diff options
| -rw-r--r-- | pack.h | 28 | ||||
| -rw-r--r-- | sha1_file.c | 17 |
2 files changed, 42 insertions, 3 deletions
@@ -15,5 +15,33 @@ struct pack_header { unsigned int hdr_entries; }; +/* + * Packed object index header + * + * struct pack_idx_header { + * uint32_t idx_signature; + * uint32_t idx_version; + * }; + * + * Note: this header isn't active yet. In future versions of git + * we may change the index file format. At that time we would start + * the first four bytes of the new index format with this signature, + * as all older git binaries would find this value illegal and abort + * reading the file. + * + * This is the case because the number of objects in a packfile + * cannot exceed 1,431,660,000 as every object would need at least + * 3 bytes of data and the overall packfile cannot exceed 4 GiB due + * to the 32 bit offsets used by the index. Clearly the signature + * exceeds this maximum. + * + * Very old git binaries will also compare the first 4 bytes to the + * next 4 bytes in the index and abort with a "non-monotonic index" + * error if the second 4 byte word is smaller than the first 4 + * byte word. This would be true in the proposed future index + * format as idx_signature would be greater than idx_version. + */ +#define PACK_IDX_SIGNATURE 0xff744f63 /* "\377tOc" */ + extern int verify_pack(struct packed_git *, int); #endif diff --git a/sha1_file.c b/sha1_file.c index 1b1c0f7b4d..0b70545562 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -456,12 +456,23 @@ static int check_packed_git_idx(const char *path, unsigned long *idx_size_, /* check index map */ if (idx_size < 4*256 + 20 + 20) - return error("index file too small"); + return error("index file %s is too small", path); + + /* a future index format would start with this, as older git + * binaries would fail the non-monotonic index check below. + * give a nicer warning to the user if we can. + */ + if (index[0] == htonl(PACK_IDX_SIGNATURE)) + return error("index file %s is a newer version" + " and is not supported by this binary" + " (try upgrading GIT to a newer version)", + path); + nr = 0; for (i = 0; i < 256; i++) { unsigned int n = ntohl(index[i]); if (n < nr) - return error("non-monotonic index"); + return error("non-monotonic index %s", path); nr = n; } @@ -473,7 +484,7 @@ static int check_packed_git_idx(const char *path, unsigned long *idx_size_, * - 20-byte SHA1 file checksum */ if (idx_size != 4*256 + nr * 24 + 20 + 20) - return error("wrong index file size"); + return error("wrong index file size in %s", path); return 0; } |