fsck: check rev-index checksums

The previous change added calls to verify_pack_revindex() in
builtin/fsck.c, but the implementation of the method was left empty. Add
the first and most-obvious check to this method: checksum verification.

While here, create a helper method in the test script that makes it easy
to adjust the .rev file and check that 'git fsck' reports the correct
error message.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/pack-revindex.c b/pack-revindex.c
index c3f2aaa3fe..007a806994 100644
--- a/pack-revindex.c
+++ b/pack-revindex.c
@@ -5,6 +5,7 @@
 #include "packfile.h"
 #include "config.h"
 #include "midx.h"
+#include "csum-file.h"
 
 struct revindex_entry {
 	off_t offset;
@@ -309,6 +310,15 @@ int load_pack_revindex(struct repository *r, struct packed_git *p)
  */
 int verify_pack_revindex(struct packed_git *p)
 {
+	/* Do not bother checking if not initialized. */
+	if (!p->revindex_map)
+		return 0;
+
+	if (!hashfile_checksum_valid((const unsigned char *)p->revindex_map, p->revindex_size)) {
+		error(_("invalid checksum"));
+		return -1;
+	}
+
 	return 0;
 }