Merge branch 'cb/maint-orphan-merge-noclobber'
[git/kirr.git] / symlinks.c
blob88601200114f857a57214a9bf0d02ffd39a83504
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(struct cache_def *cache, const char *name, int len,
68 int track_flags, int prefix_len_stat_func)
70 int match_len, last_slash, last_slash_dir, previous_slash;
71 int match_flags, ret_flags, save_flags, max_len, ret;
72 struct stat st;
74 if (cache->track_flags != track_flags ||
75 cache->prefix_len_stat_func != prefix_len_stat_func) {
77 * As a safeguard rule we clear the cache if the
78 * values of track_flags and/or prefix_len_stat_func
79 * does not match with the last supplied values.
81 reset_lstat_cache(cache);
82 cache->track_flags = track_flags;
83 cache->prefix_len_stat_func = prefix_len_stat_func;
84 match_len = last_slash = 0;
85 } else {
87 * Check to see if we have a match from the cache for
88 * the 2 "excluding" path types.
90 match_len = last_slash =
91 longest_path_match(name, len, cache->path, cache->len,
92 &previous_slash);
93 match_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
95 if (!(track_flags & FL_FULLPATH) && match_len == len)
96 match_len = last_slash = previous_slash;
98 if (match_flags && match_len == cache->len)
99 return match_flags;
101 * If we now have match_len > 0, we would know that
102 * the matched part will always be a directory.
104 * Also, if we are tracking directories and 'name' is
105 * a substring of the cache on a path component basis,
106 * we can return immediately.
108 match_flags = track_flags & FL_DIR;
109 if (match_flags && len == match_len)
110 return match_flags;
114 * Okay, no match from the cache so far, so now we have to
115 * check the rest of the path components.
117 ret_flags = FL_DIR;
118 last_slash_dir = last_slash;
119 max_len = len < PATH_MAX ? len : PATH_MAX;
120 while (match_len < max_len) {
121 do {
122 cache->path[match_len] = name[match_len];
123 match_len++;
124 } while (match_len < max_len && name[match_len] != '/');
125 if (match_len >= max_len && !(track_flags & FL_FULLPATH))
126 break;
127 last_slash = match_len;
128 cache->path[last_slash] = '\0';
130 if (last_slash <= prefix_len_stat_func)
131 ret = stat(cache->path, &st);
132 else
133 ret = lstat(cache->path, &st);
135 if (ret) {
136 ret_flags = FL_LSTATERR;
137 if (errno == ENOENT)
138 ret_flags |= FL_NOENT;
139 } else if (S_ISDIR(st.st_mode)) {
140 last_slash_dir = last_slash;
141 continue;
142 } else if (S_ISLNK(st.st_mode)) {
143 ret_flags = FL_SYMLINK;
144 } else {
145 ret_flags = FL_ERR;
147 break;
151 * At the end update the cache. Note that max 3 different
152 * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
153 * for the moment!
155 save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
156 if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
157 cache->path[last_slash] = '\0';
158 cache->len = last_slash;
159 cache->flags = save_flags;
160 } else if ((track_flags & FL_DIR) &&
161 last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
163 * We have a separate test for the directory case,
164 * since it could be that we have found a symlink or a
165 * non-existing directory and the track_flags says
166 * that we cannot cache this fact, so the cache would
167 * then have been left empty in this case.
169 * But if we are allowed to track real directories, we
170 * can still cache the path components before the last
171 * one (the found symlink or non-existing component).
173 cache->path[last_slash_dir] = '\0';
174 cache->len = last_slash_dir;
175 cache->flags = FL_DIR;
176 } else {
177 reset_lstat_cache(cache);
179 return ret_flags;
182 #define USE_ONLY_LSTAT 0
185 * Return non-zero if path 'name' has a leading symlink component
187 int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
189 return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
193 * Return non-zero if path 'name' has a leading symlink component
195 int has_symlink_leading_path(const char *name, int len)
197 return threaded_has_symlink_leading_path(&default_cache, name, len);
201 * Return non-zero if path 'name' has a leading symlink component or
202 * if some leading path component does not exists.
204 int has_symlink_or_noent_leading_path(const char *name, int len)
206 struct cache_def *cache = &default_cache; /* FIXME */
207 return lstat_cache(cache, name, len,
208 FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) &
209 (FL_SYMLINK|FL_NOENT);
213 * Return non-zero if all path components of 'name' exists as a
214 * directory. If prefix_len > 0, we will test with the stat()
215 * function instead of the lstat() function for a prefix length of
216 * 'prefix_len', thus we then allow for symlinks in the prefix part as
217 * long as those points to real existing directories.
219 int has_dirs_only_path(const char *name, int len, int prefix_len)
221 struct cache_def *cache = &default_cache; /* FIXME */
222 return lstat_cache(cache, name, len,
223 FL_DIR|FL_FULLPATH, prefix_len) &
224 FL_DIR;
227 static struct removal_def {
228 char path[PATH_MAX];
229 int len;
230 } removal;
232 static void do_remove_scheduled_dirs(int new_len)
234 while (removal.len > new_len) {
235 removal.path[removal.len] = '\0';
236 if (rmdir(removal.path))
237 break;
238 do {
239 removal.len--;
240 } while (removal.len > new_len &&
241 removal.path[removal.len] != '/');
243 removal.len = new_len;
246 void schedule_dir_for_removal(const char *name, int len)
248 int match_len, last_slash, i, previous_slash;
250 match_len = last_slash = i =
251 longest_path_match(name, len, removal.path, removal.len,
252 &previous_slash);
253 /* Find last slash inside 'name' */
254 while (i < len) {
255 if (name[i] == '/')
256 last_slash = i;
257 i++;
261 * If we are about to go down the directory tree, we check if
262 * we must first go upwards the tree, such that we then can
263 * remove possible empty directories as we go upwards.
265 if (match_len < last_slash && match_len < removal.len)
266 do_remove_scheduled_dirs(match_len);
268 * If we go deeper down the directory tree, we only need to
269 * save the new path components as we go down.
271 if (match_len < last_slash) {
272 memcpy(&removal.path[match_len], &name[match_len],
273 last_slash - match_len);
274 removal.len = last_slash;
278 void remove_scheduled_dirs(void)
280 do_remove_scheduled_dirs(0);