[thirdparty/git.git] / read-cache.c

/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include <stdarg.h>
#include "cache.h"

struct cache_entry **active_cache = NULL;
unsigned int active_nr = 0, active_alloc = 0;

int cache_match_stat(struct cache_entry *ce, struct stat *st)
{
	unsigned int changed = 0;

	if (ce->ce_mtime.sec != htonl(st->st_mtime))
		changed |= MTIME_CHANGED;
	if (ce->ce_ctime.sec != htonl(st->st_ctime))
		changed |= CTIME_CHANGED;

#ifdef NSEC
	/*
	 * nsec seems unreliable - not all filesystems support it, so
	 * as long as it is in the inode cache you get right nsec
	 * but after it gets flushed, you get zero nsec.
	 */
	if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
		changed |= MTIME_CHANGED;
	if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
		changed |= CTIME_CHANGED;
#endif	

	if (ce->ce_uid != htonl(st->st_uid) ||
	    ce->ce_gid != htonl(st->st_gid))
		changed |= OWNER_CHANGED;
	/* We consider only the owner x bit to be relevant for "mode changes" */
	if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
		changed |= MODE_CHANGED;
	if (ce->ce_dev != htonl(st->st_dev) ||
	    ce->ce_ino != htonl(st->st_ino))
		changed |= INODE_CHANGED;
	if (ce->ce_size != htonl(st->st_size))
		changed |= DATA_CHANGED;
	return changed;
}

int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
{
	int len1 = flags1 & CE_NAMEMASK;
	int len2 = flags2 & CE_NAMEMASK;
	int len = len1 < len2 ? len1 : len2;
	int cmp;

	cmp = memcmp(name1, name2, len);
	if (cmp)
		return cmp;
	if (len1 < len2)
		return -1;
	if (len1 > len2)
		return 1;
	if (flags1 < flags2)
		return -1;
	if (flags1 > flags2)
		return 1;
	return 0;
}

int cache_name_pos(const char *name, int namelen)
{
	int first, last;

	first = 0;
	last = active_nr;
	while (last > first) {
		int next = (last + first) >> 1;
		struct cache_entry *ce = active_cache[next];
		int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
		if (!cmp)
			return next;
		if (cmp < 0) {
			last = next;
			continue;
		}
		first = next+1;
	}
	return -first-1;
}

/* Remove entry, return true if there are more entries to go.. */
int remove_entry_at(int pos)
{
	active_nr--;
	if (pos >= active_nr)
		return 0;
	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
	return 1;
}

int remove_file_from_cache(char *path)
{
	int pos = cache_name_pos(path, strlen(path));
	if (pos < 0)
		pos = -pos-1;
	while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
		remove_entry_at(pos);
	return 0;
}

int same_name(struct cache_entry *a, struct cache_entry *b)
{
	int len = ce_namelen(a);
	return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
}

int add_cache_entry(struct cache_entry *ce, int ok_to_add)
{
	int pos;

	pos = cache_name_pos(ce->name, htons(ce->ce_flags));

	/* existing match? Just replace it */
	if (pos >= 0) {
		active_cache[pos] = ce;
		return 0;
	}
	pos = -pos-1;

	/*
	 * Inserting a merged entry ("stage 0") into the index
	 * will always replace all non-merged entries..
	 */
	if (pos < active_nr && ce_stage(ce) == 0) {
		while (same_name(active_cache[pos], ce)) {
			ok_to_add = 1;
			if (!remove_entry_at(pos))
				break;
		}
	}

	if (!ok_to_add)
		return -1;

	/* Make sure the array is big enough .. */
	if (active_nr == active_alloc) {
		active_alloc = alloc_nr(active_alloc);
		active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
	}

	/* Add it in.. */
	active_nr++;
	if (active_nr > pos)
		memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	active_cache[pos] = ce;
	return 0;
}

static int verify_hdr(struct cache_header *hdr, unsigned long size)
{
	SHA_CTX c;
	unsigned char sha1[20];

	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
		return error("bad signature");
	if (hdr->hdr_version != htonl(2))
		return error("bad index version");
	SHA1_Init(&c);
	SHA1_Update(&c, hdr, size - 20);
	SHA1_Final(sha1, &c);
	if (memcmp(sha1, (void *)hdr + size - 20, 20))
		return error("bad index file sha1 signature");
	return 0;
}

int read_cache(void)
{
	int fd, i;
	struct stat st;
	unsigned long size, offset;
	void *map;
	struct cache_header *hdr;

	errno = EBUSY;
	if (active_cache)
		return error("more than one cachefile");
	errno = ENOENT;
	sha1_file_directory = getenv(DB_ENVIRONMENT);
	if (!sha1_file_directory)
		sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
	if (access(sha1_file_directory, X_OK) < 0)
		return error("no access to SHA1 file directory");
	fd = open(get_index_file(), O_RDONLY);
	if (fd < 0)
		return (errno == ENOENT) ? 0 : error("open failed");

	size = 0; // avoid gcc warning
	map = (void *)-1;
	if (!fstat(fd, &st)) {
		size = st.st_size;
		errno = EINVAL;
		if (size >= sizeof(struct cache_header) + 20)
			map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
	}
	close(fd);
	if (-1 == (int)(long)map)
		return error("mmap failed");

	hdr = map;
	if (verify_hdr(hdr, size) < 0)
		goto unmap;

	active_nr = ntohl(hdr->hdr_entries);
	active_alloc = alloc_nr(active_nr);
	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));

	offset = sizeof(*hdr);
	for (i = 0; i < active_nr; i++) {
		struct cache_entry *ce = map + offset;
		offset = offset + ce_size(ce);
		active_cache[i] = ce;
	}
	return active_nr;

unmap:
	munmap(map, size);
	errno = EINVAL;
	return error("verify header failed");
}

#define WRITE_BUFFER_SIZE 8192
static char write_buffer[WRITE_BUFFER_SIZE];
static unsigned long write_buffer_len;

static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
{
	while (len) {
		unsigned int buffered = write_buffer_len;
		unsigned int partial = WRITE_BUFFER_SIZE - buffered;
		if (partial > len)
			partial = len;
		memcpy(write_buffer + buffered, data, partial);
		buffered += partial;
		if (buffered == WRITE_BUFFER_SIZE) {
			SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
			if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
				return -1;
			buffered = 0;
		}
		write_buffer_len = buffered;
		len -= partial;
		data += partial;
 	}
 	return 0;
}

static int ce_flush(SHA_CTX *context, int fd)
{
	unsigned int left = write_buffer_len;

	if (left) {
		write_buffer_len = 0;
		SHA1_Update(context, write_buffer, left);
	}

	/* Append the SHA1 signature at the end */
	SHA1_Final(write_buffer + left, context);
	left += 20;
	if (write(fd, write_buffer, left) != left)
		return -1;
	return 0;
}

int write_cache(int newfd, struct cache_entry **cache, int entries)
{
	SHA_CTX c;
	struct cache_header hdr;
	int i;

	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
	hdr.hdr_version = htonl(2);
	hdr.hdr_entries = htonl(entries);

	SHA1_Init(&c);
	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
		return -1;

	for (i = 0; i < entries; i++) {
		struct cache_entry *ce = cache[i];
		if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
			return -1;
	}
	return ce_flush(&c, newfd);
}
Commit	Line	Data
8bc9a0c7 LT	1	/*
	2	* GIT - The information manager from hell
	3	*
	4	* Copyright (C) Linus Torvalds, 2005
	5	*/
2de381f9	6	#include <stdarg.h>
e83c5163 LT	7	#include "cache.h"
e83c5163 LT	8
e83c5163 LT	9	struct cache_entry **active_cache = NULL;
	10	unsigned int active_nr = 0, active_alloc = 0;
	11
734aab75 LT	12	int cache_match_stat(struct cache_entry ce, struct stat st)
	13	{
	14	unsigned int changed = 0;
	15
ccc4feb5	16	if (ce->ce_mtime.sec != htonl(st->st_mtime))
734aab75	17	changed \|= MTIME_CHANGED;
ccc4feb5 LT	18	if (ce->ce_ctime.sec != htonl(st->st_ctime))
	19	changed \|= CTIME_CHANGED;
	20
bdd4da59	21	#ifdef NSEC
ccc4feb5 LT	22	/*
	23	* nsec seems unreliable - not all filesystems support it, so
	24	* as long as it is in the inode cache you get right nsec
	25	* but after it gets flushed, you get zero nsec.
	26	*/
94dfb7f2	27	if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
ccc4feb5	28	changed \|= MTIME_CHANGED;
94dfb7f2	29	if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
734aab75	30	changed \|= CTIME_CHANGED;
ccc4feb5 LT	31	#endif
	32
	33	if (ce->ce_uid != htonl(st->st_uid) \|\|
	34	ce->ce_gid != htonl(st->st_gid))
734aab75	35	changed \|= OWNER_CHANGED;
e4479470	36	/* We consider only the owner x bit to be relevant for "mode changes" */
e8871e88	37	if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
734aab75	38	changed \|= MODE_CHANGED;
ccc4feb5 LT	39	if (ce->ce_dev != htonl(st->st_dev) \|\|
ccc4feb5 LT	40	ce->ce_ino != htonl(st->st_ino))
734aab75	41	changed \|= INODE_CHANGED;
ccc4feb5	42	if (ce->ce_size != htonl(st->st_size))
734aab75 LT	43	changed \|= DATA_CHANGED;
	44	return changed;
	45	}
	46
95fd5bf8	47	int cache_name_compare(const char name1, int flags1, const char name2, int flags2)
eb38c22f	48	{
95fd5bf8 LT	49	int len1 = flags1 & CE_NAMEMASK;
95fd5bf8 LT	50	int len2 = flags2 & CE_NAMEMASK;
eb38c22f LT	51	int len = len1 < len2 ? len1 : len2;
	52	int cmp;
	53
	54	cmp = memcmp(name1, name2, len);
	55	if (cmp)
	56	return cmp;
	57	if (len1 < len2)
	58	return -1;
	59	if (len1 > len2)
	60	return 1;
95fd5bf8 LT	61	if (flags1 < flags2)
	62	return -1;
	63	if (flags1 > flags2)
	64	return 1;
eb38c22f LT	65	return 0;
	66	}
	67
	68	int cache_name_pos(const char *name, int namelen)
	69	{
	70	int first, last;
	71
	72	first = 0;
	73	last = active_nr;
	74	while (last > first) {
	75	int next = (last + first) >> 1;
	76	struct cache_entry *ce = active_cache[next];
95fd5bf8	77	int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
eb38c22f	78	if (!cmp)
76e7f4ec	79	return next;
eb38c22f LT	80	if (cmp < 0) {
	81	last = next;
	82	continue;
	83	}
	84	first = next+1;
	85	}
76e7f4ec	86	return -first-1;
eb38c22f LT	87	}
eb38c22f LT	88
7b937ca3	89	/* Remove entry, return true if there are more entries to go.. */
b5af9107	90	int remove_entry_at(int pos)
7b937ca3 LT	91	{
	92	active_nr--;
	93	if (pos >= active_nr)
	94	return 0;
	95	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
	96	return 1;
	97	}
	98
197ee8c9 LT	99	int remove_file_from_cache(char *path)
	100	{
	101	int pos = cache_name_pos(path, strlen(path));
c4e3cca1 JH	102	if (pos < 0)
	103	pos = -pos-1;
	104	while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
7b937ca3	105	remove_entry_at(pos);
197ee8c9 LT	106	return 0;
	107	}
	108
b5af9107	109	int same_name(struct cache_entry a, struct cache_entry b)
7b937ca3 LT	110	{
	111	int len = ce_namelen(a);
	112	return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
	113	}
	114
121481ab	115	int add_cache_entry(struct cache_entry *ce, int ok_to_add)
197ee8c9 LT	116	{
	117	int pos;
	118
95fd5bf8	119	pos = cache_name_pos(ce->name, htons(ce->ce_flags));
197ee8c9 LT	120
197ee8c9 LT	121	/* existing match? Just replace it */
76e7f4ec LT	122	if (pos >= 0) {
76e7f4ec LT	123	active_cache[pos] = ce;
197ee8c9 LT	124	return 0;
197ee8c9 LT	125	}
76e7f4ec	126	pos = -pos-1;
197ee8c9	127
7b937ca3 LT	128	/*
	129	* Inserting a merged entry ("stage 0") into the index
	130	* will always replace all non-merged entries..
	131	*/
	132	if (pos < active_nr && ce_stage(ce) == 0) {
	133	while (same_name(active_cache[pos], ce)) {
	134	ok_to_add = 1;
7b937ca3 LT	135	if (!remove_entry_at(pos))
	136	break;
	137	}
	138	}
	139
121481ab LT	140	if (!ok_to_add)
	141	return -1;
	142
197ee8c9 LT	143	/* Make sure the array is big enough .. */
	144	if (active_nr == active_alloc) {
	145	active_alloc = alloc_nr(active_alloc);
812666c8	146	active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
197ee8c9 LT	147	}
	148
	149	/* Add it in.. */
	150	active_nr++;
	151	if (active_nr > pos)
	152	memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	153	active_cache[pos] = ce;
	154	return 0;
	155	}
	156
e83c5163 LT	157	static int verify_hdr(struct cache_header *hdr, unsigned long size)
	158	{
	159	SHA_CTX c;
	160	unsigned char sha1[20];
	161
ccc4feb5	162	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
e83c5163	163	return error("bad signature");
ca9be054 LT	164	if (hdr->hdr_version != htonl(2))
ca9be054 LT	165	return error("bad index version");
e83c5163	166	SHA1_Init(&c);
ca9be054	167	SHA1_Update(&c, hdr, size - 20);
e83c5163	168	SHA1_Final(sha1, &c);
ca9be054 LT	169	if (memcmp(sha1, (void *)hdr + size - 20, 20))
ca9be054 LT	170	return error("bad index file sha1 signature");
e83c5163 LT	171	return 0;
	172	}
	173
	174	int read_cache(void)
	175	{
	176	int fd, i;
	177	struct stat st;
	178	unsigned long size, offset;
	179	void *map;
	180	struct cache_header *hdr;
	181
	182	errno = EBUSY;
	183	if (active_cache)
	184	return error("more than one cachefile");
	185	errno = ENOENT;
	186	sha1_file_directory = getenv(DB_ENVIRONMENT);
	187	if (!sha1_file_directory)
	188	sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
	189	if (access(sha1_file_directory, X_OK) < 0)
	190	return error("no access to SHA1 file directory");
bb233d69	191	fd = open(get_index_file(), O_RDONLY);
e83c5163 LT	192	if (fd < 0)
	193	return (errno == ENOENT) ? 0 : error("open failed");
	194
19b2860c	195	size = 0; // avoid gcc warning
e83c5163 LT	196	map = (void *)-1;
e83c5163 LT	197	if (!fstat(fd, &st)) {
e83c5163 LT	198	size = st.st_size;
e83c5163 LT	199	errno = EINVAL;
ca9be054	200	if (size >= sizeof(struct cache_header) + 20)
520fc241	201	map = mmap(NULL, size, PROT_READ \| PROT_WRITE, MAP_PRIVATE, fd, 0);
e83c5163 LT	202	}
	203	close(fd);
	204	if (-1 == (int)(long)map)
	205	return error("mmap failed");
	206
	207	hdr = map;
	208	if (verify_hdr(hdr, size) < 0)
	209	goto unmap;
	210
ccc4feb5	211	active_nr = ntohl(hdr->hdr_entries);
e83c5163 LT	212	active_alloc = alloc_nr(active_nr);
	213	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
	214
	215	offset = sizeof(*hdr);
ccc4feb5	216	for (i = 0; i < active_nr; i++) {
e83c5163 LT	217	struct cache_entry *ce = map + offset;
	218	offset = offset + ce_size(ce);
	219	active_cache[i] = ce;
	220	}
	221	return active_nr;
	222
	223	unmap:
	224	munmap(map, size);
	225	errno = EINVAL;
	226	return error("verify header failed");
	227	}
	228
4990aadc LT	229	#define WRITE_BUFFER_SIZE 8192
	230	static char write_buffer[WRITE_BUFFER_SIZE];
	231	static unsigned long write_buffer_len;
	232
ca9be054	233	static int ce_write(SHA_CTX context, int fd, void data, unsigned int len)
4990aadc LT	234	{
	235	while (len) {
	236	unsigned int buffered = write_buffer_len;
	237	unsigned int partial = WRITE_BUFFER_SIZE - buffered;
	238	if (partial > len)
	239	partial = len;
	240	memcpy(write_buffer + buffered, data, partial);
	241	buffered += partial;
	242	if (buffered == WRITE_BUFFER_SIZE) {
ca9be054	243	SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
4990aadc LT	244	if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
	245	return -1;
	246	buffered = 0;
	247	}
	248	write_buffer_len = buffered;
	249	len -= partial;
	250	data += partial;
	251	}
	252	return 0;
	253	}
	254
ca9be054	255	static int ce_flush(SHA_CTX *context, int fd)
4990aadc LT	256	{
4990aadc LT	257	unsigned int left = write_buffer_len;
ca9be054	258
4990aadc LT	259	if (left) {
4990aadc LT	260	write_buffer_len = 0;
ca9be054	261	SHA1_Update(context, write_buffer, left);
4990aadc	262	}
ca9be054 LT	263
	264	/* Append the SHA1 signature at the end */
	265	SHA1_Final(write_buffer + left, context);
	266	left += 20;
	267	if (write(fd, write_buffer, left) != left)
	268	return -1;
4990aadc LT	269	return 0;
	270	}
	271
197ee8c9 LT	272	int write_cache(int newfd, struct cache_entry **cache, int entries)
	273	{
	274	SHA_CTX c;
	275	struct cache_header hdr;
	276	int i;
	277
ccc4feb5	278	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
ca9be054	279	hdr.hdr_version = htonl(2);
ccc4feb5	280	hdr.hdr_entries = htonl(entries);
197ee8c9 LT	281
197ee8c9 LT	282	SHA1_Init(&c);
ca9be054	283	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
197ee8c9 LT	284	return -1;
	285
	286	for (i = 0; i < entries; i++) {
	287	struct cache_entry *ce = cache[i];
ca9be054	288	if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
197ee8c9 LT	289	return -1;
197ee8c9 LT	290	}
ca9be054	291	return ce_flush(&c, newfd);
197ee8c9	292	}