Merge branch 'jk/maint-http-half-auth-push' into maint
[git.git] / symlinks.c
blob290036744bcfd390f91e75db49bf620bb12c12ea
1 #include "cache.h"
3 /*
4 * Returns the length (on a path component basis) of the longest
5 * common prefix match of 'name_a' and 'name_b'.
6 */
7 static int longest_path_match(const char *name_a, int len_a,
8 const char *name_b, int len_b,
9 int *previous_slash)
11 int max_len, match_len = 0, match_len_prev = 0, i = 0;
13 max_len = len_a < len_b ? len_a : len_b;
14 while (i < max_len && name_a[i] == name_b[i]) {
15 if (name_a[i] == '/') {
16 match_len_prev = match_len;
17 match_len = i;
19 i++;
22 * Is 'name_b' a substring of 'name_a', the other way around,
23 * or is 'name_a' and 'name_b' the exact same string?
25 if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
26 (len_a < len_b && name_b[len_a] == '/') ||
27 (len_a == len_b))) {
28 match_len_prev = match_len;
29 match_len = i;
31 *previous_slash = match_len_prev;
32 return match_len;
35 static struct cache_def default_cache;
37 static inline void reset_lstat_cache(struct cache_def *cache)
39 cache->path[0] = '\0';
40 cache->len = 0;
41 cache->flags = 0;
43 * The track_flags and prefix_len_stat_func members is only
44 * set by the safeguard rule inside lstat_cache()
48 #define FL_DIR (1 << 0)
49 #define FL_NOENT (1 << 1)
50 #define FL_SYMLINK (1 << 2)
51 #define FL_LSTATERR (1 << 3)
52 #define FL_ERR (1 << 4)
53 #define FL_FULLPATH (1 << 5)
56 * Check if name 'name' of length 'len' has a symlink leading
57 * component, or if the directory exists and is real, or not.
59 * To speed up the check, some information is allowed to be cached.
60 * This can be indicated by the 'track_flags' argument, which also can
61 * be used to indicate that we should check the full path.
63 * The 'prefix_len_stat_func' parameter can be used to set the length
64 * of the prefix, where the cache should use the stat() function
65 * instead of the lstat() function to test each path component.
67 static int lstat_cache_matchlen(struct cache_def *cache,
68 const char *name, int len,
69 int *ret_flags, int track_flags,
70 int prefix_len_stat_func)
72 int match_len, last_slash, last_slash_dir, previous_slash;
73 int save_flags, max_len, ret;
74 struct stat st;
76 if (cache->track_flags != track_flags ||
77 cache->prefix_len_stat_func != prefix_len_stat_func) {
79 * As a safeguard rule we clear the cache if the
80 * values of track_flags and/or prefix_len_stat_func
81 * does not match with the last supplied values.
83 reset_lstat_cache(cache);
84 cache->track_flags = track_flags;
85 cache->prefix_len_stat_func = prefix_len_stat_func;
86 match_len = last_slash = 0;
87 } else {
89 * Check to see if we have a match from the cache for
90 * the 2 "excluding" path types.
92 match_len = last_slash =
93 longest_path_match(name, len, cache->path, cache->len,
94 &previous_slash);
95 *ret_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
97 if (!(track_flags & FL_FULLPATH) && match_len == len)
98 match_len = last_slash = previous_slash;
100 if (*ret_flags && match_len == cache->len)
101 return match_len;
103 * If we now have match_len > 0, we would know that
104 * the matched part will always be a directory.
106 * Also, if we are tracking directories and 'name' is
107 * a substring of the cache on a path component basis,
108 * we can return immediately.
110 *ret_flags = track_flags & FL_DIR;
111 if (*ret_flags && len == match_len)
112 return match_len;
116 * Okay, no match from the cache so far, so now we have to
117 * check the rest of the path components.
119 *ret_flags = FL_DIR;
120 last_slash_dir = last_slash;
121 max_len = len < PATH_MAX ? len : PATH_MAX;
122 while (match_len < max_len) {
123 do {
124 cache->path[match_len] = name[match_len];
125 match_len++;
126 } while (match_len < max_len && name[match_len] != '/');
127 if (match_len >= max_len && !(track_flags & FL_FULLPATH))
128 break;
129 last_slash = match_len;
130 cache->path[last_slash] = '\0';
132 if (last_slash <= prefix_len_stat_func)
133 ret = stat(cache->path, &st);
134 else
135 ret = lstat(cache->path, &st);
137 if (ret) {
138 *ret_flags = FL_LSTATERR;
139 if (errno == ENOENT)
140 *ret_flags |= FL_NOENT;
141 } else if (S_ISDIR(st.st_mode)) {
142 last_slash_dir = last_slash;
143 continue;
144 } else if (S_ISLNK(st.st_mode)) {
145 *ret_flags = FL_SYMLINK;
146 } else {
147 *ret_flags = FL_ERR;
149 break;
153 * At the end update the cache. Note that max 3 different
154 * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
155 * for the moment!
157 save_flags = *ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
158 if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
159 cache->path[last_slash] = '\0';
160 cache->len = last_slash;
161 cache->flags = save_flags;
162 } else if ((track_flags & FL_DIR) &&
163 last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
165 * We have a separate test for the directory case,
166 * since it could be that we have found a symlink or a
167 * non-existing directory and the track_flags says
168 * that we cannot cache this fact, so the cache would
169 * then have been left empty in this case.
171 * But if we are allowed to track real directories, we
172 * can still cache the path components before the last
173 * one (the found symlink or non-existing component).
175 cache->path[last_slash_dir] = '\0';
176 cache->len = last_slash_dir;
177 cache->flags = FL_DIR;
178 } else {
179 reset_lstat_cache(cache);
181 return match_len;
184 static int lstat_cache(struct cache_def *cache, const char *name, int len,
185 int track_flags, int prefix_len_stat_func)
187 int flags;
188 (void)lstat_cache_matchlen(cache, name, len, &flags, track_flags,
189 prefix_len_stat_func);
190 return flags;
193 #define USE_ONLY_LSTAT 0
196 * Return non-zero if path 'name' has a leading symlink component
198 int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
200 return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
204 * Return non-zero if path 'name' has a leading symlink component
206 int has_symlink_leading_path(const char *name, int len)
208 return threaded_has_symlink_leading_path(&default_cache, name, len);
212 * Return zero if path 'name' has a leading symlink component or
213 * if some leading path component does not exists.
215 * Return -1 if leading path exists and is a directory.
217 * Return path length if leading path exists and is neither a
218 * directory nor a symlink.
220 int check_leading_path(const char *name, int len)
222 return threaded_check_leading_path(&default_cache, name, len);
226 * Return zero if path 'name' has a leading symlink component or
227 * if some leading path component does not exists.
229 * Return -1 if leading path exists and is a directory.
231 * Return path length if leading path exists and is neither a
232 * directory nor a symlink.
234 int threaded_check_leading_path(struct cache_def *cache, const char *name, int len)
236 int flags;
237 int match_len = lstat_cache_matchlen(cache, name, len, &flags,
238 FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
239 if (flags & FL_NOENT)
240 return 0;
241 else if (flags & FL_DIR)
242 return -1;
243 else
244 return match_len;
248 * Return non-zero if all path components of 'name' exists as a
249 * directory. If prefix_len > 0, we will test with the stat()
250 * function instead of the lstat() function for a prefix length of
251 * 'prefix_len', thus we then allow for symlinks in the prefix part as
252 * long as those points to real existing directories.
254 int has_dirs_only_path(const char *name, int len, int prefix_len)
256 return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
260 * Return non-zero if all path components of 'name' exists as a
261 * directory. If prefix_len > 0, we will test with the stat()
262 * function instead of the lstat() function for a prefix length of
263 * 'prefix_len', thus we then allow for symlinks in the prefix part as
264 * long as those points to real existing directories.
266 int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len)
268 return lstat_cache(cache, name, len,
269 FL_DIR|FL_FULLPATH, prefix_len) &
270 FL_DIR;
273 static struct removal_def {
274 char path[PATH_MAX];
275 int len;
276 } removal;
278 static void do_remove_scheduled_dirs(int new_len)
280 while (removal.len > new_len) {
281 removal.path[removal.len] = '\0';
282 if (rmdir(removal.path))
283 break;
284 do {
285 removal.len--;
286 } while (removal.len > new_len &&
287 removal.path[removal.len] != '/');
289 removal.len = new_len;
292 void schedule_dir_for_removal(const char *name, int len)
294 int match_len, last_slash, i, previous_slash;
296 match_len = last_slash = i =
297 longest_path_match(name, len, removal.path, removal.len,
298 &previous_slash);
299 /* Find last slash inside 'name' */
300 while (i < len) {
301 if (name[i] == '/')
302 last_slash = i;
303 i++;
307 * If we are about to go down the directory tree, we check if
308 * we must first go upwards the tree, such that we then can
309 * remove possible empty directories as we go upwards.
311 if (match_len < last_slash && match_len < removal.len)
312 do_remove_scheduled_dirs(match_len);
314 * If we go deeper down the directory tree, we only need to
315 * save the new path components as we go down.
317 if (match_len < last_slash) {
318 memcpy(&removal.path[match_len], &name[match_len],
319 last_slash - match_len);
320 removal.len = last_slash;
324 void remove_scheduled_dirs(void)
326 do_remove_scheduled_dirs(0);