Acquire advisory lock when doing a read-write mount

[wimlib] / src / write.c

diff --git a/src/write.c b/src/write.c
index 773de0b7b6553e61ead5ef8b726e00f218b54f6a..e441b58444f6982bdeb41926a8402249326cd6a1 100644 (file)
--- a/src/write.c
+++ b/src/write.c
@@ -1492,6 +1492,29 @@ out:
        return ret;
 }
 
+#if defined(HAVE_SYS_FILE_H) && defined(HAVE_FLOCK)
+int lock_wim(FILE *fp, const char *path)
+{
+       int ret = 0;
+       if (fp) {
+               ret = flock(fileno(fp), LOCK_EX | LOCK_NB);
+               if (ret != 0) {
+                       if (errno == EWOULDBLOCK) {
+                               ERROR("`%s' is already being modified or has been "
+                                     "mounted read-write\n"
+                                     "        by another process!", path);
+                               ret = WIMLIB_ERR_ALREADY_LOCKED;
+                       } else {
+                               WARNING("Failed to lock `%s': %s",
+                                       path, strerror(errno));
+                               ret = 0;
+                       }
+               }
+       }
+       return ret;
+}
+#endif
+
 static int open_wim_writable(WIMStruct *w, const char *path,
                             bool trunc, bool readable)
 {
@@ -1513,24 +1536,13 @@ static int open_wim_writable(WIMStruct *w, const char *path,
                ERROR_WITH_ERRNO("Failed to open `%s' for writing", path);
                return WIMLIB_ERR_OPEN;
        }
-#if defined(HAVE_SYS_FILE_H) && defined(HAVE_FLOCK)
-       if (!trunc) {
-               ret = flock(fileno(w->out_fp), LOCK_EX | LOCK_NB);
+       if (trunc) {
+               ret = lock_wim(w->out_fp, path);
                if (ret != 0) {
-                       if (errno == EWOULDBLOCK) {
-                               ERROR("`%s' is already being modified "
-                                     "by another process", path);
-                               ret = WIMLIB_ERR_ALREADY_LOCKED;
-                               fclose(w->out_fp);
-                               w->out_fp = NULL;
-                       } else {
-                               WARNING("Failed to lock `%s': %s",
-                                       path, strerror(errno));
-                               ret = 0;
-                       }
+                       fclose(w->out_fp);
+                       w->out_fp = NULL;
                }
        }
-#endif
        return ret;
 }