/*
* Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* An open pack file. */
struct got_pack {
char *path_packfile;
int fd;
uint8_t *map;
size_t filesize;
};
const struct got_error *got_pack_close(struct got_pack *);
/* See Documentation/technical/pack-format.txt in Git. */
struct got_packidx_trailer {
u_int8_t packfile_sha1[SHA1_DIGEST_LENGTH];
u_int8_t packidx_sha1[SHA1_DIGEST_LENGTH];
} __attribute__((__packed__));
struct got_packidx_object_id {
u_int8_t sha1[SHA1_DIGEST_LENGTH];
} __attribute__((__packed__));
/* Ignore pack index version 1 which is no longer written by Git. */
#define GOT_PACKIDX_VERSION 2
struct got_packidx_v2_hdr {
uint32_t *magic; /* big endian */
#define GOT_PACKIDX_V2_MAGIC 0xff744f63 /* "\377t0c" */
uint32_t *version;
/*
* Each entry N in the fanout table contains the number of objects in
* the packfile whose SHA1 begins with a byte less than or equal to N.
* The last entry (index 255) contains the number of objects in the
* pack file whose first SHA1 byte is <= 0xff, and thus records the
* total number of objects in the pack file. All pointer variables
* below point to tables with a corresponding number of entries.
*/
uint32_t *fanout_table; /* values are big endian */
#define GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS (0xff + 1)
/* Sorted SHA1 checksums for each object in the pack file. */
struct got_packidx_object_id *sorted_ids;
/* CRC32 of the packed representation of each object. */
uint32_t *crc32;
/* Offset into the pack file for each object. */
uint32_t *offsets; /* values are big endian */
#define GOT_PACKIDX_OFFSET_VAL_MASK 0x7fffffff
#define GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX 0x80000000
/* Large offsets table is empty for pack files < 2 GB. */
uint64_t *large_offsets; /* values are big endian */
struct got_packidx_trailer *trailer;
};
/* An open pack index file. */
struct got_packidx {
char *path_packidx; /* actual on-disk path */
int fd;
uint8_t *map;
size_t len;
struct got_packidx_v2_hdr hdr; /* convenient pointers into map */
};
struct got_packfile_hdr {
uint32_t signature;
#define GOT_PACKFILE_SIGNATURE 0x5041434b /* 'P' 'A' 'C' 'K' */
uint32_t version; /* big endian */
#define GOT_PACKFILE_VERSION 2
uint32_t nobjects; /* big endian */
};
struct got_packfile_obj_hdr {
/*
* The object size field uses a variable length encoding:
* size0...sizeN form a 4+7+7+...+7 bit integer, where size0 is the
* least significant part and sizeN is the most significant part.
* If the MSB of a size byte is set, an additional size byte follows.
* Of the 7 remaining bits of size0, the first 3 bits indicate the
* object's type, and the remaining 4 bits contribute to the size.
*/
uint8_t *size; /* variable length */
#define GOT_PACK_OBJ_SIZE_MORE 0x80
#define GOT_PACK_OBJ_SIZE0_TYPE_MASK 0x70 /* See struct got_object->type */
#define GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT 4
#define GOT_PACK_OBJ_SIZE0_VAL_MASK 0x0f
#define GOT_PACK_OBJ_SIZE_VAL_MASK 0x7f
};
/* If object is not a DELTA type. */
struct got_packfile_object_data {
uint8_t *data; /* compressed */
};
/* If object is of type GOT_OBJ_TYPE_REF_DELTA. */
struct got_packfile_object_data_ref_delta {
uint8_t sha1[SHA1_DIGEST_LENGTH];
uint8_t *delta_data; /* compressed */
};
/* If object is of type GOT_OBJ_TYPE_OFFSET_DELTA. */
struct got_packfile_object_data_offset_delta {
/*
* This offset is interpreted as a negative offset from
* the got_packfile_obj_hdr corresponding to this object.
* The size provided in the header specifies the amount
* of compressed delta data that follows.
*
* This field uses a variable length encoding of N bytes,
* where the MSB is always set except for the last byte.
* The value is encoded as a series of N 7 bit integers,
* which are concatenated, and if N > 1 the value 2^7 +
* 2^14 + ... + 2^(7 * (n-1)) is added to the result.
*/
uint8_t *offset; /* variable length */
#define GOT_PACK_OBJ_DELTA_OFF_MORE 0x80
#define GOT_PACK_OBJ_DELTA_OFF_VAL_MASK 0x7f
uint8_t *delta_data; /* compressed */
};
struct got_packfile_obj_data {
union {
struct got_packfile_object_data data;
struct got_packfile_object_data_ref_delta ref_delta;
struct got_packfile_object_data_offset_delta offset_delta;
} __attribute__((__packed__));
} __attribute__((__packed__));
const struct got_error *got_packidx_open(struct got_packidx **,
const char *, int);
const struct got_error* got_packidx_close(struct got_packidx *);
const struct got_error *got_packfile_open_object(struct got_object **,
struct got_object_id *, struct got_repository *);
const struct got_error *got_packfile_extract_object(FILE **,
struct got_object *, struct got_repository *);
const struct got_error *got_packfile_extract_object_to_mem(uint8_t **, size_t *,
struct got_object *, struct got_repository *);
