[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;

#ifndef NO_SYMLINK_HEAD
	if (prefer_symlink_refs) {
		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;
	}
	if (adjust_shared_perm(git_HEAD)) {
		unlink(lockpath);
		error("Unable to fix permissions on %s", lockpath);
		return -4;
	}
	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 trim)
{
	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;
			if (has_extension(de->d_name, ".lock"))
				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, trim);
				if (retval)
					break;
				continue;
			}
			if (read_ref(git_path("%s", path), sha1) < 0) {
				error("%s points nowhere!", path);
				continue;
			}
			if (!has_sha1_file(sha1)) {
				error("%s does not point to a valid "
				      "commit object!", path);
				continue;
			}
			retval = fn(path + trim, 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, 0);
}

int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
	return do_for_each_ref("refs/tags", fn, 10);
}

int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
	return do_for_each_ref("refs/heads", fn, 11);
}

int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
	return do_for_each_ref("refs/remotes", fn, 13);
}

int get_ref_sha1(const char *ref, unsigned char *sha1)
{
	if (check_ref_format(ref))
		return -1;
	return read_ref(git_path("refs/%s", ref), sha1);
}

/*
 * 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;
		}
	}
}

static struct ref_lock *verify_lock(struct ref_lock *lock,
	const unsigned char *old_sha1, int mustexist)
{
	char buf[40];
	int nr, fd = open(lock->ref_file, O_RDONLY);
	if (fd < 0 && (mustexist || errno != ENOENT)) {
		error("Can't verify ref %s", lock->ref_file);
		unlock_ref(lock);
		return NULL;
	}
	nr = read(fd, buf, 40);
	close(fd);
	if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
		error("Can't verify ref %s", lock->ref_file);
		unlock_ref(lock);
		return NULL;
	}
	if (hashcmp(lock->old_sha1, old_sha1)) {
		error("Ref %s is at %s but expected %s", lock->ref_file,
			sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
		unlock_ref(lock);
		return NULL;
	}
	return lock;
}

static struct ref_lock *lock_ref_sha1_basic(const char *path,
	int plen,
	const unsigned char *old_sha1, int mustexist)
{
	const char *orig_path = path;
	struct ref_lock *lock;
	struct stat st;

	lock = xcalloc(1, sizeof(struct ref_lock));
	lock->lock_fd = -1;

	plen = strlen(path) - plen;
	path = resolve_ref(path, lock->old_sha1, mustexist);
	if (!path) {
		int last_errno = errno;
		error("unable to resolve reference %s: %s",
			orig_path, strerror(errno));
		unlock_ref(lock);
		errno = last_errno;
		return NULL;
	}
	lock->lk = xcalloc(1, sizeof(struct lock_file));

	lock->ref_file = strdup(path);
	lock->log_file = strdup(git_path("logs/%s", lock->ref_file + plen));
	lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;

	if (safe_create_leading_directories(lock->ref_file))
		die("unable to create directory for %s", lock->ref_file);
	lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);

	return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
}

struct ref_lock *lock_ref_sha1(const char *ref,
	const unsigned char *old_sha1, int mustexist)
{
	if (check_ref_format(ref))
		return NULL;
	return lock_ref_sha1_basic(git_path("refs/%s", ref),
		5 + strlen(ref), old_sha1, mustexist);
}

struct ref_lock *lock_any_ref_for_update(const char *ref,
	const unsigned char *old_sha1, int mustexist)
{
	return lock_ref_sha1_basic(git_path("%s", ref),
		strlen(ref), old_sha1, mustexist);
}

void unlock_ref(struct ref_lock *lock)
{
	if (lock->lock_fd >= 0) {
		close(lock->lock_fd);
		/* Do not free lock->lk -- atexit() still looks at them */
		if (lock->lk)
			rollback_lock_file(lock->lk);
	}
	if (lock->ref_file)
		free(lock->ref_file);
	if (lock->log_file)
		free(lock->log_file);
	free(lock);
}

static int log_ref_write(struct ref_lock *lock,
	const unsigned char *sha1, const char *msg)
{
	int logfd, written, oflags = O_APPEND | O_WRONLY;
	unsigned maxlen, len;
	char *logrec;
	const char *committer;

	if (log_all_ref_updates) {
		if (safe_create_leading_directories(lock->log_file) < 0)
			return error("unable to create directory for %s",
				lock->log_file);
		oflags |= O_CREAT;
	}

	logfd = open(lock->log_file, oflags, 0666);
	if (logfd < 0) {
		if (!log_all_ref_updates && errno == ENOENT)
			return 0;
		return error("Unable to append to %s: %s",
			lock->log_file, strerror(errno));
	}

	committer = git_committer_info(1);
	if (msg) {
		maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
		logrec = xmalloc(maxlen);
		len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
			sha1_to_hex(lock->old_sha1),
			sha1_to_hex(sha1),
			committer,
			msg);
	}
	else {
		maxlen = strlen(committer) + 2*40 + 4;
		logrec = xmalloc(maxlen);
		len = snprintf(logrec, maxlen, "%s %s %s\n",
			sha1_to_hex(lock->old_sha1),
			sha1_to_hex(sha1),
			committer);
	}
	written = len <= maxlen ? write(logfd, logrec, len) : -1;
	free(logrec);
	close(logfd);
	if (written != len)
		return error("Unable to append to %s", lock->log_file);
	return 0;
}

int write_ref_sha1(struct ref_lock *lock,
	const unsigned char *sha1, const char *logmsg)
{
	static char term = '\n';

	if (!lock)
		return -1;
	if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
		unlock_ref(lock);
		return 0;
	}
	if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
	    write(lock->lock_fd, &term, 1) != 1
		|| close(lock->lock_fd) < 0) {
		error("Couldn't write %s", lock->lk->filename);
		unlock_ref(lock);
		return -1;
	}
	if (log_ref_write(lock, sha1, logmsg) < 0) {
		unlock_ref(lock);
		return -1;
	}
	if (commit_lock_file(lock->lk)) {
		error("Couldn't set %s", lock->ref_file);
		unlock_ref(lock);
		return -1;
	}
	lock->lock_fd = -1;
	unlock_ref(lock);
	return 0;
}

int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
{
	const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
	char *tz_c;
	int logfd, tz;
	struct stat st;
	unsigned long date;
	unsigned char logged_sha1[20];

	logfile = git_path("logs/%s", ref);
	logfd = open(logfile, O_RDONLY, 0);
	if (logfd < 0)
		die("Unable to read log %s: %s", logfile, strerror(errno));
	fstat(logfd, &st);
	if (!st.st_size)
		die("Log %s is empty.", logfile);
	logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
	close(logfd);

	lastrec = NULL;
	rec = logend = logdata + st.st_size;
	while (logdata < rec) {
		if (logdata < rec && *(rec-1) == '\n')
			rec--;
		lastgt = NULL;
		while (logdata < rec && *(rec-1) != '\n') {
			rec--;
			if (*rec == '>')
				lastgt = rec;
		}
		if (!lastgt)
			die("Log %s is corrupt.", logfile);
		date = strtoul(lastgt + 1, &tz_c, 10);
		if (date <= at_time) {
			if (lastrec) {
				if (get_sha1_hex(lastrec, logged_sha1))
					die("Log %s is corrupt.", logfile);
				if (get_sha1_hex(rec + 41, sha1))
					die("Log %s is corrupt.", logfile);
				if (hashcmp(logged_sha1, sha1)) {
					tz = strtoul(tz_c, NULL, 10);
					fprintf(stderr,
						"warning: Log %s has gap after %s.\n",
						logfile, show_rfc2822_date(date, tz));
				}
			}
			else if (date == at_time) {
				if (get_sha1_hex(rec + 41, sha1))
					die("Log %s is corrupt.", logfile);
			}
			else {
				if (get_sha1_hex(rec + 41, logged_sha1))
					die("Log %s is corrupt.", logfile);
				if (hashcmp(logged_sha1, sha1)) {
					tz = strtoul(tz_c, NULL, 10);
					fprintf(stderr,
						"warning: Log %s unexpectedly ended on %s.\n",
						logfile, show_rfc2822_date(date, tz));
				}
			}
			munmap((void*)logdata, st.st_size);
			return 0;
		}
		lastrec = rec;
	}

	rec = logdata;
	while (rec < logend && *rec != '>' && *rec != '\n')
		rec++;
	if (rec == logend || *rec == '\n')
		die("Log %s is corrupt.", logfile);
	date = strtoul(rec + 1, &tz_c, 10);
	tz = strtoul(tz_c, NULL, 10);
	if (get_sha1_hex(logdata, sha1))
		die("Log %s is corrupt.", logfile);
	munmap((void*)logdata, st.st_size);
	fprintf(stderr, "warning: Log %s only goes back to %s.\n",
		logfile, show_rfc2822_date(date, tz));
	return 0;
}
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
9f0bb90d JH	79	#ifndef NO_SYMLINK_HEAD
9f0bb90d JH	80	if (prefer_symlink_refs) {
f8348be3 JS	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	}
138086a7 JH	107	if (adjust_shared_perm(git_HEAD)) {
	108	unlink(lockpath);
	109	error("Unable to fix permissions on %s", lockpath);
	110	return -4;
	111	}
8098a178	112	return 0;
8098a178 JH	113	}
8098a178 JH	114
a876ed83 JH	115	int read_ref(const char filename, unsigned char sha1)
	116	{
	117	if (resolve_ref(filename, sha1, 1))
	118	return 0;
	119	return -1;
8a65ff76 LT	120	}
8a65ff76 LT	121
a62be77f	122	static int do_for_each_ref(const char base, int (fn)(const char path, const unsigned char sha1), int trim)
8a65ff76 LT	123	{
8a65ff76 LT	124	int retval = 0;
4ec99bf0	125	DIR *dir = opendir(git_path("%s", base));
8a65ff76 LT	126
	127	if (dir) {
	128	struct dirent *de;
	129	int baselen = strlen(base);
	130	char *path = xmalloc(baselen + 257);
6cada6a9 LT	131
	132	if (!strncmp(base, "./", 2)) {
	133	base += 2;
	134	baselen -= 2;
	135	}
8a65ff76	136	memcpy(path, base, baselen);
944d8589 LT	137	if (baselen && base[baselen-1] != '/')
944d8589 LT	138	path[baselen++] = '/';
8a65ff76 LT	139
	140	while ((de = readdir(dir)) != NULL) {
	141	unsigned char sha1[20];
	142	struct stat st;
	143	int namelen;
	144
	145	if (de->d_name[0] == '.')
	146	continue;
	147	namelen = strlen(de->d_name);
	148	if (namelen > 255)
	149	continue;
5bb1cda5	150	if (has_extension(de->d_name, ".lock"))
d0740d92	151	continue;
8a65ff76	152	memcpy(path + baselen, de->d_name, namelen+1);
a7e66ae3	153	if (stat(git_path("%s", path), &st) < 0)
8a65ff76 LT	154	continue;
8a65ff76 LT	155	if (S_ISDIR(st.st_mode)) {
a62be77f	156	retval = do_for_each_ref(path, fn, trim);
8a65ff76 LT	157	if (retval)
	158	break;
	159	continue;
	160	}
c401cb48	161	if (read_ref(git_path("%s", path), sha1) < 0) {
f61c2c97	162	error("%s points nowhere!", path);
8a65ff76	163	continue;
c401cb48 JS	164	}
c401cb48 JS	165	if (!has_sha1_file(sha1)) {
f61c2c97 JH	166	error("%s does not point to a valid "
f61c2c97 JH	167	"commit object!", path);
8a65ff76	168	continue;
c401cb48	169	}
a62be77f	170	retval = fn(path + trim, sha1);
8a65ff76 LT	171	if (retval)
	172	break;
	173	}
	174	free(path);
	175	closedir(dir);
	176	}
	177	return retval;
	178	}
	179
723c31fe LT	180	int head_ref(int (fn)(const char path, const unsigned char *sha1))
	181	{
	182	unsigned char sha1[20];
ca8db142	183	if (!read_ref(git_path("HEAD"), sha1))
99a0a6e0	184	return fn("HEAD", sha1);
2f34ba32	185	return 0;
723c31fe LT	186	}
723c31fe LT	187
944d8589	188	int for_each_ref(int (fn)(const char path, const unsigned char *sha1))
8a65ff76	189	{
a62be77f SE	190	return do_for_each_ref("refs", fn, 0);
	191	}
	192
	193	int for_each_tag_ref(int (fn)(const char path, const unsigned char *sha1))
	194	{
	195	return do_for_each_ref("refs/tags", fn, 10);
	196	}
	197
	198	int for_each_branch_ref(int (fn)(const char path, const unsigned char *sha1))
	199	{
	200	return do_for_each_ref("refs/heads", fn, 11);
	201	}
	202
	203	int for_each_remote_ref(int (fn)(const char path, const unsigned char *sha1))
	204	{
	205	return do_for_each_ref("refs/remotes", fn, 13);
8a65ff76 LT	206	}
8a65ff76 LT	207
95fc7512 DB	208	int get_ref_sha1(const char ref, unsigned char sha1)
95fc7512 DB	209	{
95fc7512 DB	210	if (check_ref_format(ref))
95fc7512 DB	211	return -1;
70e1a880	212	return read_ref(git_path("refs/%s", ref), sha1);
95fc7512 DB	213	}
95fc7512 DB	214
03feddd6 JH	215	/*
	216	* Make sure "ref" is something reasonable to have under ".git/refs/";
	217	* We do not like it if:
	218	*
	219	* - any path component of it begins with ".", or
	220	* - it has double dots "..", or
	221	* - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
	222	* - it ends with a "/".
	223	*/
	224
	225	static inline int bad_ref_char(int ch)
	226	{
	227	return (((unsigned) ch) <= ' ' \|\|
68283999 JH	228	ch == '~' \|\| ch == '^' \|\| ch == ':' \|\|
	229	/* 2.13 Pattern Matching Notation */
	230	ch == '?' \|\| ch == '*' \|\| ch == '[');
03feddd6 JH	231	}
03feddd6 JH	232
95fc7512 DB	233	int check_ref_format(const char *ref)
95fc7512 DB	234	{
03feddd6 JH	235	int ch, level;
	236	const char *cp = ref;
	237
	238	level = 0;
	239	while (1) {
	240	while ((ch = *cp++) == '/')
	241	; /* tolerate duplicated slashes */
	242	if (!ch)
	243	return -1; /* should not end with slashes */
	244
	245	/* we are at the beginning of the path component */
	246	if (ch == '.' \|\| bad_ref_char(ch))
	247	return -1;
	248
	249	/* scan the rest of the path component */
	250	while ((ch = *cp++) != 0) {
	251	if (bad_ref_char(ch))
	252	return -1;
	253	if (ch == '/')
	254	break;
	255	if (ch == '.' && *cp == '.')
	256	return -1;
	257	}
	258	level++;
	259	if (!ch) {
	260	if (level < 2)
	261	return -1; /* at least of form "heads/blah" */
	262	return 0;
	263	}
	264	}
95fc7512 DB	265	}
95fc7512 DB	266
e5f38ec3	267	static struct ref_lock verify_lock(struct ref_lock lock,
4bd18c43 SP	268	const unsigned char *old_sha1, int mustexist)
	269	{
	270	char buf[40];
	271	int nr, fd = open(lock->ref_file, O_RDONLY);
	272	if (fd < 0 && (mustexist \|\| errno != ENOENT)) {
	273	error("Can't verify ref %s", lock->ref_file);
	274	unlock_ref(lock);
	275	return NULL;
	276	}
	277	nr = read(fd, buf, 40);
	278	close(fd);
	279	if (nr != 40 \|\| get_sha1_hex(buf, lock->old_sha1) < 0) {
	280	error("Can't verify ref %s", lock->ref_file);
	281	unlock_ref(lock);
	282	return NULL;
	283	}
a89fccd2	284	if (hashcmp(lock->old_sha1, old_sha1)) {
4bd18c43 SP	285	error("Ref %s is at %s but expected %s", lock->ref_file,
	286	sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
	287	unlock_ref(lock);
	288	return NULL;
	289	}
	290	return lock;
	291	}
	292
e5f38ec3	293	static struct ref_lock lock_ref_sha1_basic(const char path,
4bd18c43 SP	294	int plen,
	295	const unsigned char *old_sha1, int mustexist)
	296	{
818f477c	297	const char *orig_path = path;
4bd18c43	298	struct ref_lock *lock;
732232a1	299	struct stat st;
4bd18c43 SP	300
	301	lock = xcalloc(1, sizeof(struct ref_lock));
	302	lock->lock_fd = -1;
	303
	304	plen = strlen(path) - plen;
	305	path = resolve_ref(path, lock->old_sha1, mustexist);
	306	if (!path) {
818f477c SP	307	int last_errno = errno;
	308	error("unable to resolve reference %s: %s",
	309	orig_path, strerror(errno));
4bd18c43	310	unlock_ref(lock);
818f477c	311	errno = last_errno;
4bd18c43 SP	312	return NULL;
4bd18c43 SP	313	}
c33d5174	314	lock->lk = xcalloc(1, sizeof(struct lock_file));
4bd18c43 SP	315
4bd18c43 SP	316	lock->ref_file = strdup(path);
6de08ae6	317	lock->log_file = strdup(git_path("logs/%s", lock->ref_file + plen));
8fe92775	318	lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
4bd18c43	319
c33d5174 JH	320	if (safe_create_leading_directories(lock->ref_file))
c33d5174 JH	321	die("unable to create directory for %s", lock->ref_file);
40aaae88	322	lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
4bd18c43 SP	323
	324	return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
	325	}
	326
e5f38ec3	327	struct ref_lock lock_ref_sha1(const char ref,
4bd18c43	328	const unsigned char *old_sha1, int mustexist)
95fc7512	329	{
95fc7512	330	if (check_ref_format(ref))
4bd18c43 SP	331	return NULL;
4bd18c43 SP	332	return lock_ref_sha1_basic(git_path("refs/%s", ref),
d0740d92	333	5 + strlen(ref), old_sha1, mustexist);
4bd18c43 SP	334	}
4bd18c43 SP	335
e5f38ec3	336	struct ref_lock lock_any_ref_for_update(const char ref,
4bd18c43 SP	337	const unsigned char *old_sha1, int mustexist)
	338	{
	339	return lock_ref_sha1_basic(git_path("%s", ref),
	340	strlen(ref), old_sha1, mustexist);
	341	}
	342
e5f38ec3	343	void unlock_ref(struct ref_lock *lock)
4bd18c43 SP	344	{
	345	if (lock->lock_fd >= 0) {
	346	close(lock->lock_fd);
c33d5174 JH	347	/* Do not free lock->lk -- atexit() still looks at them */
	348	if (lock->lk)
	349	rollback_lock_file(lock->lk);
4bd18c43 SP	350	}
	351	if (lock->ref_file)
	352	free(lock->ref_file);
6de08ae6 SP	353	if (lock->log_file)
6de08ae6 SP	354	free(lock->log_file);
4bd18c43 SP	355	free(lock);
	356	}
	357
6de08ae6 SP	358	static int log_ref_write(struct ref_lock *lock,
	359	const unsigned char sha1, const char msg)
	360	{
	361	int logfd, written, oflags = O_APPEND \| O_WRONLY;
	362	unsigned maxlen, len;
	363	char *logrec;
ff4c8485	364	const char *committer;
6de08ae6 SP	365
	366	if (log_all_ref_updates) {
	367	if (safe_create_leading_directories(lock->log_file) < 0)
	368	return error("unable to create directory for %s",
	369	lock->log_file);
	370	oflags \|= O_CREAT;
	371	}
	372
	373	logfd = open(lock->log_file, oflags, 0666);
	374	if (logfd < 0) {
	375	if (!log_all_ref_updates && errno == ENOENT)
	376	return 0;
	377	return error("Unable to append to %s: %s",
	378	lock->log_file, strerror(errno));
	379	}
	380
ff4c8485	381	committer = git_committer_info(1);
6de08ae6	382	if (msg) {
ff4c8485	383	maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
6de08ae6 SP	384	logrec = xmalloc(maxlen);
	385	len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
	386	sha1_to_hex(lock->old_sha1),
	387	sha1_to_hex(sha1),
ff4c8485	388	committer,
6de08ae6	389	msg);
e5f38ec3 JH	390	}
e5f38ec3 JH	391	else {
ff4c8485	392	maxlen = strlen(committer) + 2*40 + 4;
6de08ae6 SP	393	logrec = xmalloc(maxlen);
	394	len = snprintf(logrec, maxlen, "%s %s %s\n",
	395	sha1_to_hex(lock->old_sha1),
	396	sha1_to_hex(sha1),
ff4c8485	397	committer);
6de08ae6 SP	398	}
	399	written = len <= maxlen ? write(logfd, logrec, len) : -1;
	400	free(logrec);
	401	close(logfd);
	402	if (written != len)
	403	return error("Unable to append to %s", lock->log_file);
	404	return 0;
	405	}
	406
4bd18c43 SP	407	int write_ref_sha1(struct ref_lock *lock,
	408	const unsigned char sha1, const char logmsg)
	409	{
	410	static char term = '\n';
	411
	412	if (!lock)
95fc7512	413	return -1;
a89fccd2	414	if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
4bd18c43 SP	415	unlock_ref(lock);
4bd18c43 SP	416	return 0;
95fc7512	417	}
4bd18c43 SP	418	if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 \|\|
	419	write(lock->lock_fd, &term, 1) != 1
	420	\|\| close(lock->lock_fd) < 0) {
c33d5174	421	error("Couldn't write %s", lock->lk->filename);
4bd18c43 SP	422	unlock_ref(lock);
	423	return -1;
	424	}
6de08ae6 SP	425	if (log_ref_write(lock, sha1, logmsg) < 0) {
	426	unlock_ref(lock);
	427	return -1;
	428	}
c33d5174	429	if (commit_lock_file(lock->lk)) {
4bd18c43 SP	430	error("Couldn't set %s", lock->ref_file);
	431	unlock_ref(lock);
	432	return -1;
	433	}
	434	lock->lock_fd = -1;
	435	unlock_ref(lock);
	436	return 0;
95fc7512	437	}
d556fae2 SP	438
	439	int read_ref_at(const char ref, unsigned long at_time, unsigned char sha1)
	440	{
e5229042	441	const char logfile, logdata, logend, rec, lastgt, lastrec;
d556fae2 SP	442	char *tz_c;
	443	int logfd, tz;
	444	struct stat st;
	445	unsigned long date;
e5229042	446	unsigned char logged_sha1[20];
d556fae2 SP	447
	448	logfile = git_path("logs/%s", ref);
	449	logfd = open(logfile, O_RDONLY, 0);
	450	if (logfd < 0)
	451	die("Unable to read log %s: %s", logfile, strerror(errno));
	452	fstat(logfd, &st);
	453	if (!st.st_size)
	454	die("Log %s is empty.", logfile);
	455	logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
	456	close(logfd);
	457
e5229042	458	lastrec = NULL;
d556fae2 SP	459	rec = logend = logdata + st.st_size;
	460	while (logdata < rec) {
	461	if (logdata < rec && *(rec-1) == '\n')
	462	rec--;
e5229042 SP	463	lastgt = NULL;
e5229042 SP	464	while (logdata < rec && *(rec-1) != '\n') {
d556fae2	465	rec--;
e5229042 SP	466	if (*rec == '>')
	467	lastgt = rec;
	468	}
	469	if (!lastgt)
d556fae2	470	die("Log %s is corrupt.", logfile);
e5229042	471	date = strtoul(lastgt + 1, &tz_c, 10);
d556fae2	472	if (date <= at_time) {
e5229042 SP	473	if (lastrec) {
	474	if (get_sha1_hex(lastrec, logged_sha1))
	475	die("Log %s is corrupt.", logfile);
	476	if (get_sha1_hex(rec + 41, sha1))
	477	die("Log %s is corrupt.", logfile);
a89fccd2	478	if (hashcmp(logged_sha1, sha1)) {
e5229042 SP	479	tz = strtoul(tz_c, NULL, 10);
	480	fprintf(stderr,
	481	"warning: Log %s has gap after %s.\n",
	482	logfile, show_rfc2822_date(date, tz));
	483	}
e5f38ec3 JH	484	}
e5f38ec3 JH	485	else if (date == at_time) {
e5229042 SP	486	if (get_sha1_hex(rec + 41, sha1))
e5229042 SP	487	die("Log %s is corrupt.", logfile);
e5f38ec3 JH	488	}
e5f38ec3 JH	489	else {
e5229042 SP	490	if (get_sha1_hex(rec + 41, logged_sha1))
e5229042 SP	491	die("Log %s is corrupt.", logfile);
a89fccd2	492	if (hashcmp(logged_sha1, sha1)) {
e5229042 SP	493	tz = strtoul(tz_c, NULL, 10);
	494	fprintf(stderr,
	495	"warning: Log %s unexpectedly ended on %s.\n",
	496	logfile, show_rfc2822_date(date, tz));
	497	}
	498	}
d556fae2 SP	499	munmap((void*)logdata, st.st_size);
	500	return 0;
	501	}
e5229042	502	lastrec = rec;
d556fae2 SP	503	}
d556fae2 SP	504
e5229042 SP	505	rec = logdata;
	506	while (rec < logend && rec != '>' && rec != '\n')
	507	rec++;
	508	if (rec == logend \|\| *rec == '\n')
d556fae2	509	die("Log %s is corrupt.", logfile);
e5229042	510	date = strtoul(rec + 1, &tz_c, 10);
d556fae2 SP	511	tz = strtoul(tz_c, NULL, 10);
	512	if (get_sha1_hex(logdata, sha1))
	513	die("Log %s is corrupt.", logfile);
	514	munmap((void*)logdata, st.st_size);
	515	fprintf(stderr, "warning: Log %s only goes back to %s.\n",
	516	logfile, show_rfc2822_date(date, tz));
	517	return 0;
	518	}