merge-ort: propagate callback errors from traverse_trees_wrapper()

traverse_trees_wrapper() saves entries from a first pass through
traverse_trees() and then replays them through the real callback
(collect_merge_info_callback).  However, the replay loop silently
discards the callback return value.  This means any error reported by
the callback during replay -- including a future check for malformed
trees -- would be ignored, allowing the merge to proceed with corrupt
state.

Capture the return value, stop the loop on negative (error) returns,
and propagate the error to the caller.  Note that the callback returns
a positive mask value on success, so we normalize non-negative returns
to 0 for the caller.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/merge-ort.c b/merge-ort.c
index 00923ce3cd749b4dfe379741117eac693c7d3bfc..4b8e32209d9b3ad04d840087aef97ff703f2a35d 100644 (file)
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -1008,18 +1008,20 @@ static int traverse_trees_wrapper(struct index_state *istate,
        info->traverse_path = renames->callback_data_traverse_path;
        info->fn = old_fn;
        for (i = old_offset; i < renames->callback_data_nr; ++i) {
-               info->fn(n,
-                        renames->callback_data[i].mask,
-                        renames->callback_data[i].dirmask,
-                        renames->callback_data[i].names,
-                        info);
+               ret = info->fn(n,
+                              renames->callback_data[i].mask,
+                              renames->callback_data[i].dirmask,
+                              renames->callback_data[i].names,
+                              info);
+               if (ret < 0)
+                       break;
        }
 
        renames->callback_data_nr = old_offset;
        free(renames->callback_data_traverse_path);
        renames->callback_data_traverse_path = old_callback_data_traverse_path;
        info->traverse_path = NULL;
-       return 0;
+       return ret < 0 ? ret : 0;
 }
 
 static void setup_path_info(struct merge_options *opt,