diff: don't presume empty file when corresponding object is missing

The low-level diff code will happily produce totally bogus diff output
with a broken repository via format-patch and friends by treating missing
objects as empty files.  Let's prevent that from happening any longer.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 381cc8d4fd69ca31fb8fc8af31422160e3ec1fd3..69cdae54b207b7cecd2f95bec785797dd17233fc 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -2124,10 +2124,14 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
        }
        else {
                enum object_type type;
-               if (size_only)
+               if (size_only) {
                        type = sha1_object_info(s->sha1, &s->size);
-               else {
+                       if (type < 0)
+                               die("unable to read %s", sha1_to_hex(s->sha1));
+               } else {
                        s->data = read_sha1_file(s->sha1, &type, &s->size);
+                       if (!s->data)
+                               die("unable to read %s", sha1_to_hex(s->sha1));
                        s->should_free = 1;
                }
        }