The eighth batch
[git.git] / symlinks.c
blob5232d02020c725abdf0b486843c703403dcfc012
1 #include "cache.h"
3 static int threaded_check_leading_path(struct cache_def *cache, const char *name,
4 int len, int warn_on_lstat_err);
5 static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len);
7 /*
8 * Returns the length (on a path component basis) of the longest
9 * common prefix match of 'name_a' and 'name_b'.
11 static int longest_path_match(const char *name_a, int len_a,
12 const char *name_b, int len_b,
13 int *previous_slash)
15 int max_len, match_len = 0, match_len_prev = 0, i = 0;
17 max_len = len_a < len_b ? len_a : len_b;
18 while (i < max_len && name_a[i] == name_b[i]) {
19 if (name_a[i] == '/') {
20 match_len_prev = match_len;
21 match_len = i;
23 i++;
26 * Is 'name_b' a substring of 'name_a', the other way around,
27 * or is 'name_a' and 'name_b' the exact same string?
29 if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
30 (len_a < len_b && name_b[len_a] == '/') ||
31 (len_a == len_b))) {
32 match_len_prev = match_len;
33 match_len = i;
35 *previous_slash = match_len_prev;
36 return match_len;
39 static struct cache_def default_cache = CACHE_DEF_INIT;
41 static inline void reset_lstat_cache(struct cache_def *cache)
43 strbuf_reset(&cache->path);
44 cache->flags = 0;
46 * The track_flags and prefix_len_stat_func members is only
47 * set by the safeguard rule inside lstat_cache()
51 #define FL_DIR (1 << 0)
52 #define FL_NOENT (1 << 1)
53 #define FL_SYMLINK (1 << 2)
54 #define FL_LSTATERR (1 << 3)
55 #define FL_ERR (1 << 4)
56 #define FL_FULLPATH (1 << 5)
59 * Check if name 'name' of length 'len' has a symlink leading
60 * component, or if the directory exists and is real, or not.
62 * To speed up the check, some information is allowed to be cached.
63 * This can be indicated by the 'track_flags' argument, which also can
64 * be used to indicate that we should check the full path.
66 * The 'prefix_len_stat_func' parameter can be used to set the length
67 * of the prefix, where the cache should use the stat() function
68 * instead of the lstat() function to test each path component.
70 static int lstat_cache_matchlen(struct cache_def *cache,
71 const char *name, int len,
72 int *ret_flags, int track_flags,
73 int prefix_len_stat_func)
75 int match_len, last_slash, last_slash_dir, previous_slash;
76 int save_flags, ret, saved_errno = 0;
77 struct stat st;
79 if (cache->track_flags != track_flags ||
80 cache->prefix_len_stat_func != prefix_len_stat_func) {
82 * As a safeguard rule we clear the cache if the
83 * values of track_flags and/or prefix_len_stat_func
84 * does not match with the last supplied values.
86 reset_lstat_cache(cache);
87 cache->track_flags = track_flags;
88 cache->prefix_len_stat_func = prefix_len_stat_func;
89 match_len = last_slash = 0;
90 } else {
92 * Check to see if we have a match from the cache for
93 * the 2 "excluding" path types.
95 match_len = last_slash =
96 longest_path_match(name, len, cache->path.buf,
97 cache->path.len, &previous_slash);
98 *ret_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
100 if (!(track_flags & FL_FULLPATH) && match_len == len)
101 match_len = last_slash = previous_slash;
103 if (*ret_flags && match_len == cache->path.len)
104 return match_len;
106 * If we now have match_len > 0, we would know that
107 * the matched part will always be a directory.
109 * Also, if we are tracking directories and 'name' is
110 * a substring of the cache on a path component basis,
111 * we can return immediately.
113 *ret_flags = track_flags & FL_DIR;
114 if (*ret_flags && len == match_len)
115 return match_len;
119 * Okay, no match from the cache so far, so now we have to
120 * check the rest of the path components.
122 *ret_flags = FL_DIR;
123 last_slash_dir = last_slash;
124 if (len > cache->path.len)
125 strbuf_grow(&cache->path, len - cache->path.len);
126 while (match_len < len) {
127 do {
128 cache->path.buf[match_len] = name[match_len];
129 match_len++;
130 } while (match_len < len && name[match_len] != '/');
131 if (match_len >= len && !(track_flags & FL_FULLPATH))
132 break;
133 last_slash = match_len;
134 cache->path.buf[last_slash] = '\0';
136 if (last_slash <= prefix_len_stat_func)
137 ret = stat(cache->path.buf, &st);
138 else
139 ret = lstat(cache->path.buf, &st);
141 if (ret) {
142 *ret_flags = FL_LSTATERR;
143 saved_errno = errno;
144 if (errno == ENOENT)
145 *ret_flags |= FL_NOENT;
146 } else if (S_ISDIR(st.st_mode)) {
147 last_slash_dir = last_slash;
148 continue;
149 } else if (S_ISLNK(st.st_mode)) {
150 *ret_flags = FL_SYMLINK;
151 } else {
152 *ret_flags = FL_ERR;
154 break;
158 * At the end update the cache. Note that max 3 different
159 * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
160 * for the moment!
162 save_flags = *ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
163 if (save_flags && last_slash > 0) {
164 cache->path.buf[last_slash] = '\0';
165 cache->path.len = last_slash;
166 cache->flags = save_flags;
167 } else if ((track_flags & FL_DIR) && last_slash_dir > 0) {
169 * We have a separate test for the directory case,
170 * since it could be that we have found a symlink or a
171 * non-existing directory and the track_flags says
172 * that we cannot cache this fact, so the cache would
173 * then have been left empty in this case.
175 * But if we are allowed to track real directories, we
176 * can still cache the path components before the last
177 * one (the found symlink or non-existing component).
179 cache->path.buf[last_slash_dir] = '\0';
180 cache->path.len = last_slash_dir;
181 cache->flags = FL_DIR;
182 } else {
183 reset_lstat_cache(cache);
185 if (saved_errno)
186 errno = saved_errno;
187 return match_len;
190 static int lstat_cache(struct cache_def *cache, const char *name, int len,
191 int track_flags, int prefix_len_stat_func)
193 int flags;
194 (void)lstat_cache_matchlen(cache, name, len, &flags, track_flags,
195 prefix_len_stat_func);
196 return flags;
199 #define USE_ONLY_LSTAT 0
202 * Return non-zero if path 'name' has a leading symlink component
204 int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
206 return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
209 int has_symlink_leading_path(const char *name, int len)
211 return threaded_has_symlink_leading_path(&default_cache, name, len);
214 int check_leading_path(const char *name, int len, int warn_on_lstat_err)
216 return threaded_check_leading_path(&default_cache, name, len,
217 warn_on_lstat_err);
221 * Return zero if some leading path component of 'name' does not exist.
223 * Return -1 if leading path exists and is a directory.
225 * Return the length of a leading component if it either exists but it's not a
226 * directory, or if we were unable to lstat() it. If warn_on_lstat_err is true,
227 * also emit a warning for this error.
229 static int threaded_check_leading_path(struct cache_def *cache, const char *name,
230 int len, int warn_on_lstat_err)
232 int flags;
233 int match_len = lstat_cache_matchlen(cache, name, len, &flags,
234 FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
235 int saved_errno = errno;
237 if (flags & FL_NOENT)
238 return 0;
239 else if (flags & FL_DIR)
240 return -1;
241 if (warn_on_lstat_err && (flags & FL_LSTATERR)) {
242 char *path = xmemdupz(name, match_len);
243 errno = saved_errno;
244 warning_errno(_("failed to lstat '%s'"), path);
245 free(path);
247 return match_len;
250 int has_dirs_only_path(const char *name, int len, int prefix_len)
252 return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
256 * Return non-zero if all path components of 'name' exists as a
257 * directory. If prefix_len > 0, we will test with the stat()
258 * function instead of the lstat() function for a prefix length of
259 * 'prefix_len', thus we then allow for symlinks in the prefix part as
260 * long as those points to real existing directories.
262 static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len)
265 * Note: this function is used by the checkout machinery, which also
266 * takes care to properly reset the cache when it performs an operation
267 * that would leave the cache outdated. If this function starts caching
268 * anything else besides FL_DIR, remember to also invalidate the cache
269 * when creating or deleting paths that might be in the cache.
271 return lstat_cache(cache, name, len,
272 FL_DIR|FL_FULLPATH, prefix_len) &
273 FL_DIR;
276 static struct strbuf removal = STRBUF_INIT;
278 static void do_remove_scheduled_dirs(int new_len)
280 while (removal.len > new_len) {
281 removal.buf[removal.len] = '\0';
282 if (rmdir(removal.buf))
283 break;
284 do {
285 removal.len--;
286 } while (removal.len > new_len &&
287 removal.buf[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.buf, 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 strbuf_add(&removal, &name[match_len], last_slash - match_len);
321 void remove_scheduled_dirs(void)
323 do_remove_scheduled_dirs(0);
326 void invalidate_lstat_cache(void)
328 reset_lstat_cache(&default_cache);
331 #undef rmdir
332 int lstat_cache_aware_rmdir(const char *path)
334 /* Any change in this function must be made also in `mingw_rmdir()` */
335 int ret = rmdir(path);
337 if (!ret)
338 invalidate_lstat_cache();
340 return ret;