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

/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include <stdarg.h>
#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)
{
	fprintf(stderr, "usage: %s\n", err);
	exit(1);
}

static void report(const char *prefix, const char *err, va_list params)
{
	fputs(prefix, stderr);
	vfprintf(stderr, err, params);
	fputs("\n", stderr);
}

void die(const char *err, ...)
{
	va_list params;

	va_start(params, err);
	report("fatal: ", err, params);
	va_end(params);
	exit(1);
}

int error(const char *err, ...)
{
	va_list params;

	va_start(params, err);
	report("error: ", err, params);
	va_end(params);
	return -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;
}

static inline int collision_check(char *filename, void *buf, unsigned int size)
{
#ifdef COLLISION_CHECK
	void *map;
	int fd = open(filename, O_RDONLY);
	struct stat st;
	int cmp;

	/* Unreadable object, or object went away? Strange. */
	if (fd < 0)
		return -1;

	if (fstat(fd, &st) < 0 || size != st.st_size)
		return -1;

	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);
	if (map == MAP_FAILED)
		return -1;
	cmp = memcmp(buf, map, size);
	munmap(map, size);
	if (cmp)
		return -1;
#endif
	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) {
		if (errno != EEXIST)
			return -1;
		if (collision_check(filename, buf, size))
			return error("SHA1 collision detected!"
					" This is bad, bad, BAD!\a\n");
		return 0;
	}
	write(fd, buf, size);
	close(fd);
	return 0;
}

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

	/* 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->mtime.sec  != (unsigned int)st->st_mtim.tv_sec
#ifdef NSEC
	    || ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec
#endif
	    )
		changed |= MTIME_CHANGED;
	if (ce->ctime.sec  != (unsigned int)st->st_ctim.tv_sec
#ifdef NSEC
	    || ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec
#endif
	    )
		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	*/
2de381f9	6	#include <stdarg.h>
e83c5163 LT	7	#include "cache.h"
	8
	9	const char *sha1_file_directory = NULL;
	10	struct cache_entry **active_cache = NULL;
	11	unsigned int active_nr = 0, active_alloc = 0;
	12
2de381f9	13	void usage(const char *err)
e83c5163	14	{
2de381f9 PB	15	fprintf(stderr, "usage: %s\n", err);
	16	exit(1);
	17	}
	18
	19	static void report(const char prefix, const char err, va_list params)
	20	{
	21	fputs(prefix, stderr);
	22	vfprintf(stderr, err, params);
	23	fputs("\n", stderr);
	24	}
121481ab	25
2de381f9 PB	26	void die(const char *err, ...)
	27	{
	28	va_list params;
	29
	30	va_start(params, err);
	31	report("fatal: ", err, params);
	32	va_end(params);
e83c5163 LT	33	exit(1);
	34	}
	35
2de381f9 PB	36	int error(const char *err, ...)
	37	{
	38	va_list params;
	39
	40	va_start(params, err);
	41	report("error: ", err, params);
	42	va_end(params);
	43	return -1;
	44	}
	45
	46
e83c5163 LT	47	static unsigned hexval(char c)
	48	{
	49	if (c >= '0' && c <= '9')
	50	return c - '0';
	51	if (c >= 'a' && c <= 'f')
	52	return c - 'a' + 10;
	53	if (c >= 'A' && c <= 'F')
	54	return c - 'A' + 10;
	55	return ~0;
	56	}
	57
197ee8c9	58	int get_sha1_hex(const char hex, unsigned char sha1)
e83c5163 LT	59	{
	60	int i;
	61	for (i = 0; i < 20; i++) {
	62	unsigned int val = (hexval(hex[0]) << 4) \| hexval(hex[1]);
	63	if (val & ~0xff)
	64	return -1;
	65	*sha1++ = val;
	66	hex += 2;
	67	}
	68	return 0;
	69	}
	70
197ee8c9	71	char * sha1_to_hex(const unsigned char *sha1)
e83c5163 LT	72	{
	73	static char buffer[50];
	74	static const char hex[] = "0123456789abcdef";
	75	char *buf = buffer;
	76	int i;
	77
	78	for (i = 0; i < 20; i++) {
	79	unsigned int val = *sha1++;
	80	*buf++ = hex[val >> 4];
	81	*buf++ = hex[val & 0xf];
	82	}
	83	return buffer;
	84	}
	85
	86	/*
	87	* NOTE! This returns a statically allocated buffer, so you have to be
	88	* careful about using it. Do a "strdup()" if you need to save the
	89	* filename.
	90	*/
73134b6d	91	char sha1_file_name(const unsigned char sha1)
e83c5163 LT	92	{
	93	int i;
	94	static char name, base;
	95
	96	if (!base) {
	97	char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
	98	int len = strlen(sha1_file_directory);
	99	base = malloc(len + 60);
	100	memcpy(base, sha1_file_directory, len);
	101	memset(base+len, 0, 60);
	102	base[len] = '/';
	103	base[len+3] = '/';
	104	name = base + len + 1;
	105	}
	106	for (i = 0; i < 20; i++) {
	107	static char hex[] = "0123456789abcdef";
	108	unsigned int val = sha1[i];
	109	char pos = name + i2 + (i > 0);
	110	*pos++ = hex[val >> 4];
	111	*pos = hex[val & 0xf];
	112	}
	113	return base;
	114	}
	115
2ade9340 LT	116	int check_sha1_signature(unsigned char sha1, void map, unsigned long size)
	117	{
	118	unsigned char real_sha1[20];
	119	SHA_CTX c;
	120
	121	SHA1_Init(&c);
	122	SHA1_Update(&c, map, size);
	123	SHA1_Final(real_sha1, &c);
	124	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
	125	}
	126
73134b6d	127	void map_sha1_file(const unsigned char sha1, unsigned long *size)
e83c5163	128	{
e83c5163	129	char *filename = sha1_file_name(sha1);
24778e33 LT	130	int fd = open(filename, O_RDONLY);
	131	struct stat st;
	132	void *map;
e83c5163	133
e83c5163 LT	134	if (fd < 0) {
	135	perror(filename);
	136	return NULL;
	137	}
	138	if (fstat(fd, &st) < 0) {
aebb2679	139	close(fd);
e83c5163 LT	140	return NULL;
	141	}
	142	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	143	close(fd);
	144	if (-1 == (int)(long)map)
	145	return NULL;
24778e33 LT	146	*size = st.st_size;
	147	return map;
	148	}
	149
	150	void * unpack_sha1_file(void map, unsigned long mapsize, char type, unsigned long *size)
	151	{
	152	int ret, bytes;
	153	z_stream stream;
	154	char buffer[8192];
	155	char *buf;
e83c5163 LT	156
	157	/* Get the data stream */
	158	memset(&stream, 0, sizeof(stream));
	159	stream.next_in = map;
24778e33	160	stream.avail_in = mapsize;
e83c5163 LT	161	stream.next_out = buffer;
	162	stream.avail_out = sizeof(buffer);
	163
	164	inflateInit(&stream);
	165	ret = inflate(&stream, 0);
	166	if (sscanf(buffer, "%10s %lu", type, size) != 2)
	167	return NULL;
24778e33	168
e83c5163 LT	169	bytes = strlen(buffer) + 1;
	170	buf = malloc(*size);
	171	if (!buf)
	172	return NULL;
	173
	174	memcpy(buf, buffer + bytes, stream.total_out - bytes);
	175	bytes = stream.total_out - bytes;
	176	if (bytes < *size && ret == Z_OK) {
	177	stream.next_out = buf + bytes;
	178	stream.avail_out = *size - bytes;
	179	while (inflate(&stream, Z_FINISH) == Z_OK)
	180	/* nothing */;
	181	}
	182	inflateEnd(&stream);
	183	return buf;
	184	}
	185
73134b6d	186	void * read_sha1_file(const unsigned char sha1, char type, unsigned long *size)
24778e33 LT	187	{
	188	unsigned long mapsize;
	189	void map, buf;
	190
	191	map = map_sha1_file(sha1, &mapsize);
	192	if (map) {
	193	buf = unpack_sha1_file(map, mapsize, type, size);
	194	munmap(map, mapsize);
	195	return buf;
	196	}
	197	return NULL;
	198	}
	199
d6d3f9d0	200	int write_sha1_file(char buf, unsigned len, unsigned char returnsha1)
e83c5163 LT	201	{
	202	int size;
	203	char *compressed;
	204	z_stream stream;
	205	unsigned char sha1[20];
	206	SHA_CTX c;
	207
	208	/* Set it up */
	209	memset(&stream, 0, sizeof(stream));
	210	deflateInit(&stream, Z_BEST_COMPRESSION);
	211	size = deflateBound(&stream, len);
	212	compressed = malloc(size);
	213
	214	/* Compress it */
	215	stream.next_in = buf;
	216	stream.avail_in = len;
	217	stream.next_out = compressed;
	218	stream.avail_out = size;
	219	while (deflate(&stream, Z_FINISH) == Z_OK)
	220	/* nothing */;
	221	deflateEnd(&stream);
	222	size = stream.total_out;
	223
	224	/* Sha1.. */
	225	SHA1_Init(&c);
	226	SHA1_Update(&c, compressed, size);
	227	SHA1_Final(sha1, &c);
	228
	229	if (write_sha1_buffer(sha1, compressed, size) < 0)
	230	return -1;
d6d3f9d0 LT	231	if (returnsha1)
d6d3f9d0 LT	232	memcpy(returnsha1, sha1, 20);
e83c5163 LT	233	return 0;
	234	}
	235
f864ba74 LT	236	static inline int collision_check(char filename, void buf, unsigned int size)
	237	{
	238	#ifdef COLLISION_CHECK
	239	void *map;
	240	int fd = open(filename, O_RDONLY);
	241	struct stat st;
	242	int cmp;
	243
	244	/* Unreadable object, or object went away? Strange. */
	245	if (fd < 0)
	246	return -1;
	247
	248	if (fstat(fd, &st) < 0 \|\| size != st.st_size)
	249	return -1;
	250
	251	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	252	close(fd);
	253	if (map == MAP_FAILED)
	254	return -1;
	255	cmp = memcmp(buf, map, size);
	256	munmap(map, size);
	257	if (cmp)
	258	return -1;
	259	#endif
	260	return 0;
	261	}
	262
73134b6d	263	int write_sha1_buffer(const unsigned char sha1, void buf, unsigned int size)
e83c5163 LT	264	{
e83c5163 LT	265	char *filename = sha1_file_name(sha1);
19b2860c	266	int fd;
e83c5163 LT	267
e83c5163 LT	268	fd = open(filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
5c2a7fbc	269	if (fd < 0) {
5c2a7fbc PB	270	if (errno != EEXIST)
5c2a7fbc PB	271	return -1;
f864ba74	272	if (collision_check(filename, buf, size))
5c2a7fbc PB	273	return error("SHA1 collision detected!"
5c2a7fbc PB	274	" This is bad, bad, BAD!\a\n");
5c2a7fbc PB	275	return 0;
5c2a7fbc PB	276	}
e83c5163 LT	277	write(fd, buf, size);
	278	close(fd);
	279	return 0;
	280	}
	281
734aab75 LT	282	int cache_match_stat(struct cache_entry ce, struct stat st)
	283	{
	284	unsigned int changed = 0;
	285
bdd4da59 PB	286	/* nsec seems unreliable - not all filesystems support it, so
	287	* as long as it is in the inode cache you get right nsec
	288	* but after it gets flushed, you get zero nsec. */
	289	if (ce->mtime.sec != (unsigned int)st->st_mtim.tv_sec
	290	#ifdef NSEC
	291	\|\| ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec
	292	#endif
	293	)
734aab75	294	changed \|= MTIME_CHANGED;
bdd4da59 PB	295	if (ce->ctime.sec != (unsigned int)st->st_ctim.tv_sec
	296	#ifdef NSEC
	297	\|\| ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec
	298	#endif
	299	)
734aab75 LT	300	changed \|= CTIME_CHANGED;
	301	if (ce->st_uid != (unsigned int)st->st_uid \|\|
	302	ce->st_gid != (unsigned int)st->st_gid)
	303	changed \|= OWNER_CHANGED;
	304	if (ce->st_mode != (unsigned int)st->st_mode)
	305	changed \|= MODE_CHANGED;
	306	if (ce->st_dev != (unsigned int)st->st_dev \|\|
	307	ce->st_ino != (unsigned int)st->st_ino)
	308	changed \|= INODE_CHANGED;
	309	if (ce->st_size != (unsigned int)st->st_size)
	310	changed \|= DATA_CHANGED;
	311	return changed;
	312	}
	313
79517a06	314	int cache_name_compare(const char name1, int len1, const char name2, int len2)
eb38c22f LT	315	{
	316	int len = len1 < len2 ? len1 : len2;
	317	int cmp;
	318
	319	cmp = memcmp(name1, name2, len);
	320	if (cmp)
	321	return cmp;
	322	if (len1 < len2)
	323	return -1;
	324	if (len1 > len2)
	325	return 1;
	326	return 0;
	327	}
	328
	329	int cache_name_pos(const char *name, int namelen)
	330	{
	331	int first, last;
	332
	333	first = 0;
	334	last = active_nr;
	335	while (last > first) {
	336	int next = (last + first) >> 1;
	337	struct cache_entry *ce = active_cache[next];
	338	int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
	339	if (!cmp)
76e7f4ec	340	return next;
eb38c22f LT	341	if (cmp < 0) {
	342	last = next;
	343	continue;
	344	}
	345	first = next+1;
	346	}
76e7f4ec	347	return -first-1;
eb38c22f LT	348	}
eb38c22f LT	349
197ee8c9 LT	350	int remove_file_from_cache(char *path)
	351	{
	352	int pos = cache_name_pos(path, strlen(path));
76e7f4ec	353	if (pos >= 0) {
197ee8c9 LT	354	active_nr--;
197ee8c9 LT	355	if (pos < active_nr)
76e7f4ec	356	memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
197ee8c9 LT	357	}
	358	return 0;
	359	}
	360
121481ab	361	int add_cache_entry(struct cache_entry *ce, int ok_to_add)
197ee8c9 LT	362	{
	363	int pos;
	364
	365	pos = cache_name_pos(ce->name, ce->namelen);
	366
	367	/* existing match? Just replace it */
76e7f4ec LT	368	if (pos >= 0) {
76e7f4ec LT	369	active_cache[pos] = ce;
197ee8c9 LT	370	return 0;
197ee8c9 LT	371	}
76e7f4ec	372	pos = -pos-1;
197ee8c9	373
121481ab LT	374	if (!ok_to_add)
	375	return -1;
	376
197ee8c9 LT	377	/* Make sure the array is big enough .. */
	378	if (active_nr == active_alloc) {
	379	active_alloc = alloc_nr(active_alloc);
	380	active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
	381	}
	382
	383	/* Add it in.. */
	384	active_nr++;
	385	if (active_nr > pos)
	386	memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
	387	active_cache[pos] = ce;
	388	return 0;
	389	}
	390
e83c5163 LT	391	static int verify_hdr(struct cache_header *hdr, unsigned long size)
	392	{
	393	SHA_CTX c;
	394	unsigned char sha1[20];
	395
	396	if (hdr->signature != CACHE_SIGNATURE)
	397	return error("bad signature");
	398	if (hdr->version != 1)
	399	return error("bad version");
	400	SHA1_Init(&c);
	401	SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
	402	SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
	403	SHA1_Final(sha1, &c);
	404	if (memcmp(sha1, hdr->sha1, 20))
	405	return error("bad header sha1");
	406	return 0;
	407	}
	408
	409	int read_cache(void)
	410	{
	411	int fd, i;
	412	struct stat st;
	413	unsigned long size, offset;
	414	void *map;
	415	struct cache_header *hdr;
	416
	417	errno = EBUSY;
	418	if (active_cache)
	419	return error("more than one cachefile");
	420	errno = ENOENT;
	421	sha1_file_directory = getenv(DB_ENVIRONMENT);
	422	if (!sha1_file_directory)
	423	sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
	424	if (access(sha1_file_directory, X_OK) < 0)
	425	return error("no access to SHA1 file directory");
4bb04f21	426	fd = open(".git/index", O_RDONLY);
e83c5163 LT	427	if (fd < 0)
	428	return (errno == ENOENT) ? 0 : error("open failed");
	429
19b2860c	430	size = 0; // avoid gcc warning
e83c5163 LT	431	map = (void *)-1;
e83c5163 LT	432	if (!fstat(fd, &st)) {
e83c5163 LT	433	size = st.st_size;
e83c5163 LT	434	errno = EINVAL;
59c1e249	435	if (size >= sizeof(struct cache_header))
e83c5163 LT	436	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	437	}
	438	close(fd);
	439	if (-1 == (int)(long)map)
	440	return error("mmap failed");
	441
	442	hdr = map;
	443	if (verify_hdr(hdr, size) < 0)
	444	goto unmap;
	445
	446	active_nr = hdr->entries;
	447	active_alloc = alloc_nr(active_nr);
	448	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
	449
	450	offset = sizeof(*hdr);
	451	for (i = 0; i < hdr->entries; i++) {
	452	struct cache_entry *ce = map + offset;
	453	offset = offset + ce_size(ce);
	454	active_cache[i] = ce;
	455	}
	456	return active_nr;
	457
	458	unmap:
	459	munmap(map, size);
	460	errno = EINVAL;
	461	return error("verify header failed");
	462	}
	463
197ee8c9 LT	464	int write_cache(int newfd, struct cache_entry **cache, int entries)
	465	{
	466	SHA_CTX c;
	467	struct cache_header hdr;
	468	int i;
	469
	470	hdr.signature = CACHE_SIGNATURE;
	471	hdr.version = 1;
	472	hdr.entries = entries;
	473
	474	SHA1_Init(&c);
	475	SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
	476	for (i = 0; i < entries; i++) {
	477	struct cache_entry *ce = cache[i];
	478	int size = ce_size(ce);
	479	SHA1_Update(&c, ce, size);
	480	}
	481	SHA1_Final(hdr.sha1, &c);
	482
	483	if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
	484	return -1;
	485
	486	for (i = 0; i < entries; i++) {
	487	struct cache_entry *ce = cache[i];
	488	int size = ce_size(ce);
	489	if (write(newfd, ce, size) != size)
	490	return -1;
	491	}
	492	return 0;
	493	}