src/pack.h

/*
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2,
 * as published by the Free Software Foundation.
 *
 * In addition to the permissions in the GNU General Public License,
 * the authors give you unlimited permission to link the compiled
 * version of this file into combinations with other programs,
 * and to distribute those combinations without any restriction
 * coming from the use of this file.  (The General Public License
 * restrictions do apply in other respects; for example, they cover
 * modification of the file, and distribution when not linked into
 * a combined executable.)
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifndef INCLUDE_pack_h__
#define INCLUDE_pack_h__

#include "git2/oid.h"

#include "common.h"
#include "map.h"
#include "mwindow.h"
#include "odb.h"

#define PACK_SIGNATURE 0x5041434b	/* "PACK" */
#define PACK_VERSION 2
#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
struct git_pack_header {
	uint32_t hdr_signature;
	uint32_t hdr_version;
	uint32_t hdr_entries;
};

/*
 * The first four bytes of index formats later than version 1 should
 * start 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 with
 * version 1 of the index file due to the offsets limited to 32 bits.
 * 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" */

struct git_pack_idx_header {
	uint32_t idx_signature;
	uint32_t idx_version;
};

struct git_pack_file {
	git_mwindow_file mwf;
	git_map index_map;

	uint32_t num_objects;
	uint32_t num_bad_objects;
	git_oid *bad_object_sha1; /* array of git_oid */

	int index_version;
	git_time_t mtime;
	unsigned pack_local:1, pack_keep:1, has_cache:1;
	git_oid sha1;
	git_vector cache;

	/* something like ".git/objects/pack/xxxxx.pack" */
	char pack_name[GIT_FLEX_ARRAY]; /* more */
};

struct git_pack_entry {
	off_t offset;
	git_oid sha1;
	struct git_pack_file *p;
};

int git_packfile_unpack_header(
		size_t *size_p,
		git_otype *type_p,
		git_mwindow_file *mwf,
		git_mwindow **w_curs,
		off_t *curpos);

int git_packfile_unpack(git_rawobj *obj, struct git_pack_file *p, off_t *obj_offset);

off_t get_delta_base(struct git_pack_file *p, git_mwindow **w_curs,
		off_t *curpos, git_otype type,
		off_t delta_obj_offset);

void packfile_free(struct git_pack_file *p);
int git_packfile_check(struct git_pack_file **pack_out, const char *path);
int git_pack_entry_find(
		struct git_pack_entry *e,
		struct git_pack_file *p,
		const git_oid *short_oid,
		unsigned int len);

#endif