src/client/client_cli.c

@@ -55,6 +55,7 @@ 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("  -V, --version       Show version information\n");
   printf("  --help              Show this help\n");
 }
 
@@ -80,6 +81,9 @@ int main(int argc, char* argv[]) {
     if (strcmp(argv[i], "--help") == 0) {
       print_usage();
       goto cleanup;
+    } else if (strcmp(argv[i], "--version") == 0 || strcmp(argv[i], "-V") == 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;

src/client/scanner.c

@@ -24,9 +24,58 @@ DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metada
   scanner->current_path = NULL;
   scanner->use_metadata = use_metadata;
   scanner->chunk_size = chunk_size > 0 ? chunk_size : DESIRED_CHUNK_SIZE;
-  scanner->exclude_patterns = exclude_patterns;
+  /* Deep-copy exclude patterns */
+  if (exclude_count > 0 && exclude_patterns != NULL) {
+    scanner->exclude_patterns = malloc((size_t)exclude_count * sizeof(char*));
+    if (scanner->exclude_patterns == NULL) {
+      queue_destroy(scanner->directories);
+      free(scanner);
+      return NULL;
+    }
+    for (int i = 0; i < exclude_count; i++) {
+      scanner->exclude_patterns[i] = str_dup(exclude_patterns[i]);
+      if (scanner->exclude_patterns[i] == NULL) {
+        for (int j = 0; j < i; j++)
+          free(scanner->exclude_patterns[j]);
+        free(scanner->exclude_patterns);
+        queue_destroy(scanner->directories);
+        free(scanner);
+        return NULL;
+      }
+    }
+  } else {
+    scanner->exclude_patterns = NULL;
+  }
   scanner->exclude_count = exclude_count;
-  scanner->include_patterns = include_patterns;
+
+  /* Deep-copy include patterns */
+  if (include_count > 0 && include_patterns != NULL) {
+    scanner->include_patterns = malloc((size_t)include_count * sizeof(char*));
+    if (scanner->include_patterns == NULL) {
+      for (int i = 0; i < exclude_count; i++)
+        free(scanner->exclude_patterns[i]);
+      free(scanner->exclude_patterns);
+      queue_destroy(scanner->directories);
+      free(scanner);
+      return NULL;
+    }
+    for (int i = 0; i < include_count; i++) {
+      scanner->include_patterns[i] = str_dup(include_patterns[i]);
+      if (scanner->include_patterns[i] == NULL) {
+        for (int j = 0; j < i; j++)
+          free(scanner->include_patterns[j]);
+        free(scanner->include_patterns);
+        for (int j = 0; j < exclude_count; j++)
+          free(scanner->exclude_patterns[j]);
+        free(scanner->exclude_patterns);
+        queue_destroy(scanner->directories);
+        free(scanner);
+        return NULL;
+      }
+    }
+  } else {
+    scanner->include_patterns = NULL;
+  }
   scanner->include_count = include_count;
   scanner->max_size = max_size;
   scanner->min_size = min_size;
@@ -42,6 +91,12 @@ void directory_scanner_destroy(DirectoryScanner* scanner) {
     scanner->current_dir = NULL;
   }
   free(scanner->current_path);
+  for (int i = 0; i < scanner->exclude_count; i++)
+    free(scanner->exclude_patterns[i]);
+  free(scanner->exclude_patterns);
+  for (int i = 0; i < scanner->include_count; i++)
+    free(scanner->include_patterns[i]);
+  free(scanner->include_patterns);
   queue_destroy(scanner->directories);
   free(scanner);
 }

src/server/server.c

@@ -134,6 +134,7 @@ static void print_server_usage(void) {
   printf("  --key <path>        TLS private key file (PEM)\n");
   printf("  --ca <path>         TLS CA certificate file (PEM)\n");
   printf("  -v, --verbose       Enable debug logging\n");
+  printf("  -V, --version       Show version information\n");
   printf("  --help              Show this help\n");
 }
 
@@ -149,6 +150,9 @@ int main(int argc, char* argv[]) {
     if (strcmp(argv[i], "--help") == 0) {
       print_server_usage();
       return 0;
+    } else if (strcmp(argv[i], "--version") == 0 || strcmp(argv[i], "-V") == 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);

src/shared/compression.c

@@ -66,8 +66,16 @@ Data* data_decompress(Data* compressed_data) {
     return NULL;
   }
 
-  size_t buf_size =
-      (!ZSTD_isError(dst_size) && dst_size > 0) ? (size_t)dst_size : INITIAL_DECOMPRESS_BUF_SIZE;
+  size_t buf_size = INITIAL_DECOMPRESS_BUF_SIZE;
+  if (!ZSTD_isError(dst_size) && dst_size > 0) {
+    if (dst_size > SIZE_MAX) {
+      log_message(LOG_LEVEL_ERROR,
+                  "Decompressed size %llu exceeds addressable memory, using fallback buffer",
+                  dst_size);
+    } else {
+      buf_size = (size_t)dst_size;
+    }
+  }
   Data* uncompressed_data = data_create_empty(buf_size);
   if (!uncompressed_data) {
     log_message(LOG_LEVEL_ERROR, "Failed to allocate decompression buffer");

src/shared/data.c

@@ -3,6 +3,8 @@
 #include "stdlib.h"
 
 Data* data_create_empty(size_t data_size) {
+  if (data_size == 0)
+    data_size = 1;
   void* data = malloc(data_size);
   if (data == NULL) {
     log_message(LOG_LEVEL_ERROR, "Could not allocate memory for empty data");

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/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>
@@ -16,16 +17,21 @@ void metadata_to_buf(char** buf, const FileMetadata* m) {
   *buf += sizeof(int);
   if (m == NULL)
     return;
-  memcpy(*buf, &m->mode, sizeof(mode_t));
-  *buf += sizeof(mode_t);
-  memcpy(*buf, &m->uid, sizeof(uid_t));
-  *buf += sizeof(uid_t);
-  memcpy(*buf, &m->gid, sizeof(gid_t));
-  *buf += sizeof(gid_t);
-  memcpy(*buf, &m->mtime_sec, sizeof(time_t));
-  *buf += sizeof(time_t);
-  memcpy(*buf, &m->mtime_nsec, sizeof(long));
-  *buf += sizeof(long);
+  int32_t tmp32 = (int32_t)m->mode;
+  memcpy(*buf, &tmp32, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  tmp32 = (int32_t)m->uid;
+  memcpy(*buf, &tmp32, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  tmp32 = (int32_t)m->gid;
+  memcpy(*buf, &tmp32, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  int64_t tmp64 = (int64_t)m->mtime_sec;
+  memcpy(*buf, &tmp64, sizeof(int64_t));
+  *buf += sizeof(int64_t);
+  tmp64 = (int64_t)m->mtime_nsec;
+  memcpy(*buf, &tmp64, sizeof(int64_t));
+  *buf += sizeof(int64_t);
 }
 
 FileMetadata* metadata_from_buf(char** buf) {
@@ -35,16 +41,23 @@ FileMetadata* metadata_from_buf(char** buf) {
   if (!present)
     return NULL;
   FileMetadata* m = malloc(sizeof(FileMetadata));
-  memcpy(&m->mode, *buf, sizeof(mode_t));
-  *buf += sizeof(mode_t);
-  memcpy(&m->uid, *buf, sizeof(uid_t));
-  *buf += sizeof(uid_t);
-  memcpy(&m->gid, *buf, sizeof(gid_t));
-  *buf += sizeof(gid_t);
-  memcpy(&m->mtime_sec, *buf, sizeof(time_t));
-  *buf += sizeof(time_t);
-  memcpy(&m->mtime_nsec, *buf, sizeof(long));
-  *buf += sizeof(long);
+  int32_t tmp32;
+  int64_t tmp64;
+  memcpy(&tmp32, *buf, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  m->mode = (mode_t)tmp32;
+  memcpy(&tmp32, *buf, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  m->uid = (uid_t)tmp32;
+  memcpy(&tmp32, *buf, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  m->gid = (gid_t)tmp32;
+  memcpy(&tmp64, *buf, sizeof(int64_t));
+  *buf += sizeof(int64_t);
+  m->mtime_sec = (time_t)tmp64;
+  memcpy(&tmp64, *buf, sizeof(int64_t));
+  *buf += sizeof(int64_t);
+  m->mtime_nsec = (long)tmp64;
   return m;
 }
 
@@ -54,12 +67,17 @@ bool metadata_send(int file_descriptor, FileMetadata* m) {
     return send_n_data(file_descriptor, &zero, sizeof(int));
   }
   int present = 1;
+  int32_t mode_i32 = (int32_t)m->mode;
+  int32_t uid_i32 = (int32_t)m->uid;
+  int32_t gid_i32 = (int32_t)m->gid;
+  int64_t mtime_sec_i64 = (int64_t)m->mtime_sec;
+  int64_t mtime_nsec_i64 = (int64_t)m->mtime_nsec;
   return send_n_data(file_descriptor, &present, sizeof(int)) &&
-         send_n_data(file_descriptor, &m->mode, sizeof(mode_t)) &&
-         send_n_data(file_descriptor, &m->uid, sizeof(uid_t)) &&
-         send_n_data(file_descriptor, &m->gid, sizeof(gid_t)) &&
-         send_n_data(file_descriptor, &m->mtime_sec, sizeof(time_t)) &&
-         send_n_data(file_descriptor, &m->mtime_nsec, sizeof(long));
+         send_n_data(file_descriptor, &mode_i32, sizeof(int32_t)) &&
+         send_n_data(file_descriptor, &uid_i32, sizeof(int32_t)) &&
+         send_n_data(file_descriptor, &gid_i32, sizeof(int32_t)) &&
+         send_n_data(file_descriptor, &mtime_sec_i64, sizeof(int64_t)) &&
+         send_n_data(file_descriptor, &mtime_nsec_i64, sizeof(int64_t));
 }
 
 FileMetadata* metadata_receive(int file_descriptor, int* ok) {
@@ -80,16 +98,23 @@ FileMetadata* metadata_receive(int file_descriptor, int* ok) {
       *ok = 0;
     return NULL;
   }
-  if (!receive_n_data(file_descriptor, &m->mode, sizeof(mode_t)) ||
-      !receive_n_data(file_descriptor, &m->uid, sizeof(uid_t)) ||
-      !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))) {
+  int32_t mode_i32, uid_i32, gid_i32;
+  int64_t mtime_sec_i64, mtime_nsec_i64;
+  if (!receive_n_data(file_descriptor, &mode_i32, sizeof(int32_t)) ||
+      !receive_n_data(file_descriptor, &uid_i32, sizeof(int32_t)) ||
+      !receive_n_data(file_descriptor, &gid_i32, sizeof(int32_t)) ||
+      !receive_n_data(file_descriptor, &mtime_sec_i64, sizeof(int64_t)) ||
+      !receive_n_data(file_descriptor, &mtime_nsec_i64, sizeof(int64_t))) {
     free(m);
     if (ok)
       *ok = 0;
     return NULL;
   }
+  m->mode = (mode_t)mode_i32;
+  m->uid = (uid_t)uid_i32;
+  m->gid = (gid_t)gid_i32;
+  m->mtime_sec = (time_t)mtime_sec_i64;
+  m->mtime_nsec = (long)mtime_nsec_i64;
   if (ok)
     *ok = 1;
   return m;

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                                                                    \
-  (sizeof(mode_t) + sizeof(uid_t) + sizeof(gid_t) + sizeof(time_t) + sizeof(long))
+#define FILE_METADATA_WIRE_SIZE (sizeof(int32_t) * 3 + sizeof(int64_t) * 2)
 
 void metadata_to_buf(char** buf, const FileMetadata* m);
 FileMetadata* metadata_from_buf(char** buf);

src/shared/protocol.c

@@ -34,11 +34,17 @@ static void bw_throttle(size_t bytes_written) {
   struct timespec now;
   clock_gettime(CLOCK_MONOTONIC, &now);
 
-  long long elapsed_ns =
-      (now.tv_sec - bw_last_refill.tv_sec) * 1000000000LL + (now.tv_nsec - bw_last_refill.tv_nsec);
+  /* Use unsigned long long for intermediate computation to avoid overflow.
+   * sec_diff * 1000000000LL could overflow a signed 64-bit if the elapsed
+   * time is very large; clamp to a safe maximum. */
+  unsigned long long sec_diff = (unsigned long long)(now.tv_sec - bw_last_refill.tv_sec);
+  if (sec_diff > 9223372036ULL)
+    sec_diff = 9223372036ULL;
+  unsigned long long elapsed_ns =
+      sec_diff * 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;
@@ -74,13 +80,23 @@ bool send_n_data(int file_descriptor, const void* data, size_t data_size) {
     if (io_bwlimit > 0 && chunk > 65536)
       chunk = 65536;
     ssize_t bytes_send;
-    if (io_ssl)
+    if (io_ssl) {
       bytes_send = SSL_write(io_ssl, (const char*)data + total_bytes_send, chunk);
-    else
+      if (bytes_send <= 0) {
+        int err = SSL_get_error(io_ssl, (int)bytes_send);
+        if (err == SSL_ERROR_WANT_WRITE || err == SSL_ERROR_WANT_READ) {
+          // Non-fatal: retry without counting progress
+          continue;
+        }
+        log_message(LOG_LEVEL_ERROR, "Could not send data (SSL error: %d)", err);
+        return false;
+      }
+    } else {
       bytes_send = write(fd, (const char*)data + total_bytes_send, chunk);
-    if (bytes_send <= 0) {
-      log_message(LOG_LEVEL_ERROR, "Could not send data");
-      return false;
+      if (bytes_send <= 0) {
+        log_message(LOG_LEVEL_ERROR, "Could not send data");
+        return false;
+      }
     }
     bw_throttle((size_t)bytes_send);
     total_bytes_send += bytes_send;
@@ -95,18 +111,31 @@ bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
   size_t total_bytes_received = 0;
   while (total_bytes_received < data_size) {
     ssize_t bytes_received;
-    if (io_ssl)
+    if (io_ssl) {
       bytes_received =
           SSL_read(io_ssl, (char*)data + total_bytes_received, data_size - total_bytes_received);
-    else
+      if (bytes_received <= 0) {
+        int err = SSL_get_error(io_ssl, (int)bytes_received);
+        if (err == SSL_ERROR_WANT_READ || err == SSL_ERROR_WANT_WRITE) {
+          // Non-fatal: retry without counting progress
+          continue;
+        }
+        if (bytes_received == 0)
+          log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
+        else
+          log_message(LOG_LEVEL_ERROR, "Could not receive bytes (SSL error: %d)", err);
+        return false;
+      }
+    } else {
       bytes_received =
           read(fd, (char*)data + total_bytes_received, data_size - total_bytes_received);
-    if (bytes_received <= 0) {
-      if (bytes_received == 0)
-        log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
-      else
-        log_message(LOG_LEVEL_ERROR, "Could not receive bytes");
-      return false;
+      if (bytes_received <= 0) {
+        if (bytes_received == 0)
+          log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
+        else
+          log_message(LOG_LEVEL_ERROR, "Could not receive bytes");
+        return false;
+      }
     }
     total_bytes_received += bytes_received;
   }
@@ -138,6 +167,10 @@ static const char* status_to_string(Status status) {
 }
 
 bool send_str(int file_descriptor, const char* data) {
+  if (data == NULL) {
+    log_message(LOG_LEVEL_ERROR, "send_str called with NULL data");
+    return false;
+  }
   size_t size = strlen(data);
   if (!send_n_data(file_descriptor, &size, sizeof(size_t)))
     return false;
@@ -151,6 +184,11 @@ char* receive_str(int file_descriptor) {
   size_t size;
   if (!receive_n_data(file_descriptor, &size, sizeof(size_t)))
     return NULL;
+  if (size > MAX_STRING_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "receive_str: size %zu exceeds maximum %zu", size,
+                (size_t)MAX_STRING_SIZE);
+    return NULL;
+  }
   char* data = (char*)malloc(size + 1);
   if (data == NULL)
     return NULL;

src/shared/protocol.h

@@ -5,6 +5,9 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+/* Maximum allowed string size for receive_str (10 MB) */
+#define MAX_STRING_SIZE (10 * 1024 * 1024)
+
 typedef struct ssl_st SSL;
 
 typedef int Status;

src/shared/transport_ssh.c

@@ -124,7 +124,11 @@ Client* client_connect_ssh(const char* destination, int port) {
     else
       snprintf(ssh_user, sizeof(ssh_user), "%s", r.host);
 
-    char* ssh_argv[16];
+    /* Max entries: ssh + 3 options*2 each + -p + port + user + cmd + arg + NULL = 13 */
+    size_t ssh_argv_max = 32;
+    char** ssh_argv = calloc(ssh_argv_max, sizeof(char*));
+    if (ssh_argv == NULL)
+      _exit(1);
     int ac = 0;
     char port_str[16];
     ssh_argv[ac++] = "ssh";
@@ -135,15 +139,24 @@ Client* client_connect_ssh(const char* destination, int port) {
     ssh_argv[ac++] = "-o";
     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";
       snprintf(port_str, sizeof(port_str), "%d", port);
       ssh_argv[ac++] = port_str;
     }
+    if ((size_t)ac + 3 >= ssh_argv_max) {
+      free(ssh_argv);
+      _exit(1);
+    }
     ssh_argv[ac++] = ssh_user;
     ssh_argv[ac++] = "fastsync-server";
     ssh_argv[ac++] = "--stdio";
     ssh_argv[ac] = NULL;
     execvp("ssh", ssh_argv);
+    free(ssh_argv);
     perror("exec of ssh failed");
     ssize_t wret = write(exec_pipe[1], "x", 1);
     (void)wret;

src/shared/transport_tcp.h

@@ -1,20 +1,23 @@
 #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;
-  unsigned int address_length;
+  struct sockaddr_storage address;
+  socklen_t address_length;
   int file_descriptor;
+  int port;
   void* ssl_ctx;
 } Server;
 
 typedef struct Client {
-  struct sockaddr_in address;
-  unsigned int address_length;
+  struct sockaddr_storage address;
+  socklen_t address_length;
   int file_descriptor;
   pid_t ssh_child_pid;
   void* ssl;

src/shared/utils.c

@@ -10,19 +10,23 @@
 #include <unistd.h>
 
 bool mkdir_r(const char* path) {
-  char* path_duplicate = malloc(strlen(path) + 1);
+  size_t path_len = strlen(path);
+  char* path_duplicate = malloc(path_len + 1);
   if (!path_duplicate)
     return false;
-  strcpy(path_duplicate, path);
-  char* path_current = (char*)malloc((strlen(path) + 2) * sizeof(char));
+  memcpy(path_duplicate, path, path_len + 1);
+  /* Buffer for building subpaths: path_len + 1 for leading '/' + 1 for null */
+  size_t buf_size = path_len + 2;
+  char* path_current = (char*)malloc(buf_size);
   if (!path_current) {
     free(path_duplicate);
     return false;
   }
-  char* path_current_position = path_current;
+  size_t pos = 0;
   if (path[0] == '/') {
-    strcpy(path_current, "/");
-    path_current_position += 1;
+    path_current[0] = '/';
+    path_current[1] = '\0';
+    pos = 1;
   } else {
     path_current[0] = '\0';
   }
@@ -31,10 +35,16 @@ bool mkdir_r(const char* path) {
   const char* part = strtok_r(path_duplicate, delimiter, &saveptr);
   bool ok = true;
   while (part != NULL) {
-    strcpy(path_current_position, part);
-    path_current_position += strlen(part) * sizeof(char);
-    strcpy(path_current_position, "/");
-    path_current_position += sizeof(char);
+    size_t part_len = strlen(part);
+    if (pos + part_len + 1 >= buf_size) {
+      ok = false;
+      break;
+    }
+    memcpy(path_current + pos, part, part_len);
+    pos += part_len;
+    path_current[pos] = '/';
+    pos++;
+    path_current[pos] = '\0';
     struct stat st;
     if (stat(path_current, &st) != 0) {
       if (mkdir(path_current, 0755) != 0) {

tests/test_data.c

@@ -23,6 +23,14 @@ static void test_data_create_empty() {
   data_destroy(d);
 }
 
+static void test_data_create_empty_zero() {
+  Data* d = data_create_empty(0);
+  EXPECT_NOT_NULL(d);
+  EXPECT_NOT_NULL(d->data);
+  EXPECT_EQ_INT((int)d->size, 0);
+  data_destroy(d);
+}
+
 static void test_data_create_reserve() {
   Data* d = data_create_reserve(1024);
   EXPECT_NOT_NULL(d);
@@ -44,6 +52,7 @@ static void test_data_destroy_normal() {
 void test_data() {
   test_data_create();
   test_data_create_empty();
+  test_data_create_empty_zero();
   test_data_create_reserve();
   test_data_destroy_null();
   test_data_destroy_normal();

tests/test_file_sendfile.c

@@ -0,0 +1,235 @@
+#include "test_file_sendfile.h"
+#include "file.h"
+#include "data.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>
+
+static void test_sendfile_basic() {
+  const char* content = "Hello sendfile test content!";
+  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);
+  file->data->size = len;
+  file->data->data = malloc(len);
+  EXPECT_NOT_NULL(file->data->data);
+  memcpy(file->data->data, content, 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]);
+    // Receive path: read size then data
+    unsigned long long recv_size;
+    EXPECT_TRUE(receive_n_data(p[0], &recv_size, sizeof(recv_size)));
+    EXPECT_EQ_INT((int)recv_size, (int)len);
+
+    char* buf = malloc(recv_size + 1);
+    EXPECT_NOT_NULL(buf);
+    EXPECT_TRUE(receive_n_data(p[0], buf, recv_size));
+    buf[recv_size] = '\0';
+    EXPECT_EQ_INT(memcmp(buf, content, len), 0);
+    free(buf);
+    close(p[0]);
+    _exit(0);
+  } 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_basic.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+static void test_sendfile_with_path() {
+  const char* content = "Sendfile with path test";
+  size_t len = strlen(content);
+  EXPECT_TRUE(to_disk("test_sendfile_path.txt", content, len));
+
+  File* file = file_create("test_sendfile_path.txt");
+  EXPECT_NOT_NULL(file);
+  file->data->size = len;
+  file->data->data = malloc(len);
+  EXPECT_NOT_NULL(file->data->data);
+  memcpy(file->data->data, content, 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]);
+    char* recv_path = receive_str(p[0]);
+    EXPECT_NOT_NULL(recv_path);
+    EXPECT_EQ_STR(recv_path, "test_sendfile_path.txt");
+    free(recv_path);
+
+    unsigned long long recv_size;
+    EXPECT_TRUE(receive_n_data(p[0], &recv_size, sizeof(recv_size)));
+
+    char* buf = malloc(recv_size + 1);
+    EXPECT_NOT_NULL(buf);
+    EXPECT_TRUE(receive_n_data(p[0], buf, recv_size));
+    buf[recv_size] = '\0';
+    EXPECT_EQ_INT(memcmp(buf, content, len), 0);
+    free(buf);
+    close(p[0]);
+    _exit(0);
+  } 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);
+    unlink("test_sendfile_path.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+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 = len;
+  file->data->data = NULL;
+
+  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]);
+    unsigned long long recv_size;
+    EXPECT_TRUE(receive_n_data(p[0], &recv_size, sizeof(recv_size)));
+    EXPECT_EQ_INT((int)recv_size, 0);
+    close(p[0]);
+    _exit(0);
+  } 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_empty.txt");
+
+    EXPECT_TRUE(sent);
+    EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+  }
+}
+
+static void test_sendfile_with_compression_fallback() {
+  // When compression_level > 0, sendfile falls back to file_send_single_calls
+  const char* content = "Sendfile compression fallback test data here.";
+  size_t len = strlen(content);
+  EXPECT_TRUE(to_disk("test_sendfile_comp.txt", content, len));
+
+  File* file = file_create("test_sendfile_comp.txt");
+  EXPECT_NOT_NULL(file);
+  file->data->size = len;
+  file->data->data = malloc(len);
+  EXPECT_NOT_NULL(file->data->data);
+  memcpy(file->data->data, content, len);
+
+  Config* cfg = config_create(str_dup(PROTOCOL_VERSION), str_dup("/tmp"), str_dup("/tmp"), false,
+                              false, false, false, false, 0, false, 0);
+
+  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 || 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]);
+    // Send with compression_level=1, should fall back to file_send_single_calls
+    bool sent = file_send_sendfile(file, p[1], false, 1, 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);
+  }
+}
+
+static void test_sendfile_nonexistent_file() {
+  File* file = file_create("nonexistent_file_xyz_sendfile_test.txt");
+  EXPECT_NOT_NULL(file);
+  file->data->size = 100;
+  file->data->data = malloc(100);
+  EXPECT_NOT_NULL(file->data->data);
+  memset(file->data->data, 0, 100);
+
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+  close(p[0]);
+
+  bool sent = file_send_sendfile(file, p[1], false, 0, false);
+  close(p[1]);
+
+  file_destroy(file);
+  // File doesn't exist on disk, sendfile should fail
+  EXPECT_FALSE(sent);
+}
+
+void test_file_sendfile() {
+  test_sendfile_basic();
+  test_sendfile_with_path();
+  test_sendfile_empty_file();
+  test_sendfile_with_compression_fallback();
+  test_sendfile_nonexistent_file();
+}

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_log.c

@@ -0,0 +1,78 @@
+#include "test_log.h"
+#include "log.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+// Helper to redirect stderr temporarily
+static int stderr_pipe[2];
+
+static void capture_stderr_start() {
+  fflush(stderr);
+  EXPECT_EQ_INT(pipe(stderr_pipe), 0);
+  EXPECT_EQ_INT(dup2(stderr_pipe[1], STDERR_FILENO), STDERR_FILENO);
+  close(stderr_pipe[1]);
+}
+
+static void capture_stderr_end() {
+  fflush(stderr);
+  close(stderr_pipe[0]);
+}
+
+static void test_log_message_debug() {
+  set_log_level(LOG_LEVEL_DEBUG);
+  // Should output at DEBUG level
+  log_message(LOG_LEVEL_DEBUG, "Debug message test: %d", 42);
+  log_message(LOG_LEVEL_INFO, "Info message test");
+  log_message(LOG_LEVEL_WARNING, "Warning message test");
+  log_message(LOG_LEVEL_ERROR, "Error message test");
+  // If we get here without crashing, the test passes
+  EXPECT_TRUE(true);
+}
+
+static void test_log_message_level_filtering() {
+  set_log_level(LOG_LEVEL_WARNING);
+  capture_stderr_start();
+  log_message(LOG_LEVEL_DEBUG, "Should NOT appear");
+  log_message(LOG_LEVEL_INFO, "Should NOT appear");
+  log_message(LOG_LEVEL_WARNING, "Should appear");
+  log_message(LOG_LEVEL_ERROR, "Should appear");
+  capture_stderr_end();
+  // We can't easily check the content, but we verified it doesn't crash
+  EXPECT_TRUE(true);
+}
+
+static void test_log_message_error() {
+  set_log_level(LOG_LEVEL_ERROR);
+  log_message(LOG_LEVEL_ERROR, "Error only: %s", "critical");
+  EXPECT_TRUE(true);
+}
+
+static void test_set_log_level() {
+  set_log_level(LOG_LEVEL_DEBUG);
+  log_message(LOG_LEVEL_DEBUG, "debug visible");
+  set_log_level(LOG_LEVEL_WARNING);
+  log_message(LOG_LEVEL_DEBUG, "debug hidden (no crash)");
+  log_message(LOG_LEVEL_WARNING, "warning visible");
+  set_log_level(LOG_LEVEL_INFO);
+  log_message(LOG_LEVEL_INFO, "info visible");
+  EXPECT_TRUE(true);
+}
+
+static void test_log_message_various_args() {
+  set_log_level(LOG_LEVEL_DEBUG);
+  log_message(LOG_LEVEL_INFO, "String: %s, Int: %d, Hex: %x", "test", 123, 0xFF);
+  log_message(LOG_LEVEL_WARNING, "Warning with number %d", 42);
+  log_message(LOG_LEVEL_DEBUG, "Debug with pointer %p", (void*)0x1234);
+  EXPECT_TRUE(true);
+}
+
+void test_log() {
+  test_log_message_debug();
+  test_log_message_level_filtering();
+  test_log_message_error();
+  test_set_log_level();
+  test_log_message_various_args();
+}

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 +1,91 @@
+#include "test_multiprocessing.h"
+#include "multiprocessing.h"
+#include "config.h"
+#include "queue.h"
+#include "utils.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <string.h>
+
+static void test_pipeline_context_sender_create_destroy() {
+  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);
+
+  Queue* q_scanner = queue_create(10, free);
+  EXPECT_NOT_NULL(q_scanner);
+
+  Queue* q_loader = queue_create(10, free);
+  EXPECT_NOT_NULL(q_loader);
+
+  PipelineContextSender* ctx = pipeline_context_sender_create(cfg, q_scanner, q_loader);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_INT(ctx->scanner_done, false);
+  EXPECT_EQ_INT(ctx->loader_done, false);
+  EXPECT_NULL(ctx->manifest);
+
+  pipeline_context_sender_destroy(ctx);
+  // cfg, q_scanner, q_loader are destroyed by pipeline_context_sender_destroy
+}
+
+static void test_pipeline_context_sender_create_null_config() {
+  // Passing NULL config to pipeline_context_sender_create - it will be used
+  // and destroyed, so this should be tested carefully.
+  Queue* q_scanner = queue_create(10, free);
+  EXPECT_NOT_NULL(q_scanner);
+  Queue* q_loader = queue_create(10, free);
+  EXPECT_NOT_NULL(q_loader);
+
+  PipelineContextSender* ctx = pipeline_context_sender_create(NULL, q_scanner, q_loader);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_NULL(ctx->config);
+
+  // Destroy without config - config_delete(NULL) should be safe
+  pipeline_context_sender_destroy(ctx);
+}
+
+static void test_pipeline_context_sender_destroy_null() {
+  pipeline_context_sender_destroy(NULL);
+}
+
+static void test_pipeline_context_receiver_create_destroy() {
+  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);
+
+  Queue* q = queue_create(10, free);
+  EXPECT_NOT_NULL(q);
+
+  PipelineContextReceiver* ctx = pipeline_context_receiver_create(cfg, q, 42);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_EQ_INT(ctx->file_descriptor, 42);
+  EXPECT_EQ_INT(ctx->receiver_done, false);
+
+  pipeline_context_receiver_destroy(ctx);
+  // cfg, q are destroyed by pipeline_context_receiver_destroy
+}
+
+static void test_pipeline_context_receiver_create_null_config() {
+  Queue* q = queue_create(10, free);
+  EXPECT_NOT_NULL(q);
+
+  PipelineContextReceiver* ctx = pipeline_context_receiver_create(NULL, q, -1);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_NULL(ctx->config);
+  EXPECT_EQ_INT(ctx->file_descriptor, -1);
+
+  pipeline_context_receiver_destroy(ctx);
+}
+
+static void test_pipeline_context_receiver_destroy_null() {
+  pipeline_context_receiver_destroy(NULL);
+}
+
+void test_multiprocessing() {
+  test_pipeline_context_sender_create_destroy();
+  test_pipeline_context_sender_create_null_config();
+  test_pipeline_context_sender_destroy_null();
+  test_pipeline_context_receiver_create_destroy();
+  test_pipeline_context_receiver_create_null_config();
+  test_pipeline_context_receiver_destroy_null();
+}

tests/test_multiprocessing.h

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

tests/test_transport_ssh.c

@@ -0,0 +1,34 @@
+#include "test_transport_ssh.h"
+#include "transport_ssh.h"
+#include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <string.h>
+
+static void test_ssh_connect_bad_destination() {
+  Client* client = client_connect_ssh("nosuchhost.local", 22);
+  // SSH connection to a non-existent host should fail (return NULL)
+  EXPECT_NULL(client);
+}
+
+static void test_ssh_connect_null_destination() {
+  Client* client = client_connect_ssh(NULL, 22);
+  EXPECT_NULL(client);
+}
+
+static void test_ssh_connect_bad_port() {
+  Client* client = client_connect_ssh("localhost", -1);
+  EXPECT_NULL(client);
+}
+
+static void test_ssh_connect_zero_port() {
+  Client* client = client_connect_ssh("localhost", 0);
+  EXPECT_NULL(client);
+}
+
+void test_transport_ssh() {
+  test_ssh_connect_bad_destination();
+  test_ssh_connect_null_destination();
+  test_ssh_connect_bad_port();
+  test_ssh_connect_zero_port();
+}

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 +1,90 @@
+#include "test_transport_tcp.h"
+#include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+static void test_client_create_delete() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+  EXPECT_EQ_INT(client->file_descriptor, -1);
+  EXPECT_EQ_INT(client->ssh_child_pid, -1);
+  client_delete(client);
+}
+
+static void test_client_delete_null() {
+  client_delete(NULL);
+}
+
+static void test_client_disconnect_null() {
+  client_disconnect(NULL);
+}
+
+static void test_client_connect_bad_host() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  // Connecting to a non-existent host should fail
+  bool connected = client_connect(client, "192.0.2.999", 12345);
+  EXPECT_FALSE(connected);
+
+  client_disconnect(client);
+  client_delete(client);
+}
+
+static void test_client_connect_bad_port() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  // Connecting to port 0 should fail
+  bool connected = client_connect(client, "127.0.0.1", 0);
+  EXPECT_FALSE(connected);
+
+  client_disconnect(client);
+  client_delete(client);
+}
+
+static void test_client_connect_null_host() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  bool connected = client_connect(client, NULL, 8080);
+  EXPECT_FALSE(connected);
+
+  client_disconnect(client);
+  client_delete(client);
+}
+
+static void test_server_create_delete() {
+  Server* server = server_create(0);
+  // server_create may return NULL if it fails to bind, but we need to check
+  // if it succeeds. Port 0 should bind to an ephemeral port.
+  if (server != NULL) {
+    EXPECT_NOT_NULL(server);
+    server_delete(&server);
+    EXPECT_NULL(server);
+  } else {
+    // On some systems port 0 may fail; that's okay
+    EXPECT_TRUE(true);
+  }
+}
+
+static void test_server_delete_null() {
+  Server* server = NULL;
+  server_delete(&server);
+  EXPECT_NULL(server);
+}
+
+void test_transport_tcp() {
+  test_client_create_delete();
+  test_client_delete_null();
+  test_client_disconnect_null();
+  test_client_connect_bad_host();
+  test_client_connect_bad_port();
+  test_client_connect_null_host();
+  test_server_create_delete();
+  test_server_delete_null();
+}

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 +1,69 @@
+#include "test_transport_tls.h"
+#include "transport_tls.h"
+#include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <string.h>
+
+static void test_tls_global_init() {
+  bool ok = tls_global_init();
+  // Should succeed in normal environments with OpenSSL
+  // May fail in minimal environments, but we just test it doesn't crash
+  EXPECT_TRUE(true);
+}
+
+static void test_client_connect_tls_bad_host() {
+  // Ensure TLS is initialized
+  tls_global_init();
+
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  // Connecting without TLS setup should fail
+  bool connected = client_connect_tls(client, "192.0.2.1", 443, NULL, NULL, NULL);
+  EXPECT_FALSE(connected);
+
+  client_disconnect(client);
+  client_delete(client);
+}
+
+static void test_client_connect_tls_null_params() {
+  tls_global_init();
+
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  bool connected = client_connect_tls(client, NULL, 0, NULL, NULL, NULL);
+  EXPECT_FALSE(connected);
+
+  client_disconnect(client);
+  client_delete(client);
+}
+
+static void test_server_create_tls_no_cert() {
+  Server* server = server_create(0);
+  if (server != NULL) {
+    // Trying to set up TLS without cert/key files should fail
+    bool ok = server_create_tls(server, "/nonexistent/cert.pem", "/nonexistent/key.pem",
+                                "/nonexistent/ca.pem");
+    EXPECT_FALSE(ok);
+    server_delete(&server);
+  }
+}
+
+static void test_server_create_tls_null_files() {
+  Server* server = server_create(0);
+  if (server != NULL) {
+    bool ok = server_create_tls(server, NULL, NULL, NULL);
+    EXPECT_FALSE(ok);
+    server_delete(&server);
+  }
+}
+
+void test_transport_tls() {
+  test_tls_global_init();
+  test_client_connect_tls_bad_host();
+  test_client_connect_tls_null_params();
+  test_server_create_tls_no_cert();
+  test_server_create_tls_null_files();
+}

tests/test_transport_tls.h

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