apply: don't segfault on binary files with missing data

Usually when applying a binary diff generated without
--binary, it will be rejected early, as we don't even have
the full sha1 of the pre- and post-images.

However, if the diff is generated with --full-index (but not
--binary), then we will actually try to apply it. If we have
the postimage blob, then we can take a shortcut and never
even look at the binary diff at all (e.g., this can happen
when rebasing changes within a repository).

If we don't have the postimage blob, though, we try to look
at the actual fragments, of which there are none, and get a
segfault. This patch checks explicitly for that case and
complains to the user instead of segfaulting. We need to
keep the check at a low level so that the "shortcut" case
above continues to work.

We also add a test that demonstrates the segfault. While
we're at it, let's also explicitly test the shortcut case.

Reported-by: Rafaël Carré <rafael.carre@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/builtin/apply.c b/builtin/apply.c
index 23c18c573..f051e66dc 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -2645,6 +2645,12 @@ static int apply_binary_fragment(struct image *img, struct patch *patch)
 	unsigned long len;
 	void *dst;
 
+	if (!fragment)
+		return error("missing binary patch data for '%s'",
+			     patch->new_name ?
+			     patch->new_name :
+			     patch->old_name);
+
 	/* Binary patch is irreversible without the optional second hunk */
 	if (apply_in_reverse) {
 		if (!fragment->next)