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f859c846 JH |
1 | #include "cache.h" |
2 | ||
92604b46 | 3 | static struct cache_def { |
bad4a54f | 4 | char path[PATH_MAX + 1]; |
92604b46 KB |
5 | int len; |
6 | int flags; | |
09c93066 | 7 | int track_flags; |
bad4a54f | 8 | int prefix_len_stat_func; |
92604b46 | 9 | } cache; |
c40641b7 | 10 | |
92604b46 KB |
11 | /* |
12 | * Returns the length (on a path component basis) of the longest | |
13 | * common prefix match of 'name' and the cached path string. | |
14 | */ | |
aeabab5c KB |
15 | static inline int longest_match_lstat_cache(int len, const char *name, |
16 | int *previous_slash) | |
c40641b7 | 17 | { |
aeabab5c | 18 | int max_len, match_len = 0, match_len_prev = 0, i = 0; |
92604b46 KB |
19 | |
20 | max_len = len < cache.len ? len : cache.len; | |
21 | while (i < max_len && name[i] == cache.path[i]) { | |
aeabab5c KB |
22 | if (name[i] == '/') { |
23 | match_len_prev = match_len; | |
92604b46 | 24 | match_len = i; |
aeabab5c | 25 | } |
92604b46 KB |
26 | i++; |
27 | } | |
60b458b7 KB |
28 | /* |
29 | * Is the cached path string a substring of 'name', is 'name' | |
30 | * a substring of the cached path string, or is 'name' and the | |
31 | * cached path string the exact same string? | |
32 | */ | |
33 | if (i >= max_len && ((len > cache.len && name[cache.len] == '/') || | |
34 | (len < cache.len && cache.path[len] == '/') || | |
35 | (len == cache.len))) { | |
aeabab5c | 36 | match_len_prev = match_len; |
60b458b7 | 37 | match_len = i; |
aeabab5c KB |
38 | } |
39 | *previous_slash = match_len_prev; | |
92604b46 | 40 | return match_len; |
c40641b7 LT |
41 | } |
42 | ||
60b458b7 | 43 | static inline void reset_lstat_cache(void) |
c40641b7 | 44 | { |
92604b46 KB |
45 | cache.path[0] = '\0'; |
46 | cache.len = 0; | |
47 | cache.flags = 0; | |
60b458b7 KB |
48 | /* |
49 | * The track_flags and prefix_len_stat_func members is only | |
50 | * set by the safeguard rule inside lstat_cache() | |
51 | */ | |
c40641b7 LT |
52 | } |
53 | ||
92604b46 | 54 | #define FL_DIR (1 << 0) |
09c93066 KB |
55 | #define FL_NOENT (1 << 1) |
56 | #define FL_SYMLINK (1 << 2) | |
57 | #define FL_LSTATERR (1 << 3) | |
58 | #define FL_ERR (1 << 4) | |
bad4a54f | 59 | #define FL_FULLPATH (1 << 5) |
92604b46 KB |
60 | |
61 | /* | |
62 | * Check if name 'name' of length 'len' has a symlink leading | |
09c93066 | 63 | * component, or if the directory exists and is real, or not. |
92604b46 KB |
64 | * |
65 | * To speed up the check, some information is allowed to be cached. | |
bad4a54f KB |
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. | |
68 | * | |
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. | |
92604b46 KB |
72 | */ |
73 | static int lstat_cache(int len, const char *name, | |
bad4a54f | 74 | int track_flags, int prefix_len_stat_func) |
c40641b7 | 75 | { |
aeabab5c | 76 | int match_len, last_slash, last_slash_dir, previous_slash; |
bad4a54f | 77 | int match_flags, ret_flags, save_flags, max_len, ret; |
c40641b7 | 78 | struct stat st; |
f859c846 | 79 | |
bad4a54f KB |
80 | if (cache.track_flags != track_flags || |
81 | cache.prefix_len_stat_func != prefix_len_stat_func) { | |
09c93066 | 82 | /* |
60b458b7 KB |
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. | |
09c93066 | 86 | */ |
60b458b7 KB |
87 | reset_lstat_cache(); |
88 | cache.track_flags = track_flags; | |
89 | cache.prefix_len_stat_func = prefix_len_stat_func; | |
09c93066 KB |
90 | match_len = last_slash = 0; |
91 | } else { | |
92 | /* | |
93 | * Check to see if we have a match from the cache for | |
94 | * the 2 "excluding" path types. | |
95 | */ | |
aeabab5c KB |
96 | match_len = last_slash = |
97 | longest_match_lstat_cache(len, name, &previous_slash); | |
09c93066 KB |
98 | match_flags = cache.flags & track_flags & (FL_NOENT|FL_SYMLINK); |
99 | if (match_flags && match_len == cache.len) | |
100 | return match_flags; | |
101 | /* | |
102 | * If we now have match_len > 0, we would know that | |
103 | * the matched part will always be a directory. | |
104 | * | |
105 | * Also, if we are tracking directories and 'name' is | |
106 | * a substring of the cache on a path component basis, | |
107 | * we can return immediately. | |
108 | */ | |
109 | match_flags = track_flags & FL_DIR; | |
110 | if (match_flags && len == match_len) | |
111 | return match_flags; | |
112 | } | |
c40641b7 | 113 | |
92604b46 KB |
114 | /* |
115 | * Okay, no match from the cache so far, so now we have to | |
116 | * check the rest of the path components. | |
117 | */ | |
118 | ret_flags = FL_DIR; | |
119 | last_slash_dir = last_slash; | |
120 | max_len = len < PATH_MAX ? len : PATH_MAX; | |
121 | while (match_len < max_len) { | |
122 | do { | |
123 | cache.path[match_len] = name[match_len]; | |
124 | match_len++; | |
125 | } while (match_len < max_len && name[match_len] != '/'); | |
bad4a54f | 126 | if (match_len >= max_len && !(track_flags & FL_FULLPATH)) |
92604b46 KB |
127 | break; |
128 | last_slash = match_len; | |
129 | cache.path[last_slash] = '\0'; | |
f859c846 | 130 | |
bad4a54f KB |
131 | if (last_slash <= prefix_len_stat_func) |
132 | ret = stat(cache.path, &st); | |
133 | else | |
134 | ret = lstat(cache.path, &st); | |
135 | ||
136 | if (ret) { | |
92604b46 | 137 | ret_flags = FL_LSTATERR; |
09c93066 KB |
138 | if (errno == ENOENT) |
139 | ret_flags |= FL_NOENT; | |
92604b46 KB |
140 | } else if (S_ISDIR(st.st_mode)) { |
141 | last_slash_dir = last_slash; | |
c40641b7 | 142 | continue; |
92604b46 KB |
143 | } else if (S_ISLNK(st.st_mode)) { |
144 | ret_flags = FL_SYMLINK; | |
145 | } else { | |
146 | ret_flags = FL_ERR; | |
f859c846 | 147 | } |
c40641b7 | 148 | break; |
f859c846 | 149 | } |
92604b46 KB |
150 | |
151 | /* | |
09c93066 KB |
152 | * At the end update the cache. Note that max 3 different |
153 | * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached | |
154 | * for the moment! | |
92604b46 | 155 | */ |
09c93066 | 156 | save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK); |
bad4a54f | 157 | if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) { |
92604b46 KB |
158 | cache.path[last_slash] = '\0'; |
159 | cache.len = last_slash; | |
160 | cache.flags = save_flags; | |
60b458b7 | 161 | } else if ((track_flags & FL_DIR) && |
bad4a54f | 162 | last_slash_dir > 0 && last_slash_dir <= PATH_MAX) { |
92604b46 KB |
163 | /* |
164 | * We have a separate test for the directory case, | |
09c93066 KB |
165 | * since it could be that we have found a symlink or a |
166 | * non-existing directory and the track_flags says | |
167 | * that we cannot cache this fact, so the cache would | |
168 | * then have been left empty in this case. | |
92604b46 KB |
169 | * |
170 | * But if we are allowed to track real directories, we | |
171 | * can still cache the path components before the last | |
09c93066 | 172 | * one (the found symlink or non-existing component). |
92604b46 KB |
173 | */ |
174 | cache.path[last_slash_dir] = '\0'; | |
175 | cache.len = last_slash_dir; | |
176 | cache.flags = FL_DIR; | |
177 | } else { | |
60b458b7 | 178 | reset_lstat_cache(); |
92604b46 KB |
179 | } |
180 | return ret_flags; | |
181 | } | |
182 | ||
aeabab5c KB |
183 | /* |
184 | * Invalidate the given 'name' from the cache, if 'name' matches | |
185 | * completely with the cache. | |
186 | */ | |
187 | void invalidate_lstat_cache(int len, const char *name) | |
188 | { | |
189 | int match_len, previous_slash; | |
190 | ||
191 | match_len = longest_match_lstat_cache(len, name, &previous_slash); | |
192 | if (len == match_len) { | |
193 | if ((cache.track_flags & FL_DIR) && previous_slash > 0) { | |
194 | cache.path[previous_slash] = '\0'; | |
195 | cache.len = previous_slash; | |
196 | cache.flags = FL_DIR; | |
197 | } else | |
60b458b7 | 198 | reset_lstat_cache(); |
aeabab5c KB |
199 | } |
200 | } | |
201 | ||
bda6eb0d KB |
202 | /* |
203 | * Completely clear the contents of the cache | |
204 | */ | |
205 | void clear_lstat_cache(void) | |
206 | { | |
60b458b7 | 207 | reset_lstat_cache(); |
bda6eb0d KB |
208 | } |
209 | ||
bad4a54f KB |
210 | #define USE_ONLY_LSTAT 0 |
211 | ||
92604b46 KB |
212 | /* |
213 | * Return non-zero if path 'name' has a leading symlink component | |
214 | */ | |
215 | int has_symlink_leading_path(int len, const char *name) | |
216 | { | |
217 | return lstat_cache(len, name, | |
bad4a54f | 218 | FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & |
92604b46 | 219 | FL_SYMLINK; |
f859c846 | 220 | } |
09c93066 KB |
221 | |
222 | /* | |
223 | * Return non-zero if path 'name' has a leading symlink component or | |
224 | * if some leading path component does not exists. | |
225 | */ | |
226 | int has_symlink_or_noent_leading_path(int len, const char *name) | |
227 | { | |
228 | return lstat_cache(len, name, | |
bad4a54f | 229 | FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) & |
09c93066 KB |
230 | (FL_SYMLINK|FL_NOENT); |
231 | } | |
bad4a54f KB |
232 | |
233 | /* | |
234 | * Return non-zero if all path components of 'name' exists as a | |
235 | * directory. If prefix_len > 0, we will test with the stat() | |
236 | * function instead of the lstat() function for a prefix length of | |
237 | * 'prefix_len', thus we then allow for symlinks in the prefix part as | |
238 | * long as those points to real existing directories. | |
239 | */ | |
240 | int has_dirs_only_path(int len, const char *name, int prefix_len) | |
241 | { | |
242 | return lstat_cache(len, name, | |
243 | FL_DIR|FL_FULLPATH, prefix_len) & | |
244 | FL_DIR; | |
245 | } |