From c5ced64578a82b9d172aceb2f67c6fb9e639f6d9 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <junkio@cox.net>
Date: Thu, 22 Dec 2005 22:57:20 -0800
Subject: 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)

diff --git a/sha1_file.c b/sha1_file.c
index d451a94..6b7577d 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;
 }
 
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 5b50536..7dfb1ab 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -163,6 +163,13 @@ test_expect_success \
      else :;
      fi &&
 
+     cp test-1-${packname_1}.pack test-3.pack &&
+     dd if=/dev/zero of=test-3.idx count=1 bs=1 conv=notrunc seek=1200 &&
+     if git-verify-pack test-3.pack
+     then false
+     else :;
+     fi &&
+
      :'
 
 test_expect_success \
-- 
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