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

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

const char *sha1_file_directory = NULL;
struct cache_entry **active_cache = NULL;
unsigned int active_nr = 0, active_alloc = 0;

void usage(const char *err, ...)
{
	va_list args;

	va_start(args, err);
	vfprintf(stderr, err, args);
	va_end(args);
	exit(1);
}

static unsigned hexval(char c)
{
	if (c >= '0' && c <= '9')
		return c - '0';
	if (c >= 'a' && c <= 'f')
		return c - 'a' + 10;
	if (c >= 'A' && c <= 'F')
		return c - 'A' + 10;
	return ~0;
}

int get_sha1_hex(const char *hex, unsigned char *sha1)
{
	int i;
	for (i = 0; i < 20; i++) {
		unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
		if (val & ~0xff)
			return -1;
		*sha1++ = val;
		hex += 2;
	}
	return 0;
}

char * sha1_to_hex(const unsigned char *sha1)
{
	static char buffer[50];
	static const char hex[] = "0123456789abcdef";
	char *buf = buffer;
	int i;

	for (i = 0; i < 20; i++) {
		unsigned int val = *sha1++;
		*buf++ = hex[val >> 4];
		*buf++ = hex[val & 0xf];
	}
	return buffer;
}

/*
 * NOTE! This returns a statically allocated buffer, so you have to be
 * careful about using it. Do a "strdup()" if you need to save the
 * filename.
 */
char *sha1_file_name(const unsigned char *sha1)
{
	int i;
	static char *name, *base;

	if (!base) {
		char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
		int len = strlen(sha1_file_directory);
		base = malloc(len + 60);
		memcpy(base, sha1_file_directory, len);
		memset(base+len, 0, 60);
		base[len] = '/';
		base[len+3] = '/';
		name = base + len + 1;
	}
	for (i = 0; i < 20; i++) {
		static char hex[] = "0123456789abcdef";
		unsigned int val = sha1[i];
		char *pos = name + i*2 + (i > 0);
		*pos++ = hex[val >> 4];
		*pos = hex[val & 0xf];
	}
	return base;
}

int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
{
	unsigned char real_sha1[20];
	SHA_CTX c;

	SHA1_Init(&c);
	SHA1_Update(&c, map, size);
	SHA1_Final(real_sha1, &c);
	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
}

void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
{
	char *filename = sha1_file_name(sha1);
	int fd = open(filename, O_RDONLY);
	struct stat st;
	void *map;

	if (fd < 0) {
		perror(filename);
		return NULL;
	}
	if (fstat(fd, &st) < 0) {
		close(fd);  
		return NULL;
	}
	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);
	if (-1 == (int)(long)map)
		return NULL;
	*size = st.st_size;
	return map;
}

void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
{
	int ret, bytes;
	z_stream stream;
	char buffer[8192];
	char *buf;

	/* Get the data stream */
	memset(&stream, 0, sizeof(stream));
	stream.next_in = map;
	stream.avail_in = mapsize;
	stream.next_out = buffer;
	stream.avail_out = sizeof(buffer);

	inflateInit(&stream);
	ret = inflate(&stream, 0);
	if (sscanf(buffer, "%10s %lu", type, size) != 2)
		return NULL;

	bytes = strlen(buffer) + 1;
	buf = malloc(*size);
	if (!buf)
		return NULL;

	memcpy(buf, buffer + bytes, stream.total_out - bytes);
	bytes = stream.total_out - bytes;
	if (bytes < *size && ret == Z_OK) {
		stream.next_out = buf + bytes;
		stream.avail_out = *size - bytes;
		while (inflate(&stream, Z_FINISH) == Z_OK)
			/* nothing */;
	}
	inflateEnd(&stream);
	return buf;
}

void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
{
	unsigned long mapsize;
	void *map, *buf;

	map = map_sha1_file(sha1, &mapsize);
	if (map) {
		buf = unpack_sha1_file(map, mapsize, type, size);
		munmap(map, mapsize);
		return buf;
	}
	return NULL;
}

int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
{
	int size;
	char *compressed;
	z_stream stream;
	unsigned char sha1[20];
	SHA_CTX c;

	/* Set it up */
	memset(&stream, 0, sizeof(stream));
	deflateInit(&stream, Z_BEST_COMPRESSION);
	size = deflateBound(&stream, len);
	compressed = malloc(size);

	/* Compress it */
	stream.next_in = buf;
	stream.avail_in = len;
	stream.next_out = compressed;
	stream.avail_out = size;
	while (deflate(&stream, Z_FINISH) == Z_OK)
		/* nothing */;
	deflateEnd(&stream);
	size = stream.total_out;

	/* Sha1.. */
	SHA1_Init(&c);
	SHA1_Update(&c, compressed, size);
	SHA1_Final(sha1, &c);

	if (write_sha1_buffer(sha1, compressed, size) < 0)
		return -1;
	if (returnsha1)
		memcpy(returnsha1, sha1, 20);
	return 0;
}

int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
{
	char *filename = sha1_file_name(sha1);
	int fd;

	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
	if (fd < 0)
		return (errno == EEXIST) ? 0 : -1;
	write(fd, buf, size);
	close(fd);
	return 0;
}

static int error(const char * string)
{
	fprintf(stderr, "error: %s\n", string);
	return -1;
}

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

	if (ce->mtime.sec  != (unsigned int)st->st_mtim.tv_sec ||
	    ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec)
		changed |= MTIME_CHANGED;
	if (ce->ctime.sec  != (unsigned int)st->st_ctim.tv_sec ||
	    ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec)
		changed |= CTIME_CHANGED;
	if (ce->st_uid != (unsigned int)st->st_uid ||
	    ce->st_gid != (unsigned int)st->st_gid)
		changed |= OWNER_CHANGED;
	if (ce->st_mode != (unsigned int)st->st_mode)
		changed |= MODE_CHANGED;
	if (ce->st_dev != (unsigned int)st->st_dev ||
	    ce->st_ino != (unsigned int)st->st_ino)
		changed |= INODE_CHANGED;
	if (ce->st_size != (unsigned int)st->st_size)
		changed |= DATA_CHANGED;
	return changed;
}

int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
{
	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;
	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, ce->namelen);
		if (!cmp)
			return -next-1;
		if (cmp < 0) {
			last = next;
			continue;
		}
		first = next+1;
	}
	return first;
}

int remove_file_from_cache(char *path)
{
	int pos = cache_name_pos(path, strlen(path));
	if (pos < 0) {
		pos = -pos-1;
		active_nr--;
		if (pos < active_nr)
			memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos - 1) * sizeof(struct cache_entry *));
	}
	return 0;
}

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

	pos = cache_name_pos(ce->name, ce->namelen);

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

	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 = realloc(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->signature != CACHE_SIGNATURE)
		return error("bad signature");
	if (hdr->version != 1)
		return error("bad version");
	SHA1_Init(&c);
	SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
	SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
	SHA1_Final(sha1, &c);
	if (memcmp(sha1, hdr->sha1, 20))
		return error("bad header sha1");
	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(".dircache/index", 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))
			map = mmap(NULL, size, PROT_READ, 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 = hdr->entries;
	active_alloc = alloc_nr(active_nr);
	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));

	offset = sizeof(*hdr);
	for (i = 0; i < hdr->entries; 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");
}

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

	hdr.signature = CACHE_SIGNATURE;
	hdr.version = 1;
	hdr.entries = entries;

	SHA1_Init(&c);
	SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
	for (i = 0; i < entries; i++) {
		struct cache_entry *ce = cache[i];
		int size = ce_size(ce);
		SHA1_Update(&c, ce, size);
	}
	SHA1_Final(hdr.sha1, &c);

	if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
		return -1;

	for (i = 0; i < entries; i++) {
		struct cache_entry *ce = cache[i];
		int size = ce_size(ce);
		if (write(newfd, ce, size) != size)
			return -1;
	}
	return 0;
}
Commit	Line	Data
8bc9a0c7 LT	1	/*
	2	* GIT - The information manager from hell
	3	*
	4	* Copyright (C) Linus Torvalds, 2005
	5	*/
e83c5163 LT	6	#include "cache.h"
	7
	8	const char *sha1_file_directory = NULL;
	9	struct cache_entry **active_cache = NULL;
	10	unsigned int active_nr = 0, active_alloc = 0;
	11
121481ab	12	void usage(const char *err, ...)
e83c5163	13	{
121481ab LT	14	va_list args;
	15
	16	va_start(args, err);
	17	vfprintf(stderr, err, args);
	18	va_end(args);
e83c5163 LT	19	exit(1);
	20	}
	21
	22	static unsigned hexval(char c)
	23	{
	24	if (c >= '0' && c <= '9')
	25	return c - '0';
	26	if (c >= 'a' && c <= 'f')
	27	return c - 'a' + 10;
	28	if (c >= 'A' && c <= 'F')
	29	return c - 'A' + 10;
	30	return ~0;
	31	}
	32
197ee8c9	33	int get_sha1_hex(const char hex, unsigned char sha1)
e83c5163 LT	34	{
	35	int i;
	36	for (i = 0; i < 20; i++) {
	37	unsigned int val = (hexval(hex[0]) << 4) \| hexval(hex[1]);
	38	if (val & ~0xff)
	39	return -1;
	40	*sha1++ = val;
	41	hex += 2;
	42	}
	43	return 0;
	44	}
	45
197ee8c9	46	char * sha1_to_hex(const unsigned char *sha1)
e83c5163 LT	47	{
	48	static char buffer[50];
	49	static const char hex[] = "0123456789abcdef";
	50	char *buf = buffer;
	51	int i;
	52
	53	for (i = 0; i < 20; i++) {
	54	unsigned int val = *sha1++;
	55	*buf++ = hex[val >> 4];
	56	*buf++ = hex[val & 0xf];
	57	}
	58	return buffer;
	59	}
	60
	61	/*
	62	* NOTE! This returns a statically allocated buffer, so you have to be
	63	* careful about using it. Do a "strdup()" if you need to save the
	64	* filename.
	65	*/
73134b6d	66	char sha1_file_name(const unsigned char sha1)
e83c5163 LT	67	{
	68	int i;
	69	static char name, base;
	70
	71	if (!base) {
	72	char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
	73	int len = strlen(sha1_file_directory);
	74	base = malloc(len + 60);
	75	memcpy(base, sha1_file_directory, len);
	76	memset(base+len, 0, 60);
	77	base[len] = '/';
	78	base[len+3] = '/';
	79	name = base + len + 1;
	80	}
	81	for (i = 0; i < 20; i++) {
	82	static char hex[] = "0123456789abcdef";
	83	unsigned int val = sha1[i];
	84	char pos = name + i2 + (i > 0);
	85	*pos++ = hex[val >> 4];
	86	*pos = hex[val & 0xf];
	87	}
	88	return base;
	89	}
	90
2ade9340 LT	91	int check_sha1_signature(unsigned char sha1, void map, unsigned long size)
	92	{
	93	unsigned char real_sha1[20];
	94	SHA_CTX c;
	95
	96	SHA1_Init(&c);
	97	SHA1_Update(&c, map, size);
	98	SHA1_Final(real_sha1, &c);
	99	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
	100	}
	101
73134b6d	102	void map_sha1_file(const unsigned char sha1, unsigned long *size)
e83c5163	103	{
e83c5163	104	char *filename = sha1_file_name(sha1);
24778e33 LT	105	int fd = open(filename, O_RDONLY);
	106	struct stat st;
	107	void *map;
e83c5163	108
e83c5163 LT	109	if (fd < 0) {
	110	perror(filename);
	111	return NULL;
	112	}
	113	if (fstat(fd, &st) < 0) {
24778e33	114	close(fd);
e83c5163 LT	115	return NULL;
	116	}
	117	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	118	close(fd);
	119	if (-1 == (int)(long)map)
	120	return NULL;
24778e33 LT	121	*size = st.st_size;
	122	return map;
	123	}
	124
	125	void * unpack_sha1_file(void map, unsigned long mapsize, char type, unsigned long *size)
	126	{
	127	int ret, bytes;
	128	z_stream stream;
	129	char buffer[8192];
	130	char *buf;
e83c5163 LT	131
	132	/* Get the data stream */
	133	memset(&stream, 0, sizeof(stream));
	134	stream.next_in = map;
24778e33	135	stream.avail_in = mapsize;
e83c5163 LT	136	stream.next_out = buffer;
	137	stream.avail_out = sizeof(buffer);
	138
	139	inflateInit(&stream);
	140	ret = inflate(&stream, 0);
	141	if (sscanf(buffer, "%10s %lu", type, size) != 2)
	142	return NULL;
24778e33	143
e83c5163 LT	144	bytes = strlen(buffer) + 1;
	145	buf = malloc(*size);
	146	if (!buf)
	147	return NULL;
	148
	149	memcpy(buf, buffer + bytes, stream.total_out - bytes);
	150	bytes = stream.total_out - bytes;
	151	if (bytes < *size && ret == Z_OK) {
	152	stream.next_out = buf + bytes;
	153	stream.avail_out = *size - bytes;
	154	while (inflate(&stream, Z_FINISH) == Z_OK)
	155	/* nothing */;
	156	}
	157	inflateEnd(&stream);
	158	return buf;
	159	}
	160
73134b6d	161	void * read_sha1_file(const unsigned char sha1, char type, unsigned long *size)
24778e33 LT	162	{
	163	unsigned long mapsize;
	164	void map, buf;
	165
	166	map = map_sha1_file(sha1, &mapsize);
	167	if (map) {
	168	buf = unpack_sha1_file(map, mapsize, type, size);
	169	munmap(map, mapsize);
	170	return buf;
	171	}
	172	return NULL;
	173	}
	174
d6d3f9d0	175	int write_sha1_file(char buf, unsigned len, unsigned char returnsha1)
e83c5163 LT	176	{
	177	int size;
	178	char *compressed;
	179	z_stream stream;
	180	unsigned char sha1[20];
	181	SHA_CTX c;
	182
	183	/* Set it up */
	184	memset(&stream, 0, sizeof(stream));
	185	deflateInit(&stream, Z_BEST_COMPRESSION);
	186	size = deflateBound(&stream, len);
	187	compressed = malloc(size);
	188
	189	/* Compress it */
	190	stream.next_in = buf;
	191	stream.avail_in = len;
	192	stream.next_out = compressed;
	193	stream.avail_out = size;
	194	while (deflate(&stream, Z_FINISH) == Z_OK)
	195	/* nothing */;
	196	deflateEnd(&stream);
	197	size = stream.total_out;
	198
	199	/* Sha1.. */
	200	SHA1_Init(&c);
	201	SHA1_Update(&c, compressed, size);
	202	SHA1_Final(sha1, &c);
	203
	204	if (write_sha1_buffer(sha1, compressed, size) < 0)
	205	return -1;
d6d3f9d0 LT	206	if (returnsha1)
d6d3f9d0 LT	207	memcpy(returnsha1, sha1, 20);
e83c5163 LT	208	return 0;
	209	}
	210
73134b6d	211	int write_sha1_buffer(const unsigned char sha1, void buf, unsigned int size)
e83c5163 LT	212	{
e83c5163 LT	213	char *filename = sha1_file_name(sha1);
19b2860c	214	int fd;
e83c5163 LT	215
	216	fd = open(filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	217	if (fd < 0)
	218	return (errno == EEXIST) ? 0 : -1;
	219	write(fd, buf, size);
	220	close(fd);
	221	return 0;
	222	}
	223
	224	static int error(const char * string)
	225	{
	226	fprintf(stderr, "error: %s\n", string);
	227	return -1;
	228	}
	229
734aab75 LT	230	int cache_match_stat(struct cache_entry ce, struct stat st)
	231	{
	232	unsigned int changed = 0;
	233
	234	if (ce->mtime.sec != (unsigned int)st->st_mtim.tv_sec \|\|
	235	ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec)
	236	changed \|= MTIME_CHANGED;
	237	if (ce->ctime.sec != (unsigned int)st->st_ctim.tv_sec \|\|
	238	ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec)
	239	changed \|= CTIME_CHANGED;
	240	if (ce->st_uid != (unsigned int)st->st_uid \|\|
	241	ce->st_gid != (unsigned int)st->st_gid)
	242	changed \|= OWNER_CHANGED;
	243	if (ce->st_mode != (unsigned int)st->st_mode)
	244	changed \|= MODE_CHANGED;
	245	if (ce->st_dev != (unsigned int)st->st_dev \|\|
	246	ce->st_ino != (unsigned int)st->st_ino)
	247	changed \|= INODE_CHANGED;
	248	if (ce->st_size != (unsigned int)st->st_size)
	249	changed \|= DATA_CHANGED;
	250	return changed;
	251	}
	252
79517a06	253	int cache_name_compare(const char name1, int len1, const char name2, int len2)
eb38c22f LT	254	{
	255	int len = len1 < len2 ? len1 : len2;
	256	int cmp;
	257
	258	cmp = memcmp(name1, name2, len);
	259	if (cmp)
	260	return cmp;
	261	if (len1 < len2)
	262	return -1;
	263	if (len1 > len2)
	264	return 1;
	265	return 0;
	266	}
	267
	268	int cache_name_pos(const char *name, int namelen)
	269	{
	270	int first, last;
	271
	272	first = 0;
	273	last = active_nr;
	274	while (last > first) {
	275	int next = (last + first) >> 1;
	276	struct cache_entry *ce = active_cache[next];
	277	int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
	278	if (!cmp)
	279	return -next-1;
	280	if (cmp < 0) {
	281	last = next;
	282	continue;
	283	}
	284	first = next+1;
	285	}
	286	return first;
	287	}
	288
197ee8c9 LT	289	int remove_file_from_cache(char *path)
	290	{
	291	int pos = cache_name_pos(path, strlen(path));
	292	if (pos < 0) {
	293	pos = -pos-1;
	294	active_nr--;
	295	if (pos < active_nr)
	296	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos - 1) * sizeof(struct cache_entry *));
	297	}
	298	return 0;
	299	}
	300
121481ab	301	int add_cache_entry(struct cache_entry *ce, int ok_to_add)
197ee8c9 LT	302	{
	303	int pos;
	304
	305	pos = cache_name_pos(ce->name, ce->namelen);
	306
	307	/* existing match? Just replace it */
	308	if (pos < 0) {
	309	active_cache[-pos-1] = ce;
	310	return 0;
	311	}
	312
121481ab LT	313	if (!ok_to_add)
	314	return -1;
	315
197ee8c9 LT	316	/* Make sure the array is big enough .. */
	317	if (active_nr == active_alloc) {
	318	active_alloc = alloc_nr(active_alloc);
	319	active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
	320	}
	321
	322	/* Add it in.. */
	323	active_nr++;
	324	if (active_nr > pos)
	325	memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	326	active_cache[pos] = ce;
	327	return 0;
	328	}
	329
e83c5163 LT	330	static int verify_hdr(struct cache_header *hdr, unsigned long size)
	331	{
	332	SHA_CTX c;
	333	unsigned char sha1[20];
	334
	335	if (hdr->signature != CACHE_SIGNATURE)
	336	return error("bad signature");
	337	if (hdr->version != 1)
	338	return error("bad version");
	339	SHA1_Init(&c);
	340	SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
	341	SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
	342	SHA1_Final(sha1, &c);
	343	if (memcmp(sha1, hdr->sha1, 20))
	344	return error("bad header sha1");
	345	return 0;
	346	}
	347
	348	int read_cache(void)
	349	{
	350	int fd, i;
	351	struct stat st;
	352	unsigned long size, offset;
	353	void *map;
	354	struct cache_header *hdr;
	355
	356	errno = EBUSY;
	357	if (active_cache)
	358	return error("more than one cachefile");
	359	errno = ENOENT;
	360	sha1_file_directory = getenv(DB_ENVIRONMENT);
	361	if (!sha1_file_directory)
	362	sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
	363	if (access(sha1_file_directory, X_OK) < 0)
	364	return error("no access to SHA1 file directory");
	365	fd = open(".dircache/index", O_RDONLY);
	366	if (fd < 0)
	367	return (errno == ENOENT) ? 0 : error("open failed");
	368
19b2860c	369	size = 0; // avoid gcc warning
e83c5163 LT	370	map = (void *)-1;
e83c5163 LT	371	if (!fstat(fd, &st)) {
e83c5163 LT	372	size = st.st_size;
e83c5163 LT	373	errno = EINVAL;
59c1e249	374	if (size >= sizeof(struct cache_header))
e83c5163 LT	375	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	376	}
	377	close(fd);
	378	if (-1 == (int)(long)map)
	379	return error("mmap failed");
	380
	381	hdr = map;
	382	if (verify_hdr(hdr, size) < 0)
	383	goto unmap;
	384
	385	active_nr = hdr->entries;
	386	active_alloc = alloc_nr(active_nr);
	387	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
	388
	389	offset = sizeof(*hdr);
	390	for (i = 0; i < hdr->entries; i++) {
	391	struct cache_entry *ce = map + offset;
	392	offset = offset + ce_size(ce);
	393	active_cache[i] = ce;
	394	}
	395	return active_nr;
	396
	397	unmap:
	398	munmap(map, size);
	399	errno = EINVAL;
	400	return error("verify header failed");
	401	}
	402
197ee8c9 LT	403	int write_cache(int newfd, struct cache_entry **cache, int entries)
	404	{
	405	SHA_CTX c;
	406	struct cache_header hdr;
	407	int i;
	408
	409	hdr.signature = CACHE_SIGNATURE;
	410	hdr.version = 1;
	411	hdr.entries = entries;
	412
	413	SHA1_Init(&c);
	414	SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
	415	for (i = 0; i < entries; i++) {
	416	struct cache_entry *ce = cache[i];
	417	int size = ce_size(ce);
	418	SHA1_Update(&c, ce, size);
	419	}
	420	SHA1_Final(hdr.sha1, &c);
	421
	422	if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
	423	return -1;
	424
	425	for (i = 0; i < entries; i++) {
	426	struct cache_entry *ce = cache[i];
	427	int size = ce_size(ce);
	428	if (write(newfd, ce, size) != size)
	429	return -1;
	430	}
	431	return 0;
	432	}