[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

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;

#ifdef 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) {
				fprintf(stderr, "%s points nowhere!", path);
				continue;
			}
			if (!has_sha1_file(sha1)) {
				fprintf(stderr, "%s does not point to a valid "
						"commit object!", path);
				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", 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 == ':' ||
		/* 2.13 Pattern Matching Notation */
		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" */
			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
a876ed83	9	const char resolve_ref(const char path, unsigned char *sha1, int reading)
8a65ff76	10	{
a876ed83 JH	11	int depth = MAXDEPTH, len;
a876ed83 JH	12	char buffer[256];
ca8db142	13
a876ed83 JH	14	for (;;) {
	15	struct stat st;
	16	char *buf;
	17	int fd;
8a65ff76	18
a876ed83 JH	19	if (--depth < 0)
a876ed83 JH	20	return NULL;
ca8db142	21
a876ed83 JH	22	/* Special case: non-existing file.
	23	* Not having the refs/heads/new-branch is OK
	24	* if we are writing into it, so is .git/HEAD
	25	* that points at refs/heads/master still to be
	26	* born. It is NOT OK if we are resolving for
	27	* reading.
	28	*/
	29	if (lstat(path, &st) < 0) {
	30	if (reading \|\| errno != ENOENT)
	31	return NULL;
	32	memset(sha1, 0, 20);
	33	return path;
	34	}
ca8db142	35
a876ed83 JH	36	/* Follow "normalized" - ie "refs/.." symlinks by hand */
	37	if (S_ISLNK(st.st_mode)) {
	38	len = readlink(path, buffer, sizeof(buffer)-1);
	39	if (len >= 5 && !memcmp("refs/", buffer, 5)) {
	40	path = git_path("%.*s", len, buffer);
	41	continue;
	42	}
ca8db142	43	}
a876ed83 JH	44
	45	/*
	46	* Anything else, just open it and try to use it as
	47	* a ref
	48	*/
	49	fd = open(path, O_RDONLY);
	50	if (fd < 0)
	51	return NULL;
	52	len = read(fd, buffer, sizeof(buffer)-1);
	53	close(fd);
	54
	55	/*
	56	* Is it a symbolic ref?
	57	*/
	58	if (len < 4 \|\| memcmp("ref:", buffer, 4))
	59	break;
	60	buf = buffer + 4;
	61	len -= 4;
	62	while (len && isspace(*buf))
	63	buf++, len--;
	64	while (len && isspace(buf[len-1]))
	65	buf[--len] = 0;
	66	path = git_path("%.*s", len, buf);
8a65ff76	67	}
a876ed83 JH	68	if (len < 40 \|\| get_sha1_hex(buffer, sha1))
	69	return NULL;
	70	return path;
	71	}
	72
8098a178 JH	73	int create_symref(const char git_HEAD, const char refs_heads_master)
8098a178 JH	74	{
8098a178 JH	75	const char *lockpath;
	76	char ref[1000];
	77	int fd, len, written;
	78
2fabd217	79	#ifdef USE_SYMLINK_HEAD
f8348be3 JS	80	if (!only_use_symrefs) {
	81	unlink(git_HEAD);
	82	if (!symlink(refs_heads_master, git_HEAD))
	83	return 0;
	84	fprintf(stderr, "no symlink - falling back to symbolic ref\n");
	85	}
303958dc JS	86	#endif
303958dc JS	87
8098a178 JH	88	len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
	89	if (sizeof(ref) <= len) {
	90	error("refname too long: %s", refs_heads_master);
	91	return -1;
	92	}
	93	lockpath = mkpath("%s.lock", git_HEAD);
	94	fd = open(lockpath, O_CREAT \| O_EXCL \| O_WRONLY, 0666);
	95	written = write(fd, ref, len);
	96	close(fd);
	97	if (written != len) {
	98	unlink(lockpath);
	99	error("Unable to write to %s", lockpath);
	100	return -2;
	101	}
	102	if (rename(lockpath, git_HEAD) < 0) {
	103	unlink(lockpath);
	104	error("Unable to create %s", git_HEAD);
	105	return -3;
	106	}
	107	return 0;
8098a178 JH	108	}
8098a178 JH	109
a876ed83 JH	110	int read_ref(const char filename, unsigned char sha1)
	111	{
	112	if (resolve_ref(filename, sha1, 1))
	113	return 0;
	114	return -1;
8a65ff76 LT	115	}
8a65ff76 LT	116
944d8589	117	static int do_for_each_ref(const char base, int (fn)(const char path, const unsigned char sha1))
8a65ff76 LT	118	{
8a65ff76 LT	119	int retval = 0;
4ec99bf0	120	DIR *dir = opendir(git_path("%s", base));
8a65ff76 LT	121
	122	if (dir) {
	123	struct dirent *de;
	124	int baselen = strlen(base);
	125	char *path = xmalloc(baselen + 257);
6cada6a9 LT	126
	127	if (!strncmp(base, "./", 2)) {
	128	base += 2;
	129	baselen -= 2;
	130	}
8a65ff76	131	memcpy(path, base, baselen);
944d8589 LT	132	if (baselen && base[baselen-1] != '/')
944d8589 LT	133	path[baselen++] = '/';
8a65ff76 LT	134
	135	while ((de = readdir(dir)) != NULL) {
	136	unsigned char sha1[20];
	137	struct stat st;
	138	int namelen;
	139
	140	if (de->d_name[0] == '.')
	141	continue;
	142	namelen = strlen(de->d_name);
	143	if (namelen > 255)
	144	continue;
	145	memcpy(path + baselen, de->d_name, namelen+1);
a7e66ae3	146	if (stat(git_path("%s", path), &st) < 0)
8a65ff76 LT	147	continue;
8a65ff76 LT	148	if (S_ISDIR(st.st_mode)) {
8a65ff76 LT	149	retval = do_for_each_ref(path, fn);
	150	if (retval)
	151	break;
	152	continue;
	153	}
c401cb48 JS	154	if (read_ref(git_path("%s", path), sha1) < 0) {
c401cb48 JS	155	fprintf(stderr, "%s points nowhere!", path);
8a65ff76	156	continue;
c401cb48 JS	157	}
	158	if (!has_sha1_file(sha1)) {
	159	fprintf(stderr, "%s does not point to a valid "
	160	"commit object!", path);
8a65ff76	161	continue;
c401cb48	162	}
8a65ff76 LT	163	retval = fn(path, sha1);
	164	if (retval)
	165	break;
	166	}
	167	free(path);
	168	closedir(dir);
	169	}
	170	return retval;
	171	}
	172
723c31fe LT	173	int head_ref(int (fn)(const char path, const unsigned char *sha1))
	174	{
	175	unsigned char sha1[20];
ca8db142	176	if (!read_ref(git_path("HEAD"), sha1))
99a0a6e0	177	return fn("HEAD", sha1);
2f34ba32	178	return 0;
723c31fe LT	179	}
723c31fe LT	180
944d8589	181	int for_each_ref(int (fn)(const char path, const unsigned char *sha1))
8a65ff76	182	{
99a0a6e0	183	return do_for_each_ref("refs", fn);
8a65ff76 LT	184	}
8a65ff76 LT	185
95fc7512 DB	186	static char ref_file_name(const char ref)
	187	{
	188	char *base = get_refs_directory();
	189	int baselen = strlen(base);
	190	int reflen = strlen(ref);
	191	char *ret = xmalloc(baselen + 2 + reflen);
	192	sprintf(ret, "%s/%s", base, ref);
	193	return ret;
	194	}
	195
	196	static char ref_lock_file_name(const char ref)
	197	{
	198	char *base = get_refs_directory();
	199	int baselen = strlen(base);
	200	int reflen = strlen(ref);
	201	char *ret = xmalloc(baselen + 7 + reflen);
	202	sprintf(ret, "%s/%s.lock", base, ref);
	203	return ret;
	204	}
	205
95fc7512 DB	206	int get_ref_sha1(const char ref, unsigned char sha1)
95fc7512 DB	207	{
ca8db142 LT	208	const char *filename;
ca8db142 LT	209
95fc7512 DB	210	if (check_ref_format(ref))
95fc7512 DB	211	return -1;
ca8db142 LT	212	filename = git_path("refs/%s", ref);
ca8db142 LT	213	return read_ref(filename, sha1);
95fc7512 DB	214	}
	215
	216	static int lock_ref_file(const char filename, const char lock_filename,
	217	const unsigned char *old_sha1)
	218	{
	219	int fd = open(lock_filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	220	unsigned char current_sha1[20];
	221	int retval;
	222	if (fd < 0) {
	223	return error("Couldn't open lock file for %s: %s",
	224	filename, strerror(errno));
	225	}
ca8db142	226	retval = read_ref(filename, current_sha1);
95fc7512 DB	227	if (old_sha1) {
	228	if (retval) {
	229	close(fd);
	230	unlink(lock_filename);
	231	return error("Could not read the current value of %s",
	232	filename);
	233	}
	234	if (memcmp(current_sha1, old_sha1, 20)) {
	235	close(fd);
	236	unlink(lock_filename);
	237	error("The current value of %s is %s",
	238	filename, sha1_to_hex(current_sha1));
	239	return error("Expected %s",
	240	sha1_to_hex(old_sha1));
	241	}
	242	} else {
	243	if (!retval) {
	244	close(fd);
	245	unlink(lock_filename);
	246	return error("Unexpectedly found a value of %s for %s",
	247	sha1_to_hex(current_sha1), filename);
	248	}
	249	}
	250	return fd;
	251	}
	252
	253	int lock_ref_sha1(const char ref, const unsigned char old_sha1)
	254	{
	255	char *filename;
	256	char *lock_filename;
	257	int retval;
	258	if (check_ref_format(ref))
	259	return -1;
	260	filename = ref_file_name(ref);
	261	lock_filename = ref_lock_file_name(ref);
	262	retval = lock_ref_file(filename, lock_filename, old_sha1);
	263	free(filename);
	264	free(lock_filename);
	265	return retval;
	266	}
	267
	268	static int write_ref_file(const char *filename,
	269	const char *lock_filename, int fd,
	270	const unsigned char *sha1)
	271	{
	272	char *hex = sha1_to_hex(sha1);
	273	char term = '\n';
	274	if (write(fd, hex, 40) < 40 \|\|
	275	write(fd, &term, 1) < 1) {
bd2afde8	276	error("Couldn't write %s", filename);
95fc7512 DB	277	close(fd);
	278	return -1;
	279	}
	280	close(fd);
	281	rename(lock_filename, filename);
	282	return 0;
	283	}
	284
	285	int write_ref_sha1(const char ref, int fd, const unsigned char sha1)
	286	{
	287	char *filename;
	288	char *lock_filename;
	289	int retval;
	290	if (fd < 0)
	291	return -1;
	292	if (check_ref_format(ref))
	293	return -1;
	294	filename = ref_file_name(ref);
	295	lock_filename = ref_lock_file_name(ref);
64224caf JH	296	if (safe_create_leading_directories(filename))
64224caf JH	297	die("unable to create leading directory for %s", filename);
95fc7512 DB	298	retval = write_ref_file(filename, lock_filename, fd, sha1);
	299	free(filename);
	300	free(lock_filename);
	301	return retval;
	302	}
	303
03feddd6 JH	304	/*
	305	* Make sure "ref" is something reasonable to have under ".git/refs/";
	306	* We do not like it if:
	307	*
	308	* - any path component of it begins with ".", or
	309	* - it has double dots "..", or
	310	* - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
	311	* - it ends with a "/".
	312	*/
	313
	314	static inline int bad_ref_char(int ch)
	315	{
	316	return (((unsigned) ch) <= ' ' \|\|
68283999 JH	317	ch == '~' \|\| ch == '^' \|\| ch == ':' \|\|
	318	/* 2.13 Pattern Matching Notation */
	319	ch == '?' \|\| ch == '*' \|\| ch == '[');
03feddd6 JH	320	}
03feddd6 JH	321
95fc7512 DB	322	int check_ref_format(const char *ref)
95fc7512 DB	323	{
03feddd6 JH	324	int ch, level;
	325	const char *cp = ref;
	326
	327	level = 0;
	328	while (1) {
	329	while ((ch = *cp++) == '/')
	330	; /* tolerate duplicated slashes */
	331	if (!ch)
	332	return -1; /* should not end with slashes */
	333
	334	/* we are at the beginning of the path component */
	335	if (ch == '.' \|\| bad_ref_char(ch))
	336	return -1;
	337
	338	/* scan the rest of the path component */
	339	while ((ch = *cp++) != 0) {
	340	if (bad_ref_char(ch))
	341	return -1;
	342	if (ch == '/')
	343	break;
	344	if (ch == '.' && *cp == '.')
	345	return -1;
	346	}
	347	level++;
	348	if (!ch) {
	349	if (level < 2)
	350	return -1; /* at least of form "heads/blah" */
	351	return 0;
	352	}
	353	}
95fc7512 DB	354	}
	355
	356	int write_ref_sha1_unlocked(const char ref, const unsigned char sha1)
	357	{
	358	char *filename;
	359	char *lock_filename;
	360	int fd;
	361	int retval;
	362	if (check_ref_format(ref))
	363	return -1;
	364	filename = ref_file_name(ref);
	365	lock_filename = ref_lock_file_name(ref);
64224caf JH	366	if (safe_create_leading_directories(filename))
64224caf JH	367	die("unable to create leading directory for %s", filename);
95fc7512 DB	368	fd = open(lock_filename, O_WRONLY \| O_CREAT \| O_EXCL, 0666);
	369	if (fd < 0) {
	370	error("Writing %s", lock_filename);
	371	perror("Open");
	372	}
	373	retval = write_ref_file(filename, lock_filename, fd, sha1);
	374	free(filename);
	375	free(lock_filename);
	376	return retval;
	377	}