i] = NULL;
         }
       }
@@ -368,13 +427,15 @@ int send_files(Config* config) {
     DirectoryScanner* scanner = directory_scanner_create(
         config->send_directory, config->use_metadata, config->chunk_size, config->exclude_patterns,
         config->exclude_count, config->include_patterns, config->include_count, config->max_size,
-        config->min_size);
+        config->min_size, config->max_depth);
     Chunk* chunk;
     int file_count = 0;
     unsigned long long total_bytes = 0;
+    if (!config->quiet)
       printf("Dry run: files to be transferred\n");
     while ((chunk = directory_scanner_next(scanner)) != NULL) {
       for (int i = 0; i < chunk->element_count; i++) {
+        if (!config->quiet)
           printf("  %s (%zu bytes)\n", chunk->items[i]->path, chunk->items[i]->data->size);
         total_bytes += chunk->items[i]->data->size;
         file_count++;
@@ -382,6 +443,7 @@ int send_files(Config* config) {
       chunk_destroy(chunk);
     }
     directory_scanner_destroy(scanner);
+    if (!config->quiet)
       printf("Total: %d files, %.1f MB\n", file_count, total_bytes / 1048576.0);
     return 0;
   }
@@ -418,45 +480,98 @@ int send_files(Config* config) {
     client_delete(client);
     return 1;
   }
+
+  g_abort_fd = client->file_descriptor;
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = handle_sigint;
+  sigaction(SIGINT, &sa, NULL);
+  sigaction(SIGTERM, &sa, NULL);
+
   DirectoryScanner* scanner = directory_scanner_create(
       config->send_directory, config->use_metadata, config->chunk_size, config->exclude_patterns,
       config->exclude_count, config->include_patterns, config->include_count, config->max_size,
-      config->min_size);
+      config->min_size, config->max_depth);
-  Chunk* current_chunk;
+  ArrayList* all_files = array_list_create(NULL);
-  unsigned long long total_bytes = 0;
-  time_t last_progress = 0;
-  time_t start = time(NULL);
   ArrayList* manifest = config->use_delete ? array_list_create(free) : NULL;
+  Chunk* current_chunk;
   while ((current_chunk = directory_scanner_next(scanner)) != NULL) {
-    unsigned long long chunk_bytes = 0;
     for (int i = 0; i < current_chunk->element_count; i++) {
-      chunk_bytes += current_chunk->items[i]->data->size;
+      File* f = current_chunk->items[i];
+      array_list_add(all_files, f);
+      current_chunk->items[i] = NULL;
       if (manifest) {
-        const char* p = current_chunk->items[i]->path;
+        const char* p = f->path;
         if (*p == '/')
           p++;
         array_list_add(manifest, str_dup(p));
       }
     }
-    if (!config->use_sendfile) {
+    chunk_destroy(current_chunk);
-      for (int i = 0; i < current_chunk->element_count; i++) {
+  }
-        File* f = current_chunk->items[i];
+  directory_scanner_destroy(scanner);
-        if (f->data->size > STREAM_THRESHOLD)
+  scanner = NULL;
+
+  bool batch_ok = true;
+  if (config->use_incremental && all_files->size > 0) {
+    if (!batch_incremental_check(client, all_files)) {
+      log_message(LOG_LEVEL_ERROR, "Batch incremental check failed");
+      batch_ok = false;
+    }
+  }
+
+  unsigned long long total_bytes = 0;
+  time_t last_progress = 0;
+  time_t last_activity = 0;
+  time_t start = time(NULL);
+  bool use_sendfile = config->use_sendfile && !config->use_compression;
+  for (int i = 0; i < all_files->size; i++) {
+    File* file = (File*)all_files->items[i];
+    if (file->skip)
       continue;
-        if (!file_load_data(f)) {
+    if (g_abort_requested) {
+      send_status(client->file_descriptor, STATUS_ABORT);
+      batch_ok = false;
+      break;
+    }
+    time_t now = time(NULL);
+    if (now - last_activity >= KEEPALIVE_INTERVAL) {
+      if (!send_status(client->file_descriptor, STATUS_KEEPALIVE)) {
+        batch_ok = false;
+        break;
+      }
+      Status s;
+      if (!receive_status(client->file_descriptor, &s)) {
+        batch_ok = false;
+        break;
+      }
+      last_activity = now;
+    }
+    int compression_level = config->use_compression ? config->compression_level : 0;
+    if (!send_status(client->file_descriptor, STATUS_NEXT)) {
+      batch_ok = false;
+      break;
+    }
+    if (use_sendfile) {
+      if (!file_send_sendfile(file, client->file_descriptor, config->use_metadata, 0, true)) {
+        log_message(LOG_LEVEL_ERROR, "Failed to send file via sendfile");
+        batch_ok = false;
+        break;
+      }
+    } else {
+      if (!file_load_data(file)) {
         log_message(LOG_LEVEL_ERROR, "Failed to load file data");
         continue;
       }
-      }
+      if (!file_send_single_calls(file, client->file_descriptor, config->use_metadata,
-    }
+                                  compression_level, true)) {
-    if (send_chunk(client, current_chunk, config) != 0) {
+        log_message(LOG_LEVEL_ERROR, "Failed to send file");
-      log_message(LOG_LEVEL_ERROR, "Failed to send chunk");
+        batch_ok = false;
-      chunk_destroy(current_chunk);
         break;
       }
+    }
+    total_bytes += file->data ? file->data->size : 0;
     if (config->show_progress) {
-      total_bytes += chunk_bytes;
-      time_t now = time(NULL);
       if (now - last_progress >= 1) {
         last_progress = now;
         double elapsed = difftime(now, start);
@@ -465,58 +580,56 @@ int send_files(Config* config) {
         fflush(stderr);
       }
     }
-    chunk_destroy(current_chunk);
   }
-  if (config->use_delete) {
+
-    if (!send_status(client->file_descriptor, STATUS_MANIFEST)) {
+  if (batch_ok && config->use_delete && manifest) {
-      array_list_delete(manifest);
+    if (!send_status(client->file_descriptor, STATUS_MANIFEST))
-      goto send_fail;
+      batch_ok = false;
+    else if (!send_int(client->file_descriptor, manifest->size))
+      batch_ok = false;
+    else {
+      for (int i = 0; i < manifest->size && batch_ok; i++) {
+        if (!send_str(client->file_descriptor, (char*)manifest->items[i]))
+          batch_ok = false;
       }
-    if (!send_int(client->file_descriptor, manifest->size)) {
-      array_list_delete(manifest);
-      goto send_fail;
-    }
-    for (int i = 0; i < manifest->size; i++) {
-      if (!send_str(client->file_descriptor, (char*)manifest->items[i])) {
-        array_list_delete(manifest);
-        goto send_fail;
     }
   }
   array_list_delete(manifest);
-  }
+
-  if (!send_status(client->file_descriptor, STATUS_FINISHED))
+  if (batch_ok && !send_status(client->file_descriptor, STATUS_FINISHED))
-    goto send_fail;
+    batch_ok = false;
   Status s;
-  int ok = receive_status(client->file_descriptor, &s) && s == STATUS_OK;
+  int ok = 0;
+  if (batch_ok)
+    ok = receive_status(client->file_descriptor, &s) && s == STATUS_OK;
   if (config->show_progress) {
     double elapsed = difftime(time(NULL), start);
     double rate = elapsed > 0 ? total_bytes / (1048576.0 * elapsed) : 0;
     fprintf(stderr, "\rSent %.1f MB  (%.1f MB/s)  Done.\n", total_bytes / 1048576.0, rate);
   }
-  directory_scanner_destroy(scanner);
+  for (int i = 0; i < all_files->size; i++)
+    file_destroy(all_files->items[i]);
+  array_list_delete(all_files);
   client_disconnect(client);
   client_delete(client);
-  return ok ? 0 : -1;
+  return (batch_ok && ok) ? 0 : -1;
-
-send_fail:
-  directory_scanner_destroy(scanner);
-  client_disconnect(client);
-  client_delete(client);
-  return -1;
 }
 
 int send_files_multithreaded(Config* config) {
+  time_t start_time = time(NULL);
   if (config->dry_run) {
     DirectoryScanner* scanner = directory_scanner_create(
         config->send_directory, config->use_metadata, config->chunk_size, config->exclude_patterns,
         config->exclude_count, config->include_patterns, config->include_count, config->max_size,
-        config->min_size);
+        config->min_size, config->max_depth);
     Chunk* chunk;
     int file_count = 0;
     unsigned long long total_bytes = 0;
+    if (!config->quiet)
       printf("Dry run: files to be transferred\n");
     while ((chunk = directory_scanner_next(scanner)) != NULL) {
       for (int i = 0; i < chunk->element_count; i++) {
+        if (!config->quiet)
           printf("  %s (%zu bytes)\n", chunk->items[i]->path, chunk->items[i]->data->size);
         total_bytes += chunk->items[i]->data->size;
         file_count++;
@@ -524,22 +637,12 @@ int send_files_multithreaded(Config* config) {
       chunk_destroy(chunk);
     }
     directory_scanner_destroy(scanner);
+    if (!config->quiet)
       printf("Total: %d files, %.1f MB\n", file_count, total_bytes / 1048576.0);
     return 0;
   }
 
-  long pages = sysconf(_SC_AVPHYS_PAGES);
+  int qsize = config->queue_size > 0 ? config->queue_size : 100;
-  long page_size = sysconf(_SC_PAGE_SIZE);
-  unsigned long long available_memory =
-      pages > 0 && page_size > 0 ? (unsigned long long)pages * (unsigned long long)page_size
-                                 : 512ULL * 1024 * 1024;
-  unsigned long long avg_file_size = 1024 * 1024;
-  int qsize = (int)(available_memory / avg_file_size);
-  if (qsize < 10)
-    qsize = 10;
-  if (qsize > 1000)
-    qsize = 1000;
-
   Queue* q1 = queue_create(qsize, chunk_destroy);
   Queue* q2 = queue_create(qsize, chunk_destroy);
   if (!q1 || !q2) {
@@ -572,6 +675,12 @@ int send_files_multithreaded(Config* config) {
   thrd_join(loader, NULL);
   thrd_join(sender, &sender_result);
 
+  if (config->stats && !config->quiet) {
+    double elapsed = difftime(time(NULL), start_time);
+    printf("\nTransfer statistics:\n");
+    printf("  Elapsed time: %.1f sec\n", elapsed);
+  }
+
   pipeline_context_sender_destroy(context);
   return sender_result == thrd_success ? 0 : -1;
 }

src/client/scanner.c

@@ -9,18 +9,39 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
-#include <threads.h>
 #include <unistd.h>
 
-DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metadata,
+typedef struct {
+  char* path;
+  int depth;
+} DirEntry;
+
+static void dir_entry_destroy(void* item) {
+  if (item) {
+    DirEntry* de = (DirEntry*)item;
+    free(de->path);
+    free(de);
+  }
+}
+
+static DirEntry* dir_entry_create(const char* path, int depth) {
+  DirEntry* de = malloc(sizeof(DirEntry));
+  if (de) {
+    de->path = str_dup(path);
+    de->depth = depth;
+  }
+  return de;
+}
+
+DirectoryScanner* directory_scanner_create(const 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) {
+                                           unsigned long long min_size, int max_depth) {
   DirectoryScanner* scanner = malloc(sizeof(DirectoryScanner));
   if (scanner == NULL)
     return NULL;
-  scanner->directories = queue_create(100, free);
+  scanner->directories = queue_create(100, dir_entry_destroy);
   scanner->current_dir = NULL;
   scanner->current_path = NULL;
   scanner->use_metadata = use_metadata;
@@ -31,7 +52,9 @@ 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;
-  queue_enqueue(scanner->directories, str_dup(root_directory));
+  scanner->max_depth = max_depth;
+  scanner->current_depth = 0;
+  queue_enqueue(scanner->directories, dir_entry_create(root_directory, 0));
   return scanner;
 }
 
@@ -56,6 +79,7 @@ static Chunk* chunk_data_to_chunk(ArrayList* chunk_data) {
   return chunk;
 }
 
+// Returns: 1 on success, 0 if no more directories in queue, -1 on opendir failure
 static int open_next_directory(DirectoryScanner* scanner) {
   if (scanner->current_dir) {
     closedir(scanner->current_dir);
@@ -66,7 +90,10 @@ static int open_next_directory(DirectoryScanner* scanner) {
   if (queue_is_empty(scanner->directories))
     return 0;
 
-  scanner->current_path = (char*)queue_dequeue(scanner->directories);
+  DirEntry* de = (DirEntry*)queue_dequeue(scanner->directories);
+  scanner->current_path = de->path;
+  scanner->current_depth = de->depth;
+  free(de);
   scanner->current_dir = opendir(scanner->current_path);
   if (scanner->current_dir == NULL) {
     perror("Could not open directory");
@@ -110,8 +137,16 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {
     }
 
     if (S_ISDIR(stats.st_mode)) {
-      queue_enqueue(scanner->directories, (void*)cur_path);
+      int next_depth = scanner->current_depth + 1;
+      if (scanner->max_depth <= 0 || next_depth < scanner->max_depth)
+        queue_enqueue(scanner->directories, dir_entry_create(cur_path, next_depth));
+      else
+        free(cur_path);
     } else {
+      if (scanner->max_depth > 0 && scanner->current_depth + 1 > scanner->max_depth) {
+        free(cur_path);
+        continue;
+      }
       bool excluded = false;
       for (int i = 0; i < scanner->exclude_count; i++) {
         if (glob_match(scanner->exclude_patterns[i], entry->d_name)) {
@@ -167,253 +202,3 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {
   array_list_delete(chunk_data);
   return NULL;
 }
-
-typedef struct {
-  ParallelScanner* ps;
-  char** dirs;
-  int dir_count;
-  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;
-} ParallelWorkerArg;
-
-static int parallel_worker_thread(void* arg) {
-  ParallelWorkerArg* wa = (ParallelWorkerArg*)arg;
-  for (int i = 0; i < wa->dir_count; i++) {
-    DirectoryScanner* ds = directory_scanner_create(
-        wa->dirs[i], wa->use_metadata, wa->chunk_size, wa->exclude_patterns, wa->exclude_count,
-        wa->include_patterns, wa->include_count, wa->max_size, wa->min_size);
-    Chunk* chunk;
-    while ((chunk = directory_scanner_next(ds)) != NULL) {
-      queue_enqueue_multithreaded(wa->ps->result_queue, chunk, &wa->ps->result_mutex,
-                                  &wa->ps->result_not_empty, &wa->ps->result_not_full);
-    }
-    directory_scanner_destroy(ds);
-    free(wa->dirs[i]);
-  }
-  ParallelScanner* ps = wa->ps;
-  free(wa->dirs);
-  free(wa);
-  mtx_lock(&ps->result_mutex);
-  ps->completed++;
-  if (ps->completed >= ps->num_threads) {
-    ps->done = true;
-    cnd_signal(&ps->result_not_empty);
-  }
-  mtx_unlock(&ps->result_mutex);
-  return thrd_success;
-}
-
-ParallelScanner* parallel_scanner_create(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, int num_threads) {
-  ParallelScanner* ps = calloc(1, sizeof(ParallelScanner));
-  if (!ps)
-    return NULL;
-  ps->result_queue = queue_create(100, chunk_destroy);
-  if (!ps->result_queue) {
-    free(ps);
-    return NULL;
-  }
-  if (mtx_init(&ps->result_mutex, mtx_plain) != thrd_success ||
-      cnd_init(&ps->result_not_empty) != thrd_success ||
-      cnd_init(&ps->result_not_full) != thrd_success) {
-    queue_destroy(ps->result_queue);
-    free(ps);
-    return NULL;
-  }
-
-  DIR* dir = opendir(root_directory);
-  if (!dir) {
-    perror("Could not open root directory for parallel scan");
-    parallel_scanner_destroy(ps);
-    return NULL;
-  }
-
-  ArrayList* root_files = array_list_create(file_destroy);
-  ArrayList* subdirs = array_list_create(free);
-  struct dirent* entry;
-  while ((entry = readdir(dir)) != NULL) {
-    if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
-      continue;
-    char* cur_path = path_cat(root_directory, entry->d_name);
-    if (!cur_path)
-      continue;
-    struct stat st;
-    if (stat(cur_path, &st) != 0) {
-      free(cur_path);
-      continue;
-    }
-    if (S_ISDIR(st.st_mode)) {
-      array_list_add(subdirs, cur_path);
-    } else {
-      bool excluded = false;
-      for (int i = 0; i < exclude_count; i++) {
-        if (glob_match(exclude_patterns[i], entry->d_name)) {
-          excluded = true;
-          break;
-        }
-      }
-      if (excluded) {
-        free(cur_path);
-        continue;
-      }
-      if (include_count > 0) {
-        bool included = false;
-        for (int i = 0; i < include_count; i++) {
-          if (glob_match(include_patterns[i], entry->d_name)) {
-            included = true;
-            break;
-          }
-        }
-        if (!included) {
-          free(cur_path);
-          continue;
-        }
-      }
-      if ((max_size > 0 && (unsigned long long)st.st_size > max_size) ||
-          (min_size > 0 && (unsigned long long)st.st_size < min_size)) {
-        free(cur_path);
-        continue;
-      }
-      File* file = file_create(cur_path);
-      free(cur_path);
-      if (!file)
-        continue;
-      file->data->size = st.st_size;
-      if (use_metadata)
-        file->metadata = file_metadata_create(&st);
-      array_list_add(root_files, file);
-    }
-  }
-  closedir(dir);
-
-  unsigned long long cs = chunk_size > 0 ? chunk_size : DESIRED_CHUNK_SIZE;
-  if (root_files->size > 0) {
-    ArrayList* batch = array_list_create(NULL);
-    unsigned long long batch_size = 0;
-    Chunk* first = NULL;
-    for (int i = 0; i < root_files->size; i++) {
-      File* f = (File*)root_files->items[i];
-      array_list_add(batch, f);
-      batch_size += f->data->size;
-      if (batch_size >= cs || i == root_files->size - 1) {
-        void** items = array_list_to_array(batch);
-        Chunk* c = chunk_create((File**)items, batch->size);
-        free(items);
-        batch->item_destroyer = NULL;
-        array_list_delete(batch);
-        batch = NULL;
-        if (!first) {
-          first = c;
-        } else {
-          queue_enqueue_multithreaded(ps->result_queue, c, &ps->result_mutex, &ps->result_not_empty,
-                                      &ps->result_not_full);
-        }
-        if (i < root_files->size - 1) {
-          batch = array_list_create(NULL);
-          batch_size = 0;
-        }
-      }
-    }
-    if (batch) {
-      batch->item_destroyer = NULL;
-      array_list_delete(batch);
-    }
-    ps->initial_chunk = first;
-    root_files->item_destroyer = NULL;
-  }
-  array_list_delete(root_files);
-
-  int n = num_threads > 0 ? num_threads : 4;
-  if (n > subdirs->size)
-    n = subdirs->size > 0 ? subdirs->size : 1;
-
-  if (subdirs->size > 0) {
-    ps->num_threads = n;
-    ps->threads = calloc(n, sizeof(thrd_t));
-    if (!ps->threads) {
-      array_list_delete(subdirs);
-      parallel_scanner_destroy(ps);
-      return NULL;
-    }
-    int dirs_per_thread = subdirs->size / n;
-    int remainder = subdirs->size % n;
-    int start = 0;
-    for (int t = 0; t < n; t++) {
-      int count = dirs_per_thread + (t < remainder ? 1 : 0);
-      if (count == 0)
-        break;
-      ParallelWorkerArg* wa = calloc(1, sizeof(ParallelWorkerArg));
-      if (!wa)
-        break;
-      wa->ps = ps;
-      wa->dirs = calloc(count, sizeof(char*));
-      if (!wa->dirs) {
-        free(wa);
-        break;
-      }
-      for (int j = 0; j < count; j++)
-        wa->dirs[j] = str_dup((char*)subdirs->items[start + j]);
-      wa->dir_count = count;
-      wa->use_metadata = use_metadata;
-      wa->chunk_size = cs;
-      wa->exclude_patterns = exclude_patterns;
-      wa->exclude_count = exclude_count;
-      wa->include_patterns = include_patterns;
-      wa->include_count = include_count;
-      wa->max_size = max_size;
-      wa->min_size = min_size;
-      start += count;
-      if (thrd_create(&ps->threads[t], parallel_worker_thread, wa) != thrd_success) {
-        for (int j = 0; j < count; j++)
-          free(wa->dirs[j]);
-        free(wa->dirs);
-        free(wa);
-        ps->num_threads = t;
-        break;
-      }
-    }
-  }
-  array_list_delete(subdirs);
-  return ps;
-}
-
-Chunk* parallel_scanner_next(ParallelScanner* ps) {
-  if (ps->initial_chunk) {
-    Chunk* c = ps->initial_chunk;
-    ps->initial_chunk = NULL;
-    return c;
-  }
-  if (ps->num_threads == 0) {
-    ps->done = true;
-    return NULL;
-  }
-  Chunk* chunk = queue_dequeue_multithreaded(
-      ps->result_queue, &ps->result_mutex, &ps->result_not_empty, &ps->result_not_full, &ps->done);
-  return chunk;
-}
-
-void parallel_scanner_destroy(ParallelScanner* ps) {
-  if (!ps)
-    return;
-  ps->done = true;
-  cnd_signal(&ps->result_not_empty);
-  for (int i = 0; i < ps->num_threads; i++)
-    thrd_join(ps->threads[i], NULL);
-  free(ps->threads);
-  if (ps->initial_chunk)
-    chunk_destroy(ps->initial_chunk);
-  queue_destroy(ps->result_queue);
-  mtx_destroy(&ps->result_mutex);
-  cnd_destroy(&ps->result_not_empty);
-  cnd_destroy(&ps->result_not_full);
-  free(ps);
-}

src/client/scanner.h

@@ -5,7 +5,6 @@
 #include "queue.h"
 #include <dirent.h>
 #include <stdbool.h>
-#include <threads.h>
 
 typedef struct {
   Queue* directories;
@@ -19,34 +18,16 @@ typedef struct {
   int include_count;
   unsigned long long max_size;
   unsigned long long min_size;
+  int max_depth;
+  int current_depth;
 } DirectoryScanner;
 
-typedef struct {
+DirectoryScanner* directory_scanner_create(const char* root_directory, bool use_metadata,
-  Queue* result_queue;
-  mtx_t result_mutex;
-  cnd_t result_not_empty;
-  cnd_t result_not_full;
-  int num_threads;
-  thrd_t* threads;
-  bool done;
-  int completed;
-  Chunk* initial_chunk;
-} ParallelScanner;
-
-DirectoryScanner* directory_scanner_create(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);
+                                           unsigned long long min_size, int max_depth);
 Chunk* directory_scanner_next(DirectoryScanner* scanner);
 void directory_scanner_destroy(DirectoryScanner* scanner);
 
-ParallelScanner* parallel_scanner_create(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, int num_threads);
-Chunk* parallel_scanner_next(ParallelScanner* scanner);
-void parallel_scanner_destroy(ParallelScanner* scanner);
-
 #endif

src/server/server.c

@@ -21,7 +21,16 @@ int receive_files(Config* config, int fd) {
   if (!receive_status(fd, &status))
     return -1;
 
-  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK) {
+  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK ||
+         status == STATUS_KEEPALIVE || status == STATUS_ABORT || status == STATUS_CHECK_BATCH) {
+    if (status == STATUS_KEEPALIVE) {
+      send_status(fd, STATUS_KEEPALIVE);
+      goto next;
+    }
+    if (status == STATUS_ABORT) {
+      log_message(LOG_LEVEL_INFO, "Received abort from client, cleaning up");
+      return -1;
+    }
     if (status == STATUS_CHECK) {
       bool skipped;
       File* file = receive_incremental_check(fd, config, &skipped);
@@ -30,7 +39,7 @@ int receive_files(Config* config, int fd) {
       if (file == NULL && !skipped)
         return -1;
       if (config->save_to_disk)
-        file_save_to_disk(config->receive_root_directory, file);
+        file_save_to_disk(config->receive_root_directory, file, NULL);
       file_destroy(file);
     } else if (status == STATUS_CHUNK) {
       Chunk* chunk = receive_chunk_data(fd, config);
@@ -40,9 +49,37 @@ int receive_files(Config* config, int fd) {
       }
       for (int i = 0; i < chunk->element_count; i++) {
         if (config->save_to_disk)
-          file_save_to_disk(config->receive_root_directory, chunk->items[i]);
+          file_save_to_disk(config->receive_root_directory, chunk->items[i], NULL);
       }
       chunk_destroy(chunk);
+    } else if (status == STATUS_CHECK_BATCH) {
+      int count;
+      if (!receive_int(fd, &count))
+        return -1;
+      for (int i = 0; i < count; i++) {
+        char* check_path = receive_str(fd);
+        if (!check_path)
+          return -1;
+        unsigned long long check_size;
+        long long check_mtime;
+        if (!receive_n_data(fd, &check_size, sizeof(check_size)) ||
+            !receive_n_data(fd, &check_mtime, sizeof(check_mtime))) {
+          free(check_path);
+          return -1;
+        }
+        char* full_path = path_cat(config->receive_root_directory, check_path);
+        struct stat st;
+        bool has_old = full_path && stat(full_path, &st) == 0;
+        bool match = has_old && (unsigned long long)st.st_size == check_size &&
+                     (long long)st.st_mtime == check_mtime;
+        if (match)
+          send_status(fd, STATUS_OK);
+        else
+          send_status(fd, STATUS_NEXT);
+        free(full_path);
+        free(check_path);
+      }
+      goto next;
     } else {
       File* file = file_receive(config, fd);
       if (file == NULL) {
@@ -51,7 +88,7 @@ int receive_files(Config* config, int fd) {
         return -1;
       }
       if (config->save_to_disk)
-        file_save_to_disk(config->receive_root_directory, file);
+        file_save_to_disk(config->receive_root_directory, file, NULL);
       file_destroy(file);
     }
   next:

src/shared/compression.c

@@ -2,28 +2,10 @@
 #include "data.h"
 #include "log.h"
 #include "stdlib.h"
-#include "string.h"
-#include <strings.h>
 #include "zstd.h"
 
 #define INITIAL_DECOMPRESS_BUF_SIZE (1024 * 1024)
 
-static const char* SKIP_COMPRESSION_EXTENSIONS[] = {".jpg", ".jpeg", ".png", ".gif", ".mp4", ".mkv",
-                                                    ".zip", ".gz",   ".xz",  ".zst", NULL};
-
-bool compression_should_skip(const char* path) {
-  if (!path)
-    return false;
-  const char* dot = strrchr(path, '.');
-  if (!dot)
-    return false;
-  for (int i = 0; SKIP_COMPRESSION_EXTENSIONS[i]; i++) {
-    if (strcasecmp(dot, SKIP_COMPRESSION_EXTENSIONS[i]) == 0)
-      return true;
-  }
-  return false;
-}
-
 Data* data_compress(Data* data_to_compress, int compression_level) {
   log_message(LOG_LEVEL_DEBUG, "Starting to compress data");
   size_t dst_size = ZSTD_compressBound(data_to_compress->size);

src/shared/compression.h

@@ -2,10 +2,8 @@
 #define COMPRESSION_H
 
 #include "data.h"
-#include <stdbool.h>
 
 Data* data_compress(Data* data_to_compress, int compression_level);
 Data* data_decompress(Data* compressed_data);
-bool compression_should_skip(const char* path);
 
 #endif

src/shared/config.c

@@ -47,6 +47,15 @@ Config* config_create(char* version, char* send_directory, char* receive_directo
   config->tls_ca = NULL;
   config->server_host = str_dup("127.0.0.1");
   config->server_port = 8080;
+  config->timeout = 30;
+  config->contimeout = 10;
+  config->quiet = false;
+  config->backup = false;
+  config->backup_dir = NULL;
+  config->stats = false;
+  config->max_depth = 0;
+  config->log_file = NULL;
+  config->queue_size = 100;
   return config;
 }
 
@@ -90,6 +99,7 @@ void config_delete(Config* config) {
   free(config->tls_cert);
   free(config->tls_key);
   free(config->tls_ca);
+  free(config->backup_dir);
   free(config->server_host);
   free(config);
 }
@@ -127,6 +137,10 @@ 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->backup))
+    return false;
+  if (!send_str(file_descriptor, config->backup_dir ? config->backup_dir : ""))
+    return false;
   Status status;
   if (!receive_status(file_descriptor, &status))
     return false;
@@ -221,6 +235,19 @@ Config* config_receive(int file_descriptor) {
   config->tls_cert = NULL;
   config->tls_key = NULL;
   config->tls_ca = NULL;
+  config->timeout = 30;
+  config->contimeout = 10;
+  config->quiet = false;
+  config->stats = false;
+  config->max_depth = 0;
+  config->log_file = NULL;
+  config->queue_size = 100;
+  if (!receive_int(file_descriptor, &tmp))
+    goto error;
+  config->backup = tmp;
+  config->backup_dir = receive_str(file_descriptor);
+  if (config->backup_dir == NULL)
+    goto error;
   config->server_host = str_dup("127.0.0.1");
   config->server_port = 8080;
   if (!send_status(file_descriptor, STATUS_OK))

src/shared/config.h

@@ -3,6 +3,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdio.h>
 
 typedef enum { TRANSPORT_TCP, TRANSPORT_SSH } TransportType;
 
@@ -40,6 +41,15 @@ typedef struct Config {
   char* tls_cert;
   char* tls_key;
   char* tls_ca;
+  int timeout;
+  int contimeout;
+  bool quiet;
+  bool backup;
+  char* backup_dir;
+  bool stats;
+  int max_depth;
+  FILE* log_file;
+  int queue_size;
 } Config;
 
 #define PROTOCOL_VERSION "1.3.0"

src/shared/delta.c

@@ -108,7 +108,12 @@ DeltaSignature* delta_signature_deserialize(const Data* data) {
     return NULL;
   }
 
-  sig->blocks = malloc(sig->block_count * sizeof(DeltaBlockSig));
+  uint64_t blocks_size = (uint64_t)sig->block_count * sizeof(DeltaBlockSig);
+  if (blocks_size > SIZE_MAX) {
+    free(sig);
+    return NULL;
+  }
+  sig->blocks = malloc((size_t)blocks_size);
   if (!sig->blocks) {
     free(sig);
     return NULL;

src/shared/file.c

@@ -1,4 +1,5 @@
 #include <dirent.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <stddef.h>
@@ -42,6 +43,7 @@ File* file_create(const char* path) {
     return NULL;
   }
   file->metadata = NULL;
+  file->skip = false;
   return file;
 }
 
@@ -102,7 +104,7 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
                             int compression_level, bool send_path) {
   const Data* data_to_send = file->data;
   Data* compressed_data = NULL;
-  if (compression_level > 0 && !compression_should_skip(file->path)) {
+  if (compression_level > 0) {
     compressed_data = data_compress(file->data, compression_level);
     if (compressed_data == NULL) {
       log_message(LOG_LEVEL_ERROR, "Failed to compress file data");
@@ -126,7 +128,12 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
   return true;
 }
 
-bool file_save_to_disk(const char* root_directory, File* file) {
+bool file_save_to_disk(const char* root_directory, File* file, const Config* config) {
+  (void)config;
+  if (has_path_traversal(file->path)) {
+    log_message(LOG_LEVEL_ERROR, "Path traversal detected in file path: %s", file->path);
+    return false;
+  }
   char* disk_path = path_cat((char*)root_directory, file->path);
   if (disk_path == NULL)
     return false;
@@ -325,6 +332,13 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     return NULL;
   }
 
+  if (has_path_traversal(check_path)) {
+    log_message(LOG_LEVEL_ERROR, "Path traversal detected: %s", check_path);
+    free(check_path);
+    send_status(fd, STATUS_ERROR);
+    return NULL;
+  }
+
   char* full_path = path_cat(config->receive_root_directory, check_path);
   struct stat st;
   bool has_old_file = (full_path && stat(full_path, &st) == 0);
@@ -409,37 +423,55 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
 }
 
 bool to_disk(const char* path, const void* data, unsigned long long data_size) {
-  // dirname() may modify its argument and may return a pointer to static storage.
+  char* tmp_path = NULL;
-  // We must use a copy of the result to be safe.
+  char* directory = NULL;
+
   char* path_dup = str_dup(path);
   if (!path_dup)
     return false;
   const char* dir_result = dirname(path_dup);
-  char* directory = str_dup(dir_result);
+  directory = str_dup(dir_result);
   free(path_dup);
   if (!directory)
     return false;
 
   bool ok = true;
-  if (!mkdir_r(directory)) {
+  if (!mkdir_r(directory))
+    goto done;
+
+  size_t path_len = strlen(path);
+  tmp_path = malloc(path_len + 5);
+  if (!tmp_path) {
     ok = false;
     goto done;
   }
-  FILE* file_pointer = fopen(path, "wb");
+  memcpy(tmp_path, path, path_len);
+  memcpy(tmp_path + path_len, ".tmp", 5);
+
+  FILE* file_pointer = fopen(tmp_path, "wb");
   if (file_pointer == NULL) {
-    perror("Could not open File");
+    perror("Could not open temporary file");
     ok = false;
     goto done;
   }
   if (fwrite(data, 1, data_size, file_pointer) != data_size) {
-    perror("Failed to write all data to disk");
+    perror("Failed to write all data to temporary file");
     fclose(file_pointer);
+    unlink(tmp_path);
     ok = false;
     goto done;
   }
   fclose(file_pointer);
 
+  if (rename(tmp_path, path) != 0) {
+    perror("Failed to atomically rename temporary file");
+    unlink(tmp_path);
+    ok = false;
+    goto done;
+  }
+
 done:
+  free(tmp_path);
   free(directory);
   return ok;
 }

src/shared/file.h

@@ -18,6 +18,7 @@ typedef struct {
   char* path;
   Data* data;
   FileMetadata* metadata;
+  bool skip;
 } File;
 
 File* file_create(const char* path);
@@ -32,7 +33,7 @@ size_t file_content_to_buffer(File* file);
 FileMetadata* file_metadata_create(const struct stat* stats);
 void file_metadata_destroy(void* metadata);
 bool to_disk(const char* path, const void* data, unsigned long long data_size);
-bool file_save_to_disk(const char* root_directory, File* file);
+bool file_save_to_disk(const char* root_directory, File* file, const Config* config);
 File* receive_incremental_check(int fd, const Config* config, bool* skipped);
 int receive_manifest(int fd, const Config* config, int* next_status);
 

src/shared/log.c

@@ -5,11 +5,16 @@
 
 static const char* log_level_strings[] = {"DEBUG", "INFO", "WARN", "ERROR"};
 static LogLevel current_log_level = LOG_LEVEL_WARNING;
+static FILE* log_fp = NULL;
 
 void set_log_level(LogLevel level) {
   current_log_level = level;
 }
 
+void log_set_file(FILE* fp) {
+  log_fp = fp;
+}
+
 void log_message(LogLevel log_level, char* format, ...) {
   if (log_level < current_log_level)
     return;
@@ -24,4 +29,14 @@ void log_message(LogLevel log_level, char* format, ...) {
   vfprintf(stderr, format, args);
   va_end(args);
   fprintf(stderr, "\n");
+
+  if (log_fp) {
+    fprintf(log_fp, "%04d-%02d-%02d %02d:%02d:%02d [%s]: ", t->tm_year + 1900, t->tm_mon + 1,
+            t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, log_level_strings[log_level]);
+    va_start(args, format);
+    vfprintf(log_fp, format, args);
+    va_end(args);
+    fprintf(log_fp, "\n");
+    fflush(log_fp);
+  }
 }

src/shared/log.h

@@ -1,9 +1,12 @@
 #ifndef LOG_H
 #define LOG_H
 
+#include <stdio.h>
+
 typedef enum { LOG_LEVEL_DEBUG, LOG_LEVEL_INFO, LOG_LEVEL_WARNING, LOG_LEVEL_ERROR } LogLevel;
 
 void log_message(LogLevel log_level, char* message, ...);
 void set_log_level(LogLevel level);
+void log_set_file(FILE* fp);
 
 #endif

src/shared/multiprocessing.c

@@ -105,7 +105,16 @@ int receive_thread(void* pipeline_context) {
   Status status;
   if (!receive_status(file_descriptor, &status))
     return thrd_error;
-  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK) {
+  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK ||
+         status == STATUS_KEEPALIVE || status == STATUS_ABORT || status == STATUS_CHECK_BATCH) {
+    if (status == STATUS_KEEPALIVE) {
+      send_status(file_descriptor, STATUS_KEEPALIVE);
+      goto next;
+    }
+    if (status == STATUS_ABORT) {
+      log_message(LOG_LEVEL_INFO, "Received abort from client, cleaning up");
+      return thrd_error;
+    }
     if (status == STATUS_CHECK) {
       bool skipped;
       File* file = receive_incremental_check(file_descriptor, config, &skipped);
@@ -117,6 +126,34 @@ int receive_thread(void* pipeline_context) {
       }
     } else if (status == STATUS_CHUNK) {
       receive_chunk_enqueue(file_descriptor, context);
+    } else if (status == STATUS_CHECK_BATCH) {
+      int count;
+      if (!receive_int(file_descriptor, &count))
+        return thrd_error;
+      for (int i = 0; i < count; i++) {
+        char* check_path = receive_str(file_descriptor);
+        if (!check_path)
+          return thrd_error;
+        unsigned long long check_size;
+        long long check_mtime;
+        if (!receive_n_data(file_descriptor, &check_size, sizeof(check_size)) ||
+            !receive_n_data(file_descriptor, &check_mtime, sizeof(check_mtime))) {
+          free(check_path);
+          return thrd_error;
+        }
+        char* full_path = path_cat(config->receive_root_directory, check_path);
+        struct stat st;
+        bool has_old = full_path && stat(full_path, &st) == 0;
+        bool match = has_old && (unsigned long long)st.st_size == check_size &&
+                     (long long)st.st_mtime == check_mtime;
+        if (match)
+          send_status(file_descriptor, STATUS_OK);
+        else
+          send_status(file_descriptor, STATUS_NEXT);
+        free(full_path);
+        free(check_path);
+      }
+      goto next;
     } else {
       File* file = file_receive(config, file_descriptor);
       if (file) {
@@ -126,6 +163,7 @@ int receive_thread(void* pipeline_context) {
         log_message(LOG_LEVEL_ERROR, "Failed to receive file");
       }
     }
+  next:
     if (!receive_status(file_descriptor, &status))
       return thrd_error;
   }
@@ -156,7 +194,7 @@ int write_thread(void* pipeline_context) {
       return thrd_success;
     }
     if (save_to_disk)
-      file_save_to_disk(root_directory, file);
+      file_save_to_disk(root_directory, file, context->config);
     file_destroy(file);
   }
 }

src/shared/protocol.c

@@ -2,21 +2,26 @@
 #include "log.h"
 #include <errno.h>
 #include <openssl/ssl.h>
-#include <poll.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
 
+#define MAX_DATA_SIZE (256ULL * 1024 * 1024)          /* 256 MB max per message */
+#define RECEIVE_TIMEOUT_SEC 60                        /* 60 second per-message timeout */
+#define MAX_CONNECTION_MEMORY (1024ULL * 1024 * 1024) /* 1 GB total per connection */
+
 static __thread int io_read_fd = -1;
 static __thread int io_write_fd = -1;
-static SSL* io_ssl;
+static SSL* io_ssl = NULL;
 
 static unsigned long long io_bwlimit = 0;
 static long long bw_tokens = 0;
 static struct timespec bw_last_refill = {0, 0};
 
+static __thread unsigned long long total_allocated_bytes = 0;
+
 void io_set_fds(int read_fd, int write_fd) {
   io_read_fd = read_fd;
   io_write_fd = write_fd;
@@ -47,11 +52,12 @@ static void bw_throttle(size_t bytes_written) {
   bw_tokens -= (long long)bytes_written;
 
   if (bw_tokens < 0) {
-    long long deficit_us = (long long)((double)(-bw_tokens) / io_bwlimit * 1000000.0);
+    long long deficit_ns = (long long)((double)(-bw_tokens) / io_bwlimit * 1000000000.0);
-    if (deficit_us >= 1000)
+    struct timespec sleep_time, remaining;
-      poll(NULL, 0, (int)(deficit_us / 1000));
+    sleep_time.tv_sec = deficit_ns / 1000000000LL;
-    else
+    sleep_time.tv_nsec = deficit_ns % 1000000000LL;
-      usleep((useconds_t)deficit_us);
+    while (nanosleep(&sleep_time, &remaining) < 0 && errno == EINTR)
+      sleep_time = remaining;
     bw_tokens = 0;
     clock_gettime(CLOCK_MONOTONIC, &bw_last_refill);
   }
@@ -92,8 +98,21 @@ bool send_n_data(int file_descriptor, const void* data, size_t data_size) {
 bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
   log_message(LOG_LEVEL_DEBUG, "    Receiving n Data: %zu", data_size);
   int fd = io_fd(io_read_fd, file_descriptor);
+
+  struct timespec deadline;
+  clock_gettime(CLOCK_MONOTONIC, &deadline);
+  deadline.tv_sec += RECEIVE_TIMEOUT_SEC;
+
   size_t total_bytes_received = 0;
   while (total_bytes_received < data_size) {
+    struct timespec now;
+    clock_gettime(CLOCK_MONOTONIC, &now);
+    if (now.tv_sec > deadline.tv_sec ||
+        (now.tv_sec == deadline.tv_sec && now.tv_nsec > deadline.tv_nsec)) {
+      log_message(LOG_LEVEL_ERROR, "Receive timeout after %ds", RECEIVE_TIMEOUT_SEC);
+      return false;
+    }
+
     ssize_t bytes_received;
     if (io_ssl)
       bytes_received =
@@ -132,6 +151,12 @@ static const char* status_to_string(Status status) {
     return "DELTA_SIGNATURE";
   case STATUS_DELTA_DATA:
     return "DELTA_DATA";
+  case STATUS_KEEPALIVE:
+    return "KEEPALIVE";
+  case STATUS_ABORT:
+    return "ABORT";
+  case STATUS_CHECK_BATCH:
+    return "CHECK_BATCH";
   default:
     return "UNKNOWN";
   }
@@ -151,6 +176,11 @@ char* receive_str(int file_descriptor) {
   size_t size;
   if (!receive_n_data(file_descriptor, &size, sizeof(size_t)))
     return NULL;
+  if (size > MAX_DATA_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "String size %zu exceeds maximum %llu", size,
+                (unsigned long long)MAX_DATA_SIZE);
+    return NULL;
+  }
   char* data = (char*)malloc(size + 1);
   if (data == NULL)
     return NULL;
@@ -177,6 +207,17 @@ 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, "Data size %llu exceeds maximum %llu", size,
+                (unsigned long long)MAX_DATA_SIZE);
+    return NULL;
+  }
+  if (total_allocated_bytes + size > MAX_CONNECTION_MEMORY) {
+    log_message(LOG_LEVEL_ERROR, "Per-connection memory limit exceeded (%llu + %llu > %llu)",
+                (unsigned long long)total_allocated_bytes, size,
+                (unsigned long long)MAX_CONNECTION_MEMORY);
+    return NULL;
+  }
   void* data = malloc((size_t)size);
   if (data == NULL)
     return NULL;
@@ -184,6 +225,7 @@ Data* receive_data(int file_descriptor) {
     free(data);
     return NULL;
   }
+  total_allocated_bytes += size;
   log_message(LOG_LEVEL_DEBUG, "Received %lld data", size);
   return data_create(data, (size_t)size);
 }

src/shared/transport_ssh.c

@@ -118,11 +118,18 @@ Client* client_connect_ssh(const char* destination, int port) {
     if (sv[1] > 1)
       close(sv[1]);
 
-    char ssh_user[512];
+    size_t ssh_user_len;
     if (r.user && r.user[0] != '\0')
-      snprintf(ssh_user, sizeof(ssh_user), "%s@%s", r.user, r.host);
+      ssh_user_len = strlen(r.user) + 1 + strlen(r.host) + 1;
     else
-      snprintf(ssh_user, sizeof(ssh_user), "%s", r.host);
+      ssh_user_len = strlen(r.host) + 1;
+    char* ssh_user = malloc(ssh_user_len);
+    if (!ssh_user)
+      _exit(1);
+    if (r.user && r.user[0] != '\0')
+      snprintf(ssh_user, ssh_user_len, "%s@%s", r.user, r.host);
+    else
+      snprintf(ssh_user, ssh_user_len, "%s", r.host);
 
     char* ssh_argv[16];
     int ac = 0;

src/shared/transport_tcp.c

@@ -2,6 +2,7 @@
 #include "log.h"
 #include "protocol.h"
 #include <arpa/inet.h>
+#include <errno.h>
 #include <openssl/ssl.h>
 #include <signal.h>
 #include <stdio.h>
@@ -11,6 +12,18 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+static volatile unsigned int g_active_connections = 0;
+
+static void sigchld_handler(int sig) {
+  (void)sig;
+  int saved_errno = errno;
+  while (waitpid(-1, NULL, WNOHANG) > 0) {
+    if (g_active_connections > 0)
+      g_active_connections--;
+  }
+  errno = saved_errno;
+}
+
 Server* server_create(int port) {
   Server* server = (Server*)malloc(sizeof(Server));
   if (server == NULL) {
@@ -38,6 +51,8 @@ Server* server_create(int port) {
   server->address.sin_port = htons(port);
   server->address_length = sizeof(server->address);
   server->ssl_ctx = NULL;
+  server->max_connections = 100;
+  server->active_connections = 0;
 
   if (bind(server->file_descriptor, (struct sockaddr*)&server->address, server->address_length) <
       0) {
@@ -68,7 +83,7 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
     perror("Could not listen on port!");
     return;
   }
-  signal(SIGCHLD, SIG_IGN);
+  signal(SIGCHLD, sigchld_handler);
   while (1) {
     struct sockaddr_in client_addr;
     socklen_t client_len = sizeof(client_addr);
@@ -77,6 +92,12 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
       perror("Could not accept the connection");
       continue;
     }
+    if (g_active_connections >= server->max_connections) {
+      log_message(LOG_LEVEL_WARNING, "Max connections (%u) reached, rejecting",
+                  server->max_connections);
+      close(fd);
+      continue;
+    }
     log_message(LOG_LEVEL_INFO, "%s", log_fmt);
     pid_t pid = fork();
     if (pid == 0) {
@@ -84,6 +105,8 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
       child_fn(fd, child_ctx);
       close(fd);
       _exit(0);
+    } else if (pid > 0) {
+      g_active_connections++;
     }
     close(fd);
   }
@@ -110,6 +133,24 @@ void server_accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
   accept_loop(server, child_fn, child_ctx, log_fmt);
 }
 
+static int g_timeout_sec = 30;
+static int g_contimeout_sec = 10;
+
+void tcp_set_timeouts(int timeout_sec, int contimeout_sec) {
+  if (timeout_sec > 0)
+    g_timeout_sec = timeout_sec;
+  if (contimeout_sec > 0)
+    g_contimeout_sec = contimeout_sec;
+}
+
+static void tcp_apply_socket_timeout(int fd) {
+  struct timeval tv;
+  tv.tv_sec = g_timeout_sec;
+  tv.tv_usec = 0;
+  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+  setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
+}
+
 Client* client_create() {
   int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
   if (file_descriptor < 0) {
@@ -133,17 +174,27 @@ Client* client_create() {
 
 bool client_connect(Client* client, char* host, int port) {
   client->address.sin_port = htons(port);
+  client->address.sin_family = AF_INET;
+  client->address_length = sizeof(client->address);
 
   if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
     perror("Could not convert host address!");
     return false;
   }
 
+  struct timeval ct;
+  ct.tv_sec = g_contimeout_sec;
+  ct.tv_usec = 0;
+  setsockopt(client->file_descriptor, SOL_SOCKET, SO_RCVTIMEO, &ct, sizeof(ct));
+  setsockopt(client->file_descriptor, SOL_SOCKET, SO_SNDTIMEO, &ct, sizeof(ct));
+
   if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
       0) {
     perror("Could not connect to Server!");
     return false;
   }
+
+  tcp_apply_socket_timeout(client->file_descriptor);
   return true;
 }
 

src/shared/transport_tcp.h

@@ -10,6 +10,8 @@ typedef struct Server {
   unsigned int address_length;
   int file_descriptor;
   void* ssl_ctx;
+  unsigned int max_connections;
+  volatile unsigned int active_connections;
 } Server;
 
 typedef struct Client {
@@ -30,5 +32,6 @@ Client* client_create();
 bool client_connect(Client* client, char* host, int port);
 void client_disconnect(Client* client);
 void client_delete(Client* client);
+void tcp_set_timeouts(int timeout_sec, int contimeout_sec);
 
 #endif

src/shared/transport_tls.c

@@ -72,6 +72,8 @@ 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 {
+    SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
   }
 
   return ctx;

src/shared/utils.c

@@ -149,6 +149,25 @@ void delete_extras(const char* dest_root, ArrayList* manifest) {
   delete_extras_walk(dest_root, "", manifest);
 }
 
+bool has_path_traversal(const char* path) {
+  if (!path)
+    return false;
+  char* dup = str_dup(path);
+  if (!dup)
+    return false;
+  char* saveptr;
+  const char* part = strtok_r(dup, "/", &saveptr);
+  while (part) {
+    if (strcmp(part, "..") == 0) {
+      free(dup);
+      return true;
+    }
+    part = strtok_r(NULL, "/", &saveptr);
+  }
+  free(dup);
+  return false;
+}
+
 char* path_cat(const char* path1, char* path2) {
   if (path1 == NULL || *path1 == '\0')
     return str_dup(path2);

src/shared/utils.h

@@ -9,5 +9,6 @@ char* str_dup(const char* string);
 char* path_cat(const char* path1, char* path2);
 bool glob_match(const char* pattern, const char* str);
 void delete_extras(const char* dest_root, ArrayList* manifest);
+bool has_path_traversal(const char* path);
 
 #endif

tests/test_file.c

@@ -69,7 +69,7 @@ static void test_file_save_to_disk() {
   memcpy(f->data->data, content, strlen(content));
   f->data->size = strlen(content);
 
-  EXPECT_TRUE(file_save_to_disk("test_save_tmp", f));
+  EXPECT_TRUE(file_save_to_disk("test_save_tmp", f, NULL));
 
   struct stat st;
   EXPECT_EQ_INT(stat("test_save_tmp/saved_file.txt", &st), 0);

tests/test_scanner.c

@@ -19,7 +19,7 @@ static void test_scanner_single_file() {
   create_test_file(file1, content1);
 
   DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
   EXPECT_NOT_NULL(scanner);
 
   Chunk* chunk = directory_scanner_next(scanner);
@@ -48,7 +48,7 @@ static void test_scanner_multiple_files() {
   create_test_file(file2, content2);
 
   DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
   EXPECT_NOT_NULL(scanner);
 
   const Chunk* chunk = directory_scanner_next(scanner);
@@ -88,7 +88,7 @@ static void test_scanner_subdirectory() {
   create_test_file(sub_file, content);
 
   DirectoryScanner* scanner =
-      directory_scanner_create((char*)root, false, 0, NULL, 0, NULL, 0, 0, 0);
+      directory_scanner_create((char*)root, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
   EXPECT_NOT_NULL(scanner);
 
   int total_files = 0;
@@ -112,7 +112,7 @@ static void test_scanner_empty_directory() {
   mkdir(dir, 0755);
 
   DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
   EXPECT_NOT_NULL(scanner);
 
   const Chunk* chunk = directory_scanner_next(scanner);