Merge branch 'maint'
[git.git] / symlinks.c
blob5261e8cf499006c1d84fc42a3e96e4dee7f09ba1
1 #include "cache.h"
3 static int threaded_check_leading_path(struct cache_def *cache, const char *name, int len);
4 static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len);
6 /*
7 * Returns the length (on a path component basis) of the longest
8 * common prefix match of 'name_a' and 'name_b'.
9 */
10 static int longest_path_match(const char *name_a, int len_a,
11 const char *name_b, int len_b,
12 int *previous_slash)
14 int max_len, match_len = 0, match_len_prev = 0, i = 0;
16 max_len = len_a < len_b ? len_a : len_b;
17 while (i < max_len && name_a[i] == name_b[i]) {
18 if (name_a[i] == '/') {
19 match_len_prev = match_len;
20 match_len = i;
22 i++;
25 * Is 'name_b' a substring of 'name_a', the other way around,
26 * or is 'name_a' and 'name_b' the exact same string?
28 if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
29 (len_a < len_b && name_b[len_a] == '/') ||
30 (len_a == len_b))) {
31 match_len_prev = match_len;
32 match_len = i;
34 *previous_slash = match_len_prev;
35 return match_len;
38 static struct cache_def default_cache = CACHE_DEF_INIT;
40 static inline void reset_lstat_cache(struct cache_def *cache)
42 strbuf_reset(&cache->path);
43 cache->flags = 0;
45 * The track_flags and prefix_len_stat_func members is only
46 * set by the safeguard rule inside lstat_cache()
50 #define FL_DIR (1 << 0)
51 #define FL_NOENT (1 << 1)
52 #define FL_SYMLINK (1 << 2)
53 #define FL_LSTATERR (1 << 3)
54 #define FL_ERR (1 << 4)
55 #define FL_FULLPATH (1 << 5)
58 * Check if name 'name' of length 'len' has a symlink leading
59 * component, or if the directory exists and is real, or not.
61 * To speed up the check, some information is allowed to be cached.
62 * This can be indicated by the 'track_flags' argument, which also can
63 * be used to indicate that we should check the full path.
65 * The 'prefix_len_stat_func' parameter can be used to set the length
66 * of the prefix, where the cache should use the stat() function
67 * instead of the lstat() function to test each path component.
69 static int lstat_cache_matchlen(struct cache_def *cache,
70 const char *name, int len,
71 int *ret_flags, int track_flags,
72 int prefix_len_stat_func)
74 int match_len, last_slash, last_slash_dir, previous_slash;
75 int save_flags, ret;
76 struct stat st;
78 if (cache->track_flags != track_flags ||
79 cache->prefix_len_stat_func != prefix_len_stat_func) {
81 * As a safeguard rule we clear the cache if the
82 * values of track_flags and/or prefix_len_stat_func
83 * does not match with the last supplied values.
85 reset_lstat_cache(cache);
86 cache->track_flags = track_flags;
87 cache->prefix_len_stat_func = prefix_len_stat_func;
88 match_len = last_slash = 0;
89 } else {
91 * Check to see if we have a match from the cache for
92 * the 2 "excluding" path types.
94 match_len = last_slash =
95 longest_path_match(name, len, cache->path.buf,
96 cache->path.len, &previous_slash);
97 *ret_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
99 if (!(track_flags & FL_FULLPATH) && match_len == len)
100 match_len = last_slash = previous_slash;
102 if (*ret_flags && match_len == cache->path.len)
103 return match_len;
105 * If we now have match_len > 0, we would know that
106 * the matched part will always be a directory.
108 * Also, if we are tracking directories and 'name' is
109 * a substring of the cache on a path component basis,
110 * we can return immediately.
112 *ret_flags = track_flags & FL_DIR;
113 if (*ret_flags && len == match_len)
114 return match_len;
118 * Okay, no match from the cache so far, so now we have to
119 * check the rest of the path components.
121 *ret_flags = FL_DIR;
122 last_slash_dir = last_slash;
123 if (len > cache->path.len)
124 strbuf_grow(&cache->path, len - cache->path.len);
125 while (match_len < len) {
126 do {
127 cache->path.buf[match_len] = name[match_len];
128 match_len++;
129 } while (match_len < len && name[match_len] != '/');
130 if (match_len >= len && !(track_flags & FL_FULLPATH))
131 break;
132 last_slash = match_len;
133 cache->path.buf[last_slash] = '\0';
135 if (last_slash <= prefix_len_stat_func)
136 ret = stat(cache->path.buf, &st);
137 else
138 ret = lstat(cache->path.buf, &st);
140 if (ret) {
141 *ret_flags = FL_LSTATERR;
142 if (errno == ENOENT)
143 *ret_flags |= FL_NOENT;
144 } else if (S_ISDIR(st.st_mode)) {
145 last_slash_dir = last_slash;
146 continue;
147 } else if (S_ISLNK(st.st_mode)) {
148 *ret_flags = FL_SYMLINK;
149 } else {
150 *ret_flags = FL_ERR;
152 break;
156 * At the end update the cache. Note that max 3 different
157 * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
158 * for the moment!
160 save_flags = *ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
161 if (save_flags && last_slash > 0) {
162 cache->path.buf[last_slash] = '\0';
163 cache->path.len = last_slash;
164 cache->flags = save_flags;
165 } else if ((track_flags & FL_DIR) && last_slash_dir > 0) {
167 * We have a separate test for the directory case,
168 * since it could be that we have found a symlink or a
169 * non-existing directory and the track_flags says
170 * that we cannot cache this fact, so the cache would
171 * then have been left empty in this case.
173 * But if we are allowed to track real directories, we
174 * can still cache the path components before the last
175 * one (the found symlink or non-existing component).
177 cache->path.buf[last_slash_dir] = '\0';
178 cache->path.len = last_slash_dir;
179 cache->flags = FL_DIR;
180 } else {
181 reset_lstat_cache(cache);
183 return match_len;
186 static int lstat_cache(struct cache_def *cache, const char *name, int len,
187 int track_flags, int prefix_len_stat_func)
189 int flags;
190 (void)lstat_cache_matchlen(cache, name, len, &flags, track_flags,
191 prefix_len_stat_func);
192 return flags;
195 #define USE_ONLY_LSTAT 0
198 * Return non-zero if path 'name' has a leading symlink component
200 int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
202 return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
206 * Return non-zero if path 'name' has a leading symlink component
208 int has_symlink_leading_path(const char *name, int len)
210 return threaded_has_symlink_leading_path(&default_cache, name, len);
214 * Return zero if path 'name' has a leading symlink component or
215 * if some leading path component does not exists.
217 * Return -1 if leading path exists and is a directory.
219 * Return path length if leading path exists and is neither a
220 * directory nor a symlink.
222 int check_leading_path(const char *name, int len)
224 return threaded_check_leading_path(&default_cache, name, len);
228 * Return zero if path 'name' has a leading symlink component or
229 * if some leading path component does not exists.
231 * Return -1 if leading path exists and is a directory.
233 * Return path length if leading path exists and is neither a
234 * directory nor a symlink.
236 static int threaded_check_leading_path(struct cache_def *cache, const char *name, int len)
238 int flags;
239 int match_len = lstat_cache_matchlen(cache, name, len, &flags,
240 FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
241 if (flags & FL_NOENT)
242 return 0;
243 else if (flags & FL_DIR)
244 return -1;
245 else
246 return match_len;
250 * Return non-zero if all path components of 'name' exists as a
251 * directory. If prefix_len > 0, we will test with the stat()
252 * function instead of the lstat() function for a prefix length of
253 * 'prefix_len', thus we then allow for symlinks in the prefix part as
254 * long as those points to real existing directories.
256 int has_dirs_only_path(const char *name, int len, int prefix_len)
258 return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
262 * Return non-zero if all path components of 'name' exists as a
263 * directory. If prefix_len > 0, we will test with the stat()
264 * function instead of the lstat() function for a prefix length of
265 * 'prefix_len', thus we then allow for symlinks in the prefix part as
266 * long as those points to real existing directories.
268 static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len)
270 return lstat_cache(cache, name, len,
271 FL_DIR|FL_FULLPATH, prefix_len) &
272 FL_DIR;
275 static struct strbuf removal = STRBUF_INIT;
277 static void do_remove_scheduled_dirs(int new_len)
279 while (removal.len > new_len) {
280 removal.buf[removal.len] = '\0';
281 if (rmdir(removal.buf))
282 break;
283 do {
284 removal.len--;
285 } while (removal.len > new_len &&
286 removal.buf[removal.len] != '/');
288 removal.len = new_len;
291 void schedule_dir_for_removal(const char *name, int len)
293 int match_len, last_slash, i, previous_slash;
295 match_len = last_slash = i =
296 longest_path_match(name, len, removal.buf, removal.len,
297 &previous_slash);
298 /* Find last slash inside 'name' */
299 while (i < len) {
300 if (name[i] == '/')
301 last_slash = i;
302 i++;
306 * If we are about to go down the directory tree, we check if
307 * we must first go upwards the tree, such that we then can
308 * remove possible empty directories as we go upwards.
310 if (match_len < last_slash && match_len < removal.len)
311 do_remove_scheduled_dirs(match_len);
313 * If we go deeper down the directory tree, we only need to
314 * save the new path components as we go down.
316 if (match_len < last_slash)
317 strbuf_add(&removal, &name[match_len], last_slash - match_len);
320 void remove_scheduled_dirs(void)
322 do_remove_scheduled_dirs(0);