[thirdparty/git.git] / path.c

/*
 * Utilities for paths and pathnames
 */
#include "cache.h"
#include "strbuf.h"
#include "string-list.h"

#ifndef get_st_mode_bits
/*
 * The replacement lstat(2) we use on Cygwin is incomplete and
 * may return wrong permission bits. Most of the time we do not care,
 * but the callsites of this wrapper do care.
 */
int get_st_mode_bits(const char *path, int *mode)
{
	struct stat st;
	if (lstat(path, &st) < 0)
		return -1;
	*mode = st.st_mode;
	return 0;
}
#endif

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) {
		strlcpy(buf, bad_path, n);
		return buf;
	}
	return cleanup_path(buf);
}

static char *vsnpath(char *buf, size_t n, const char *fmt, va_list args)
{
	const char *git_dir = get_git_dir();
	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++] = '/';
	len += vsnprintf(buf + len, n - len, fmt, args);
	if (len >= n)
		goto bad;
	return cleanup_path(buf);
bad:
	strlcpy(buf, bad_path, n);
	return buf;
}

char *git_snpath(char *buf, size_t n, const char *fmt, ...)
{
	char *ret;
	va_list args;
	va_start(args, fmt);
	ret = vsnpath(buf, n, fmt, args);
	va_end(args);
	return ret;
}

char *git_pathdup(const char *fmt, ...)
{
	char path[PATH_MAX], *ret;
	va_list args;
	va_start(args, fmt);
	ret = vsnpath(path, sizeof(path), fmt, args);
	va_end(args);
	return xstrdup(ret);
}

char *mkpathdup(const char *fmt, ...)
{
	char *path;
	struct strbuf sb = STRBUF_INIT;
	va_list args;

	va_start(args, fmt);
	strbuf_vaddf(&sb, fmt, args);
	va_end(args);
	path = xstrdup(cleanup_path(sb.buf));

	strbuf_release(&sb);
	return path;
}

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, ...)
{
	char *pathname = get_pathname();
	va_list args;
	char *ret;

	va_start(args, fmt);
	ret = vsnpath(pathname, PATH_MAX, fmt, args);
	va_end(args);
	return ret;
}

void home_config_paths(char **global, char **xdg, char *file)
{
	char *xdg_home = getenv("XDG_CONFIG_HOME");
	char *home = getenv("HOME");
	char *to_free = NULL;

	if (!home) {
		if (global)
			*global = NULL;
	} else {
		if (!xdg_home) {
			to_free = mkpathdup("%s/.config", home);
			xdg_home = to_free;
		}
		if (global)
			*global = mkpathdup("%s/.gitconfig", home);
	}

	if (!xdg_home)
		*xdg = NULL;
	else
		*xdg = mkpathdup("%s/git/%s", xdg_home, file);

	free(to_free);
}

char *git_path_submodule(const char *path, const char *fmt, ...)
{
	char *pathname = get_pathname();
	struct strbuf buf = STRBUF_INIT;
	const char *git_dir;
	va_list args;
	unsigned len;

	len = strlen(path);
	if (len > PATH_MAX-100)
		return bad_path;

	strbuf_addstr(&buf, path);
	if (len && path[len-1] != '/')
		strbuf_addch(&buf, '/');
	strbuf_addstr(&buf, ".git");

	git_dir = read_gitfile(buf.buf);
	if (git_dir) {
		strbuf_reset(&buf);
		strbuf_addstr(&buf, git_dir);
	}
	strbuf_addch(&buf, '/');

	if (buf.len >= PATH_MAX)
		return bad_path;
	memcpy(pathname, buf.buf, buf.len + 1);

	strbuf_release(&buf);
	len = strlen(pathname);

	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);
}

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 struct passwd *getpw_str(const char *username, size_t len)
{
	struct passwd *pw;
	char *username_z = xmalloc(len + 1);
	memcpy(username_z, username, len);
	username_z[len] = '\0';
	pw = getpwnam(username_z);
	free(username_z);
	return pw;
}

/*
 * Return a string with ~ and ~user expanded via getpw*.  If buf != NULL,
 * then it is a newly allocated string. Returns NULL on getpw failure or
 * if path is NULL.
 */
char *expand_user_path(const char *path)
{
	struct strbuf user_path = STRBUF_INIT;
	const char *first_slash = strchrnul(path, '/');
	const char *to_copy = path;

	if (path == NULL)
		goto return_null;
	if (path[0] == '~') {
		const char *username = path + 1;
		size_t username_len = first_slash - username;
		if (username_len == 0) {
			const char *home = getenv("HOME");
			if (!home)
				goto return_null;
			strbuf_add(&user_path, home, strlen(home));
		} else {
			struct passwd *pw = getpw_str(username, username_len);
			if (!pw)
				goto return_null;
			strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
		}
		to_copy = first_slash;
	}
	strbuf_add(&user_path, to_copy, strlen(to_copy));
	return strbuf_detach(&user_path, NULL);
return_null:
	strbuf_release(&user_path);
	return NULL;
}

/*
 * 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.
 */
const char *enter_repo(const 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,
		};
		const char *gitfile;
		int len = strlen(path);
		int i;
		while ((1 < len) && (path[len-1] == '/'))
			len--;

		if (PATH_MAX <= len)
			return NULL;
		strncpy(used_path, path, len); used_path[len] = 0 ;
		strcpy(validated_path, used_path);

		if (used_path[0] == '~') {
			char *newpath = expand_user_path(used_path);
			if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
				free(newpath);
				return NULL;
			}
			/*
			 * Copy back into the static buffer. A pity
			 * since newpath was not bounded, but other
			 * branches of the if are limited by PATH_MAX
			 * anyway.
			 */
			strcpy(used_path, newpath); free(newpath);
		}
		else if (PATH_MAX - 10 < len)
			return NULL;
		len = strlen(used_path);
		for (i = 0; suffix[i]; i++) {
			struct stat st;
			strcpy(used_path + len, suffix[i]);
			if (!stat(used_path, &st) &&
			    (S_ISREG(st.st_mode) ||
			    (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
				strcat(validated_path, suffix[i]);
				break;
			}
		}
		if (!suffix[i])
			return NULL;
		gitfile = read_gitfile(used_path) ;
		if (gitfile)
			strcpy(used_path, gitfile);
		if (chdir(used_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) {
		set_git_dir(".");
		check_repository_format();
		return path;
	}

	return NULL;
}

static int calc_shared_perm(int mode)
{
	int tweak;

	if (shared_repository < 0)
		tweak = -shared_repository;
	else
		tweak = shared_repository;

	if (!(mode & S_IWUSR))
		tweak &= ~0222;
	if (mode & S_IXUSR)
		/* Copy read bits to execute bits */
		tweak |= (tweak & 0444) >> 2;
	if (shared_repository < 0)
		mode = (mode & ~0777) | tweak;
	else
		mode |= tweak;

	return mode;
}


int adjust_shared_perm(const char *path)
{
	int old_mode, new_mode;

	if (!shared_repository)
		return 0;
	if (get_st_mode_bits(path, &old_mode) < 0)
		return -1;

	new_mode = calc_shared_perm(old_mode);
	if (S_ISDIR(old_mode)) {
		/* Copy read bits to execute bits */
		new_mode |= (new_mode & 0444) >> 2;
		new_mode |= FORCE_DIR_SET_GID;
	}

	if (((old_mode ^ new_mode) & ~S_IFMT) &&
			chmod(path, (new_mode & ~S_IFMT)) < 0)
		return -2;
	return 0;
}

const char *relative_path(const char *abs, const char *base)
{
	static char buf[PATH_MAX + 1];
	int i = 0, j = 0;

	if (!base || !base[0])
		return abs;
	while (base[i]) {
		if (is_dir_sep(base[i])) {
			if (!is_dir_sep(abs[j]))
				return abs;
			while (is_dir_sep(base[i]))
				i++;
			while (is_dir_sep(abs[j]))
				j++;
			continue;
		} else if (abs[j] != base[i]) {
			return abs;
		}
		i++;
		j++;
	}
	if (
	    /* "/foo" is a prefix of "/foo" */
	    abs[j] &&
	    /* "/foo" is not a prefix of "/foobar" */
	    !is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
	   )
		return abs;
	while (is_dir_sep(abs[j]))
		j++;
	if (!abs[j])
		strcpy(buf, ".");
	else
		strcpy(buf, abs + j);
	return buf;
}

/*
 * It is okay if dst == src, but they should not overlap otherwise.
 *
 * Performs the following normalizations on src, storing the result in dst:
 * - Ensures that components are separated by '/' (Windows only)
 * - Squashes sequences of '/'.
 * - Removes "." components.
 * - Removes ".." components, and the components the precede them.
 * Returns failure (non-zero) if a ".." component appears as first path
 * component anytime during the normalization. Otherwise, returns success (0).
 *
 * 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_path_copy(char *dst, const char *src)
{
	char *dst0;

	if (has_dos_drive_prefix(src)) {
		*dst++ = *src++;
		*dst++ = *src++;
	}
	dst0 = dst;

	if (is_dir_sep(*src)) {
		*dst++ = '/';
		while (is_dir_sep(*src))
			src++;
	}

	for (;;) {
		char c = *src;

		/*
		 * A path component that begins with . could be
		 * special:
		 * (1) "." and ends   -- ignore and terminate.
		 * (2) "./"           -- ignore them, eat slash and continue.
		 * (3) ".." and ends  -- strip one and terminate.
		 * (4) "../"          -- strip one, eat slash and continue.
		 */
		if (c == '.') {
			if (!src[1]) {
				/* (1) */
				src++;
			} else if (is_dir_sep(src[1])) {
				/* (2) */
				src += 2;
				while (is_dir_sep(*src))
					src++;
				continue;
			} else if (src[1] == '.') {
				if (!src[2]) {
					/* (3) */
					src += 2;
					goto up_one;
				} else if (is_dir_sep(src[2])) {
					/* (4) */
					src += 3;
					while (is_dir_sep(*src))
						src++;
					goto up_one;
				}
			}
		}

		/* copy up to the next '/', and eat all '/' */
		while ((c = *src++) != '\0' && !is_dir_sep(c))
			*dst++ = c;
		if (is_dir_sep(c)) {
			*dst++ = '/';
			while (is_dir_sep(c))
				c = *src++;
			src--;
		} else if (!c)
			break;
		continue;

	up_one:
		/*
		 * dst0..dst is prefix portion, and dst[-1] is '/';
		 * go up one level.
		 */
		dst--;	/* go to trailing '/' */
		if (dst <= dst0)
			return -1;
		/* Windows: dst[-1] cannot be backslash anymore */
		while (dst0 < dst && dst[-1] != '/')
			dst--;
	}
	*dst = '\0';
	return 0;
}

/*
 * path = Canonical absolute path
 * prefixes = string_list containing normalized, absolute paths without
 * trailing slashes (except for the root directory, which is denoted by "/").
 *
 * Determines, for each path in prefixes, whether the "prefix"
 * 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 prefixes 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.
 */
int longest_ancestor_length(const char *path, struct string_list *prefixes)
{
	int i, max_len = -1;

	if (!strcmp(path, "/"))
		return -1;

	for (i = 0; i < prefixes->nr; i++) {
		const char *ceil = prefixes->items[i].string;
		int len = strlen(ceil);

		if (len == 1 && ceil[0] == '/')
			len = 0; /* root matches anything, with length 0 */
		else if (!strncmp(path, ceil, len) && path[len] == '/')
			; /* match of length len */
		else
			continue; /* no match */

		if (len > max_len)
			max_len = len;
	}

	return max_len;
}

/* strip arbitrary amount of directory separators at end of path */
static inline int chomp_trailing_dir_sep(const char *path, int len)
{
	while (len && is_dir_sep(path[len - 1]))
		len--;
	return len;
}

/*
 * If path ends with suffix (complete path components), returns the
 * part before suffix (sans trailing directory separators).
 * Otherwise returns NULL.
 */
char *strip_path_suffix(const char *path, const char *suffix)
{
	int path_len = strlen(path), suffix_len = strlen(suffix);

	while (suffix_len) {
		if (!path_len)
			return NULL;

		if (is_dir_sep(path[path_len - 1])) {
			if (!is_dir_sep(suffix[suffix_len - 1]))
				return NULL;
			path_len = chomp_trailing_dir_sep(path, path_len);
			suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
		}
		else if (path[--path_len] != suffix[--suffix_len])
			return NULL;
	}

	if (path_len && !is_dir_sep(path[path_len - 1]))
		return NULL;
	return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
}

int daemon_avoid_alias(const char *p)
{
	int sl, ndot;

	/*
	 * This resurrects the belts and suspenders paranoia check by HPA
	 * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
	 * does not do getcwd() based path canonicalization.
	 *
	 * sl becomes true immediately after seeing '/' and continues to
	 * be true as long as dots continue after that without intervening
	 * non-dot character.
	 */
	if (!p || (*p != '/' && *p != '~'))
		return -1;
	sl = 1; ndot = 0;
	p++;

	while (1) {
		char ch = *p++;
		if (sl) {
			if (ch == '.')
				ndot++;
			else if (ch == '/') {
				if (ndot < 3)
					/* reject //, /./ and /../ */
					return -1;
				ndot = 0;
			}
			else if (ch == 0) {
				if (0 < ndot && ndot < 3)
					/* reject /.$ and /..$ */
					return -1;
				return 0;
			}
			else
				sl = ndot = 0;
		}
		else if (ch == 0)
			return 0;
		else if (ch == '/') {
			sl = 1;
			ndot = 0;
		}
	}
}

int offset_1st_component(const char *path)
{
	if (has_dos_drive_prefix(path))
		return 2 + is_dir_sep(path[2]);
	return is_dir_sep(path[0]);
}
Commit	Line	Data
26c8a533	1	/*
3a429d3b	2	* Utilities for paths and pathnames
26c8a533 LT	3	*/
26c8a533 LT	4	#include "cache.h"
395de250	5	#include "strbuf.h"
a5ccdbe4	6	#include "string-list.h"
26c8a533	7
0117c2f0 TB	8	#ifndef get_st_mode_bits
	9	/*
	10	* The replacement lstat(2) we use on Cygwin is incomplete and
	11	* may return wrong permission bits. Most of the time we do not care,
	12	* but the callsites of this wrapper do care.
	13	*/
	14	int get_st_mode_bits(const char path, int mode)
	15	{
	16	struct stat st;
	17	if (lstat(path, &st) < 0)
	18	return -1;
	19	*mode = st.st_mode;
	20	return 0;
	21	}
	22	#endif
	23
26c8a533 LT	24	static char bad_path[] = "/bad-path/";
26c8a533 LT	25
e7676d2f LT	26	static char *get_pathname(void)
	27	{
	28	static char pathname_array[4][PATH_MAX];
	29	static int index;
	30	return pathname_array[3 & ++index];
	31	}
	32
26c8a533 LT	33	static char cleanup_path(char path)
	34	{
	35	/* Clean it up */
	36	if (!memcmp(path, "./", 2)) {
	37	path += 2;
	38	while (*path == '/')
	39	path++;
	40	}
	41	return path;
	42	}
	43
108bebea AR	44	char mksnpath(char buf, size_t n, const char *fmt, ...)
	45	{
	46	va_list args;
	47	unsigned len;
	48
	49	va_start(args, fmt);
	50	len = vsnprintf(buf, n, fmt, args);
	51	va_end(args);
	52	if (len >= n) {
9db56f71	53	strlcpy(buf, bad_path, n);
108bebea AR	54	return buf;
	55	}
	56	return cleanup_path(buf);
	57	}
	58
5b3b8fa2	59	static char vsnpath(char buf, size_t n, const char *fmt, va_list args)
fe2d7776 AR	60	{
fe2d7776 AR	61	const char *git_dir = get_git_dir();
fe2d7776 AR	62	size_t len;
	63
	64	len = strlen(git_dir);
	65	if (n < len + 1)
	66	goto bad;
	67	memcpy(buf, git_dir, len);
	68	if (len && !is_dir_sep(git_dir[len-1]))
	69	buf[len++] = '/';
fe2d7776	70	len += vsnprintf(buf + len, n - len, fmt, args);
fe2d7776 AR	71	if (len >= n)
	72	goto bad;
	73	return cleanup_path(buf);
	74	bad:
9db56f71	75	strlcpy(buf, bad_path, n);
fe2d7776 AR	76	return buf;
	77	}
	78
aba13e7c AR	79	char git_snpath(char buf, size_t n, const char *fmt, ...)
aba13e7c AR	80	{
66a51a9a	81	char *ret;
aba13e7c AR	82	va_list args;
aba13e7c AR	83	va_start(args, fmt);
66a51a9a	84	ret = vsnpath(buf, n, fmt, args);
aba13e7c	85	va_end(args);
66a51a9a	86	return ret;
aba13e7c AR	87	}
	88
	89	char git_pathdup(const char fmt, ...)
	90	{
66a51a9a	91	char path[PATH_MAX], *ret;
aba13e7c AR	92	va_list args;
aba13e7c AR	93	va_start(args, fmt);
66a51a9a	94	ret = vsnpath(path, sizeof(path), fmt, args);
aba13e7c	95	va_end(args);
66a51a9a	96	return xstrdup(ret);
aba13e7c AR	97	}
aba13e7c AR	98
21cf3227 HKNN	99	char mkpathdup(const char fmt, ...)
	100	{
	101	char *path;
	102	struct strbuf sb = STRBUF_INIT;
	103	va_list args;
	104
	105	va_start(args, fmt);
	106	strbuf_vaddf(&sb, fmt, args);
	107	va_end(args);
	108	path = xstrdup(cleanup_path(sb.buf));
	109
	110	strbuf_release(&sb);
	111	return path;
	112	}
	113
26c8a533 LT	114	char mkpath(const char fmt, ...)
	115	{
	116	va_list args;
	117	unsigned len;
e7676d2f	118	char *pathname = get_pathname();
26c8a533 LT	119
	120	va_start(args, fmt);
	121	len = vsnprintf(pathname, PATH_MAX, fmt, args);
	122	va_end(args);
	123	if (len >= PATH_MAX)
	124	return bad_path;
	125	return cleanup_path(pathname);
	126	}
	127
	128	char git_path(const char fmt, ...)
	129	{
e7676d2f	130	char *pathname = get_pathname();
26c8a533	131	va_list args;
5c44252e	132	char *ret;
26c8a533	133
26c8a533	134	va_start(args, fmt);
5c44252e	135	ret = vsnpath(pathname, PATH_MAX, fmt, args);
26c8a533	136	va_end(args);
5c44252e	137	return ret;
26c8a533	138	}
f2db68ed	139
21cf3227 HKNN	140	void home_config_paths(char global, char xdg, char *file)
	141	{
	142	char *xdg_home = getenv("XDG_CONFIG_HOME");
	143	char *home = getenv("HOME");
	144	char *to_free = NULL;
	145
	146	if (!home) {
	147	if (global)
	148	*global = NULL;
	149	} else {
	150	if (!xdg_home) {
	151	to_free = mkpathdup("%s/.config", home);
	152	xdg_home = to_free;
	153	}
	154	if (global)
	155	*global = mkpathdup("%s/.gitconfig", home);
	156	}
	157
	158	if (!xdg_home)
	159	*xdg = NULL;
	160	else
	161	*xdg = mkpathdup("%s/git/%s", xdg_home, file);
	162
	163	free(to_free);
	164	}
	165
0bad611b HV	166	char git_path_submodule(const char path, const char *fmt, ...)
	167	{
	168	char *pathname = get_pathname();
	169	struct strbuf buf = STRBUF_INIT;
	170	const char *git_dir;
	171	va_list args;
	172	unsigned len;
	173
	174	len = strlen(path);
	175	if (len > PATH_MAX-100)
	176	return bad_path;
	177
	178	strbuf_addstr(&buf, path);
	179	if (len && path[len-1] != '/')
	180	strbuf_addch(&buf, '/');
	181	strbuf_addstr(&buf, ".git");
	182
13d6ec91	183	git_dir = read_gitfile(buf.buf);
0bad611b HV	184	if (git_dir) {
	185	strbuf_reset(&buf);
	186	strbuf_addstr(&buf, git_dir);
	187	}
	188	strbuf_addch(&buf, '/');
	189
	190	if (buf.len >= PATH_MAX)
	191	return bad_path;
	192	memcpy(pathname, buf.buf, buf.len + 1);
	193
	194	strbuf_release(&buf);
	195	len = strlen(pathname);
	196
	197	va_start(args, fmt);
	198	len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
	199	va_end(args);
	200	if (len >= PATH_MAX)
	201	return bad_path;
	202	return cleanup_path(pathname);
	203	}
f2db68ed	204
c847f537	205	int validate_headref(const char *path)
0870ca7f JH	206	{
	207	struct stat st;
	208	char *buf, buffer[256];
c847f537	209	unsigned char sha1[20];
0104ca09 HO	210	int fd;
0104ca09 HO	211	ssize_t len;
0870ca7f JH	212
	213	if (lstat(path, &st) < 0)
	214	return -1;
	215
	216	/* Make sure it is a "refs/.." symlink */
	217	if (S_ISLNK(st.st_mode)) {
	218	len = readlink(path, buffer, sizeof(buffer)-1);
222b1673	219	if (len >= 5 && !memcmp("refs/", buffer, 5))
0870ca7f JH	220	return 0;
	221	return -1;
	222	}
	223
	224	/*
	225	* Anything else, just open it and try to see if it is a symbolic ref.
	226	*/
	227	fd = open(path, O_RDONLY);
	228	if (fd < 0)
	229	return -1;
93d26e4c	230	len = read_in_full(fd, buffer, sizeof(buffer)-1);
0870ca7f JH	231	close(fd);
	232
	233	/*
	234	* Is it a symbolic ref?
	235	*/
c847f537	236	if (len < 4)
0870ca7f	237	return -1;
c847f537 JH	238	if (!memcmp("ref:", buffer, 4)) {
	239	buf = buffer + 4;
	240	len -= 4;
	241	while (len && isspace(*buf))
	242	buf++, len--;
222b1673	243	if (len >= 5 && !memcmp("refs/", buf, 5))
c847f537 JH	244	return 0;
	245	}
	246
	247	/*
	248	* Is this a detached HEAD?
	249	*/
	250	if (!get_sha1_hex(buffer, sha1))
0870ca7f	251	return 0;
c847f537	252
0870ca7f JH	253	return -1;
	254	}
	255
395de250	256	static struct passwd getpw_str(const char username, size_t len)
54f4b874	257	{
d79374c7	258	struct passwd *pw;
395de250 MM	259	char *username_z = xmalloc(len + 1);
	260	memcpy(username_z, username, len);
	261	username_z[len] = '\0';
	262	pw = getpwnam(username_z);
	263	free(username_z);
	264	return pw;
	265	}
54f4b874	266
395de250 MM	267	/*
	268	* Return a string with ~ and ~user expanded via getpw*. If buf != NULL,
	269	* then it is a newly allocated string. Returns NULL on getpw failure or
	270	* if path is NULL.
	271	*/
	272	char expand_user_path(const char path)
	273	{
	274	struct strbuf user_path = STRBUF_INIT;
	275	const char *first_slash = strchrnul(path, '/');
	276	const char *to_copy = path;
	277
	278	if (path == NULL)
	279	goto return_null;
	280	if (path[0] == '~') {
	281	const char *username = path + 1;
	282	size_t username_len = first_slash - username;
df2a79f4 MM	283	if (username_len == 0) {
df2a79f4 MM	284	const char *home = getenv("HOME");
79bf1490 JN	285	if (!home)
79bf1490 JN	286	goto return_null;
df2a79f4 MM	287	strbuf_add(&user_path, home, strlen(home));
	288	} else {
	289	struct passwd *pw = getpw_str(username, username_len);
	290	if (!pw)
	291	goto return_null;
	292	strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
54f4b874	293	}
395de250	294	to_copy = first_slash;
d79374c7	295	}
395de250 MM	296	strbuf_add(&user_path, to_copy, strlen(to_copy));
	297	return strbuf_detach(&user_path, NULL);
	298	return_null:
	299	strbuf_release(&user_path);
	300	return NULL;
54f4b874 AE	301	}
54f4b874 AE	302
d79374c7 JH	303	/*
	304	* First, one directory to try is determined by the following algorithm.
	305	*
	306	* (0) If "strict" is given, the path is used as given and no DWIM is
	307	* done. Otherwise:
	308	* (1) "~/path" to mean path under the running user's home directory;
	309	* (2) "~user/path" to mean path under named user's home directory;
	310	* (3) "relative/path" to mean cwd relative directory; or
	311	* (4) "/absolute/path" to mean absolute directory.
	312	*
	313	* Unless "strict" is given, we try access() for existence of "%s.git/.git",
	314	* "%s/.git", "%s.git", "%s" in this order. The first one that exists is
	315	* what we try.
	316	*
	317	* Second, we try chdir() to that. Upon failure, we return NULL.
	318	*
	319	* Then, we try if the current directory is a valid git repository.
	320	* Upon failure, we return NULL.
	321	*
	322	* If all goes well, we return the directory we used to chdir() (but
	323	* before ~user is expanded), avoiding getcwd() resolving symbolic
	324	* links. User relative paths are also returned as they are given,
	325	* except DWIM suffixing.
	326	*/
1c64b48e	327	const char enter_repo(const char path, int strict)
54f4b874	328	{
d79374c7 JH	329	static char used_path[PATH_MAX];
	330	static char validated_path[PATH_MAX];
	331
	332	if (!path)
54f4b874 AE	333	return NULL;
54f4b874 AE	334
d79374c7 JH	335	if (!strict) {
d79374c7 JH	336	static const char *suffix[] = {
b3256eb8	337	"/.git", "", ".git/.git", ".git", NULL,
d79374c7	338	};
03106768	339	const char *gitfile;
d79374c7 JH	340	int len = strlen(path);
d79374c7 JH	341	int i;
1c64b48e	342	while ((1 < len) && (path[len-1] == '/'))
d79374c7	343	len--;
1c64b48e	344
d79374c7	345	if (PATH_MAX <= len)
54f4b874	346	return NULL;
1c64b48e EFL	347	strncpy(used_path, path, len); used_path[len] = 0 ;
	348	strcpy(validated_path, used_path);
	349
	350	if (used_path[0] == '~') {
	351	char *newpath = expand_user_path(used_path);
395de250 MM	352	if (!newpath \|\| (PATH_MAX - 10 < strlen(newpath))) {
395de250 MM	353	free(newpath);
d79374c7	354	return NULL;
395de250 MM	355	}
	356	/*
	357	* Copy back into the static buffer. A pity
	358	* since newpath was not bounded, but other
	359	* branches of the if are limited by PATH_MAX
	360	* anyway.
	361	*/
	362	strcpy(used_path, newpath); free(newpath);
d79374c7 JH	363	}
	364	else if (PATH_MAX - 10 < len)
	365	return NULL;
1c64b48e	366	len = strlen(used_path);
d79374c7	367	for (i = 0; suffix[i]; i++) {
b3256eb8	368	struct stat st;
1c64b48e	369	strcpy(used_path + len, suffix[i]);
b3256eb8 JK	370	if (!stat(used_path, &st) &&
	371	(S_ISREG(st.st_mode) \|\|
	372	(S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
d79374c7 JH	373	strcat(validated_path, suffix[i]);
	374	break;
	375	}
	376	}
03106768 PH	377	if (!suffix[i])
	378	return NULL;
	379	gitfile = read_gitfile(used_path) ;
	380	if (gitfile)
	381	strcpy(used_path, gitfile);
	382	if (chdir(used_path))
0870ca7f	383	return NULL;
d79374c7	384	path = validated_path;
0870ca7f	385	}
d79374c7 JH	386	else if (chdir(path))
d79374c7 JH	387	return NULL;
54f4b874	388
d79374c7	389	if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
c847f537	390	validate_headref("HEAD") == 0) {
717c3972	391	set_git_dir(".");
1644162a	392	check_repository_format();
d79374c7	393	return path;
54f4b874 AE	394	}
	395
	396	return NULL;
	397	}
138086a7	398
cbe43b84	399	static int calc_shared_perm(int mode)
138086a7	400	{
cbe43b84	401	int tweak;
138086a7	402
5a688fe4	403	if (shared_repository < 0)
cbe43b84	404	tweak = -shared_repository;
5a688fe4	405	else
cbe43b84	406	tweak = shared_repository;
5a688fe4 JH	407
	408	if (!(mode & S_IWUSR))
	409	tweak &= ~0222;
	410	if (mode & S_IXUSR)
	411	/* Copy read bits to execute bits */
	412	tweak \|= (tweak & 0444) >> 2;
	413	if (shared_repository < 0)
	414	mode = (mode & ~0777) \| tweak;
	415	else
8c6202d8	416	mode \|= tweak;
06cbe855	417
cbe43b84 TB	418	return mode;
	419	}
	420
	421
	422	int adjust_shared_perm(const char *path)
	423	{
	424	int old_mode, new_mode;
	425
	426	if (!shared_repository)
	427	return 0;
	428	if (get_st_mode_bits(path, &old_mode) < 0)
	429	return -1;
	430
	431	new_mode = calc_shared_perm(old_mode);
	432	if (S_ISDIR(old_mode)) {
06cbe855	433	/* Copy read bits to execute bits */
cbe43b84 TB	434	new_mode \|= (new_mode & 0444) >> 2;
cbe43b84 TB	435	new_mode \|= FORCE_DIR_SET_GID;
06cbe855 HO	436	}
06cbe855 HO	437
cbe43b84 TB	438	if (((old_mode ^ new_mode) & ~S_IFMT) &&
cbe43b84 TB	439	chmod(path, (new_mode & ~S_IFMT)) < 0)
138086a7 JH	440	return -2;
	441	return 0;
	442	}
e5392c51	443
e2a57aac	444	const char relative_path(const char abs, const char *base)
044bbbcb LT	445	{
044bbbcb LT	446	static char buf[PATH_MAX + 1];
288123f0 JH	447	int i = 0, j = 0;
	448
	449	if (!base \|\| !base[0])
044bbbcb	450	return abs;
288123f0 JH	451	while (base[i]) {
	452	if (is_dir_sep(base[i])) {
	453	if (!is_dir_sep(abs[j]))
	454	return abs;
	455	while (is_dir_sep(base[i]))
	456	i++;
	457	while (is_dir_sep(abs[j]))
	458	j++;
	459	continue;
	460	} else if (abs[j] != base[i]) {
	461	return abs;
	462	}
	463	i++;
	464	j++;
	465	}
	466	if (
	467	/* "/foo" is a prefix of "/foo" */
	468	abs[j] &&
	469	/* "/foo" is not a prefix of "/foobar" */
	470	!is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
	471	)
044bbbcb	472	return abs;
288123f0 JH	473	while (is_dir_sep(abs[j]))
	474	j++;
	475	if (!abs[j])
	476	strcpy(buf, ".");
	477	else
	478	strcpy(buf, abs + j);
044bbbcb LT	479	return buf;
044bbbcb LT	480	}
ae299be0 DR	481
ae299be0 DR	482	/*
f2a782b8	483	* It is okay if dst == src, but they should not overlap otherwise.
ae299be0	484	*
f2a782b8 JS	485	* Performs the following normalizations on src, storing the result in dst:
	486	* - Ensures that components are separated by '/' (Windows only)
	487	* - Squashes sequences of '/'.
ae299be0 DR	488	* - Removes "." components.
ae299be0 DR	489	* - Removes ".." components, and the components the precede them.
f2a782b8 JS	490	* Returns failure (non-zero) if a ".." component appears as first path
f2a782b8 JS	491	* component anytime during the normalization. Otherwise, returns success (0).
ae299be0 DR	492	*
	493	* Note that this function is purely textual. It does not follow symlinks,
	494	* verify the existence of the path, or make any system calls.
	495	*/
f3cad0ad	496	int normalize_path_copy(char dst, const char src)
ae299be0	497	{
f3cad0ad	498	char *dst0;
ae299be0	499
f3cad0ad JS	500	if (has_dos_drive_prefix(src)) {
	501	dst++ = src++;
	502	dst++ = src++;
ae299be0	503	}
f3cad0ad	504	dst0 = dst;
ae299be0	505
f3cad0ad	506	if (is_dir_sep(*src)) {
ae299be0	507	*dst++ = '/';
f3cad0ad JS	508	while (is_dir_sep(*src))
	509	src++;
	510	}
	511
	512	for (;;) {
	513	char c = *src;
	514
	515	/*
	516	* A path component that begins with . could be
	517	* special:
	518	* (1) "." and ends -- ignore and terminate.
	519	* (2) "./" -- ignore them, eat slash and continue.
	520	* (3) ".." and ends -- strip one and terminate.
	521	* (4) "../" -- strip one, eat slash and continue.
	522	*/
	523	if (c == '.') {
	524	if (!src[1]) {
	525	/* (1) */
	526	src++;
	527	} else if (is_dir_sep(src[1])) {
	528	/* (2) */
	529	src += 2;
	530	while (is_dir_sep(*src))
	531	src++;
	532	continue;
	533	} else if (src[1] == '.') {
	534	if (!src[2]) {
	535	/* (3) */
	536	src += 2;
	537	goto up_one;
	538	} else if (is_dir_sep(src[2])) {
	539	/* (4) */
	540	src += 3;
	541	while (is_dir_sep(*src))
	542	src++;
	543	goto up_one;
	544	}
	545	}
	546	}
ae299be0	547
f3cad0ad JS	548	/* copy up to the next '/', and eat all '/' */
	549	while ((c = *src++) != '\0' && !is_dir_sep(c))
	550	*dst++ = c;
	551	if (is_dir_sep(c)) {
	552	*dst++ = '/';
	553	while (is_dir_sep(c))
	554	c = *src++;
	555	src--;
	556	} else if (!c)
	557	break;
	558	continue;
	559
	560	up_one:
	561	/*
	562	* dst0..dst is prefix portion, and dst[-1] is '/';
	563	* go up one level.
	564	*/
f42302b4 JS	565	dst--; /* go to trailing '/' */
f42302b4 JS	566	if (dst <= dst0)
f3cad0ad	567	return -1;
f42302b4 JS	568	/* Windows: dst[-1] cannot be backslash anymore */
	569	while (dst0 < dst && dst[-1] != '/')
	570	dst--;
f3cad0ad	571	}
ae299be0	572	*dst = '\0';
f3cad0ad	573	return 0;
ae299be0	574	}
0454dd93 DR	575
	576	/*
	577	* path = Canonical absolute path
9e2326c7 MH	578	* prefixes = string_list containing normalized, absolute paths without
9e2326c7 MH	579	* trailing slashes (except for the root directory, which is denoted by "/").
0454dd93	580	*
9e2326c7	581	* Determines, for each path in prefixes, whether the "prefix"
0454dd93 DR	582	* is an ancestor directory of path. Returns the length of the longest
0454dd93 DR	583	* ancestor directory, excluding any trailing slashes, or -1 if no prefix
31171d9e MH	584	* is an ancestor. (Note that this means 0 is returned if prefixes is
31171d9e MH	585	* ["/"].) "/foo" is not considered an ancestor of "/foobar". Directories
0454dd93 DR	586	* are not considered to be their own ancestors. path must be in a
0454dd93 DR	587	* canonical form: empty components, or "." or ".." components are not
9e2326c7	588	* allowed.
0454dd93	589	*/
31171d9e	590	int longest_ancestor_length(const char path, struct string_list prefixes)
0454dd93	591	{
a5ccdbe4	592	int i, max_len = -1;
0454dd93	593
31171d9e	594	if (!strcmp(path, "/"))
0454dd93 DR	595	return -1;
0454dd93 DR	596
31171d9e MH	597	for (i = 0; i < prefixes->nr; i++) {
31171d9e MH	598	const char *ceil = prefixes->items[i].string;
a5ccdbe4 MH	599	int len = strlen(ceil);
a5ccdbe4 MH	600
9e2326c7 MH	601	if (len == 1 && ceil[0] == '/')
	602	len = 0; /* root matches anything, with length 0 */
	603	else if (!strncmp(path, ceil, len) && path[len] == '/')
	604	; /* match of length len */
	605	else
	606	continue; /* no match */
0454dd93	607
9e2326c7	608	if (len > max_len)
0454dd93	609	max_len = len;
0454dd93 DR	610	}
	611
	612	return max_len;
	613	}
4fcc86b0 JS	614
	615	/* strip arbitrary amount of directory separators at end of path */
	616	static inline int chomp_trailing_dir_sep(const char *path, int len)
	617	{
	618	while (len && is_dir_sep(path[len - 1]))
	619	len--;
	620	return len;
	621	}
	622
	623	/*
	624	* If path ends with suffix (complete path components), returns the
	625	* part before suffix (sans trailing directory separators).
	626	* Otherwise returns NULL.
	627	*/
	628	char strip_path_suffix(const char path, const char *suffix)
	629	{
	630	int path_len = strlen(path), suffix_len = strlen(suffix);
	631
	632	while (suffix_len) {
	633	if (!path_len)
	634	return NULL;
	635
	636	if (is_dir_sep(path[path_len - 1])) {
	637	if (!is_dir_sep(suffix[suffix_len - 1]))
	638	return NULL;
	639	path_len = chomp_trailing_dir_sep(path, path_len);
	640	suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
	641	}
	642	else if (path[--path_len] != suffix[--suffix_len])
	643	return NULL;
	644	}
	645
	646	if (path_len && !is_dir_sep(path[path_len - 1]))
	647	return NULL;
	648	return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
	649	}
34b6cb8b SP	650
	651	int daemon_avoid_alias(const char *p)
	652	{
	653	int sl, ndot;
	654
	655	/*
	656	* This resurrects the belts and suspenders paranoia check by HPA
	657	* done in <435560F7.4080006@zytor.com> thread, now enter_repo()
9517e6b8	658	* does not do getcwd() based path canonicalization.
34b6cb8b SP	659	*
	660	* sl becomes true immediately after seeing '/' and continues to
	661	* be true as long as dots continue after that without intervening
	662	* non-dot character.
	663	*/
	664	if (!p \|\| (p != '/' && p != '~'))
	665	return -1;
	666	sl = 1; ndot = 0;
	667	p++;
	668
	669	while (1) {
	670	char ch = *p++;
	671	if (sl) {
	672	if (ch == '.')
	673	ndot++;
	674	else if (ch == '/') {
	675	if (ndot < 3)
	676	/* reject //, /./ and /../ */
	677	return -1;
	678	ndot = 0;
	679	}
	680	else if (ch == 0) {
	681	if (0 < ndot && ndot < 3)
	682	/* reject /.$ and /..$ */
	683	return -1;
	684	return 0;
	685	}
	686	else
	687	sl = ndot = 0;
	688	}
	689	else if (ch == 0)
	690	return 0;
	691	else if (ch == '/') {
	692	sl = 1;
	693	ndot = 0;
	694	}
	695	}
	696	}
4bb43de2 NTND	697
	698	int offset_1st_component(const char *path)
	699	{
	700	if (has_dos_drive_prefix(path))
	701	return 2 + is_dir_sep(path[2]);
	702	return is_dir_sep(path[0]);
	703	}