[thirdparty/git.git] / refs.c

#include "refs.h"
#include "cache.h"

#include <errno.h>

/* We allow "recursive" symbolic refs. Only within reason, though */
#define MAXDEPTH 5

#ifndef USE_SYMLINK_HEAD
#define USE_SYMLINK_HEAD 1
#endif

const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
{
	int depth = MAXDEPTH, len;
	char buffer[256];

	for (;;) {
		struct stat st;
		char *buf;
		int fd;

		if (--depth < 0)
			return NULL;

		/* Special case: non-existing file.
		 * Not having the refs/heads/new-branch is OK
		 * if we are writing into it, so is .git/HEAD
		 * that points at refs/heads/master still to be
		 * born.  It is NOT OK if we are resolving for
		 * reading.
		 */
		if (lstat(path, &st) < 0) {
			if (reading || errno != ENOENT)
				return NULL;
			memset(sha1, 0, 20);
			return path;
		}

		/* Follow "normalized" - ie "refs/.." symlinks by hand */
		if (S_ISLNK(st.st_mode)) {
			len = readlink(path, buffer, sizeof(buffer)-1);
			if (len >= 5 && !memcmp("refs/", buffer, 5)) {
				path = git_path("%.*s", len, buffer);
				continue;
			}
		}

		/*
		 * Anything else, just open it and try to use it as
		 * a ref
		 */
		fd = open(path, O_RDONLY);
		if (fd < 0)
			return NULL;
		len = read(fd, buffer, sizeof(buffer)-1);
		close(fd);

		/*
		 * Is it a symbolic ref?
		 */
		if (len < 4 || memcmp("ref:", buffer, 4))
			break;
		buf = buffer + 4;
		len -= 4;
		while (len && isspace(*buf))
			buf++, len--;
		while (len && isspace(buf[len-1]))
			buf[--len] = 0;
		path = git_path("%.*s", len, buf);
	}
	if (len < 40 || get_sha1_hex(buffer, sha1))
		return NULL;
	return path;
}

int create_symref(const char *git_HEAD, const char *refs_heads_master)
{
	const char *lockpath;
	char ref[1000];
	int fd, len, written;

#if USE_SYMLINK_HEAD
	if (!only_use_symrefs) {
		unlink(git_HEAD);
		if (!symlink(refs_heads_master, git_HEAD))
			return 0;
		fprintf(stderr, "no symlink - falling back to symbolic ref\n");
	}
#endif

	len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
	if (sizeof(ref) <= len) {
		error("refname too long: %s", refs_heads_master);
		return -1;
	}
	lockpath = mkpath("%s.lock", git_HEAD);
	fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);	
	written = write(fd, ref, len);
	close(fd);
	if (written != len) {
		unlink(lockpath);
		error("Unable to write to %s", lockpath);
		return -2;
	}
	if (rename(lockpath, git_HEAD) < 0) {
		unlink(lockpath);
		error("Unable to create %s", git_HEAD);
		return -3;
	}
	return 0;
}

int read_ref(const char *filename, unsigned char *sha1)
{
	if (resolve_ref(filename, sha1, 1))
		return 0;
	return -1;
}

static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
{
	int retval = 0;
	DIR *dir = opendir(git_path("%s", base));

	if (dir) {
		struct dirent *de;
		int baselen = strlen(base);
		char *path = xmalloc(baselen + 257);

		if (!strncmp(base, "./", 2)) {
			base += 2;
			baselen -= 2;
		}
		memcpy(path, base, baselen);
		if (baselen && base[baselen-1] != '/')
			path[baselen++] = '/';

		while ((de = readdir(dir)) != NULL) {
			unsigned char sha1[20];
			struct stat st;
			int namelen;

			if (de->d_name[0] == '.')
				continue;
			namelen = strlen(de->d_name);
			if (namelen > 255)
				continue;
			memcpy(path + baselen, de->d_name, namelen+1);
			if (stat(git_path("%s", path), &st) < 0)
				continue;
			if (S_ISDIR(st.st_mode)) {
				retval = do_for_each_ref(path, fn);
				if (retval)
					break;
				continue;
			}
			if (read_ref(git_path("%s", path), sha1) < 0)
				continue;
			if (!has_sha1_file(sha1))
				continue;
			retval = fn(path, sha1);
			if (retval)
				break;
		}
		free(path);
		closedir(dir);
	}
	return retval;
}

int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
	unsigned char sha1[20];
	if (!read_ref(git_path("HEAD"), sha1))
		return fn("HEAD", sha1);
	return 0;
}

int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
	return do_for_each_ref("refs", fn);
}

static char *ref_file_name(const char *ref)
{
	char *base = get_refs_directory();
	int baselen = strlen(base);
	int reflen = strlen(ref);
	char *ret = xmalloc(baselen + 2 + reflen);
	sprintf(ret, "%s/%s", base, ref);
	return ret;
}

static char *ref_lock_file_name(const char *ref)
{
	char *base = get_refs_directory();
	int baselen = strlen(base);
	int reflen = strlen(ref);
	char *ret = xmalloc(baselen + 7 + reflen);
	sprintf(ret, "%s/%s.lock", base, ref);
	return ret;
}

int get_ref_sha1(const char *ref, unsigned char *sha1)
{
	const char *filename;

	if (check_ref_format(ref))
		return -1;
	filename = git_path("refs/%s", ref);
	return read_ref(filename, sha1);
}

static int lock_ref_file(const char *filename, const char *lock_filename,
			 const unsigned char *old_sha1)
{
	int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
	unsigned char current_sha1[20];
	int retval;
	if (fd < 0) {
		return error("Couldn't open lock file for %s: %s",
			     filename, strerror(errno));
	}
	retval = read_ref(filename, current_sha1);
	if (old_sha1) {
		if (retval) {
			close(fd);
			unlink(lock_filename);
			return error("Could not read the current value of %s",
				     filename);
		}
		if (memcmp(current_sha1, old_sha1, 20)) {
			close(fd);
			unlink(lock_filename);
			error("The current value of %s is %s",
			      filename, sha1_to_hex(current_sha1));
			return error("Expected %s",
				     sha1_to_hex(old_sha1));
		}
	} else {
		if (!retval) {
			close(fd);
			unlink(lock_filename);
			return error("Unexpectedly found a value of %s for %s",
				     sha1_to_hex(current_sha1), filename);
		}
	}
	return fd;
}

int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
{
	char *filename;
	char *lock_filename;
	int retval;
	if (check_ref_format(ref))
		return -1;
	filename = ref_file_name(ref);
	lock_filename = ref_lock_file_name(ref);
	retval = lock_ref_file(filename, lock_filename, old_sha1);
	free(filename);
	free(lock_filename);
	return retval;
}

static int write_ref_file(const char *filename,
			  const char *lock_filename, int fd,
			  const unsigned char *sha1)
{
	char *hex = sha1_to_hex(sha1);
	char term = '\n';
	if (write(fd, hex, 40) < 40 ||
	    write(fd, &term, 1) < 1) {
		error("Couldn't write %s\n", filename);
		close(fd);
		return -1;
	}
	close(fd);
	rename(lock_filename, filename);
	return 0;
}

int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
{
	char *filename;
	char *lock_filename;
	int retval;
	if (fd < 0)
		return -1;
	if (check_ref_format(ref))
		return -1;
	filename = ref_file_name(ref);
	lock_filename = ref_lock_file_name(ref);
	if (safe_create_leading_directories(filename))
		die("unable to create leading directory for %s", filename);
	retval = write_ref_file(filename, lock_filename, fd, sha1);
	free(filename);
	free(lock_filename);
	return retval;
}

/*
 * Make sure "ref" is something reasonable to have under ".git/refs/";
 * We do not like it if:
 *
 * - any path component of it begins with ".", or
 * - it has double dots "..", or
 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 * - it ends with a "/".
 */

static inline int bad_ref_char(int ch)
{
	return (((unsigned) ch) <= ' ' ||
		ch == '~' || ch == '^' || ch == ':');
}

int check_ref_format(const char *ref)
{
	int ch, level;
	const char *cp = ref;

	level = 0;
	while (1) {
		while ((ch = *cp++) == '/')
			; /* tolerate duplicated slashes */
		if (!ch)
			return -1; /* should not end with slashes */

		/* we are at the beginning of the path component */
		if (ch == '.' || bad_ref_char(ch))
			return -1;

		/* scan the rest of the path component */
		while ((ch = *cp++) != 0) {
			if (bad_ref_char(ch))
				return -1;
			if (ch == '/')
				break;
			if (ch == '.' && *cp == '.')
				return -1;
		}
		level++;
		if (!ch) {
			if (level < 2)
				return -1; /* at least of form "heads/blah" */

			/* Do not allow ref name to end in "HEAD"
			 * Note that cp is poiting at one past NUL at the end.
			 * i.e. cp[-1] = NUL.
			 */
			if (5 <= cp - ref && !strcmp(cp - 5, "HEAD"))
				return -1;

			return 0;
		}
	}
}

int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
{
	char *filename;
	char *lock_filename;
	int fd;
	int retval;
	if (check_ref_format(ref))
		return -1;
	filename = ref_file_name(ref);
	lock_filename = ref_lock_file_name(ref);
	if (safe_create_leading_directories(filename))
		die("unable to create leading directory for %s", filename);
	fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
	if (fd < 0) {
		error("Writing %s", lock_filename);
		perror("Open");
	}
	retval = write_ref_file(filename, lock_filename, fd, sha1);
	free(filename);
	free(lock_filename);
	return retval;
}
Commit	Line	Data
95fc7512 DB	1	#include "refs.h"
	2	#include "cache.h"
	3
	4	#include <errno.h>
	5
ca8db142 LT	6	/* We allow "recursive" symbolic refs. Only within reason, though */
	7	#define MAXDEPTH 5
	8
8098a178 JH	9	#ifndef USE_SYMLINK_HEAD
	10	#define USE_SYMLINK_HEAD 1
	11	#endif
	12
a876ed83	13	const char resolve_ref(const char path, unsigned char *sha1, int reading)
8a65ff76	14	{
a876ed83 JH	15	int depth = MAXDEPTH, len;
a876ed83 JH	16	char buffer[256];
ca8db142	17
a876ed83 JH	18	for (;;) {
	19	struct stat st;
	20	char *buf;
	21	int fd;
8a65ff76	22
a876ed83 JH	23	if (--depth < 0)
a876ed83 JH	24	return NULL;
ca8db142	25
a876ed83 JH	26	/* Special case: non-existing file.
	27	* Not having the refs/heads/new-branch is OK
	28	* if we are writing into it, so is .git/HEAD
	29	* that points at refs/heads/master still to be
	30	* born. It is NOT OK if we are resolving for
	31	* reading.
	32	*/
	33	if (lstat(path, &st) < 0) {
	34	if (reading \|\| errno != ENOENT)
	35	return NULL;
	36	memset(sha1, 0, 20);
	37	return path;
	38	}
ca8db142	39
a876ed83 JH	40	/* Follow "normalized" - ie "refs/.." symlinks by hand */
	41	if (S_ISLNK(st.st_mode)) {
	42	len = readlink(path, buffer, sizeof(buffer)-1);
	43	if (len >= 5 && !memcmp("refs/", buffer, 5)) {
	44	path = git_path("%.*s", len, buffer);
	45	continue;
	46	}
ca8db142	47	}
a876ed83 JH	48
	49	/*
	50	* Anything else, just open it and try to use it as
	51	* a ref
	52	*/
	53	fd = open(path, O_RDONLY);
	54	if (fd < 0)
	55	return NULL;
	56	len = read(fd, buffer, sizeof(buffer)-1);
	57	close(fd);
	58
	59	/*
	60	* Is it a symbolic ref?
	61	*/
	62	if (len < 4 \|\| memcmp("ref:", buffer, 4))
	63	break;
	64	buf = buffer + 4;
	65	len -= 4;
	66	while (len && isspace(*buf))
	67	buf++, len--;
	68	while (len && isspace(buf[len-1]))
	69	buf[--len] = 0;
	70	path = git_path("%.*s", len, buf);
8a65ff76	71	}
a876ed83 JH	72	if (len < 40 \|\| get_sha1_hex(buffer, sha1))
	73	return NULL;
	74	return path;
	75	}
	76
8098a178 JH	77	int create_symref(const char git_HEAD, const char refs_heads_master)
8098a178 JH	78	{
8098a178 JH	79	const char *lockpath;
	80	char ref[1000];
	81	int fd, len, written;
	82
303958dc	83	#if USE_SYMLINK_HEAD
f8348be3 JS	84	if (!only_use_symrefs) {
	85	unlink(git_HEAD);
	86	if (!symlink(refs_heads_master, git_HEAD))
	87	return 0;
	88	fprintf(stderr, "no symlink - falling back to symbolic ref\n");
	89	}
303958dc JS	90	#endif
303958dc JS	91
8098a178 JH	92	len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
	93	if (sizeof(ref) <= len) {
	94	error("refname too long: %s", refs_heads_master);
	95	return -1;
	96	}
	97	lockpath = mkpath("%s.lock", git_HEAD);
	98	fd = open(lockpath, O_CREAT \| O_EXCL \| O_WRONLY, 0666);
	99	written = write(fd, ref, len);
	100	close(fd);
	101	if (written != len) {
	102	unlink(lockpath);
	103	error("Unable to write to %s", lockpath);
	104	return -2;
	105	}
	106	if (rename(lockpath, git_HEAD) < 0) {
	107	unlink(lockpath);
	108	error("Unable to create %s", git_HEAD);
	109	return -3;
	110	}
	111	return 0;
8098a178 JH	112	}
8098a178 JH	113
a876ed83 JH	114	int read_ref(const char filename, unsigned char sha1)
	115	{
	116	if (resolve_ref(filename, sha1, 1))
	117	return 0;
	118	return -1;
8a65ff76 LT	119	}
8a65ff76 LT	120
944d8589	121	static int do_for_each_ref(const char base, int (fn)(const char path, const unsigned char sha1))
8a65ff76 LT	122	{
8a65ff76 LT	123	int retval = 0;
4ec99bf0	124	DIR *dir = opendir(git_path("%s", base));
8a65ff76 LT	125
	126	if (dir) {
	127	struct dirent *de;
	128	int baselen = strlen(base);
	129	char *path = xmalloc(baselen + 257);
6cada6a9 LT	130
	131	if (!strncmp(base, "./", 2)) {
	132	base += 2;
	133	baselen -= 2;
	134	}
8a65ff76	135	memcpy(path, base, baselen);
944d8589 LT	136	if (baselen && base[baselen-1] != '/')
944d8589 LT	137	path[baselen++] = '/';
8a65ff76 LT	138
	139	while ((de = readdir(dir)) != NULL) {
	140	unsigned char sha1[20];
	141	struct stat st;
	142	int namelen;
	143
	144	if (de->d_name[0] == '.')
	145	continue;
	146	namelen = strlen(de->d_name);
	147	if (namelen > 255)
	148	continue;
	149	memcpy(path + baselen, de->d_name, namelen+1);
a7e66ae3	150	if (stat(git_path("%s", path), &st) < 0)
8a65ff76 LT	151	continue;
8a65ff76 LT	152	if (S_ISDIR(st.st_mode)) {
8a65ff76 LT	153	retval = do_for_each_ref(path, fn);
	154	if (retval)
	155	break;
	156	continue;
	157	}
ca8db142	158	if (read_ref(git_path("%s", path), sha1) < 0)
8a65ff76 LT	159	continue;
	160	if (!has_sha1_file(sha1))
	161	continue;
	162	retval = fn(path, sha1);
	163	if (retval)
	164	break;
	165	}
	166	free(path);
	167	closedir(dir);
	168	}
	169	return retval;
	170	}
	171
723c31fe LT	172	int head_ref(int (fn)(const char path, const unsigned char *sha1))
	173	{
	174	unsigned char sha1[20];
ca8db142	175	if (!read_ref(git_path("HEAD"), sha1))
99a0a6e0	176	return fn("HEAD", sha1);
2f34ba32	177	return 0;
723c31fe LT	178	}
723c31fe LT	179
944d8589	180	int for_each_ref(int (fn)(const char path, const unsigned char *sha1))
8a65ff76	181	{
99a0a6e0	182	return do_for_each_ref("refs", fn);
8a65ff76 LT	183	}
8a65ff76 LT	184
95fc7512 DB	185	static char ref_file_name(const char ref)
	186	{
	187	char *base = get_refs_directory();
	188	int baselen = strlen(base);
	189	int reflen = strlen(ref);
	190	char *ret = xmalloc(baselen + 2 + reflen);
	191	sprintf(ret, "%s/%s", base, ref);
	192	return ret;
	193	}
	194
	195	static char ref_lock_file_name(const char ref)
	196	{
	197	char *base = get_refs_directory();
	198	int baselen = strlen(base);
	199	int reflen = strlen(ref);
	200	char *ret = xmalloc(baselen + 7 + reflen);
	201	sprintf(ret, "%s/%s.lock", base, ref);
	202	return ret;
	203	}
	204
95fc7512 DB	205	int get_ref_sha1(const char ref, unsigned char sha1)
95fc7512 DB	206	{
ca8db142 LT	207	const char *filename;
ca8db142 LT	208
95fc7512 DB	209	if (check_ref_format(ref))
95fc7512 DB	210	return -1;
ca8db142 LT	211	filename = git_path("refs/%s", ref);
ca8db142 LT	212	return read_ref(filename, sha1);
95fc7512 DB	213	}
	214
	215	static int lock_ref_file(const char filename, const char lock_filename,
	216	const unsigned char *old_sha1)
	217	{
	218	int fd = open(lock_filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	219	unsigned char current_sha1[20];
	220	int retval;
	221	if (fd < 0) {
	222	return error("Couldn't open lock file for %s: %s",
	223	filename, strerror(errno));
	224	}
ca8db142	225	retval = read_ref(filename, current_sha1);
95fc7512 DB	226	if (old_sha1) {
	227	if (retval) {
	228	close(fd);
	229	unlink(lock_filename);
	230	return error("Could not read the current value of %s",
	231	filename);
	232	}
	233	if (memcmp(current_sha1, old_sha1, 20)) {
	234	close(fd);
	235	unlink(lock_filename);
	236	error("The current value of %s is %s",
	237	filename, sha1_to_hex(current_sha1));
	238	return error("Expected %s",
	239	sha1_to_hex(old_sha1));
	240	}
	241	} else {
	242	if (!retval) {
	243	close(fd);
	244	unlink(lock_filename);
	245	return error("Unexpectedly found a value of %s for %s",
	246	sha1_to_hex(current_sha1), filename);
	247	}
	248	}
	249	return fd;
	250	}
	251
	252	int lock_ref_sha1(const char ref, const unsigned char old_sha1)
	253	{
	254	char *filename;
	255	char *lock_filename;
	256	int retval;
	257	if (check_ref_format(ref))
	258	return -1;
	259	filename = ref_file_name(ref);
	260	lock_filename = ref_lock_file_name(ref);
	261	retval = lock_ref_file(filename, lock_filename, old_sha1);
	262	free(filename);
	263	free(lock_filename);
	264	return retval;
	265	}
	266
	267	static int write_ref_file(const char *filename,
	268	const char *lock_filename, int fd,
	269	const unsigned char *sha1)
	270	{
	271	char *hex = sha1_to_hex(sha1);
	272	char term = '\n';
	273	if (write(fd, hex, 40) < 40 \|\|
	274	write(fd, &term, 1) < 1) {
	275	error("Couldn't write %s\n", filename);
	276	close(fd);
	277	return -1;
	278	}
	279	close(fd);
	280	rename(lock_filename, filename);
	281	return 0;
	282	}
	283
	284	int write_ref_sha1(const char ref, int fd, const unsigned char sha1)
	285	{
	286	char *filename;
	287	char *lock_filename;
	288	int retval;
	289	if (fd < 0)
290	return -1;
291	if (check_ref_format(ref))
292	return -1;
293	filename = ref_file_name(ref);
294	lock_filename = ref_lock_file_name(ref);
64224caf JH	295	if (safe_create_leading_directories(filename))
64224caf JH	296	die("unable to create leading directory for %s", filename);
95fc7512 DB	297	retval = write_ref_file(filename, lock_filename, fd, sha1);
	298	free(filename);
	299	free(lock_filename);
	300	return retval;
	301	}
	302
03feddd6 JH	303	/*
	304	* Make sure "ref" is something reasonable to have under ".git/refs/";
	305	* We do not like it if:
	306	*
	307	* - any path component of it begins with ".", or
	308	* - it has double dots "..", or
	309	* - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
	310	* - it ends with a "/".
	311	*/
	312
	313	static inline int bad_ref_char(int ch)
	314	{
	315	return (((unsigned) ch) <= ' ' \|\|
	316	ch == '~' \|\| ch == '^' \|\| ch == ':');
	317	}
	318
95fc7512 DB	319	int check_ref_format(const char *ref)
95fc7512 DB	320	{
03feddd6 JH	321	int ch, level;
	322	const char *cp = ref;
	323
	324	level = 0;
	325	while (1) {
	326	while ((ch = *cp++) == '/')
	327	; /* tolerate duplicated slashes */
	328	if (!ch)
	329	return -1; /* should not end with slashes */
	330
	331	/* we are at the beginning of the path component */
	332	if (ch == '.' \|\| bad_ref_char(ch))
	333	return -1;
	334
	335	/* scan the rest of the path component */
	336	while ((ch = *cp++) != 0) {
	337	if (bad_ref_char(ch))
	338	return -1;
	339	if (ch == '/')
	340	break;
	341	if (ch == '.' && *cp == '.')
	342	return -1;
	343	}
	344	level++;
	345	if (!ch) {
	346	if (level < 2)
	347	return -1; /* at least of form "heads/blah" */
ee34518d	348
06bf6ac4 JH	349	/* Do not allow ref name to end in "HEAD"
	350	* Note that cp is poiting at one past NUL at the end.
	351	* i.e. cp[-1] = NUL.
	352	*/
	353	if (5 <= cp - ref && !strcmp(cp - 5, "HEAD"))
ee34518d JS	354	return -1;
ee34518d JS	355
03feddd6 JH	356	return 0;
	357	}
	358	}
95fc7512 DB	359	}
	360
	361	int write_ref_sha1_unlocked(const char ref, const unsigned char sha1)
	362	{
	363	char *filename;
	364	char *lock_filename;
	365	int fd;
	366	int retval;
	367	if (check_ref_format(ref))
	368	return -1;
	369	filename = ref_file_name(ref);
	370	lock_filename = ref_lock_file_name(ref);
64224caf JH	371	if (safe_create_leading_directories(filename))
64224caf JH	372	die("unable to create leading directory for %s", filename);
95fc7512 DB	373	fd = open(lock_filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	374	if (fd < 0) {
	375	error("Writing %s", lock_filename);
	376	perror("Open");
	377	}
	378	retval = write_ref_file(filename, lock_filename, fd, sha1);
	379	free(filename);
	380	free(lock_filename);
	381	return retval;
	382	}