check_packed_git_idx(): check integrity of the idx file itself.

Although pack-check.c had routine to verify the checksum for the
pack index file itself, the core did not check it before using
it.

This is stolen from the patch to tighten packname requirements.

Signed-off-by: Junio C Hamano <junkio@cox.net>
(cherry picked from 797bd6f490c91c07986382b9f268e0df712cb246 commit)

1 files changed, 15 insertions, 1 deletions

diff --git a/sha1_file.c b/sha1_file.c
index d451a94efe..6b7577dbc4 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -321,12 +321,16 @@ struct packed_git *packed_git;
 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 				void **idx_map_)
 {
+	SHA_CTX ctx;
+	unsigned char sha1[20];
 	void *idx_map;
 	unsigned int *index;
 	unsigned long idx_size;
 	int nr, i;
-	int fd = open(path, O_RDONLY);
+	int fd;
 	struct stat st;
+
+	fd = open(path, O_RDONLY);
 	if (fd < 0)
 		return -1;
 	if (fstat(fd, &st)) {
@@ -364,6 +368,16 @@ static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 	if (idx_size != 4*256 + nr * 24 + 20 + 20)
 		return error("wrong index file size");
 
+	/*
+	 * File checksum.
+	 */
+	SHA1_Init(&ctx);
+	SHA1_Update(&ctx, idx_map, idx_size-20);
+	SHA1_Final(sha1, &ctx);
+
+	if (memcmp(sha1, idx_map + idx_size - 20, 20))
+		return error("index checksum mismatch");
+
 	return 0;
 }