[thirdparty/git.git] / pack-write.c

#include "cache.h"
#include "pack.h"
#include "csum-file.h"

void reset_pack_idx_option(struct pack_idx_option *opts)
{
	memset(opts, 0, sizeof(*opts));
	opts->version = 2;
	opts->off32_limit = 0x7fffffff;
}

static int sha1_compare(const void *_a, const void *_b)
{
	struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
	struct pack_idx_entry *b = *(struct pack_idx_entry **)_b;
	return hashcmp(a->sha1, b->sha1);
}

/*
 * On entry *sha1 contains the pack content SHA1 hash, on exit it is
 * the SHA1 hash of sorted object names. The objects array passed in
 * will be sorted by SHA1 on exit.
 */
const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects,
			   int nr_objects, const struct pack_idx_option *opts,
			   unsigned char *sha1)
{
	struct sha1file *f;
	struct pack_idx_entry **sorted_by_sha, **list, **last;
	off_t last_obj_offset = 0;
	uint32_t array[256];
	int i, fd;
	git_SHA_CTX ctx;
	uint32_t index_version;

	if (nr_objects) {
		sorted_by_sha = objects;
		list = sorted_by_sha;
		last = sorted_by_sha + nr_objects;
		for (i = 0; i < nr_objects; ++i) {
			if (objects[i]->offset > last_obj_offset)
				last_obj_offset = objects[i]->offset;
		}
		qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
		      sha1_compare);
	}
	else
		sorted_by_sha = list = last = NULL;

	if (opts->flags & WRITE_IDX_VERIFY) {
		assert(index_name);
		f = sha1fd_check(index_name);
	} else {
		if (!index_name) {
			static char tmpfile[PATH_MAX];
			fd = odb_mkstemp(tmpfile, sizeof(tmpfile), "pack/tmp_idx_XXXXXX");
			index_name = xstrdup(tmpfile);
		} else {
			unlink(index_name);
			fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
		}
		if (fd < 0)
			die_errno("unable to create '%s'", index_name);
		f = sha1fd(fd, index_name);
	}

	/* if last object's offset is >= 2^31 we should use index V2 */
	index_version = (last_obj_offset >> 31) ? 2 : opts->version;

	/* index versions 2 and above need a header */
	if (index_version >= 2) {
		struct pack_idx_header hdr;
		hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
		hdr.idx_version = htonl(index_version);
		sha1write(f, &hdr, sizeof(hdr));
	}

	/*
	 * Write the first-level table (the list is sorted,
	 * but we use a 256-entry lookup to be able to avoid
	 * having to do eight extra binary search iterations).
	 */
	for (i = 0; i < 256; i++) {
		struct pack_idx_entry **next = list;
		while (next < last) {
			struct pack_idx_entry *obj = *next;
			if (obj->sha1[0] != i)
				break;
			next++;
		}
		array[i] = htonl(next - sorted_by_sha);
		list = next;
	}
	sha1write(f, array, 256 * 4);

	/* compute the SHA1 hash of sorted object names. */
	git_SHA1_Init(&ctx);

	/*
	 * Write the actual SHA1 entries..
	 */
	list = sorted_by_sha;
	for (i = 0; i < nr_objects; i++) {
		struct pack_idx_entry *obj = *list++;
		if (index_version < 2) {
			uint32_t offset = htonl(obj->offset);
			sha1write(f, &offset, 4);
		}
		sha1write(f, obj->sha1, 20);
		git_SHA1_Update(&ctx, obj->sha1, 20);
	}

	if (index_version >= 2) {
		unsigned int nr_large_offset = 0;

		/* write the crc32 table */
		list = sorted_by_sha;
		for (i = 0; i < nr_objects; i++) {
			struct pack_idx_entry *obj = *list++;
			uint32_t crc32_val = htonl(obj->crc32);
			sha1write(f, &crc32_val, 4);
		}

		/* write the 32-bit offset table */
		list = sorted_by_sha;
		for (i = 0; i < nr_objects; i++) {
			struct pack_idx_entry *obj = *list++;
			uint32_t offset = (obj->offset <= opts->off32_limit) ?
				obj->offset : (0x80000000 | nr_large_offset++);
			offset = htonl(offset);
			sha1write(f, &offset, 4);
		}

		/* write the large offset table */
		list = sorted_by_sha;
		while (nr_large_offset) {
			struct pack_idx_entry *obj = *list++;
			uint64_t offset = obj->offset;
			if (offset > opts->off32_limit) {
				uint32_t split[2];
				split[0] = htonl(offset >> 32);
				split[1] = htonl(offset & 0xffffffff);
				sha1write(f, split, 8);
				nr_large_offset--;
			}
		}
	}

	sha1write(f, sha1, 20);
	sha1close(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
			    ? CSUM_CLOSE : CSUM_FSYNC));
	git_SHA1_Final(sha1, &ctx);
	return index_name;
}

/*
 * Update pack header with object_count and compute new SHA1 for pack data
 * associated to pack_fd, and write that SHA1 at the end.  That new SHA1
 * is also returned in new_pack_sha1.
 *
 * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
 * (without the header update) is computed and validated against the
 * one provided in partial_pack_sha1.  The validation is performed at
 * partial_pack_offset bytes in the pack file.  The SHA1 of the remaining
 * data (i.e. from partial_pack_offset to the end) is then computed and
 * returned in partial_pack_sha1.
 *
 * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
 * partial_pack_sha1 can refer to the same buffer if the caller is not
 * interested in the resulting SHA1 of pack data above partial_pack_offset.
 */
void fixup_pack_header_footer(int pack_fd,
			 unsigned char *new_pack_sha1,
			 const char *pack_name,
			 uint32_t object_count,
			 unsigned char *partial_pack_sha1,
			 off_t partial_pack_offset)
{
	int aligned_sz, buf_sz = 8 * 1024;
	git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
	struct pack_header hdr;
	char *buf;

	git_SHA1_Init(&old_sha1_ctx);
	git_SHA1_Init(&new_sha1_ctx);

	if (lseek(pack_fd, 0, SEEK_SET) != 0)
		die_errno("Failed seeking to start of '%s'", pack_name);
	if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
		die_errno("Unable to reread header of '%s'", pack_name);
	if (lseek(pack_fd, 0, SEEK_SET) != 0)
		die_errno("Failed seeking to start of '%s'", pack_name);
	git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
	hdr.hdr_entries = htonl(object_count);
	git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
	write_or_die(pack_fd, &hdr, sizeof(hdr));
	partial_pack_offset -= sizeof(hdr);

	buf = xmalloc(buf_sz);
	aligned_sz = buf_sz - sizeof(hdr);
	for (;;) {
		ssize_t m, n;
		m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
			partial_pack_offset : aligned_sz;
		n = xread(pack_fd, buf, m);
		if (!n)
			break;
		if (n < 0)
			die_errno("Failed to checksum '%s'", pack_name);
		git_SHA1_Update(&new_sha1_ctx, buf, n);

		aligned_sz -= n;
		if (!aligned_sz)
			aligned_sz = buf_sz;

		if (!partial_pack_sha1)
			continue;

		git_SHA1_Update(&old_sha1_ctx, buf, n);
		partial_pack_offset -= n;
		if (partial_pack_offset == 0) {
			unsigned char sha1[20];
			git_SHA1_Final(sha1, &old_sha1_ctx);
			if (hashcmp(sha1, partial_pack_sha1) != 0)
				die("Unexpected checksum for %s "
				    "(disk corruption?)", pack_name);
			/*
			 * Now let's compute the SHA1 of the remainder of the
			 * pack, which also means making partial_pack_offset
			 * big enough not to matter anymore.
			 */
			git_SHA1_Init(&old_sha1_ctx);
			partial_pack_offset = ~partial_pack_offset;
			partial_pack_offset -= MSB(partial_pack_offset, 1);
		}
	}
	free(buf);

	if (partial_pack_sha1)
		git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
	git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
	write_or_die(pack_fd, new_pack_sha1, 20);
	fsync_or_die(pack_fd, pack_name);
}

char *index_pack_lockfile(int ip_out)
{
	char packname[46];

	/*
	 * The first thing we expect from index-pack's output
	 * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
	 * %40s is the newly created pack SHA1 name.  In the "keep"
	 * case, we need it to remove the corresponding .keep file
	 * later on.  If we don't get that then tough luck with it.
	 */
	if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
	    memcmp(packname, "keep\t", 5) == 0) {
		char path[PATH_MAX];
		packname[45] = 0;
		snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
			 get_object_directory(), packname + 5);
		return xstrdup(path);
	}
	return NULL;
}

/*
 * The per-object header is a pretty dense thing, which is
 *  - first byte: low four bits are "size", then three bits of "type",
 *    and the high bit is "size continues".
 *  - each byte afterwards: low seven bits are size continuation,
 *    with the high bit being "size continues"
 */
int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
{
	int n = 1;
	unsigned char c;

	if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
		die("bad type %d", type);

	c = (type << 4) | (size & 15);
	size >>= 4;
	while (size) {
		*hdr++ = c | 0x80;
		c = size & 0x7f;
		size >>= 7;
		n++;
	}
	*hdr = c;
	return n;
}
Commit	Line	Data
8b0eca7c DH	1	#include "cache.h"
8b0eca7c DH	2	#include "pack.h"
aa7e44bf GB	3	#include "csum-file.h"
aa7e44bf GB	4
ebcfb379 JH	5	void reset_pack_idx_option(struct pack_idx_option *opts)
	6	{
	7	memset(opts, 0, sizeof(*opts));
	8	opts->version = 2;
	9	opts->off32_limit = 0x7fffffff;
	10	}
aa7e44bf GB	11
	12	static int sha1_compare(const void _a, const void _b)
	13	{
	14	struct pack_idx_entry a = (struct pack_idx_entry **)_a;
	15	struct pack_idx_entry b = (struct pack_idx_entry **)_b;
	16	return hashcmp(a->sha1, b->sha1);
	17	}
	18
	19	/*
	20	* On entry *sha1 contains the pack content SHA1 hash, on exit it is
	21	* the SHA1 hash of sorted object names. The objects array passed in
	22	* will be sorted by SHA1 on exit.
	23	*/
3bb72562	24	const char write_idx_file(const char index_name, struct pack_idx_entry **objects,
ebcfb379 JH	25	int nr_objects, const struct pack_idx_option *opts,
ebcfb379 JH	26	unsigned char *sha1)
aa7e44bf GB	27	{
	28	struct sha1file *f;
	29	struct pack_idx_entry sorted_by_sha, list, **last;
	30	off_t last_obj_offset = 0;
	31	uint32_t array[256];
	32	int i, fd;
9126f009	33	git_SHA_CTX ctx;
aa7e44bf GB	34	uint32_t index_version;
	35
	36	if (nr_objects) {
	37	sorted_by_sha = objects;
	38	list = sorted_by_sha;
	39	last = sorted_by_sha + nr_objects;
	40	for (i = 0; i < nr_objects; ++i) {
	41	if (objects[i]->offset > last_obj_offset)
	42	last_obj_offset = objects[i]->offset;
	43	}
	44	qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
	45	sha1_compare);
	46	}
	47	else
	48	sorted_by_sha = list = last = NULL;
	49
e337a04d JH	50	if (opts->flags & WRITE_IDX_VERIFY) {
	51	assert(index_name);
	52	f = sha1fd_check(index_name);
aa7e44bf	53	} else {
e337a04d JH	54	if (!index_name) {
	55	static char tmpfile[PATH_MAX];
	56	fd = odb_mkstemp(tmpfile, sizeof(tmpfile), "pack/tmp_idx_XXXXXX");
	57	index_name = xstrdup(tmpfile);
	58	} else {
	59	unlink(index_name);
	60	fd = open(index_name, O_CREAT\|O_EXCL\|O_WRONLY, 0600);
	61	}
	62	if (fd < 0)
	63	die_errno("unable to create '%s'", index_name);
	64	f = sha1fd(fd, index_name);
aa7e44bf	65	}
aa7e44bf GB	66
aa7e44bf GB	67	/* if last object's offset is >= 2^31 we should use index V2 */
ebcfb379	68	index_version = (last_obj_offset >> 31) ? 2 : opts->version;
aa7e44bf GB	69
	70	/* index versions 2 and above need a header */
	71	if (index_version >= 2) {
	72	struct pack_idx_header hdr;
	73	hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
	74	hdr.idx_version = htonl(index_version);
	75	sha1write(f, &hdr, sizeof(hdr));
	76	}
	77
	78	/*
	79	* Write the first-level table (the list is sorted,
	80	* but we use a 256-entry lookup to be able to avoid
	81	* having to do eight extra binary search iterations).
	82	*/
	83	for (i = 0; i < 256; i++) {
	84	struct pack_idx_entry **next = list;
	85	while (next < last) {
	86	struct pack_idx_entry obj = next;
	87	if (obj->sha1[0] != i)
	88	break;
	89	next++;
	90	}
	91	array[i] = htonl(next - sorted_by_sha);
	92	list = next;
	93	}
	94	sha1write(f, array, 256 * 4);
	95
	96	/* compute the SHA1 hash of sorted object names. */
9126f009	97	git_SHA1_Init(&ctx);
aa7e44bf GB	98
	99	/*
	100	* Write the actual SHA1 entries..
	101	*/
	102	list = sorted_by_sha;
	103	for (i = 0; i < nr_objects; i++) {
	104	struct pack_idx_entry obj = list++;
	105	if (index_version < 2) {
	106	uint32_t offset = htonl(obj->offset);
	107	sha1write(f, &offset, 4);
	108	}
	109	sha1write(f, obj->sha1, 20);
9126f009	110	git_SHA1_Update(&ctx, obj->sha1, 20);
aa7e44bf GB	111	}
	112
	113	if (index_version >= 2) {
	114	unsigned int nr_large_offset = 0;
	115
	116	/* write the crc32 table */
	117	list = sorted_by_sha;
	118	for (i = 0; i < nr_objects; i++) {
	119	struct pack_idx_entry obj = list++;
	120	uint32_t crc32_val = htonl(obj->crc32);
	121	sha1write(f, &crc32_val, 4);
	122	}
	123
	124	/* write the 32-bit offset table */
	125	list = sorted_by_sha;
	126	for (i = 0; i < nr_objects; i++) {
	127	struct pack_idx_entry obj = list++;
ebcfb379	128	uint32_t offset = (obj->offset <= opts->off32_limit) ?
aa7e44bf GB	129	obj->offset : (0x80000000 \| nr_large_offset++);
	130	offset = htonl(offset);
	131	sha1write(f, &offset, 4);
	132	}
	133
	134	/* write the large offset table */
	135	list = sorted_by_sha;
	136	while (nr_large_offset) {
	137	struct pack_idx_entry obj = list++;
	138	uint64_t offset = obj->offset;
ebcfb379	139	if (offset > opts->off32_limit) {
aa7e44bf GB	140	uint32_t split[2];
	141	split[0] = htonl(offset >> 32);
	142	split[1] = htonl(offset & 0xffffffff);
	143	sha1write(f, split, 8);
	144	nr_large_offset--;
	145	}
	146	}
	147	}
	148
	149	sha1write(f, sha1, 20);
e337a04d JH	150	sha1close(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
e337a04d JH	151	? CSUM_CLOSE : CSUM_FSYNC));
9126f009	152	git_SHA1_Final(sha1, &ctx);
aa7e44bf GB	153	return index_name;
aa7e44bf GB	154	}
8b0eca7c	155
abeb40e5 NP	156	/*
	157	* Update pack header with object_count and compute new SHA1 for pack data
	158	* associated to pack_fd, and write that SHA1 at the end. That new SHA1
	159	* is also returned in new_pack_sha1.
	160	*
	161	* If partial_pack_sha1 is non null, then the SHA1 of the existing pack
	162	* (without the header update) is computed and validated against the
	163	* one provided in partial_pack_sha1. The validation is performed at
	164	* partial_pack_offset bytes in the pack file. The SHA1 of the remaining
	165	* data (i.e. from partial_pack_offset to the end) is then computed and
	166	* returned in partial_pack_sha1.
	167	*
	168	* Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
	169	* partial_pack_sha1 can refer to the same buffer if the caller is not
	170	* interested in the resulting SHA1 of pack data above partial_pack_offset.
	171	*/
8b0eca7c	172	void fixup_pack_header_footer(int pack_fd,
abeb40e5	173	unsigned char *new_pack_sha1,
8b0eca7c	174	const char *pack_name,
abeb40e5 NP	175	uint32_t object_count,
	176	unsigned char *partial_pack_sha1,
	177	off_t partial_pack_offset)
8b0eca7c	178	{
d35825da	179	int aligned_sz, buf_sz = 8 * 1024;
9126f009	180	git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
8b0eca7c DH	181	struct pack_header hdr;
	182	char *buf;
	183
9126f009 NP	184	git_SHA1_Init(&old_sha1_ctx);
9126f009 NP	185	git_SHA1_Init(&new_sha1_ctx);
abeb40e5	186
8b0eca7c	187	if (lseek(pack_fd, 0, SEEK_SET) != 0)
d824cbba	188	die_errno("Failed seeking to start of '%s'", pack_name);
8b0eca7c	189	if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
d824cbba	190	die_errno("Unable to reread header of '%s'", pack_name);
8b0eca7c	191	if (lseek(pack_fd, 0, SEEK_SET) != 0)
d824cbba	192	die_errno("Failed seeking to start of '%s'", pack_name);
9126f009	193	git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
8b0eca7c	194	hdr.hdr_entries = htonl(object_count);
9126f009	195	git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
8b0eca7c	196	write_or_die(pack_fd, &hdr, sizeof(hdr));
abeb40e5	197	partial_pack_offset -= sizeof(hdr);
8b0eca7c DH	198
8b0eca7c DH	199	buf = xmalloc(buf_sz);
d35825da	200	aligned_sz = buf_sz - sizeof(hdr);
8b0eca7c	201	for (;;) {
abeb40e5	202	ssize_t m, n;
d35825da NP	203	m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
d35825da NP	204	partial_pack_offset : aligned_sz;
abeb40e5	205	n = xread(pack_fd, buf, m);
8b0eca7c DH	206	if (!n)
	207	break;
	208	if (n < 0)
d824cbba	209	die_errno("Failed to checksum '%s'", pack_name);
9126f009	210	git_SHA1_Update(&new_sha1_ctx, buf, n);
abeb40e5	211
d35825da NP	212	aligned_sz -= n;
	213	if (!aligned_sz)
	214	aligned_sz = buf_sz;
	215
abeb40e5 NP	216	if (!partial_pack_sha1)
	217	continue;
	218
9126f009	219	git_SHA1_Update(&old_sha1_ctx, buf, n);
abeb40e5 NP	220	partial_pack_offset -= n;
	221	if (partial_pack_offset == 0) {
	222	unsigned char sha1[20];
9126f009	223	git_SHA1_Final(sha1, &old_sha1_ctx);
abeb40e5 NP	224	if (hashcmp(sha1, partial_pack_sha1) != 0)
	225	die("Unexpected checksum for %s "
	226	"(disk corruption?)", pack_name);
	227	/*
	228	* Now let's compute the SHA1 of the remainder of the
	229	* pack, which also means making partial_pack_offset
	230	* big enough not to matter anymore.
	231	*/
9126f009	232	git_SHA1_Init(&old_sha1_ctx);
abeb40e5 NP	233	partial_pack_offset = ~partial_pack_offset;
	234	partial_pack_offset -= MSB(partial_pack_offset, 1);
	235	}
8b0eca7c DH	236	}
	237	free(buf);
	238
abeb40e5	239	if (partial_pack_sha1)
9126f009 NP	240	git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
9126f009 NP	241	git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
abeb40e5	242	write_or_die(pack_fd, new_pack_sha1, 20);
0c68d386	243	fsync_or_die(pack_fd, pack_name);
8b0eca7c	244	}
106764e6 SP	245
	246	char *index_pack_lockfile(int ip_out)
	247	{
106764e6 SP	248	char packname[46];
	249
	250	/*
6e180cdc	251	* The first thing we expect from index-pack's output
106764e6 SP	252	* is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
	253	* %40s is the newly created pack SHA1 name. In the "keep"
	254	* case, we need it to remove the corresponding .keep file
	255	* later on. If we don't get that then tough luck with it.
	256	*/
c697ad14 HO	257	if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n' &&
c697ad14 HO	258	memcmp(packname, "keep\t", 5) == 0) {
106764e6 SP	259	char path[PATH_MAX];
	260	packname[45] = 0;
	261	snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
	262	get_object_directory(), packname + 5);
	263	return xstrdup(path);
	264	}
	265	return NULL;
	266	}
f965c525 NP	267
	268	/*
	269	* The per-object header is a pretty dense thing, which is
	270	* - first byte: low four bits are "size", then three bits of "type",
	271	* and the high bit is "size continues".
	272	* - each byte afterwards: low seven bits are size continuation,
	273	* with the high bit being "size continues"
	274	*/
	275	int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
	276	{
	277	int n = 1;
	278	unsigned char c;
	279
	280	if (type < OBJ_COMMIT \|\| type > OBJ_REF_DELTA)
	281	die("bad type %d", type);
	282
	283	c = (type << 4) \| (size & 15);
	284	size >>= 4;
	285	while (size) {
	286	*hdr++ = c \| 0x80;
	287	c = size & 0x7f;
	288	size >>= 7;
	289	n++;
	290	}
	291	*hdr = c;
	292	return n;
	293	}