refactor: standardize error reporting on the log module

- Add log_perror() helper (context + strerror(errno)) to the log module
- Replace all bare perror() calls with log_perror() so errors are routed
  through the unified logger (stderr sink + optional --log-file sink)
- Convert fprintf(stderr, "Error:/Warning: ...") in client code to
  log_message(); raw fprintf kept only for progress/stats output

src/shared/array_list.c

@@ -1,3 +1,4 @@
+#include "log.h"
 #include "array_list.h"
 #include <stdio.h>
 #include <stdlib.h>
@@ -6,7 +7,7 @@
 ArrayList* array_list_create(void (*item_destroyer)(void* item)) {
   ArrayList* list = (ArrayList*)malloc(sizeof(ArrayList));
   if (list == NULL) {
-    perror("ERROR: Could not allocate memory for array list struct");
+    log_perror("ERROR: Could not allocate memory for array list struct");
     return NULL;
   }
 
@@ -42,7 +43,7 @@ static bool array_list_extend(ArrayList* array_list) {
     new_capacity = INITIAL_ARRAY_SIZE;
   void* new_items = realloc(array_list->items, new_capacity * sizeof(void*));
   if (new_items == NULL) {
-    perror("ERROR: Could not reallocate memory for array list items");
+    log_perror("ERROR: Could not reallocate memory for array list items");
     return false;
   }
   array_list->items = new_items;
@@ -68,7 +69,7 @@ void** array_list_to_array(const ArrayList* array_list) {
   }
   void** array = malloc(array_list->size * sizeof(void*));
   if (array == NULL) {
-    perror("Could not malloc space for array from array list!");
+    log_perror("Could not malloc space for array from array list!");
     return NULL;
   }
   memcpy(array, array_list->items, array_list->size * sizeof(void*));

src/shared/chunk.c

@@ -20,7 +20,7 @@
 Chunk* chunk_create(File** items, int element_count) {
   Chunk* chunk = (Chunk*)malloc(sizeof(Chunk));
   if (chunk == NULL) {
-    perror("ERROR: Could not allocate memory for chunk structure");
+    log_perror("ERROR: Could not allocate memory for chunk structure");
     return NULL;
   }
 
@@ -118,7 +118,7 @@ Chunk* chunk_deserialize(Data* data, bool use_metadata) {
 
     char* path = malloc(path_len + 1);
     if (path == NULL) {
-      perror("Could not allocate memory for file path");
+      log_perror("Could not allocate memory for file path");
       array_list_delete(files);
       return NULL;
     }
@@ -191,7 +191,7 @@ Chunk* chunk_deserialize(Data* data, bool use_metadata) {
 
     void* file_data = malloc(file_data_size > 0 ? file_data_size : 1);
     if (file_data == NULL) {
-      perror("Could not allocate memory for file data");
+      log_perror("Could not allocate memory for file data");
       file_destroy(file);
       array_list_delete(files);
       return NULL;

src/shared/file.c

@@ -29,7 +29,7 @@ File* file_create(const char* path) {
     return NULL;
   File* file = (File*)malloc(sizeof(File));
   if (file == NULL) {
-    perror("ERROR: Could not allocate memory for file struct");
+    log_perror("ERROR: Could not allocate memory for file struct");
     return NULL;
   }
 
@@ -69,7 +69,7 @@ void file_destroy(void* item) {
 FileMetadata* file_metadata_create(const struct stat* stats) {
   FileMetadata* m = malloc(sizeof(FileMetadata));
   if (m == NULL) {
-    perror("ERROR: Could not allocate memory for file metadata");
+    log_perror("ERROR: Could not allocate memory for file metadata");
     return NULL;
   }
   m->mode = stats->st_mode;
@@ -96,7 +96,7 @@ bool file_load_data(File* file) {
       return true;
     file->data->data = malloc(file->data->size);
     if (file->data->data == NULL) {
-      perror("Could not allocate memory for file data");
+      log_perror("Could not allocate memory for file data");
       return false;
     }
   }
@@ -125,13 +125,13 @@ bool file_write_to_disk(const char* path, const void* data, unsigned long long d
 size_t file_content_to_buffer(File* file) {
   FILE* file_pointer = fopen(file->path, "rb");
   if (file_pointer == NULL) {
-    perror("Could not open the file!");
+    log_perror("Could not open the file!");
     return 0;
   }
   size_t bytes_read = fread(file->data->data, 1, file->data->size, file_pointer);
   if (bytes_read != (size_t)file->data->size) {
     fclose(file_pointer);
-    perror("Read unexpected number of bytes from File!");
+    log_perror("Read unexpected number of bytes from File!");
     return 0;
   }
   fclose(file_pointer);

src/shared/file_send.c

@@ -62,7 +62,7 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int
 
   int fd = open(file->path, O_RDONLY);
   if (fd == -1) {
-    perror("Could not open file for sendfile");
+    log_perror("Could not open file for sendfile");
     return false;
   }
 
@@ -121,7 +121,7 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int
     if (sent == -1) {
       if (errno == EAGAIN || errno == EINTR)
         continue;
-      perror("sendfile failed");
+      log_perror("sendfile failed");
       close(fd);
       return false;
     }

src/shared/log.c

@@ -1,6 +1,8 @@
 #include "log.h"
+#include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <string.h>
 #include <time.h>
 
 static const char* log_level_strings[] = {"DEBUG", "INFO", "WARN", "ERROR"};
@@ -50,3 +52,7 @@ void log_message(LogLevel log_level, const char* format, ...) {
     va_end(args);
   }
 }
+
+void log_perror(const char* context) {
+  log_message(LOG_LEVEL_ERROR, "%s: %s", context, strerror(errno));
+}

src/shared/log.h

@@ -6,6 +6,7 @@
 typedef enum { LOG_LEVEL_DEBUG, LOG_LEVEL_INFO, LOG_LEVEL_WARNING, LOG_LEVEL_ERROR } LogLevel;
 
 void log_message(LogLevel log_level, const char* message, ...);
+void log_perror(const char* context);
 void set_log_level(LogLevel level);
 void log_set_file(FILE* fp);
 

src/shared/multiprocessing.c

@@ -55,7 +55,7 @@ PipelineContextSender* pipeline_context_sender_create(Config* config, Queue* que
   return context;
 
 fail:
-  perror("Error initializing synchronization objects");
+  log_perror("Error initializing synchronization objects");
   if (init >= 6)
     cnd_destroy(&context->condition_not_empty_loader);
   if (init >= 5)
@@ -116,7 +116,7 @@ PipelineContextReceiver* pipeline_context_receiver_create(Config* config, Queue*
   return context;
 
 fail:
-  perror("Error initializing synchronization objects");
+  log_perror("Error initializing synchronization objects");
   if (init >= 3)
     cnd_destroy(&context->condition_not_empty);
   if (init >= 2)

src/shared/queue.c

@@ -1,3 +1,4 @@
+#include "log.h"
 #include <stdbool.h>
 #include <limits.h>
 #include <stdio.h>
@@ -13,7 +14,7 @@ Queue* queue_create(int capacity, void (*destroyer)(void* item)) {
 
   Queue* queue = (Queue*)malloc(sizeof(Queue));
   if (queue == NULL) {
-    perror("ERROR: Could not allocate memory for queue structure");
+    log_perror("ERROR: Could not allocate memory for queue structure");
     return NULL;
   }
 
@@ -72,7 +73,7 @@ static bool queue_double_capacity(Queue* queue) {
     new_capacity = 100;
   void** new_items = malloc(new_capacity * sizeof(void*));
   if (new_items == NULL) {
-    perror("ERROR: Could not allocate memory for doubling capacity of queue.");
+    log_perror("ERROR: Could not allocate memory for doubling capacity of queue.");
     return false;
   }
   for (int i = 0; i < queue->size; i++)
@@ -127,7 +128,7 @@ bool queue_enqueue_multithreaded_cancel(Queue* queue, void* item, mtx_t* mutex,
 
 void* queue_dequeue(Queue* queue) {
   if (queue == NULL || queue_is_empty(queue)) {
-    perror("ERROR: Could not dequeue from null or empty queue.");
+    log_perror("ERROR: Could not dequeue from null or empty queue.");
     return NULL;
   }
 

src/shared/transport_ssh.c

@@ -1,3 +1,4 @@
+#include "log.h"
 #include "transport_ssh.h"
 #include "utils.h"
 #include <fcntl.h>
@@ -76,7 +77,7 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
 
   int sv[2];
   if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0) {
-    perror("socketpair failed");
+    log_perror("socketpair failed");
     remote_dest_destroy(&r);
     return NULL;
   }
@@ -89,7 +90,7 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
 
   int exec_pipe[2];
   if (pipe(exec_pipe) < 0) {
-    perror("pipe failed");
+    log_perror("pipe failed");
     close(sv[0]);
     close(sv[1]);
     remote_dest_destroy(&r);
@@ -98,7 +99,7 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
 
   pid_t pid = fork();
   if (pid < 0) {
-    perror("fork failed");
+    log_perror("fork failed");
     close(sv[0]);
     close(sv[1]);
     close(exec_pipe[0]);
@@ -151,7 +152,7 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
     ssh_argv[ac++] = "--stdio";
     ssh_argv[ac] = NULL;
     execvp("ssh", ssh_argv);
-    perror("exec of ssh failed");
+    log_perror("exec of ssh failed");
     ssize_t wret = write(exec_pipe[1], "x", 1);
     (void)wret;
     _exit(1);

src/shared/transport_tcp.c

@@ -30,20 +30,20 @@ static void sigchld_handler(int sig) {
 Server* server_create(int port) {
   Server* server = (Server*)malloc(sizeof(Server));
   if (server == NULL) {
-    perror("Could not allocate space for Server");
+    log_perror("Could not allocate space for Server");
     return NULL;
   }
 
   int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
   if (file_descriptor < 0) {
-    perror("Could not create Socket!");
+    log_perror("Could not create Socket!");
     free(server);
     return NULL;
   }
   server->file_descriptor = file_descriptor;
   int opt = 1;
   if (setsockopt(server->file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
-    perror("Error setting a socket option!");
+    log_perror("Error setting a socket option!");
     close(server->file_descriptor);
     free(server);
     return NULL;
@@ -59,7 +59,7 @@ Server* server_create(int port) {
 
   if (bind(server->file_descriptor, (struct sockaddr*)&server->address, server->address_length) <
       0) {
-    perror("Could not bind server");
+    log_perror("Could not bind server");
     close(server->file_descriptor);
     free(server);
     return NULL;
@@ -83,7 +83,7 @@ void server_delete(Server** server) {
 static void accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt) {
   if (listen(server->file_descriptor, SOMAXCONN) < 0) {
-    perror("Could not listen on port!");
+    log_perror("Could not listen on port!");
     return;
   }
   signal(SIGCHLD, sigchld_handler);
@@ -92,7 +92,7 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
     socklen_t client_len = sizeof(client_addr);
     int fd = accept(server->file_descriptor, (struct sockaddr*)&client_addr, &client_len);
     if (fd < 0) {
-      perror("Could not accept the connection");
+      log_perror("Could not accept the connection");
       continue;
     }
     tcp_apply_socket_timeout(fd);
@@ -222,7 +222,7 @@ bool tcp_connect_socket(Client* client, char* host, int port) {
   freeaddrinfo(result);
 
   if (!connected) {
-    perror("Could not connect to Server!");
+    log_perror("Could not connect to Server!");
     return false;
   }
 

src/shared/utils.c

@@ -1,3 +1,4 @@
+#include "log.h"
 #include "utils.h"
 #include "array_list.h"
 #include "libgen.h"
@@ -54,7 +55,7 @@ bool mkdir_r(const char* path) {
     struct stat st;
     if (stat(path_current, &st) != 0) {
       if (mkdir(path_current, 0755) != 0) {
-        perror("Could not create directory");
+        log_perror("Could not create directory");
         ok = false;
         break;
       }