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

diff --git a/sha1_file.c b/sha1_file.c
index d451a94efed7d36d55cf1b77324eaf55e0d50d69..6b7577dbc4ed845da1a70b6d727370423b086735 100644 (file)
--- 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;
 }