Documentation/perf_counter/path.c - maze/linux - 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.perf", base, name), O_RDONLY);
  *
  * which is what it's designed for.
  */
 #include "cache.h"

 static char bad_path[] = "/bad-path/";
 /*
  * Two hacks:
  */

 static char *get_perf_dir(void)
 {
 	return ".";
 }

 size_t strlcpy(char *dest, const char *src, size_t size)
 {
 	size_t ret = strlen(src);

 	if (size) {
 		size_t len = (ret >= size) ? size - 1 : ret;
 		memcpy(dest, src, len);
 		dest[len] = '\0';
 	}
 	return ret;
 }


 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 *perf_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
 {
 	const char *perf_dir = get_perf_dir();
 	size_t len;

 	len = strlen(perf_dir);
 	if (n < len + 1)
 		goto bad;
 	memcpy(buf, perf_dir, len);
 	if (len && !is_dir_sep(perf_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 *perf_snpath(char *buf, size_t n, const char *fmt, ...)
 {
 	va_list args;
 	va_start(args, fmt);
 	(void)perf_vsnpath(buf, n, fmt, args);
 	va_end(args);
 	return buf;
 }

 char *perf_pathdup(const char *fmt, ...)
 {
 	char path[PATH_MAX];
 	va_list args;
 	va_start(args, fmt);
 	(void)perf_vsnpath(path, sizeof(path), fmt, args);
 	va_end(args);
 	return xstrdup(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 *perf_path(const char *fmt, ...)
 {
 	const char *perf_dir = get_perf_dir();
 	char *pathname = get_pathname();
 	va_list args;
 	unsigned len;

 	len = strlen(perf_dir);
 	if (len > PATH_MAX-100)
 		return bad_path;
 	memcpy(pathname, perf_dir, len);
 	if (len && perf_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);
 }


 /* perf_mkstemp() - create tmp file honoring TMPDIR variable */
 int perf_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);
 }


 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;
 }

 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;
 }

 /*
  * 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
  * 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 != PATH_SEP; colon++);
 		len = colon - ceil;
 		if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
 			continue;
 		strlcpy(buf, ceil, len+1);
 		if (normalize_path_copy(buf, buf) < 0)
 			continue;
 		len = strlen(buf);
 		if (len > 0 && buf[len-1] == '/')
 			buf[--len] = '\0';

 		if (!strncmp(path, buf, len) &&
 		    path[len] == '/' &&
 		    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));
 }
	/*
	* 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.perf", base, name), O_RDONLY);
	*
	* which is what it's designed for.
	*/
	#include "cache.h"

	static char bad_path[] = "/bad-path/";
	/*
	* Two hacks:
	*/

	static char *get_perf_dir(void)
	{
	return ".";
	}

	size_t strlcpy(char dest, const char src, size_t size)
	{
	size_t ret = strlen(src);

	if (size) {
	size_t len = (ret >= size) ? size - 1 : ret;
	memcpy(dest, src, len);
	dest[len] = '\0';
	}
	return ret;
	}


	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 perf_vsnpath(char buf, size_t n, const char *fmt, va_list args)
	{
	const char *perf_dir = get_perf_dir();
	size_t len;

	len = strlen(perf_dir);
	if (n < len + 1)
	goto bad;
	memcpy(buf, perf_dir, len);
	if (len && !is_dir_sep(perf_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 perf_snpath(char buf, size_t n, const char *fmt, ...)
	{
	va_list args;
	va_start(args, fmt);
	(void)perf_vsnpath(buf, n, fmt, args);
	va_end(args);
	return buf;
	}

	char perf_pathdup(const char fmt, ...)
	{
	char path[PATH_MAX];
	va_list args;
	va_start(args, fmt);
	(void)perf_vsnpath(path, sizeof(path), fmt, args);
	va_end(args);
	return xstrdup(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 perf_path(const char fmt, ...)
	{
	const char *perf_dir = get_perf_dir();
	char *pathname = get_pathname();
	va_list args;
	unsigned len;

	len = strlen(perf_dir);
	if (len > PATH_MAX-100)
	return bad_path;
	memcpy(pathname, perf_dir, len);
	if (len && perf_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);
	}


	/* perf_mkstemp() - create tmp file honoring TMPDIR variable */
	int perf_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);
	}


	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;
	}

	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;
	}

	/*
	* 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
	* 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 != PATH_SEP; colon++);
	len = colon - ceil;
	if (len == 0 \|\| len > PATH_MAX \|\| !is_absolute_path(ceil))
	continue;
	strlcpy(buf, ceil, len+1);
	if (normalize_path_copy(buf, buf) < 0)
	continue;
	len = strlen(buf);
	if (len > 0 && buf[len-1] == '/')
	buf[--len] = '\0';

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