diff options
Diffstat (limited to 'pack.h')
| -rw-r--r-- | pack.h | 28 |
1 files changed, 28 insertions, 0 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 |