[thirdparty/git.git] / path.c

/*
 * I'm tired of doing "vsnprintf()" etc just to open a
 * file, so here's a "return static buffer with printf"
 * interface for paths.
 *
 * It's obviously not thread-safe. Sue me. But it's quite
 * useful for doing things like
 *
 *   f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
 *
 * which is what it's designed for.
 */
#include "cache.h"

static char bad_path[] = "/bad-path/";

static char *get_pathname(void)
{
	static char pathname_array[4][PATH_MAX];
	static int index;
	return pathname_array[3 & ++index];
}

static char *cleanup_path(char *path)
{
	/* Clean it up */
	if (!memcmp(path, "./", 2)) {
		path += 2;
		while (*path == '/')
			path++;
	}
	return path;
}

char *mksnpath(char *buf, size_t n, const char *fmt, ...)
{
	va_list args;
	unsigned len;

	va_start(args, fmt);
	len = vsnprintf(buf, n, fmt, args);
	va_end(args);
	if (len >= n) {
		snprintf(buf, n, bad_path);
		return buf;
	}
	return cleanup_path(buf);
}

char *git_snpath(char *buf, size_t n, const char *fmt, ...)
{
	const char *git_dir = get_git_dir();
	va_list args;
	size_t len;

	len = strlen(git_dir);
	if (n < len + 1)
		goto bad;
	memcpy(buf, git_dir, len);
	if (len && !is_dir_sep(git_dir[len-1]))
		buf[len++] = '/';
	va_start(args, fmt);
	len += vsnprintf(buf + len, n - len, fmt, args);
	va_end(args);
	if (len >= n)
		goto bad;
	return cleanup_path(buf);
bad:
	snprintf(buf, n, bad_path);
	return buf;
}

char *mkpath(const char *fmt, ...)
{
	va_list args;
	unsigned len;
	char *pathname = get_pathname();

	va_start(args, fmt);
	len = vsnprintf(pathname, PATH_MAX, fmt, args);
	va_end(args);
	if (len >= PATH_MAX)
		return bad_path;
	return cleanup_path(pathname);
}

char *git_path(const char *fmt, ...)
{
	const char *git_dir = get_git_dir();
	char *pathname = get_pathname();
	va_list args;
	unsigned len;

	len = strlen(git_dir);
	if (len > PATH_MAX-100)
		return bad_path;
	memcpy(pathname, git_dir, len);
	if (len && git_dir[len-1] != '/')
		pathname[len++] = '/';
	va_start(args, fmt);
	len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
	va_end(args);
	if (len >= PATH_MAX)
		return bad_path;
	return cleanup_path(pathname);
}


/* git_mkstemp() - create tmp file honoring TMPDIR variable */
int git_mkstemp(char *path, size_t len, const char *template)
{
	const char *tmp;
	size_t n;

	tmp = getenv("TMPDIR");
	if (!tmp)
		tmp = "/tmp";
	n = snprintf(path, len, "%s/%s", tmp, template);
	if (len <= n) {
		errno = ENAMETOOLONG;
		return -1;
	}
	return mkstemp(path);
}


int validate_headref(const char *path)
{
	struct stat st;
	char *buf, buffer[256];
	unsigned char sha1[20];
	int fd;
	ssize_t len;

	if (lstat(path, &st) < 0)
		return -1;

	/* Make sure it is a "refs/.." symlink */
	if (S_ISLNK(st.st_mode)) {
		len = readlink(path, buffer, sizeof(buffer)-1);
		if (len >= 5 && !memcmp("refs/", buffer, 5))
			return 0;
		return -1;
	}

	/*
	 * Anything else, just open it and try to see if it is a symbolic ref.
	 */
	fd = open(path, O_RDONLY);
	if (fd < 0)
		return -1;
	len = read_in_full(fd, buffer, sizeof(buffer)-1);
	close(fd);

	/*
	 * Is it a symbolic ref?
	 */
	if (len < 4)
		return -1;
	if (!memcmp("ref:", buffer, 4)) {
		buf = buffer + 4;
		len -= 4;
		while (len && isspace(*buf))
			buf++, len--;
		if (len >= 5 && !memcmp("refs/", buf, 5))
			return 0;
	}

	/*
	 * Is this a detached HEAD?
	 */
	if (!get_sha1_hex(buffer, sha1))
		return 0;

	return -1;
}

static char *user_path(char *buf, char *path, int sz)
{
	struct passwd *pw;
	char *slash;
	int len, baselen;

	if (!path || path[0] != '~')
		return NULL;
	path++;
	slash = strchr(path, '/');
	if (path[0] == '/' || !path[0]) {
		pw = getpwuid(getuid());
	}
	else {
		if (slash) {
			*slash = 0;
			pw = getpwnam(path);
			*slash = '/';
		}
		else
			pw = getpwnam(path);
	}
	if (!pw || !pw->pw_dir || sz <= strlen(pw->pw_dir))
		return NULL;
	baselen = strlen(pw->pw_dir);
	memcpy(buf, pw->pw_dir, baselen);
	while ((1 < baselen) && (buf[baselen-1] == '/')) {
		buf[baselen-1] = 0;
		baselen--;
	}
	if (slash && slash[1]) {
		len = strlen(slash);
		if (sz <= baselen + len)
			return NULL;
		memcpy(buf + baselen, slash, len + 1);
	}
	return buf;
}

/*
 * First, one directory to try is determined by the following algorithm.
 *
 * (0) If "strict" is given, the path is used as given and no DWIM is
 *     done. Otherwise:
 * (1) "~/path" to mean path under the running user's home directory;
 * (2) "~user/path" to mean path under named user's home directory;
 * (3) "relative/path" to mean cwd relative directory; or
 * (4) "/absolute/path" to mean absolute directory.
 *
 * Unless "strict" is given, we try access() for existence of "%s.git/.git",
 * "%s/.git", "%s.git", "%s" in this order.  The first one that exists is
 * what we try.
 *
 * Second, we try chdir() to that.  Upon failure, we return NULL.
 *
 * Then, we try if the current directory is a valid git repository.
 * Upon failure, we return NULL.
 *
 * If all goes well, we return the directory we used to chdir() (but
 * before ~user is expanded), avoiding getcwd() resolving symbolic
 * links.  User relative paths are also returned as they are given,
 * except DWIM suffixing.
 */
char *enter_repo(char *path, int strict)
{
	static char used_path[PATH_MAX];
	static char validated_path[PATH_MAX];

	if (!path)
		return NULL;

	if (!strict) {
		static const char *suffix[] = {
			".git/.git", "/.git", ".git", "", NULL,
		};
		int len = strlen(path);
		int i;
		while ((1 < len) && (path[len-1] == '/')) {
			path[len-1] = 0;
			len--;
		}
		if (PATH_MAX <= len)
			return NULL;
		if (path[0] == '~') {
			if (!user_path(used_path, path, PATH_MAX))
				return NULL;
			strcpy(validated_path, path);
			path = used_path;
		}
		else if (PATH_MAX - 10 < len)
			return NULL;
		else {
			path = strcpy(used_path, path);
			strcpy(validated_path, path);
		}
		len = strlen(path);
		for (i = 0; suffix[i]; i++) {
			strcpy(path + len, suffix[i]);
			if (!access(path, F_OK)) {
				strcat(validated_path, suffix[i]);
				break;
			}
		}
		if (!suffix[i] || chdir(path))
			return NULL;
		path = validated_path;
	}
	else if (chdir(path))
		return NULL;

	if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
	    validate_headref("HEAD") == 0) {
		setenv(GIT_DIR_ENVIRONMENT, ".", 1);
		check_repository_format();
		return path;
	}

	return NULL;
}

int adjust_shared_perm(const char *path)
{
	struct stat st;
	int mode;

	if (!shared_repository)
		return 0;
	if (lstat(path, &st) < 0)
		return -1;
	mode = st.st_mode;

	if (shared_repository) {
		int tweak = shared_repository;
		if (!(mode & S_IWUSR))
			tweak &= ~0222;
		mode |= tweak;
	} else {
		/* Preserve old PERM_UMASK behaviour */
		if (mode & S_IWUSR)
			mode |= S_IWGRP;
	}

	if (S_ISDIR(mode)) {
		mode |= FORCE_DIR_SET_GID;

		/* Copy read bits to execute bits */
		mode |= (shared_repository & 0444) >> 2;
	}

	if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
		return -2;
	return 0;
}

const char *make_relative_path(const char *abs, const char *base)
{
	static char buf[PATH_MAX + 1];
	int baselen;
	if (!base)
		return abs;
	baselen = strlen(base);
	if (prefixcmp(abs, base))
		return abs;
	if (abs[baselen] == '/')
		baselen++;
	else if (base[baselen - 1] != '/')
		return abs;
	strcpy(buf, abs + baselen);
	return buf;
}

/*
 * path = absolute path
 * buf = buffer of at least max(2, strlen(path)+1) bytes
 * It is okay if buf == path, but they should not overlap otherwise.
 *
 * Performs the following normalizations on path, storing the result in buf:
 * - Removes trailing slashes.
 * - Removes empty components.
 * - Removes "." components.
 * - Removes ".." components, and the components the precede them.
 * "" and paths that contain only slashes are normalized to "/".
 * Returns the length of the output.
 *
 * Note that this function is purely textual.  It does not follow symlinks,
 * verify the existence of the path, or make any system calls.
 */
int normalize_absolute_path(char *buf, const char *path)
{
	const char *comp_start = path, *comp_end = path;
	char *dst = buf;
	int comp_len;
	assert(buf);
	assert(path);

	while (*comp_start) {
		assert(*comp_start == '/');
		while (*++comp_end && *comp_end != '/')
			; /* nothing */
		comp_len = comp_end - comp_start;

		if (!strncmp("/",  comp_start, comp_len) ||
		    !strncmp("/.", comp_start, comp_len))
			goto next;

		if (!strncmp("/..", comp_start, comp_len)) {
			while (dst > buf && *--dst != '/')
				; /* nothing */
			goto next;
		}

		memcpy(dst, comp_start, comp_len);
		dst += comp_len;
	next:
		comp_start = comp_end;
	}

	if (dst == buf)
		*dst++ = '/';

	*dst = '\0';
	return dst - buf;
}

/*
 * path = Canonical absolute path
 * prefix_list = Colon-separated list of absolute paths
 *
 * Determines, for each path in prefix_list, whether the "prefix" really
 * is an ancestor directory of path.  Returns the length of the longest
 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 * is an ancestor.  (Note that this means 0 is returned if prefix_list is
 * "/".) "/foo" is not considered an ancestor of "/foobar".  Directories
 * are not considered to be their own ancestors.  path must be in a
 * canonical form: empty components, or "." or ".." components are not
 * allowed.  prefix_list may be null, which is like "".
 */
int longest_ancestor_length(const char *path, const char *prefix_list)
{
	char buf[PATH_MAX+1];
	const char *ceil, *colon;
	int len, max_len = -1;

	if (prefix_list == NULL || !strcmp(path, "/"))
		return -1;

	for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
		for (colon = ceil; *colon && *colon != ':'; colon++);
		len = colon - ceil;
		if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
			continue;
		strlcpy(buf, ceil, len+1);
		len = normalize_absolute_path(buf, buf);
		/* Strip "trailing slashes" from "/". */
		if (len == 1)
			len = 0;

		if (!strncmp(path, buf, len) &&
		    path[len] == '/' &&
		    len > max_len) {
			max_len = len;
		}
	}

	return max_len;
}
Commit	Line	Data
26c8a533 LT	1	/*
	2	* I'm tired of doing "vsnprintf()" etc just to open a
	3	* file, so here's a "return static buffer with printf"
	4	* interface for paths.
	5	*
	6	* It's obviously not thread-safe. Sue me. But it's quite
	7	* useful for doing things like
	8	*
	9	* f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
	10	*
	11	* which is what it's designed for.
	12	*/
	13	#include "cache.h"
	14
26c8a533 LT	15	static char bad_path[] = "/bad-path/";
26c8a533 LT	16
e7676d2f LT	17	static char *get_pathname(void)
	18	{
	19	static char pathname_array[4][PATH_MAX];
	20	static int index;
	21	return pathname_array[3 & ++index];
	22	}
	23
26c8a533 LT	24	static char cleanup_path(char path)
	25	{
	26	/* Clean it up */
	27	if (!memcmp(path, "./", 2)) {
	28	path += 2;
	29	while (*path == '/')
	30	path++;
	31	}
	32	return path;
	33	}
	34
108bebea AR	35	char mksnpath(char buf, size_t n, const char *fmt, ...)
	36	{
	37	va_list args;
	38	unsigned len;
	39
	40	va_start(args, fmt);
	41	len = vsnprintf(buf, n, fmt, args);
	42	va_end(args);
	43	if (len >= n) {
	44	snprintf(buf, n, bad_path);
	45	return buf;
	46	}
	47	return cleanup_path(buf);
	48	}
	49
fe2d7776 AR	50	char git_snpath(char buf, size_t n, const char *fmt, ...)
	51	{
	52	const char *git_dir = get_git_dir();
	53	va_list args;
	54	size_t len;
	55
	56	len = strlen(git_dir);
	57	if (n < len + 1)
	58	goto bad;
	59	memcpy(buf, git_dir, len);
	60	if (len && !is_dir_sep(git_dir[len-1]))
	61	buf[len++] = '/';
	62	va_start(args, fmt);
	63	len += vsnprintf(buf + len, n - len, fmt, args);
	64	va_end(args);
	65	if (len >= n)
	66	goto bad;
	67	return cleanup_path(buf);
	68	bad:
	69	snprintf(buf, n, bad_path);
	70	return buf;
	71	}
	72
26c8a533 LT	73	char mkpath(const char fmt, ...)
	74	{
	75	va_list args;
	76	unsigned len;
e7676d2f	77	char *pathname = get_pathname();
26c8a533 LT	78
	79	va_start(args, fmt);
	80	len = vsnprintf(pathname, PATH_MAX, fmt, args);
	81	va_end(args);
	82	if (len >= PATH_MAX)
	83	return bad_path;
	84	return cleanup_path(pathname);
	85	}
	86
	87	char git_path(const char fmt, ...)
	88	{
5da1606d	89	const char *git_dir = get_git_dir();
e7676d2f	90	char *pathname = get_pathname();
26c8a533 LT	91	va_list args;
	92	unsigned len;
	93
	94	len = strlen(git_dir);
	95	if (len > PATH_MAX-100)
	96	return bad_path;
	97	memcpy(pathname, git_dir, len);
	98	if (len && git_dir[len-1] != '/')
	99	pathname[len++] = '/';
	100	va_start(args, fmt);
	101	len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
	102	va_end(args);
	103	if (len >= PATH_MAX)
	104	return bad_path;
	105	return cleanup_path(pathname);
	106	}
f2db68ed HE	107
	108
	109	/* git_mkstemp() - create tmp file honoring TMPDIR variable */
	110	int git_mkstemp(char path, size_t len, const char template)
	111	{
e7a7be88 JH	112	const char *tmp;
	113	size_t n;
	114
	115	tmp = getenv("TMPDIR");
	116	if (!tmp)
	117	tmp = "/tmp";
	118	n = snprintf(path, len, "%s/%s", tmp, template);
	119	if (len <= n) {
	120	errno = ENAMETOOLONG;
	121	return -1;
35c3c629	122	}
f2db68ed HE	123	return mkstemp(path);
	124	}
	125
	126
c847f537	127	int validate_headref(const char *path)
0870ca7f JH	128	{
	129	struct stat st;
	130	char *buf, buffer[256];
c847f537	131	unsigned char sha1[20];
0104ca09 HO	132	int fd;
0104ca09 HO	133	ssize_t len;
0870ca7f JH	134
	135	if (lstat(path, &st) < 0)
	136	return -1;
	137
	138	/* Make sure it is a "refs/.." symlink */
	139	if (S_ISLNK(st.st_mode)) {
	140	len = readlink(path, buffer, sizeof(buffer)-1);
	141	if (len >= 5 && !memcmp("refs/", buffer, 5))
	142	return 0;
	143	return -1;
	144	}
	145
	146	/*
	147	* Anything else, just open it and try to see if it is a symbolic ref.
	148	*/
	149	fd = open(path, O_RDONLY);
	150	if (fd < 0)
	151	return -1;
93d26e4c	152	len = read_in_full(fd, buffer, sizeof(buffer)-1);
0870ca7f JH	153	close(fd);
	154
	155	/*
	156	* Is it a symbolic ref?
	157	*/
c847f537	158	if (len < 4)
0870ca7f	159	return -1;
c847f537 JH	160	if (!memcmp("ref:", buffer, 4)) {
	161	buf = buffer + 4;
	162	len -= 4;
	163	while (len && isspace(*buf))
	164	buf++, len--;
	165	if (len >= 5 && !memcmp("refs/", buf, 5))
	166	return 0;
	167	}
	168
	169	/*
	170	* Is this a detached HEAD?
	171	*/
	172	if (!get_sha1_hex(buffer, sha1))
0870ca7f	173	return 0;
c847f537	174
0870ca7f JH	175	return -1;
	176	}
	177
d79374c7	178	static char user_path(char buf, char *path, int sz)
54f4b874	179	{
d79374c7 JH	180	struct passwd *pw;
	181	char *slash;
	182	int len, baselen;
54f4b874	183
d79374c7 JH	184	if (!path \|\| path[0] != '~')
	185	return NULL;
	186	path++;
	187	slash = strchr(path, '/');
	188	if (path[0] == '/' \|\| !path[0]) {
	189	pw = getpwuid(getuid());
	190	}
	191	else {
	192	if (slash) {
	193	*slash = 0;
	194	pw = getpwnam(path);
	195	*slash = '/';
54f4b874	196	}
d79374c7 JH	197	else
d79374c7 JH	198	pw = getpwnam(path);
54f4b874	199	}
d79374c7 JH	200	if (!pw \|\| !pw->pw_dir \|\| sz <= strlen(pw->pw_dir))
	201	return NULL;
	202	baselen = strlen(pw->pw_dir);
	203	memcpy(buf, pw->pw_dir, baselen);
	204	while ((1 < baselen) && (buf[baselen-1] == '/')) {
	205	buf[baselen-1] = 0;
	206	baselen--;
	207	}
	208	if (slash && slash[1]) {
	209	len = strlen(slash);
	210	if (sz <= baselen + len)
	211	return NULL;
	212	memcpy(buf + baselen, slash, len + 1);
	213	}
	214	return buf;
54f4b874 AE	215	}
54f4b874 AE	216
d79374c7 JH	217	/*
	218	* First, one directory to try is determined by the following algorithm.
	219	*
	220	* (0) If "strict" is given, the path is used as given and no DWIM is
	221	* done. Otherwise:
	222	* (1) "~/path" to mean path under the running user's home directory;
	223	* (2) "~user/path" to mean path under named user's home directory;
	224	* (3) "relative/path" to mean cwd relative directory; or
	225	* (4) "/absolute/path" to mean absolute directory.
	226	*
	227	* Unless "strict" is given, we try access() for existence of "%s.git/.git",
	228	* "%s/.git", "%s.git", "%s" in this order. The first one that exists is
	229	* what we try.
	230	*
	231	* Second, we try chdir() to that. Upon failure, we return NULL.
	232	*
	233	* Then, we try if the current directory is a valid git repository.
	234	* Upon failure, we return NULL.
	235	*
	236	* If all goes well, we return the directory we used to chdir() (but
	237	* before ~user is expanded), avoiding getcwd() resolving symbolic
	238	* links. User relative paths are also returned as they are given,
	239	* except DWIM suffixing.
	240	*/
54f4b874 AE	241	char enter_repo(char path, int strict)
54f4b874 AE	242	{
d79374c7 JH	243	static char used_path[PATH_MAX];
	244	static char validated_path[PATH_MAX];
	245
	246	if (!path)
54f4b874 AE	247	return NULL;
54f4b874 AE	248
d79374c7 JH	249	if (!strict) {
	250	static const char *suffix[] = {
	251	".git/.git", "/.git", ".git", "", NULL,
	252	};
	253	int len = strlen(path);
	254	int i;
	255	while ((1 < len) && (path[len-1] == '/')) {
	256	path[len-1] = 0;
	257	len--;
	258	}
	259	if (PATH_MAX <= len)
54f4b874	260	return NULL;
d79374c7 JH	261	if (path[0] == '~') {
	262	if (!user_path(used_path, path, PATH_MAX))
	263	return NULL;
	264	strcpy(validated_path, path);
	265	path = used_path;
	266	}
	267	else if (PATH_MAX - 10 < len)
	268	return NULL;
	269	else {
	270	path = strcpy(used_path, path);
	271	strcpy(validated_path, path);
	272	}
	273	len = strlen(path);
	274	for (i = 0; suffix[i]; i++) {
	275	strcpy(path + len, suffix[i]);
	276	if (!access(path, F_OK)) {
	277	strcat(validated_path, suffix[i]);
	278	break;
	279	}
	280	}
	281	if (!suffix[i] \|\| chdir(path))
0870ca7f	282	return NULL;
d79374c7	283	path = validated_path;
0870ca7f	284	}
d79374c7 JH	285	else if (chdir(path))
d79374c7 JH	286	return NULL;
54f4b874	287
d79374c7	288	if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
c847f537	289	validate_headref("HEAD") == 0) {
7627943a	290	setenv(GIT_DIR_ENVIRONMENT, ".", 1);
1644162a	291	check_repository_format();
d79374c7	292	return path;
54f4b874 AE	293	}
	294
	295	return NULL;
	296	}
138086a7 JH	297
	298	int adjust_shared_perm(const char *path)
	299	{
	300	struct stat st;
	301	int mode;
	302
	303	if (!shared_repository)
	304	return 0;
	305	if (lstat(path, &st) < 0)
	306	return -1;
	307	mode = st.st_mode;
06cbe855 HO	308
	309	if (shared_repository) {
	310	int tweak = shared_repository;
	311	if (!(mode & S_IWUSR))
	312	tweak &= ~0222;
8c6202d8	313	mode \|= tweak;
06cbe855 HO	314	} else {
	315	/* Preserve old PERM_UMASK behaviour */
	316	if (mode & S_IWUSR)
	317	mode \|= S_IWGRP;
	318	}
	319
	320	if (S_ISDIR(mode)) {
81a24b52	321	mode \|= FORCE_DIR_SET_GID;
06cbe855 HO	322
	323	/* Copy read bits to execute bits */
	324	mode \|= (shared_repository & 0444) >> 2;
	325	}
	326
fe732ede	327	if ((mode & st.st_mode) != mode && chmod(path, mode) < 0)
138086a7 JH	328	return -2;
	329	return 0;
	330	}
e5392c51	331
044bbbcb LT	332	const char make_relative_path(const char abs, const char *base)
	333	{
	334	static char buf[PATH_MAX + 1];
	335	int baselen;
	336	if (!base)
	337	return abs;
	338	baselen = strlen(base);
	339	if (prefixcmp(abs, base))
	340	return abs;
	341	if (abs[baselen] == '/')
	342	baselen++;
	343	else if (base[baselen - 1] != '/')
	344	return abs;
	345	strcpy(buf, abs + baselen);
	346	return buf;
	347	}
ae299be0 DR	348
	349	/*
	350	* path = absolute path
	351	* buf = buffer of at least max(2, strlen(path)+1) bytes
	352	* It is okay if buf == path, but they should not overlap otherwise.
	353	*
	354	* Performs the following normalizations on path, storing the result in buf:
	355	* - Removes trailing slashes.
	356	* - Removes empty components.
	357	* - Removes "." components.
	358	* - Removes ".." components, and the components the precede them.
	359	* "" and paths that contain only slashes are normalized to "/".
	360	* Returns the length of the output.
	361	*
	362	* Note that this function is purely textual. It does not follow symlinks,
	363	* verify the existence of the path, or make any system calls.
	364	*/
	365	int normalize_absolute_path(char buf, const char path)
	366	{
	367	const char comp_start = path, comp_end = path;
	368	char *dst = buf;
	369	int comp_len;
	370	assert(buf);
	371	assert(path);
	372
	373	while (*comp_start) {
	374	assert(*comp_start == '/');
	375	while (++comp_end && comp_end != '/')
	376	; /* nothing */
	377	comp_len = comp_end - comp_start;
	378
	379	if (!strncmp("/", comp_start, comp_len) \|\|
	380	!strncmp("/.", comp_start, comp_len))
	381	goto next;
	382
	383	if (!strncmp("/..", comp_start, comp_len)) {
	384	while (dst > buf && *--dst != '/')
	385	; /* nothing */
	386	goto next;
	387	}
	388
	389	memcpy(dst, comp_start, comp_len);
	390	dst += comp_len;
	391	next:
	392	comp_start = comp_end;
	393	}
	394
	395	if (dst == buf)
	396	*dst++ = '/';
	397
	398	*dst = '\0';
	399	return dst - buf;
	400	}
0454dd93 DR	401
	402	/*
	403	* path = Canonical absolute path
	404	* prefix_list = Colon-separated list of absolute paths
	405	*
2860b57a	406	* Determines, for each path in prefix_list, whether the "prefix" really
0454dd93 DR	407	* is an ancestor directory of path. Returns the length of the longest
	408	* ancestor directory, excluding any trailing slashes, or -1 if no prefix
	409	* is an ancestor. (Note that this means 0 is returned if prefix_list is
	410	* "/".) "/foo" is not considered an ancestor of "/foobar". Directories
	411	* are not considered to be their own ancestors. path must be in a
	412	* canonical form: empty components, or "." or ".." components are not
	413	* allowed. prefix_list may be null, which is like "".
	414	*/
	415	int longest_ancestor_length(const char path, const char prefix_list)
	416	{
	417	char buf[PATH_MAX+1];
	418	const char ceil, colon;
	419	int len, max_len = -1;
	420
	421	if (prefix_list == NULL \|\| !strcmp(path, "/"))
	422	return -1;
	423
	424	for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
	425	for (colon = ceil; colon && colon != ':'; colon++);
	426	len = colon - ceil;
	427	if (len == 0 \|\| len > PATH_MAX \|\| !is_absolute_path(ceil))
	428	continue;
	429	strlcpy(buf, ceil, len+1);
	430	len = normalize_absolute_path(buf, buf);
	431	/* Strip "trailing slashes" from "/". */
	432	if (len == 1)
	433	len = 0;
	434
	435	if (!strncmp(path, buf, len) &&
	436	path[len] == '/' &&
	437	len > max_len) {
	438	max_len = len;
	439	}
	440	}
	441
	442	return max_len;
	443	}