pack-objects: Fix segfault when object count is less than thread count

When partitioning the work amongst threads, dividing the number of
objects by the number of threads may return 0 when there are less
objects than threads; this will cause the subsequent code to segfault
when accessing list[sub_size-1].  Allow some threads to have
zero objects to work on instead of barfing, while letting others
to have more.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index ec10238e4a0d81773820d255ed0861dd66e0c3d6..d3efeff03f89cc0f4d0da463ddf878c28effb31e 100644 (file)
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -1672,7 +1672,8 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
                p[i].data_ready = 0;
 
                /* try to split chunks on "path" boundaries */
-               while (sub_size < list_size && list[sub_size]->hash &&
+               while (sub_size && sub_size < list_size &&
+                      list[sub_size]->hash &&
                       list[sub_size]->hash == list[sub_size-1]->hash)
                        sub_size++;