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	#include "cache.h"

	static int threaded_check_leading_path(struct cache_def cache, const char name,
	int len, int warn_on_lstat_err);
	static int threaded_has_dirs_only_path(struct cache_def cache, const char name, int len, int prefix_len);

	/*
	* Returns the length (on a path component basis) of the longest
	* common prefix match of 'name_a' and 'name_b'.
	*/
	static int longest_path_match(const char *name_a, int len_a,
	const char *name_b, int len_b,
	int *previous_slash)
	{
	int max_len, match_len = 0, match_len_prev = 0, i = 0;

	max_len = len_a < len_b ? len_a : len_b;
	while (i < max_len && name_a[i] == name_b[i]) {
	if (name_a[i] == '/') {
	match_len_prev = match_len;
	match_len = i;
	}
	i++;
	}
	/*
	* Is 'name_b' a substring of 'name_a', the other way around,
	* or is 'name_a' and 'name_b' the exact same string?
	*/
	if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') \|\|
	(len_a < len_b && name_b[len_a] == '/') \|\|
	(len_a == len_b))) {
	match_len_prev = match_len;
	match_len = i;
	}
	*previous_slash = match_len_prev;
	return match_len;
	}

	static struct cache_def default_cache = CACHE_DEF_INIT;

	static inline void reset_lstat_cache(struct cache_def *cache)
	{
	strbuf_reset(&cache->path);
	cache->flags = 0;
	/*
	* The track_flags and prefix_len_stat_func members is only
	* set by the safeguard rule inside lstat_cache()
	*/
	}

	#define FL_DIR (1 << 0)
	#define FL_NOENT (1 << 1)
	#define FL_SYMLINK (1 << 2)
	#define FL_LSTATERR (1 << 3)
	#define FL_ERR (1 << 4)
	#define FL_FULLPATH (1 << 5)

	/*
	* Check if name 'name' of length 'len' has a symlink leading
	* component, or if the directory exists and is real, or not.
	*
	* To speed up the check, some information is allowed to be cached.
	* This can be indicated by the 'track_flags' argument, which also can
	* be used to indicate that we should check the full path.
	*
	* The 'prefix_len_stat_func' parameter can be used to set the length
	* of the prefix, where the cache should use the stat() function
	* instead of the lstat() function to test each path component.
	*/
	static int lstat_cache_matchlen(struct cache_def *cache,
	const char *name, int len,
	int *ret_flags, int track_flags,
	int prefix_len_stat_func)
	{
	int match_len, last_slash, last_slash_dir, previous_slash;
	int save_flags, ret, saved_errno = 0;
	struct stat st;

	if (cache->track_flags != track_flags \|\|
	cache->prefix_len_stat_func != prefix_len_stat_func) {
	/*
	* As a safeguard rule we clear the cache if the
	* values of track_flags and/or prefix_len_stat_func
	* does not match with the last supplied values.
	*/
	reset_lstat_cache(cache);
	cache->track_flags = track_flags;
	cache->prefix_len_stat_func = prefix_len_stat_func;
	match_len = last_slash = 0;
	} else {
	/*
	* Check to see if we have a match from the cache for
	* the 2 "excluding" path types.
	*/
	match_len = last_slash =
	longest_path_match(name, len, cache->path.buf,
	cache->path.len, &previous_slash);
	*ret_flags = cache->flags & track_flags & (FL_NOENT\|FL_SYMLINK);

	if (!(track_flags & FL_FULLPATH) && match_len == len)
	match_len = last_slash = previous_slash;

	if (*ret_flags && match_len == cache->path.len)
	return match_len;
	/*
	* If we now have match_len > 0, we would know that
	* the matched part will always be a directory.
	*
	* Also, if we are tracking directories and 'name' is
	* a substring of the cache on a path component basis,
	* we can return immediately.
	*/
	*ret_flags = track_flags & FL_DIR;
	if (*ret_flags && len == match_len)
	return match_len;
	}

	/*
	* Okay, no match from the cache so far, so now we have to
	* check the rest of the path components.
	*/
	*ret_flags = FL_DIR;
	last_slash_dir = last_slash;
	if (len > cache->path.len)
	strbuf_grow(&cache->path, len - cache->path.len);
	while (match_len < len) {
	do {
	cache->path.buf[match_len] = name[match_len];
	match_len++;
	} while (match_len < len && name[match_len] != '/');
	if (match_len >= len && !(track_flags & FL_FULLPATH))
	break;
	last_slash = match_len;
	cache->path.buf[last_slash] = '\0';

	if (last_slash <= prefix_len_stat_func)
	ret = stat(cache->path.buf, &st);
	else
	ret = lstat(cache->path.buf, &st);

	if (ret) {
	*ret_flags = FL_LSTATERR;
	saved_errno = errno;
	if (errno == ENOENT)
	*ret_flags \|= FL_NOENT;
	} else if (S_ISDIR(st.st_mode)) {
	last_slash_dir = last_slash;
	continue;
	} else if (S_ISLNK(st.st_mode)) {
	*ret_flags = FL_SYMLINK;
	} else {
	*ret_flags = FL_ERR;
	}
	break;
	}

	/*
	* At the end update the cache. Note that max 3 different
	* path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
	* for the moment!
	*/
	save_flags = *ret_flags & track_flags & (FL_NOENT\|FL_SYMLINK);
	if (save_flags && last_slash > 0) {
	cache->path.buf[last_slash] = '\0';
	cache->path.len = last_slash;
	cache->flags = save_flags;
	} else if ((track_flags & FL_DIR) && last_slash_dir > 0) {
	/*
	* We have a separate test for the directory case,
	* since it could be that we have found a symlink or a
	* non-existing directory and the track_flags says
	* that we cannot cache this fact, so the cache would
	* then have been left empty in this case.
	*
	* But if we are allowed to track real directories, we
	* can still cache the path components before the last
	* one (the found symlink or non-existing component).
	*/
	cache->path.buf[last_slash_dir] = '\0';
	cache->path.len = last_slash_dir;
	cache->flags = FL_DIR;
	} else {
	reset_lstat_cache(cache);
	}
	if (saved_errno)
	errno = saved_errno;
	return match_len;
	}

	static int lstat_cache(struct cache_def cache, const char name, int len,
	int track_flags, int prefix_len_stat_func)
	{
	int flags;
	(void)lstat_cache_matchlen(cache, name, len, &flags, track_flags,
	prefix_len_stat_func);
	return flags;
	}

	#define USE_ONLY_LSTAT 0

	/*
	* Return non-zero if path 'name' has a leading symlink component
	*/
	int threaded_has_symlink_leading_path(struct cache_def cache, const char name, int len)
	{
	return lstat_cache(cache, name, len, FL_SYMLINK\|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
	}

	int has_symlink_leading_path(const char *name, int len)
	{
	return threaded_has_symlink_leading_path(&default_cache, name, len);
	}

	int check_leading_path(const char *name, int len, int warn_on_lstat_err)
	{
	return threaded_check_leading_path(&default_cache, name, len,
	warn_on_lstat_err);
	}

	/*
	* Return zero if some leading path component of 'name' does not exist.
	*
	* Return -1 if leading path exists and is a directory.
	*
	* Return the length of a leading component if it either exists but it's not a
	* directory, or if we were unable to lstat() it. If warn_on_lstat_err is true,
	* also emit a warning for this error.
	*/
	static int threaded_check_leading_path(struct cache_def cache, const char name,
	int len, int warn_on_lstat_err)
	{
	int flags;
	int match_len = lstat_cache_matchlen(cache, name, len, &flags,
	FL_SYMLINK\|FL_NOENT\|FL_DIR, USE_ONLY_LSTAT);
	int saved_errno = errno;

	if (flags & FL_NOENT)
	return 0;
	else if (flags & FL_DIR)
	return -1;
	if (warn_on_lstat_err && (flags & FL_LSTATERR)) {
	char *path = xmemdupz(name, match_len);
	errno = saved_errno;
	warning_errno(_("failed to lstat '%s'"), path);
	free(path);
	}
	return match_len;
	}

	int has_dirs_only_path(const char *name, int len, int prefix_len)
	{
	return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
	}

	/*
	* Return non-zero if all path components of 'name' exists as a
	* directory. If prefix_len > 0, we will test with the stat()
	* function instead of the lstat() function for a prefix length of
	* 'prefix_len', thus we then allow for symlinks in the prefix part as
	* long as those points to real existing directories.
	*/
	static int threaded_has_dirs_only_path(struct cache_def cache, const char name, int len, int prefix_len)
	{
	/*
	* Note: this function is used by the checkout machinery, which also
	* takes care to properly reset the cache when it performs an operation
	* that would leave the cache outdated. If this function starts caching
	* anything else besides FL_DIR, remember to also invalidate the cache
	* when creating or deleting paths that might be in the cache.
	*/
	return lstat_cache(cache, name, len,
	FL_DIR\|FL_FULLPATH, prefix_len) &
	FL_DIR;
	}

	static struct strbuf removal = STRBUF_INIT;

	static void do_remove_scheduled_dirs(int new_len)
	{
	while (removal.len > new_len) {
	removal.buf[removal.len] = '\0';
	if (rmdir(removal.buf))
	break;
	do {
	removal.len--;
	} while (removal.len > new_len &&
	removal.buf[removal.len] != '/');
	}
	removal.len = new_len;
	}

	void schedule_dir_for_removal(const char *name, int len)
	{
	int match_len, last_slash, i, previous_slash;

	match_len = last_slash = i =
	longest_path_match(name, len, removal.buf, removal.len,
	&previous_slash);
	/* Find last slash inside 'name' */
	while (i < len) {
	if (name[i] == '/')
	last_slash = i;
	i++;
	}

	/*
	* If we are about to go down the directory tree, we check if
	* we must first go upwards the tree, such that we then can
	* remove possible empty directories as we go upwards.
	*/
	if (match_len < last_slash && match_len < removal.len)
	do_remove_scheduled_dirs(match_len);
	/*
	* If we go deeper down the directory tree, we only need to
	* save the new path components as we go down.
	*/
	if (match_len < last_slash)
	strbuf_add(&removal, &name[match_len], last_slash - match_len);
	}

	void remove_scheduled_dirs(void)
	{
	do_remove_scheduled_dirs(0);
	}

	void invalidate_lstat_cache(void)
	{
	reset_lstat_cache(&default_cache);
	}

	#undef rmdir
	int lstat_cache_aware_rmdir(const char *path)
	{
	/* Any change in this function must be made also in `mingw_rmdir()` */
	int ret = rmdir(path);

	if (!ret)
	invalidate_lstat_cache();

	return ret;
	}

git / git

git/symlinks.c