add function check_ok_to_remove()
[git/git.git] / symlinks.c
CommitLineData
f859c846
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1#include "cache.h"
2
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3/*
4 * Returns the length (on a path component basis) of the longest
148bc06b 5 * common prefix match of 'name_a' and 'name_b'.
92604b46 6 */
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7static int longest_path_match(const char *name_a, int len_a,
8 const char *name_b, int len_b,
9 int *previous_slash)
c40641b7 10{
aeabab5c 11 int max_len, match_len = 0, match_len_prev = 0, i = 0;
92604b46 12
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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] == '/') {
aeabab5c 16 match_len_prev = match_len;
92604b46 17 match_len = i;
aeabab5c 18 }
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19 i++;
20 }
60b458b7 21 /*
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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?
60b458b7 24 */
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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))) {
aeabab5c 28 match_len_prev = match_len;
60b458b7 29 match_len = i;
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30 }
31 *previous_slash = match_len_prev;
92604b46 32 return match_len;
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33}
34
b9fd2846 35static struct cache_def default_cache;
148bc06b 36
867f72bf 37static inline void reset_lstat_cache(struct cache_def *cache)
c40641b7 38{
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39 cache->path[0] = '\0';
40 cache->len = 0;
41 cache->flags = 0;
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42 /*
43 * The track_flags and prefix_len_stat_func members is only
44 * set by the safeguard rule inside lstat_cache()
45 */
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46}
47
92604b46 48#define FL_DIR (1 << 0)
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49#define FL_NOENT (1 << 1)
50#define FL_SYMLINK (1 << 2)
51#define FL_LSTATERR (1 << 3)
52#define FL_ERR (1 << 4)
bad4a54f 53#define FL_FULLPATH (1 << 5)
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54
55/*
56 * Check if name 'name' of length 'len' has a symlink leading
09c93066 57 * component, or if the directory exists and is real, or not.
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58 *
59 * To speed up the check, some information is allowed to be cached.
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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.
62 *
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.
92604b46 66 */
867f72bf 67static int lstat_cache(struct cache_def *cache, const char *name, int len,
bad4a54f 68 int track_flags, int prefix_len_stat_func)
c40641b7 69{
aeabab5c 70 int match_len, last_slash, last_slash_dir, previous_slash;
bad4a54f 71 int match_flags, ret_flags, save_flags, max_len, ret;
c40641b7 72 struct stat st;
f859c846 73
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74 if (cache->track_flags != track_flags ||
75 cache->prefix_len_stat_func != prefix_len_stat_func) {
09c93066 76 /*
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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.
09c93066 80 */
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81 reset_lstat_cache(cache);
82 cache->track_flags = track_flags;
83 cache->prefix_len_stat_func = prefix_len_stat_func;
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84 match_len = last_slash = 0;
85 } else {
86 /*
87 * Check to see if we have a match from the cache for
88 * the 2 "excluding" path types.
89 */
aeabab5c 90 match_len = last_slash =
867f72bf 91 longest_path_match(name, len, cache->path, cache->len,
148bc06b 92 &previous_slash);
867f72bf 93 match_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
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94
95 if (!(track_flags & FL_FULLPATH) && match_len == len)
96 match_len = last_slash = previous_slash;
97
867f72bf 98 if (match_flags && match_len == cache->len)
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99 return match_flags;
100 /*
101 * If we now have match_len > 0, we would know that
102 * the matched part will always be a directory.
103 *
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.
107 */
108 match_flags = track_flags & FL_DIR;
109 if (match_flags && len == match_len)
110 return match_flags;
111 }
c40641b7 112
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113 /*
114 * Okay, no match from the cache so far, so now we have to
115 * check the rest of the path components.
116 */
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 {
867f72bf 122 cache->path[match_len] = name[match_len];
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123 match_len++;
124 } while (match_len < max_len && name[match_len] != '/');
bad4a54f 125 if (match_len >= max_len && !(track_flags & FL_FULLPATH))
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126 break;
127 last_slash = match_len;
867f72bf 128 cache->path[last_slash] = '\0';
f859c846 129
bad4a54f 130 if (last_slash <= prefix_len_stat_func)
867f72bf 131 ret = stat(cache->path, &st);
bad4a54f 132 else
867f72bf 133 ret = lstat(cache->path, &st);
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134
135 if (ret) {
92604b46 136 ret_flags = FL_LSTATERR;
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137 if (errno == ENOENT)
138 ret_flags |= FL_NOENT;
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139 } else if (S_ISDIR(st.st_mode)) {
140 last_slash_dir = last_slash;
c40641b7 141 continue;
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142 } else if (S_ISLNK(st.st_mode)) {
143 ret_flags = FL_SYMLINK;
144 } else {
145 ret_flags = FL_ERR;
f859c846 146 }
c40641b7 147 break;
f859c846 148 }
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149
150 /*
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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!
92604b46 154 */
09c93066 155 save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
bad4a54f 156 if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
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157 cache->path[last_slash] = '\0';
158 cache->len = last_slash;
159 cache->flags = save_flags;
60b458b7 160 } else if ((track_flags & FL_DIR) &&
bad4a54f 161 last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
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162 /*
163 * We have a separate test for the directory case,
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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.
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168 *
169 * But if we are allowed to track real directories, we
170 * can still cache the path components before the last
09c93066 171 * one (the found symlink or non-existing component).
92604b46 172 */
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173 cache->path[last_slash_dir] = '\0';
174 cache->len = last_slash_dir;
175 cache->flags = FL_DIR;
92604b46 176 } else {
867f72bf 177 reset_lstat_cache(cache);
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178 }
179 return ret_flags;
180}
181
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182#define USE_ONLY_LSTAT 0
183
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184/*
185 * Return non-zero if path 'name' has a leading symlink component
186 */
187int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
188{
189 return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
190}
191
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192/*
193 * Return non-zero if path 'name' has a leading symlink component
194 */
57199892 195int has_symlink_leading_path(const char *name, int len)
92604b46 196{
b9fd2846 197 return threaded_has_symlink_leading_path(&default_cache, name, len);
f859c846 198}
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199
200/*
201 * Return non-zero if path 'name' has a leading symlink component or
202 * if some leading path component does not exists.
203 */
57199892 204int has_symlink_or_noent_leading_path(const char *name, int len)
09c93066 205{
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206 struct cache_def *cache = &default_cache; /* FIXME */
207 return lstat_cache(cache, name, len,
bad4a54f 208 FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) &
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209 (FL_SYMLINK|FL_NOENT);
210}
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211
212/*
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.
218 */
57199892 219int has_dirs_only_path(const char *name, int len, int prefix_len)
bad4a54f 220{
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221 struct cache_def *cache = &default_cache; /* FIXME */
222 return lstat_cache(cache, name, len,
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223 FL_DIR|FL_FULLPATH, prefix_len) &
224 FL_DIR;
225}
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226
227static struct removal_def {
228 char path[PATH_MAX];
229 int len;
230} removal;
231
232static void do_remove_scheduled_dirs(int new_len)
233{
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] != '/');
242 }
243 removal.len = new_len;
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244}
245
246void schedule_dir_for_removal(const char *name, int len)
247{
248 int match_len, last_slash, i, previous_slash;
249
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++;
258 }
259
260 /*
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.
264 */
265 if (match_len < last_slash && match_len < removal.len)
266 do_remove_scheduled_dirs(match_len);
267 /*
268 * If we go deeper down the directory tree, we only need to
269 * save the new path components as we go down.
270 */
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;
275 }
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276}
277
278void remove_scheduled_dirs(void)
279{
280 do_remove_scheduled_dirs(0);
78478927 281}