[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;

	switch (ntohl(ce->ce_mode) & S_IFMT) {
	case S_IFREG:
		changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
		break;
	case S_IFLNK:
		changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
		break;
	default:
		die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
	}
	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
8ae0a8c5 KS	16	switch (ntohl(ce->ce_mode) & S_IFMT) {
	17	case S_IFREG:
	18	changed \|= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
	19	break;
	20	case S_IFLNK:
	21	changed \|= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
	22	break;
	23	default:
	24	die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
	25	}
ccc4feb5	26	if (ce->ce_mtime.sec != htonl(st->st_mtime))
734aab75	27	changed \|= MTIME_CHANGED;
ccc4feb5 LT	28	if (ce->ce_ctime.sec != htonl(st->st_ctime))
	29	changed \|= CTIME_CHANGED;
	30
bdd4da59	31	#ifdef NSEC
ccc4feb5 LT	32	/*
	33	* nsec seems unreliable - not all filesystems support it, so
	34	* as long as it is in the inode cache you get right nsec
	35	* but after it gets flushed, you get zero nsec.
	36	*/
94dfb7f2	37	if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
ccc4feb5	38	changed \|= MTIME_CHANGED;
94dfb7f2	39	if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
734aab75	40	changed \|= CTIME_CHANGED;
ccc4feb5 LT	41	#endif
	42
	43	if (ce->ce_uid != htonl(st->st_uid) \|\|
	44	ce->ce_gid != htonl(st->st_gid))
734aab75	45	changed \|= OWNER_CHANGED;
e4479470	46	/* We consider only the owner x bit to be relevant for "mode changes" */
e8871e88	47	if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
734aab75	48	changed \|= MODE_CHANGED;
ccc4feb5 LT	49	if (ce->ce_dev != htonl(st->st_dev) \|\|
ccc4feb5 LT	50	ce->ce_ino != htonl(st->st_ino))
734aab75	51	changed \|= INODE_CHANGED;
ccc4feb5	52	if (ce->ce_size != htonl(st->st_size))
734aab75 LT	53	changed \|= DATA_CHANGED;
	54	return changed;
	55	}
	56
95fd5bf8	57	int cache_name_compare(const char name1, int flags1, const char name2, int flags2)
eb38c22f	58	{
95fd5bf8 LT	59	int len1 = flags1 & CE_NAMEMASK;
95fd5bf8 LT	60	int len2 = flags2 & CE_NAMEMASK;
eb38c22f LT	61	int len = len1 < len2 ? len1 : len2;
	62	int cmp;
	63
	64	cmp = memcmp(name1, name2, len);
	65	if (cmp)
	66	return cmp;
	67	if (len1 < len2)
	68	return -1;
	69	if (len1 > len2)
	70	return 1;
95fd5bf8 LT	71	if (flags1 < flags2)
	72	return -1;
	73	if (flags1 > flags2)
	74	return 1;
eb38c22f LT	75	return 0;
	76	}
	77
	78	int cache_name_pos(const char *name, int namelen)
	79	{
	80	int first, last;
	81
	82	first = 0;
	83	last = active_nr;
	84	while (last > first) {
	85	int next = (last + first) >> 1;
	86	struct cache_entry *ce = active_cache[next];
95fd5bf8	87	int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
eb38c22f	88	if (!cmp)
76e7f4ec	89	return next;
eb38c22f LT	90	if (cmp < 0) {
	91	last = next;
	92	continue;
	93	}
	94	first = next+1;
	95	}
76e7f4ec	96	return -first-1;
eb38c22f LT	97	}
eb38c22f LT	98
7b937ca3	99	/* Remove entry, return true if there are more entries to go.. */
b5af9107	100	int remove_entry_at(int pos)
7b937ca3 LT	101	{
	102	active_nr--;
	103	if (pos >= active_nr)
	104	return 0;
	105	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
	106	return 1;
	107	}
	108
197ee8c9 LT	109	int remove_file_from_cache(char *path)
	110	{
	111	int pos = cache_name_pos(path, strlen(path));
c4e3cca1 JH	112	if (pos < 0)
	113	pos = -pos-1;
	114	while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
7b937ca3	115	remove_entry_at(pos);
197ee8c9 LT	116	return 0;
	117	}
	118
b5af9107	119	int same_name(struct cache_entry a, struct cache_entry b)
7b937ca3 LT	120	{
	121	int len = ce_namelen(a);
	122	return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
	123	}
	124
121481ab	125	int add_cache_entry(struct cache_entry *ce, int ok_to_add)
197ee8c9 LT	126	{
	127	int pos;
	128
95fd5bf8	129	pos = cache_name_pos(ce->name, htons(ce->ce_flags));
197ee8c9 LT	130
197ee8c9 LT	131	/* existing match? Just replace it */
76e7f4ec LT	132	if (pos >= 0) {
76e7f4ec LT	133	active_cache[pos] = ce;
197ee8c9 LT	134	return 0;
197ee8c9 LT	135	}
76e7f4ec	136	pos = -pos-1;
197ee8c9	137
7b937ca3 LT	138	/*
	139	* Inserting a merged entry ("stage 0") into the index
	140	* will always replace all non-merged entries..
	141	*/
	142	if (pos < active_nr && ce_stage(ce) == 0) {
	143	while (same_name(active_cache[pos], ce)) {
	144	ok_to_add = 1;
7b937ca3 LT	145	if (!remove_entry_at(pos))
	146	break;
	147	}
	148	}
	149
121481ab LT	150	if (!ok_to_add)
	151	return -1;
	152
197ee8c9 LT	153	/* Make sure the array is big enough .. */
	154	if (active_nr == active_alloc) {
	155	active_alloc = alloc_nr(active_alloc);
812666c8	156	active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
197ee8c9 LT	157	}
	158
	159	/* Add it in.. */
	160	active_nr++;
	161	if (active_nr > pos)
	162	memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	163	active_cache[pos] = ce;
	164	return 0;
	165	}
	166
e83c5163 LT	167	static int verify_hdr(struct cache_header *hdr, unsigned long size)
	168	{
	169	SHA_CTX c;
	170	unsigned char sha1[20];
	171
ccc4feb5	172	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
e83c5163	173	return error("bad signature");
ca9be054 LT	174	if (hdr->hdr_version != htonl(2))
ca9be054 LT	175	return error("bad index version");
e83c5163	176	SHA1_Init(&c);
ca9be054	177	SHA1_Update(&c, hdr, size - 20);
e83c5163	178	SHA1_Final(sha1, &c);
ca9be054 LT	179	if (memcmp(sha1, (void *)hdr + size - 20, 20))
ca9be054 LT	180	return error("bad index file sha1 signature");
e83c5163 LT	181	return 0;
	182	}
	183
	184	int read_cache(void)
	185	{
	186	int fd, i;
	187	struct stat st;
	188	unsigned long size, offset;
	189	void *map;
	190	struct cache_header *hdr;
	191
	192	errno = EBUSY;
	193	if (active_cache)
	194	return error("more than one cachefile");
	195	errno = ENOENT;
	196	sha1_file_directory = getenv(DB_ENVIRONMENT);
	197	if (!sha1_file_directory)
	198	sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
	199	if (access(sha1_file_directory, X_OK) < 0)
	200	return error("no access to SHA1 file directory");
bb233d69	201	fd = open(get_index_file(), O_RDONLY);
e83c5163 LT	202	if (fd < 0)
	203	return (errno == ENOENT) ? 0 : error("open failed");
	204
19b2860c	205	size = 0; // avoid gcc warning
e83c5163 LT	206	map = (void *)-1;
e83c5163 LT	207	if (!fstat(fd, &st)) {
e83c5163 LT	208	size = st.st_size;
e83c5163 LT	209	errno = EINVAL;
ca9be054	210	if (size >= sizeof(struct cache_header) + 20)
520fc241	211	map = mmap(NULL, size, PROT_READ \| PROT_WRITE, MAP_PRIVATE, fd, 0);
e83c5163 LT	212	}
	213	close(fd);
	214	if (-1 == (int)(long)map)
	215	return error("mmap failed");
	216
	217	hdr = map;
	218	if (verify_hdr(hdr, size) < 0)
	219	goto unmap;
	220
ccc4feb5	221	active_nr = ntohl(hdr->hdr_entries);
e83c5163 LT	222	active_alloc = alloc_nr(active_nr);
	223	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
	224
	225	offset = sizeof(*hdr);
ccc4feb5	226	for (i = 0; i < active_nr; i++) {
e83c5163 LT	227	struct cache_entry *ce = map + offset;
	228	offset = offset + ce_size(ce);
	229	active_cache[i] = ce;
	230	}
	231	return active_nr;
	232
	233	unmap:
	234	munmap(map, size);
	235	errno = EINVAL;
	236	return error("verify header failed");
	237	}
	238
4990aadc LT	239	#define WRITE_BUFFER_SIZE 8192
	240	static char write_buffer[WRITE_BUFFER_SIZE];
	241	static unsigned long write_buffer_len;
	242
ca9be054	243	static int ce_write(SHA_CTX context, int fd, void data, unsigned int len)
4990aadc LT	244	{
	245	while (len) {
	246	unsigned int buffered = write_buffer_len;
	247	unsigned int partial = WRITE_BUFFER_SIZE - buffered;
	248	if (partial > len)
	249	partial = len;
	250	memcpy(write_buffer + buffered, data, partial);
	251	buffered += partial;
	252	if (buffered == WRITE_BUFFER_SIZE) {
ca9be054	253	SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
4990aadc LT	254	if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
	255	return -1;
	256	buffered = 0;
	257	}
	258	write_buffer_len = buffered;
	259	len -= partial;
	260	data += partial;
	261	}
	262	return 0;
	263	}
	264
ca9be054	265	static int ce_flush(SHA_CTX *context, int fd)
4990aadc LT	266	{
4990aadc LT	267	unsigned int left = write_buffer_len;
ca9be054	268
4990aadc LT	269	if (left) {
4990aadc LT	270	write_buffer_len = 0;
ca9be054	271	SHA1_Update(context, write_buffer, left);
4990aadc	272	}
ca9be054 LT	273
	274	/* Append the SHA1 signature at the end */
	275	SHA1_Final(write_buffer + left, context);
	276	left += 20;
	277	if (write(fd, write_buffer, left) != left)
	278	return -1;
4990aadc LT	279	return 0;
	280	}
	281
197ee8c9 LT	282	int write_cache(int newfd, struct cache_entry **cache, int entries)
	283	{
	284	SHA_CTX c;
	285	struct cache_header hdr;
	286	int i;
	287
ccc4feb5	288	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
ca9be054	289	hdr.hdr_version = htonl(2);
ccc4feb5	290	hdr.hdr_entries = htonl(entries);
197ee8c9 LT	291
197ee8c9 LT	292	SHA1_Init(&c);
ca9be054	293	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
197ee8c9 LT	294	return -1;
	295
	296	for (i = 0; i < entries; i++) {
	297	struct cache_entry *ce = cache[i];
ca9be054	298	if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
197ee8c9 LT	299	return -1;
197ee8c9 LT	300	}
ca9be054	301	return ce_flush(&c, newfd);
197ee8c9	302	}