add shared target + improve error handling in lib

src/drivers/unix_fs/unix_fs_driver.c

@@ -1,5 +1,6 @@
 #define _GNU_SOURCE /* ahh, didn't know asprintf is a GNU extension */
 /* TODO: remove this bullshit */
+/* TODO: more robust error handling */
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -15,6 +16,16 @@
 
 #define READ_BUF_SZ 256
 
+#define SWRITE(fd, buf, count) \
+    if (write(fd, buf, count) < count) { \
+        return -EINVAL; \
+    }
+
+#define SREAD(fd, buf, count) \
+    if (read(fd, buf, count) < count) { \
+        return -EINVAL; \
+    }
+
 int
 is_valid_directory(const char *path)
 {
@@ -25,26 +36,24 @@ is_valid_directory(const char *path)
     return S_ISDIR(path_stat.st_mode);
 }
 
-/* TODO: handle errors */
 int
 serialize_header(int fd, const CommentHeader *header)
 {
-    write(fd, &header->reply_id, sizeof(int));
-    write(fd, &header->creation_time, sizeof(time_t));
-    write(fd, &header->text_length, sizeof(size_t));
-    write(fd, header->user_sid, strlen(header->user_sid) + 1);
-    write(fd, header->user_displayname, strlen(header->user_displayname) + 1);
+    SWRITE(fd, &header->reply_id, sizeof(int));
+    SWRITE(fd, &header->creation_time, sizeof(time_t));
+    SWRITE(fd, &header->text_length, sizeof(size_t));
+    SWRITE(fd, header->user_sid, strlen(header->user_sid) + 1);
+    SWRITE(fd, header->user_displayname, strlen(header->user_displayname) + 1);
     return 0;
 }
 
-/* TODO: handle errors */
 /* header string buffers must be long enough */
 int
 deserialize_header(int fd, CommentHeader *header)
 {
     char buf[READ_BUF_SZ], *dst_bufs[2];
     int bytes_read;
-    size_t len, dst_idx, i;
+    size_t dst_idx, i;
 
     i = 0;
 
@@ -52,11 +61,14 @@ deserialize_header(int fd, CommentHeader *header)
     dst_bufs[1] = header->user_displayname;
     dst_idx = 0;
 
-    read(fd, &header->reply_id, sizeof(int));
-    read(fd, &header->creation_time, sizeof(time_t));
-    read(fd, &header->text_length, sizeof(size_t));
+    SREAD(fd, &header->reply_id, sizeof(int));
+    SREAD(fd, &header->creation_time, sizeof(time_t));
+    SREAD(fd, &header->text_length, sizeof(size_t));
 
     while ((bytes_read = read(fd, buf, READ_BUF_SZ))) {
+        if (bytes_read < 0) {
+            return -EINVAL;
+        }
         for (; i < bytes_read; ++i) {
             *(dst_bufs[dst_idx]++) = buf[i];
             if (buf[i] == '\0') {
@@ -64,17 +76,20 @@ deserialize_header(int fd, CommentHeader *header)
             }
         }
     }
+    if (dst_idx != 2) {
+        return -EINVAL;
+    }
     return 0;
 }
 
 /* TODO: validate driver_data_ptr */
 
 int
-unix_fs_driver_leave_comment(void *driver_data_ptr, CommentHeader *header, char *text)
+unix_fs_driver_leave_comment(void *driver_data_ptr, const CommentHeader *header, const char *text)
 {
     char *path, *header_file_path, *text_file_path, *id_ctrl_file_path;
     FILE *id_ctrl_file;
-    size_t path_len, text_len;
+    size_t text_len;
     int max_id;
     int retval;
     int header_fd, text_fd, id_ctrl_fd;
@@ -91,7 +106,6 @@ unix_fs_driver_leave_comment(void *driver_data_ptr, CommentHeader *header, char
         goto defer;
     }
 
-    path_len = strlen(path);
     text_len = strlen(text);
     
     if (asprintf(&id_ctrl_file_path, "%s/%s", path, ID_CTRL_FILE) < 0) {