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git.ipfire.org Git - thirdparty/git.git/blob - symlinks.c
4 * Returns the length (on a path component basis) of the longest
5 * common prefix match of 'name_a' and 'name_b'.
7 static int longest_path_match(const char *name_a
, int len_a
,
8 const char *name_b
, int len_b
,
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
;
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
] == '/') ||
28 match_len_prev
= match_len
;
31 *previous_slash
= match_len_prev
;
35 static struct cache_def
{
36 char path
[PATH_MAX
+ 1];
40 int prefix_len_stat_func
;
43 static inline void reset_lstat_cache(struct cache_def
*cache
)
45 cache
->path
[0] = '\0';
49 * The track_flags and prefix_len_stat_func members is only
50 * set by the safeguard rule inside lstat_cache()
54 #define FL_DIR (1 << 0)
55 #define FL_NOENT (1 << 1)
56 #define FL_SYMLINK (1 << 2)
57 #define FL_LSTATERR (1 << 3)
58 #define FL_ERR (1 << 4)
59 #define FL_FULLPATH (1 << 5)
62 * Check if name 'name' of length 'len' has a symlink leading
63 * component, or if the directory exists and is real, or not.
65 * To speed up the check, some information is allowed to be cached.
66 * This can be indicated by the 'track_flags' argument, which also can
67 * be used to indicate that we should check the full path.
69 * The 'prefix_len_stat_func' parameter can be used to set the length
70 * of the prefix, where the cache should use the stat() function
71 * instead of the lstat() function to test each path component.
73 static int lstat_cache(struct cache_def
*cache
, const char *name
, int len
,
74 int track_flags
, int prefix_len_stat_func
)
76 int match_len
, last_slash
, last_slash_dir
, previous_slash
;
77 int match_flags
, ret_flags
, save_flags
, max_len
, ret
;
80 if (cache
->track_flags
!= track_flags
||
81 cache
->prefix_len_stat_func
!= prefix_len_stat_func
) {
83 * As a safeguard rule we clear the cache if the
84 * values of track_flags and/or prefix_len_stat_func
85 * does not match with the last supplied values.
87 reset_lstat_cache(cache
);
88 cache
->track_flags
= track_flags
;
89 cache
->prefix_len_stat_func
= prefix_len_stat_func
;
90 match_len
= last_slash
= 0;
93 * Check to see if we have a match from the cache for
94 * the 2 "excluding" path types.
96 match_len
= last_slash
=
97 longest_path_match(name
, len
, cache
->path
, cache
->len
,
99 match_flags
= cache
->flags
& track_flags
& (FL_NOENT
|FL_SYMLINK
);
100 if (match_flags
&& match_len
== cache
->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 match_flags
= track_flags
& FL_DIR
;
111 if (match_flags
&& len
== match_len
)
116 * Okay, no match from the cache so far, so now we have to
117 * check the rest of the path components.
120 last_slash_dir
= last_slash
;
121 max_len
= len
< PATH_MAX
? len
: PATH_MAX
;
122 while (match_len
< max_len
) {
124 cache
->path
[match_len
] = name
[match_len
];
126 } while (match_len
< max_len
&& name
[match_len
] != '/');
127 if (match_len
>= max_len
&& !(track_flags
& FL_FULLPATH
))
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
);
135 ret
= lstat(cache
->path
, &st
);
138 ret_flags
= FL_LSTATERR
;
140 ret_flags
|= FL_NOENT
;
141 } else if (S_ISDIR(st
.st_mode
)) {
142 last_slash_dir
= last_slash
;
144 } else if (S_ISLNK(st
.st_mode
)) {
145 ret_flags
= FL_SYMLINK
;
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
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
;
179 reset_lstat_cache(cache
);
185 * Invalidate the given 'name' from the cache, if 'name' matches
186 * completely with the cache.
188 void invalidate_lstat_cache(const char *name
, int len
)
190 int match_len
, previous_slash
;
191 struct cache_def
*cache
= &default_cache
; /* FIXME */
193 match_len
= longest_path_match(name
, len
, cache
->path
, cache
->len
,
195 if (len
== match_len
) {
196 if ((cache
->track_flags
& FL_DIR
) && previous_slash
> 0) {
197 cache
->path
[previous_slash
] = '\0';
198 cache
->len
= previous_slash
;
199 cache
->flags
= FL_DIR
;
201 reset_lstat_cache(cache
);
207 * Completely clear the contents of the cache
209 void clear_lstat_cache(void)
211 struct cache_def
*cache
= &default_cache
; /* FIXME */
212 reset_lstat_cache(cache
);
215 #define USE_ONLY_LSTAT 0
218 * Return non-zero if path 'name' has a leading symlink component
220 int has_symlink_leading_path(const char *name
, int len
)
222 struct cache_def
*cache
= &default_cache
; /* FIXME */
223 return lstat_cache(cache
, name
, len
,
224 FL_SYMLINK
|FL_DIR
, USE_ONLY_LSTAT
) &
229 * Return non-zero if path 'name' has a leading symlink component or
230 * if some leading path component does not exists.
232 int has_symlink_or_noent_leading_path(const char *name
, int len
)
234 struct cache_def
*cache
= &default_cache
; /* FIXME */
235 return lstat_cache(cache
, name
, len
,
236 FL_SYMLINK
|FL_NOENT
|FL_DIR
, USE_ONLY_LSTAT
) &
237 (FL_SYMLINK
|FL_NOENT
);
241 * Return non-zero if all path components of 'name' exists as a
242 * directory. If prefix_len > 0, we will test with the stat()
243 * function instead of the lstat() function for a prefix length of
244 * 'prefix_len', thus we then allow for symlinks in the prefix part as
245 * long as those points to real existing directories.
247 int has_dirs_only_path(const char *name
, int len
, int prefix_len
)
249 struct cache_def
*cache
= &default_cache
; /* FIXME */
250 return lstat_cache(cache
, name
, len
,
251 FL_DIR
|FL_FULLPATH
, prefix_len
) &
255 static struct removal_def
{
260 static void do_remove_scheduled_dirs(int new_len
)
262 while (removal
.len
> new_len
) {
263 removal
.path
[removal
.len
] = '\0';
264 if (rmdir(removal
.path
))
268 } while (removal
.len
> new_len
&&
269 removal
.path
[removal
.len
] != '/');
271 removal
.len
= new_len
;
274 void schedule_dir_for_removal(const char *name
, int len
)
276 int match_len
, last_slash
, i
, previous_slash
;
278 match_len
= last_slash
= i
=
279 longest_path_match(name
, len
, removal
.path
, removal
.len
,
281 /* Find last slash inside 'name' */
289 * If we are about to go down the directory tree, we check if
290 * we must first go upwards the tree, such that we then can
291 * remove possible empty directories as we go upwards.
293 if (match_len
< last_slash
&& match_len
< removal
.len
)
294 do_remove_scheduled_dirs(match_len
);
296 * If we go deeper down the directory tree, we only need to
297 * save the new path components as we go down.
299 if (match_len
< last_slash
) {
300 memcpy(&removal
.path
[match_len
], &name
[match_len
],
301 last_slash
- match_len
);
302 removal
.len
= last_slash
;
306 void remove_scheduled_dirs(void)
308 do_remove_scheduled_dirs(0);