Update: Report on readdir() errors #6610

Author: ckamm

src/csync/csync_update.cpp

@@ -641,6 +641,7 @@ int csync_ftw(CSYNC *ctx, const char *uri, csync_walker_fn fn,
   csync_file_stat_t *previous_fs = NULL;
   int read_from_db = 0;
   int rc = 0;
+  int last_errno = 0;
 
   bool do_read_from_db = (ctx->current == REMOTE_REPLICA && ctx->remote.read_from_db);
   const char *db_uri = uri;
@@ -712,7 +713,30 @@ int csync_ftw(CSYNC *ctx, const char *uri, csync_walker_fn fn,
       goto error;
   }
 
-  while ((dirent = csync_vio_readdir(ctx, dh))) {
+  while (true) {
+    errno = 0;
+    dirent = csync_vio_readdir(ctx, dh);
+    if (!dirent) {
+        // Normal case: End of items in directory
+        if (errno == 0)
+            break;
+
+        // Note: Windows vio converts any error into EACCES
+        qCWarning(lcUpdate, "readdir failed for file in %s - errno %d", uri, errno);
+
+        // If we get an error during readdir, maybe that's a single unreadable
+        // item that we can skip? It's unclear whether that can happen.
+        // We definitely don't want to get stuck in an infinite loop here,
+        // so stop if we get the same errno twice in a row.
+        if (errno == last_errno) {
+            qCWarning(lcUpdate, "Second failure, giving up on directory");
+            goto error;
+        }
+        last_errno = errno;
+        continue;
+    }
+    last_errno = 0;
+
     /* Conversion error */
     if (dirent->path.isEmpty() && !dirent->original_path.isEmpty()) {
         ctx->status_code = CSYNC_STATUS_INVALID_CHARACTERS;