Merge branch 'dl/compat-cleanup'
[git/git.git] / symlinks.c
CommitLineData
f859c846
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1#include "cache.h"
2
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3static int threaded_check_leading_path(struct cache_def *cache, const char *name, int len);
4static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len);
5
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6/*
7 * Returns the length (on a path component basis) of the longest
148bc06b 8 * common prefix match of 'name_a' and 'name_b'.
92604b46 9 */
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10static int longest_path_match(const char *name_a, int len_a,
11 const char *name_b, int len_b,
12 int *previous_slash)
c40641b7 13{
aeabab5c 14 int max_len, match_len = 0, match_len_prev = 0, i = 0;
92604b46 15
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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] == '/') {
aeabab5c 19 match_len_prev = match_len;
92604b46 20 match_len = i;
aeabab5c 21 }
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22 i++;
23 }
60b458b7 24 /*
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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?
60b458b7 27 */
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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))) {
aeabab5c 31 match_len_prev = match_len;
60b458b7 32 match_len = i;
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33 }
34 *previous_slash = match_len_prev;
92604b46 35 return match_len;
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36}
37
e7c73053 38static struct cache_def default_cache = CACHE_DEF_INIT;
148bc06b 39
867f72bf 40static inline void reset_lstat_cache(struct cache_def *cache)
c40641b7 41{
e7c73053 42 strbuf_reset(&cache->path);
867f72bf 43 cache->flags = 0;
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44 /*
45 * The track_flags and prefix_len_stat_func members is only
46 * set by the safeguard rule inside lstat_cache()
47 */
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48}
49
92604b46 50#define FL_DIR (1 << 0)
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51#define FL_NOENT (1 << 1)
52#define FL_SYMLINK (1 << 2)
53#define FL_LSTATERR (1 << 3)
54#define FL_ERR (1 << 4)
bad4a54f 55#define FL_FULLPATH (1 << 5)
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56
57/*
58 * Check if name 'name' of length 'len' has a symlink leading
09c93066 59 * component, or if the directory exists and is real, or not.
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60 *
61 * To speed up the check, some information is allowed to be cached.
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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.
64 *
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.
92604b46 68 */
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69static 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)
c40641b7 73{
aeabab5c 74 int match_len, last_slash, last_slash_dir, previous_slash;
e7c73053 75 int save_flags, ret;
c40641b7 76 struct stat st;
f859c846 77
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78 if (cache->track_flags != track_flags ||
79 cache->prefix_len_stat_func != prefix_len_stat_func) {
09c93066 80 /*
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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.
09c93066 84 */
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85 reset_lstat_cache(cache);
86 cache->track_flags = track_flags;
87 cache->prefix_len_stat_func = prefix_len_stat_func;
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88 match_len = last_slash = 0;
89 } else {
90 /*
91 * Check to see if we have a match from the cache for
92 * the 2 "excluding" path types.
93 */
aeabab5c 94 match_len = last_slash =
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95 longest_path_match(name, len, cache->path.buf,
96 cache->path.len, &previous_slash);
4856ff2a 97 *ret_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
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98
99 if (!(track_flags & FL_FULLPATH) && match_len == len)
100 match_len = last_slash = previous_slash;
101
e7c73053 102 if (*ret_flags && match_len == cache->path.len)
4856ff2a 103 return match_len;
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104 /*
105 * If we now have match_len > 0, we would know that
106 * the matched part will always be a directory.
107 *
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.
111 */
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112 *ret_flags = track_flags & FL_DIR;
113 if (*ret_flags && len == match_len)
114 return match_len;
09c93066 115 }
c40641b7 116
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117 /*
118 * Okay, no match from the cache so far, so now we have to
119 * check the rest of the path components.
120 */
4856ff2a 121 *ret_flags = FL_DIR;
92604b46 122 last_slash_dir = last_slash;
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123 if (len > cache->path.len)
124 strbuf_grow(&cache->path, len - cache->path.len);
125 while (match_len < len) {
92604b46 126 do {
e7c73053 127 cache->path.buf[match_len] = name[match_len];
92604b46 128 match_len++;
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129 } while (match_len < len && name[match_len] != '/');
130 if (match_len >= len && !(track_flags & FL_FULLPATH))
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131 break;
132 last_slash = match_len;
e7c73053 133 cache->path.buf[last_slash] = '\0';
f859c846 134
bad4a54f 135 if (last_slash <= prefix_len_stat_func)
e7c73053 136 ret = stat(cache->path.buf, &st);
bad4a54f 137 else
e7c73053 138 ret = lstat(cache->path.buf, &st);
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139
140 if (ret) {
4856ff2a 141 *ret_flags = FL_LSTATERR;
09c93066 142 if (errno == ENOENT)
4856ff2a 143 *ret_flags |= FL_NOENT;
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144 } else if (S_ISDIR(st.st_mode)) {
145 last_slash_dir = last_slash;
c40641b7 146 continue;
92604b46 147 } else if (S_ISLNK(st.st_mode)) {
4856ff2a 148 *ret_flags = FL_SYMLINK;
92604b46 149 } else {
4856ff2a 150 *ret_flags = FL_ERR;
f859c846 151 }
c40641b7 152 break;
f859c846 153 }
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154
155 /*
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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!
92604b46 159 */
4856ff2a 160 save_flags = *ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
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161 if (save_flags && last_slash > 0) {
162 cache->path.buf[last_slash] = '\0';
163 cache->path.len = last_slash;
867f72bf 164 cache->flags = save_flags;
e7c73053 165 } else if ((track_flags & FL_DIR) && last_slash_dir > 0) {
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166 /*
167 * We have a separate test for the directory case,
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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.
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172 *
173 * But if we are allowed to track real directories, we
174 * can still cache the path components before the last
09c93066 175 * one (the found symlink or non-existing component).
92604b46 176 */
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177 cache->path.buf[last_slash_dir] = '\0';
178 cache->path.len = last_slash_dir;
867f72bf 179 cache->flags = FL_DIR;
92604b46 180 } else {
867f72bf 181 reset_lstat_cache(cache);
92604b46 182 }
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183 return match_len;
184}
185
186static int lstat_cache(struct cache_def *cache, const char *name, int len,
187 int track_flags, int prefix_len_stat_func)
188{
189 int flags;
190 (void)lstat_cache_matchlen(cache, name, len, &flags, track_flags,
191 prefix_len_stat_func);
192 return flags;
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193}
194
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195#define USE_ONLY_LSTAT 0
196
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197/*
198 * Return non-zero if path 'name' has a leading symlink component
199 */
200int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
201{
202 return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
203}
204
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205/*
206 * Return non-zero if path 'name' has a leading symlink component
207 */
57199892 208int has_symlink_leading_path(const char *name, int len)
92604b46 209{
b9fd2846 210 return threaded_has_symlink_leading_path(&default_cache, name, len);
f859c846 211}
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212
213/*
f66caaf9 214 * Return zero if path 'name' has a leading symlink component or
09c93066 215 * if some leading path component does not exists.
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216 *
217 * Return -1 if leading path exists and is a directory.
218 *
219 * Return path length if leading path exists and is neither a
220 * directory nor a symlink.
09c93066 221 */
f66caaf9 222int check_leading_path(const char *name, int len)
09c93066 223{
ec36c42a 224 return threaded_check_leading_path(&default_cache, name, len);
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225}
226
227/*
228 * Return zero if path 'name' has a leading symlink component or
229 * if some leading path component does not exists.
230 *
231 * Return -1 if leading path exists and is a directory.
232 *
233 * Return path length if leading path exists and is neither a
234 * directory nor a symlink.
235 */
72f3196a 236static int threaded_check_leading_path(struct cache_def *cache, const char *name, int len)
15438d5a 237{
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238 int flags;
239 int match_len = lstat_cache_matchlen(cache, name, len, &flags,
240 FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
1d718a51 241 if (flags & FL_NOENT)
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242 return 0;
243 else if (flags & FL_DIR)
244 return -1;
245 else
246 return match_len;
09c93066 247}
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248
249/*
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.
255 */
57199892 256int has_dirs_only_path(const char *name, int len, int prefix_len)
bad4a54f 257{
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258 return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
259}
260
261/*
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.
267 */
72f3196a 268static int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len)
15438d5a 269{
867f72bf 270 return lstat_cache(cache, name, len,
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271 FL_DIR|FL_FULLPATH, prefix_len) &
272 FL_DIR;
273}
78478927 274
e7c73053 275static struct strbuf removal = STRBUF_INIT;
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276
277static void do_remove_scheduled_dirs(int new_len)
278{
279 while (removal.len > new_len) {
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280 removal.buf[removal.len] = '\0';
281 if (rmdir(removal.buf))
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282 break;
283 do {
284 removal.len--;
285 } while (removal.len > new_len &&
e7c73053 286 removal.buf[removal.len] != '/');
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287 }
288 removal.len = new_len;
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289}
290
291void schedule_dir_for_removal(const char *name, int len)
292{
293 int match_len, last_slash, i, previous_slash;
294
295 match_len = last_slash = i =
e7c73053 296 longest_path_match(name, len, removal.buf, removal.len,
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297 &previous_slash);
298 /* Find last slash inside 'name' */
299 while (i < len) {
300 if (name[i] == '/')
301 last_slash = i;
302 i++;
303 }
304
305 /*
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.
309 */
310 if (match_len < last_slash && match_len < removal.len)
311 do_remove_scheduled_dirs(match_len);
312 /*
313 * If we go deeper down the directory tree, we only need to
314 * save the new path components as we go down.
315 */
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316 if (match_len < last_slash)
317 strbuf_add(&removal, &name[match_len], last_slash - match_len);
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318}
319
320void remove_scheduled_dirs(void)
321{
322 do_remove_scheduled_dirs(0);
78478927 323}