1#ifndef PACK_H 2#define PACK_H 3 4#include"object.h" 5 6/* 7 * Packed object header 8 */ 9#define PACK_SIGNATURE 0x5041434b/* "PACK" */ 10#define PACK_VERSION 2 11#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3)) 12struct pack_header { 13uint32_t hdr_signature; 14uint32_t hdr_version; 15uint32_t hdr_entries; 16}; 17 18/* 19 * Packed object index header 20 * 21 * struct pack_idx_header { 22 * uint32_t idx_signature; 23 * uint32_t idx_version; 24 * }; 25 * 26 * Note: this header isn't active yet. In future versions of git 27 * we may change the index file format. At that time we would start 28 * the first four bytes of the new index format with this signature, 29 * as all older git binaries would find this value illegal and abort 30 * reading the file. 31 * 32 * This is the case because the number of objects in a packfile 33 * cannot exceed 1,431,660,000 as every object would need at least 34 * 3 bytes of data and the overall packfile cannot exceed 4 GiB due 35 * to the 32 bit offsets used by the index. Clearly the signature 36 * exceeds this maximum. 37 * 38 * Very old git binaries will also compare the first 4 bytes to the 39 * next 4 bytes in the index and abort with a "non-monotonic index" 40 * error if the second 4 byte word is smaller than the first 4 41 * byte word. This would be true in the proposed future index 42 * format as idx_signature would be greater than idx_version. 43 */ 44#define PACK_IDX_SIGNATURE 0xff744f63/* "\377tOc" */ 45 46externintverify_pack(struct packed_git *,int); 47#endif