path.c - jrn/git - Git at Google

 /*
  * 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 *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 = (mode & ~0777) | 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;
 }

 static const char *get_pwd_cwd(void)
 {
 	static char cwd[PATH_MAX + 1];
 	char *pwd;
 	struct stat cwd_stat, pwd_stat;
 	if (getcwd(cwd, PATH_MAX) == NULL)
 		return NULL;
 	pwd = getenv("PWD");
 	if (pwd && strcmp(pwd, cwd)) {
 		stat(cwd, &cwd_stat);
 		if (!stat(pwd, &pwd_stat) &&
 		    pwd_stat.st_dev == cwd_stat.st_dev &&
 		    pwd_stat.st_ino == cwd_stat.st_ino) {
 			strlcpy(cwd, pwd, PATH_MAX);
 		}
 	}
 	return cwd;
 }

 const char *make_nonrelative_path(const char *path)
 {
 	static char buf[PATH_MAX + 1];

 	if (is_absolute_path(path)) {
 		if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 			die ("Too long path: %.*s", 60, path);
 	} else {
 		const char *cwd = get_pwd_cwd();
 		if (!cwd)
 			die("Cannot determine the current working directory");
 		if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX)
 			die ("Too long path: %.*s", 60, path);
 	}
 	return buf;
 }

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

 const char *make_absolute_path(const char *path)
 {
 	static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
 	char cwd[1024] = "";
 	int buf_index = 1, len;

 	int depth = MAXDEPTH;
 	char *last_elem = NULL;
 	struct stat st;

 	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
 		die ("Too long path: %.*s", 60, path);

 	while (depth--) {
 		if (stat(buf, &st) || !S_ISDIR(st.st_mode)) {
 			char *last_slash = strrchr(buf, '/');
 			if (last_slash) {
 				*last_slash = '\0';
 				last_elem = xstrdup(last_slash + 1);
 			} else {
 				last_elem = xstrdup(buf);
 				*buf = '\0';
 			}
 		}

 		if (*buf) {
 			if (!*cwd && !getcwd(cwd, sizeof(cwd)))
 				die ("Could not get current working directory");

 			if (chdir(buf))
 				die ("Could not switch to '%s'", buf);
 		}
 		if (!getcwd(buf, PATH_MAX))
 			die ("Could not get current working directory");

 		if (last_elem) {
 			int len = strlen(buf);
 			if (len + strlen(last_elem) + 2 > PATH_MAX)
 				die ("Too long path name: '%s/%s'",
 						buf, last_elem);
 			buf[len] = '/';
 			strcpy(buf + len + 1, last_elem);
 			free(last_elem);
 			last_elem = NULL;
 		}

 		if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
 			len = readlink(buf, next_buf, PATH_MAX);
 			if (len < 0)
 				die ("Invalid symlink: %s", buf);
 			next_buf[len] = '\0';
 			buf = next_buf;
 			buf_index = 1 - buf_index;
 			next_buf = bufs[buf_index];
 		} else
 			break;
 	}

 	if (*cwd && chdir(cwd))
 		die ("Could not change back to '%s'", cwd);

 	return buf;
 }
	/*
	* 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 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 = (mode & ~0777) \| 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;
	}

	static const char *get_pwd_cwd(void)
	{
	static char cwd[PATH_MAX + 1];
	char *pwd;
	struct stat cwd_stat, pwd_stat;
	if (getcwd(cwd, PATH_MAX) == NULL)
	return NULL;
	pwd = getenv("PWD");
	if (pwd && strcmp(pwd, cwd)) {
	stat(cwd, &cwd_stat);
	if (!stat(pwd, &pwd_stat) &&
	pwd_stat.st_dev == cwd_stat.st_dev &&
	pwd_stat.st_ino == cwd_stat.st_ino) {
	strlcpy(cwd, pwd, PATH_MAX);
	}
	}
	return cwd;
	}

	const char make_nonrelative_path(const char path)
	{
	static char buf[PATH_MAX + 1];

	if (is_absolute_path(path)) {
	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
	die ("Too long path: %.*s", 60, path);
	} else {
	const char *cwd = get_pwd_cwd();
	if (!cwd)
	die("Cannot determine the current working directory");
	if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX)
	die ("Too long path: %.*s", 60, path);
	}
	return buf;
	}

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

	const char make_absolute_path(const char path)
	{
	static char bufs[2][PATH_MAX + 1], buf = bufs[0], next_buf = bufs[1];
	char cwd[1024] = "";
	int buf_index = 1, len;

	int depth = MAXDEPTH;
	char *last_elem = NULL;
	struct stat st;

	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
	die ("Too long path: %.*s", 60, path);

	while (depth--) {
	if (stat(buf, &st) \|\| !S_ISDIR(st.st_mode)) {
	char *last_slash = strrchr(buf, '/');
	if (last_slash) {
	*last_slash = '\0';
	last_elem = xstrdup(last_slash + 1);
	} else {
	last_elem = xstrdup(buf);
	*buf = '\0';
	}
	}

	if (*buf) {
	if (!*cwd && !getcwd(cwd, sizeof(cwd)))
	die ("Could not get current working directory");

	if (chdir(buf))
	die ("Could not switch to '%s'", buf);
	}
	if (!getcwd(buf, PATH_MAX))
	die ("Could not get current working directory");

	if (last_elem) {
	int len = strlen(buf);
	if (len + strlen(last_elem) + 2 > PATH_MAX)
	die ("Too long path name: '%s/%s'",
	buf, last_elem);
	buf[len] = '/';
	strcpy(buf + len + 1, last_elem);
	free(last_elem);
	last_elem = NULL;
	}

	if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
	len = readlink(buf, next_buf, PATH_MAX);
	if (len < 0)
	die ("Invalid symlink: %s", buf);
	next_buf[len] = '\0';
	buf = next_buf;
	buf_index = 1 - buf_index;
	next_buf = bufs[buf_index];
	} else
	break;
	}

	if (*cwd && chdir(cwd))
	die ("Could not change back to '%s'", cwd);

	return buf;
	}