Fix file locking

[wimlib] / src / write.c

diff --git a/src/write.c b/src/write.c
index 27463d90d059879426f9df0f17121df8e08f4fea..5217838192cdb886cf98cdea9474a718e7120ed1 100644 (file)
--- a/src/write.c
+++ b/src/write.c
@@ -2400,28 +2400,30 @@ finish_write(WIMStruct *wim, int image, int write_flags,
 }
 
 #if defined(HAVE_SYS_FILE_H) && defined(HAVE_FLOCK)
+
+/* Set advisory lock on WIM file (if not already done so)  */
 int
-lock_wim(WIMStruct *wim, int fd)
+lock_wim_for_append(WIMStruct *wim)
 {
-       int ret = 0;
-       if (fd != -1 && !wim->wim_locked) {
-               ret = flock(fd, LOCK_EX | LOCK_NB);
-               if (ret != 0) {
-                       if (errno == EWOULDBLOCK) {
-                               ERROR("`%"TS"' is already being modified or has been "
-                                     "mounted read-write\n"
-                                     "        by another process!", wim->filename);
-                               ret = WIMLIB_ERR_ALREADY_LOCKED;
-                       } else {
-                               WARNING_WITH_ERRNO("Failed to lock `%"TS"'",
-                                                  wim->filename);
-                               ret = 0;
-                       }
-               } else {
-                       wim->wim_locked = 1;
-               }
+       if (wim->locked_for_append)
+               return 0;
+       if (!flock(wim->in_fd.fd, LOCK_EX | LOCK_NB)) {
+               wim->locked_for_append = 1;
+               return 0;
+       }
+       if (errno != EWOULDBLOCK)
+               return 0;
+       return WIMLIB_ERR_ALREADY_LOCKED;
+}
+
+/* Remove advisory lock on WIM file (if present)  */
+void
+unlock_wim_for_append(WIMStruct *wim)
+{
+       if (wim->locked_for_append) {
+               flock(wim->in_fd.fd, LOCK_UN);
+               wim->locked_for_append = 0;
        }
-       return ret;
 }
 #endif
 
@@ -3062,7 +3064,7 @@ overwrite_wim_inplace(WIMStruct *wim, int write_flags, unsigned num_threads)
        if (ret)
                goto out_restore_memory_hdr;
 
-       ret = lock_wim(wim, wim->out_fd.fd);
+       ret = lock_wim_for_append(wim);
        if (ret)
                goto out_close_wim;
 
@@ -3098,7 +3100,7 @@ overwrite_wim_inplace(WIMStruct *wim, int write_flags, unsigned num_threads)
        if (ret)
                goto out_truncate;
 
-       wim->wim_locked = 0;
+       unlock_wim_for_append(wim);
        return 0;
 
 out_truncate:
@@ -3112,7 +3114,7 @@ out_truncate:
 out_restore_physical_hdr:
        (void)write_wim_header_flags(hdr_save.flags, &wim->out_fd);
 out_unlock_wim:
-       wim->wim_locked = 0;
+       unlock_wim_for_append(wim);
 out_close_wim:
        (void)close_wim_writable(wim, write_flags);
 out_restore_memory_hdr: