[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;
	char string[200];

	va_start(args, err);
	vsnprintf(string, sizeof(string), err, args);
	va_end(args);
	fprintf(stderr, "%s\n", string);
	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;
		if (cmp < 0) {
			last = next;
			continue;
		}
		first = next+1;
	}
	return -first-1;
}

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

	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(".git/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	14	va_list args;
0dcad32a	15	char string[200];
121481ab LT	16
121481ab LT	17	va_start(args, err);
0dcad32a	18	vsnprintf(string, sizeof(string), err, args);
121481ab	19	va_end(args);
0dcad32a	20	fprintf(stderr, "%s\n", string);
e83c5163 LT	21	exit(1);
	22	}
	23
	24	static unsigned hexval(char c)
	25	{
	26	if (c >= '0' && c <= '9')
	27	return c - '0';
	28	if (c >= 'a' && c <= 'f')
	29	return c - 'a' + 10;
	30	if (c >= 'A' && c <= 'F')
	31	return c - 'A' + 10;
	32	return ~0;
	33	}
	34
197ee8c9	35	int get_sha1_hex(const char hex, unsigned char sha1)
e83c5163 LT	36	{
	37	int i;
	38	for (i = 0; i < 20; i++) {
	39	unsigned int val = (hexval(hex[0]) << 4) \| hexval(hex[1]);
	40	if (val & ~0xff)
	41	return -1;
	42	*sha1++ = val;
	43	hex += 2;
	44	}
	45	return 0;
	46	}
	47
197ee8c9	48	char * sha1_to_hex(const unsigned char *sha1)
e83c5163 LT	49	{
	50	static char buffer[50];
	51	static const char hex[] = "0123456789abcdef";
	52	char *buf = buffer;
	53	int i;
	54
	55	for (i = 0; i < 20; i++) {
	56	unsigned int val = *sha1++;
	57	*buf++ = hex[val >> 4];
	58	*buf++ = hex[val & 0xf];
	59	}
	60	return buffer;
	61	}
	62
	63	/*
	64	* NOTE! This returns a statically allocated buffer, so you have to be
	65	* careful about using it. Do a "strdup()" if you need to save the
	66	* filename.
	67	*/
73134b6d	68	char sha1_file_name(const unsigned char sha1)
e83c5163 LT	69	{
	70	int i;
	71	static char name, base;
	72
	73	if (!base) {
	74	char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
	75	int len = strlen(sha1_file_directory);
	76	base = malloc(len + 60);
	77	memcpy(base, sha1_file_directory, len);
	78	memset(base+len, 0, 60);
	79	base[len] = '/';
	80	base[len+3] = '/';
	81	name = base + len + 1;
	82	}
	83	for (i = 0; i < 20; i++) {
	84	static char hex[] = "0123456789abcdef";
	85	unsigned int val = sha1[i];
	86	char pos = name + i2 + (i > 0);
	87	*pos++ = hex[val >> 4];
	88	*pos = hex[val & 0xf];
	89	}
	90	return base;
	91	}
	92
2ade9340 LT	93	int check_sha1_signature(unsigned char sha1, void map, unsigned long size)
	94	{
	95	unsigned char real_sha1[20];
	96	SHA_CTX c;
	97
	98	SHA1_Init(&c);
	99	SHA1_Update(&c, map, size);
	100	SHA1_Final(real_sha1, &c);
	101	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
	102	}
	103
73134b6d	104	void map_sha1_file(const unsigned char sha1, unsigned long *size)
e83c5163	105	{
e83c5163	106	char *filename = sha1_file_name(sha1);
24778e33 LT	107	int fd = open(filename, O_RDONLY);
	108	struct stat st;
	109	void *map;
e83c5163	110
e83c5163 LT	111	if (fd < 0) {
	112	perror(filename);
	113	return NULL;
	114	}
	115	if (fstat(fd, &st) < 0) {
24778e33	116	close(fd);
e83c5163 LT	117	return NULL;
	118	}
	119	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	120	close(fd);
	121	if (-1 == (int)(long)map)
	122	return NULL;
24778e33 LT	123	*size = st.st_size;
	124	return map;
	125	}
	126
	127	void * unpack_sha1_file(void map, unsigned long mapsize, char type, unsigned long *size)
	128	{
	129	int ret, bytes;
	130	z_stream stream;
	131	char buffer[8192];
	132	char *buf;
e83c5163 LT	133
	134	/* Get the data stream */
	135	memset(&stream, 0, sizeof(stream));
	136	stream.next_in = map;
24778e33	137	stream.avail_in = mapsize;
e83c5163 LT	138	stream.next_out = buffer;
	139	stream.avail_out = sizeof(buffer);
	140
	141	inflateInit(&stream);
	142	ret = inflate(&stream, 0);
	143	if (sscanf(buffer, "%10s %lu", type, size) != 2)
	144	return NULL;
24778e33	145
e83c5163 LT	146	bytes = strlen(buffer) + 1;
	147	buf = malloc(*size);
	148	if (!buf)
	149	return NULL;
	150
	151	memcpy(buf, buffer + bytes, stream.total_out - bytes);
	152	bytes = stream.total_out - bytes;
	153	if (bytes < *size && ret == Z_OK) {
	154	stream.next_out = buf + bytes;
	155	stream.avail_out = *size - bytes;
	156	while (inflate(&stream, Z_FINISH) == Z_OK)
	157	/* nothing */;
	158	}
	159	inflateEnd(&stream);
	160	return buf;
	161	}
	162
73134b6d	163	void * read_sha1_file(const unsigned char sha1, char type, unsigned long *size)
24778e33 LT	164	{
	165	unsigned long mapsize;
	166	void map, buf;
	167
	168	map = map_sha1_file(sha1, &mapsize);
	169	if (map) {
	170	buf = unpack_sha1_file(map, mapsize, type, size);
	171	munmap(map, mapsize);
	172	return buf;
	173	}
	174	return NULL;
	175	}
	176
d6d3f9d0	177	int write_sha1_file(char buf, unsigned len, unsigned char returnsha1)
e83c5163 LT	178	{
	179	int size;
	180	char *compressed;
	181	z_stream stream;
	182	unsigned char sha1[20];
	183	SHA_CTX c;
	184
	185	/* Set it up */
	186	memset(&stream, 0, sizeof(stream));
	187	deflateInit(&stream, Z_BEST_COMPRESSION);
	188	size = deflateBound(&stream, len);
	189	compressed = malloc(size);
	190
	191	/* Compress it */
	192	stream.next_in = buf;
	193	stream.avail_in = len;
	194	stream.next_out = compressed;
	195	stream.avail_out = size;
	196	while (deflate(&stream, Z_FINISH) == Z_OK)
	197	/* nothing */;
	198	deflateEnd(&stream);
	199	size = stream.total_out;
	200
	201	/* Sha1.. */
	202	SHA1_Init(&c);
	203	SHA1_Update(&c, compressed, size);
	204	SHA1_Final(sha1, &c);
	205
	206	if (write_sha1_buffer(sha1, compressed, size) < 0)
	207	return -1;
d6d3f9d0 LT	208	if (returnsha1)
d6d3f9d0 LT	209	memcpy(returnsha1, sha1, 20);
e83c5163 LT	210	return 0;
	211	}
	212
73134b6d	213	int write_sha1_buffer(const unsigned char sha1, void buf, unsigned int size)
e83c5163 LT	214	{
e83c5163 LT	215	char *filename = sha1_file_name(sha1);
19b2860c	216	int fd;
e83c5163 LT	217
	218	fd = open(filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	219	if (fd < 0)
	220	return (errno == EEXIST) ? 0 : -1;
	221	write(fd, buf, size);
	222	close(fd);
	223	return 0;
	224	}
	225
	226	static int error(const char * string)
	227	{
	228	fprintf(stderr, "error: %s\n", string);
	229	return -1;
	230	}
	231
734aab75 LT	232	int cache_match_stat(struct cache_entry ce, struct stat st)
	233	{
	234	unsigned int changed = 0;
	235
	236	if (ce->mtime.sec != (unsigned int)st->st_mtim.tv_sec \|\|
	237	ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec)
	238	changed \|= MTIME_CHANGED;
	239	if (ce->ctime.sec != (unsigned int)st->st_ctim.tv_sec \|\|
	240	ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec)
	241	changed \|= CTIME_CHANGED;
	242	if (ce->st_uid != (unsigned int)st->st_uid \|\|
	243	ce->st_gid != (unsigned int)st->st_gid)
	244	changed \|= OWNER_CHANGED;
	245	if (ce->st_mode != (unsigned int)st->st_mode)
	246	changed \|= MODE_CHANGED;
	247	if (ce->st_dev != (unsigned int)st->st_dev \|\|
	248	ce->st_ino != (unsigned int)st->st_ino)
	249	changed \|= INODE_CHANGED;
	250	if (ce->st_size != (unsigned int)st->st_size)
	251	changed \|= DATA_CHANGED;
	252	return changed;
	253	}
	254
79517a06	255	int cache_name_compare(const char name1, int len1, const char name2, int len2)
eb38c22f LT	256	{
	257	int len = len1 < len2 ? len1 : len2;
	258	int cmp;
	259
	260	cmp = memcmp(name1, name2, len);
	261	if (cmp)
	262	return cmp;
	263	if (len1 < len2)
	264	return -1;
	265	if (len1 > len2)
	266	return 1;
	267	return 0;
	268	}
	269
	270	int cache_name_pos(const char *name, int namelen)
	271	{
	272	int first, last;
	273
	274	first = 0;
	275	last = active_nr;
	276	while (last > first) {
	277	int next = (last + first) >> 1;
	278	struct cache_entry *ce = active_cache[next];
	279	int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
	280	if (!cmp)
76e7f4ec	281	return next;
eb38c22f LT	282	if (cmp < 0) {
	283	last = next;
	284	continue;
	285	}
	286	first = next+1;
	287	}
76e7f4ec	288	return -first-1;
eb38c22f LT	289	}
eb38c22f LT	290
197ee8c9 LT	291	int remove_file_from_cache(char *path)
	292	{
	293	int pos = cache_name_pos(path, strlen(path));
76e7f4ec	294	if (pos >= 0) {
197ee8c9 LT	295	active_nr--;
197ee8c9 LT	296	if (pos < active_nr)
76e7f4ec	297	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
197ee8c9 LT	298	}
	299	return 0;
	300	}
	301
121481ab	302	int add_cache_entry(struct cache_entry *ce, int ok_to_add)
197ee8c9 LT	303	{
	304	int pos;
	305
	306	pos = cache_name_pos(ce->name, ce->namelen);
	307
	308	/* existing match? Just replace it */
76e7f4ec LT	309	if (pos >= 0) {
76e7f4ec LT	310	active_cache[pos] = ce;
197ee8c9 LT	311	return 0;
197ee8c9 LT	312	}
76e7f4ec	313	pos = -pos-1;
197ee8c9	314
121481ab LT	315	if (!ok_to_add)
	316	return -1;
	317
197ee8c9 LT	318	/* Make sure the array is big enough .. */
	319	if (active_nr == active_alloc) {
	320	active_alloc = alloc_nr(active_alloc);
	321	active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
	322	}
	323
	324	/* Add it in.. */
	325	active_nr++;
	326	if (active_nr > pos)
	327	memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	328	active_cache[pos] = ce;
	329	return 0;
	330	}
	331
e83c5163 LT	332	static int verify_hdr(struct cache_header *hdr, unsigned long size)
	333	{
	334	SHA_CTX c;
	335	unsigned char sha1[20];
	336
	337	if (hdr->signature != CACHE_SIGNATURE)
	338	return error("bad signature");
	339	if (hdr->version != 1)
	340	return error("bad version");
	341	SHA1_Init(&c);
	342	SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
	343	SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
	344	SHA1_Final(sha1, &c);
	345	if (memcmp(sha1, hdr->sha1, 20))
	346	return error("bad header sha1");
	347	return 0;
	348	}
	349
	350	int read_cache(void)
	351	{
	352	int fd, i;
	353	struct stat st;
	354	unsigned long size, offset;
	355	void *map;
	356	struct cache_header *hdr;
	357
	358	errno = EBUSY;
	359	if (active_cache)
	360	return error("more than one cachefile");
	361	errno = ENOENT;
	362	sha1_file_directory = getenv(DB_ENVIRONMENT);
	363	if (!sha1_file_directory)
	364	sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
	365	if (access(sha1_file_directory, X_OK) < 0)
	366	return error("no access to SHA1 file directory");
4bb04f21	367	fd = open(".git/index", O_RDONLY);
e83c5163 LT	368	if (fd < 0)
	369	return (errno == ENOENT) ? 0 : error("open failed");
	370
19b2860c	371	size = 0; // avoid gcc warning
e83c5163 LT	372	map = (void *)-1;
e83c5163 LT	373	if (!fstat(fd, &st)) {
e83c5163 LT	374	size = st.st_size;
e83c5163 LT	375	errno = EINVAL;
59c1e249	376	if (size >= sizeof(struct cache_header))
e83c5163 LT	377	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	378	}
	379	close(fd);
	380	if (-1 == (int)(long)map)
	381	return error("mmap failed");
	382
	383	hdr = map;
	384	if (verify_hdr(hdr, size) < 0)
	385	goto unmap;
	386
	387	active_nr = hdr->entries;
	388	active_alloc = alloc_nr(active_nr);
	389	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
	390
	391	offset = sizeof(*hdr);
	392	for (i = 0; i < hdr->entries; i++) {
	393	struct cache_entry *ce = map + offset;
	394	offset = offset + ce_size(ce);
	395	active_cache[i] = ce;
	396	}
	397	return active_nr;
	398
	399	unmap:
	400	munmap(map, size);
	401	errno = EINVAL;
	402	return error("verify header failed");
	403	}
	404
197ee8c9 LT	405	int write_cache(int newfd, struct cache_entry **cache, int entries)
	406	{
	407	SHA_CTX c;
	408	struct cache_header hdr;
	409	int i;
	410
	411	hdr.signature = CACHE_SIGNATURE;
	412	hdr.version = 1;
	413	hdr.entries = entries;
	414
	415	SHA1_Init(&c);
	416	SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
	417	for (i = 0; i < entries; i++) {
	418	struct cache_entry *ce = cache[i];
	419	int size = ce_size(ce);
	420	SHA1_Update(&c, ce, size);
	421	}
	422	SHA1_Final(hdr.sha1, &c);
	423
	424	if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
	425	return -1;
	426
	427	for (i = 0; i < entries; i++) {
	428	struct cache_entry *ce = cache[i];
	429	int size = ce_size(ce);
	430	if (write(newfd, ce, size) != size)
	431	return -1;
	432	}
	433	return 0;
	434	}