t800[12]: work around MSys limitation
[git/mingw/4msysgit.git] / name-hash.c
blobe5b6e1ad239bac6914fecfb9071d208e1e6a11cc
1 /*
2 * name-hash.c
4 * Hashing names in the index state
6 * Copyright (C) 2008 Linus Torvalds
7 */
8 #define NO_THE_INDEX_COMPATIBILITY_MACROS
9 #include "cache.h"
12 * This removes bit 5 if bit 6 is set.
14 * That will make US-ASCII characters hash to their upper-case
15 * equivalent. We could easily do this one whole word at a time,
16 * but that's for future worries.
18 static inline unsigned char icase_hash(unsigned char c)
20 return c & ~((c & 0x40) >> 1);
23 static unsigned int hash_name(const char *name, int namelen)
25 unsigned int hash = 0x123;
27 while (namelen--) {
28 unsigned char c = *name++;
29 c = icase_hash(c);
30 hash = hash*101 + c;
32 return hash;
35 struct dir_entry {
36 struct dir_entry *next;
37 struct dir_entry *parent;
38 struct cache_entry *ce;
39 int nr;
40 unsigned int namelen;
43 static struct dir_entry *find_dir_entry(struct index_state *istate,
44 const char *name, unsigned int namelen)
46 unsigned int hash = hash_name(name, namelen);
47 struct dir_entry *dir;
49 for (dir = lookup_hash(hash, &istate->dir_hash); dir; dir = dir->next)
50 if (dir->namelen == namelen &&
51 !strncasecmp(dir->ce->name, name, namelen))
52 return dir;
53 return NULL;
56 static struct dir_entry *hash_dir_entry(struct index_state *istate,
57 struct cache_entry *ce, int namelen)
60 * Throw each directory component in the hash for quick lookup
61 * during a git status. Directory components are stored without their
62 * closing slash. Despite submodules being a directory, they never
63 * reach this point, because they are stored
64 * in index_state.name_hash (as ordinary cache_entries).
66 * Note that the cache_entry stored with the dir_entry merely
67 * supplies the name of the directory (up to dir_entry.namelen). We
68 * track the number of 'active' files in a directory in dir_entry.nr,
69 * so we can tell if the directory is still relevant, e.g. for git
70 * status. However, if cache_entries are removed, we cannot pinpoint
71 * an exact cache_entry that's still active. It is very possible that
72 * multiple dir_entries point to the same cache_entry.
74 struct dir_entry *dir;
76 /* get length of parent directory */
77 while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
78 namelen--;
79 if (namelen <= 0)
80 return NULL;
81 namelen--;
83 /* lookup existing entry for that directory */
84 dir = find_dir_entry(istate, ce->name, namelen);
85 if (!dir) {
86 /* not found, create it and add to hash table */
87 void **pdir;
88 unsigned int hash = hash_name(ce->name, namelen);
90 dir = xcalloc(1, sizeof(struct dir_entry));
91 dir->namelen = namelen;
92 dir->ce = ce;
94 pdir = insert_hash(hash, dir, &istate->dir_hash);
95 if (pdir) {
96 dir->next = *pdir;
97 *pdir = dir;
100 /* recursively add missing parent directories */
101 dir->parent = hash_dir_entry(istate, ce, namelen);
103 return dir;
106 static void add_dir_entry(struct index_state *istate, struct cache_entry *ce)
108 /* Add reference to the directory entry (and parents if 0). */
109 struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
110 while (dir && !(dir->nr++))
111 dir = dir->parent;
114 static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
117 * Release reference to the directory entry (and parents if 0).
119 * Note: we do not remove / free the entry because there's no
120 * hash.[ch]::remove_hash and dir->next may point to other entries
121 * that are still valid, so we must not free the memory.
123 struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
124 while (dir && dir->nr && !(--dir->nr))
125 dir = dir->parent;
128 static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
130 void **pos;
131 unsigned int hash;
133 if (ce->ce_flags & CE_HASHED)
134 return;
135 ce->ce_flags |= CE_HASHED;
136 ce->next = NULL;
137 hash = hash_name(ce->name, ce_namelen(ce));
138 pos = insert_hash(hash, ce, &istate->name_hash);
139 if (pos) {
140 ce->next = *pos;
141 *pos = ce;
144 if (ignore_case && !(ce->ce_flags & CE_UNHASHED))
145 add_dir_entry(istate, ce);
148 static void lazy_init_name_hash(struct index_state *istate)
150 int nr;
152 if (istate->name_hash_initialized)
153 return;
154 if (istate->cache_nr)
155 preallocate_hash(&istate->name_hash, istate->cache_nr);
156 for (nr = 0; nr < istate->cache_nr; nr++)
157 hash_index_entry(istate, istate->cache[nr]);
158 istate->name_hash_initialized = 1;
161 void add_name_hash(struct index_state *istate, struct cache_entry *ce)
163 /* if already hashed, add reference to directory entries */
164 if (ignore_case && (ce->ce_flags & CE_STATE_MASK) == CE_STATE_MASK)
165 add_dir_entry(istate, ce);
167 ce->ce_flags &= ~CE_UNHASHED;
168 if (istate->name_hash_initialized)
169 hash_index_entry(istate, ce);
173 * We don't actually *remove* it, we can just mark it invalid so that
174 * we won't find it in lookups.
176 * Not only would we have to search the lists (simple enough), but
177 * we'd also have to rehash other hash buckets in case this makes the
178 * hash bucket empty (common). So it's much better to just mark
179 * it.
181 void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
183 /* if already hashed, release reference to directory entries */
184 if (ignore_case && (ce->ce_flags & CE_STATE_MASK) == CE_HASHED)
185 remove_dir_entry(istate, ce);
187 ce->ce_flags |= CE_UNHASHED;
190 static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
192 if (len1 != len2)
193 return 0;
195 while (len1) {
196 unsigned char c1 = *name1++;
197 unsigned char c2 = *name2++;
198 len1--;
199 if (c1 != c2) {
200 c1 = toupper(c1);
201 c2 = toupper(c2);
202 if (c1 != c2)
203 return 0;
206 return 1;
209 static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
211 int len = ce_namelen(ce);
214 * Always do exact compare, even if we want a case-ignoring comparison;
215 * we do the quick exact one first, because it will be the common case.
217 if (len == namelen && !cache_name_compare(name, namelen, ce->name, len))
218 return 1;
220 if (!icase)
221 return 0;
223 return slow_same_name(name, namelen, ce->name, len);
226 struct cache_entry *index_dir_exists(struct index_state *istate, const char *name, int namelen)
228 struct cache_entry *ce;
229 struct dir_entry *dir;
231 lazy_init_name_hash(istate);
232 dir = find_dir_entry(istate, name, namelen);
233 if (dir && dir->nr)
234 return dir->ce;
237 * It might be a submodule. Unlike plain directories, which are stored
238 * in the dir-hash, submodules are stored in the name-hash, so check
239 * there, as well.
241 ce = index_file_exists(istate, name, namelen, 1);
242 if (ce && S_ISGITLINK(ce->ce_mode))
243 return ce;
245 return NULL;
248 struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
250 unsigned int hash = hash_name(name, namelen);
251 struct cache_entry *ce;
253 lazy_init_name_hash(istate);
254 ce = lookup_hash(hash, &istate->name_hash);
256 while (ce) {
257 if (!(ce->ce_flags & CE_UNHASHED)) {
258 if (same_name(ce, name, namelen, icase))
259 return ce;
261 ce = ce->next;
263 return NULL;
266 struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen, int icase)
268 if (namelen > 0 && name[namelen - 1] == '/')
269 return index_dir_exists(istate, name, namelen - 1);
270 return index_file_exists(istate, name, namelen, icase);
273 static int free_dir_entry(void *entry, void *unused)
275 struct dir_entry *dir = entry;
276 while (dir) {
277 struct dir_entry *next = dir->next;
278 free(dir);
279 dir = next;
281 return 0;
284 void free_name_hash(struct index_state *istate)
286 if (!istate->name_hash_initialized)
287 return;
288 istate->name_hash_initialized = 0;
289 if (ignore_case)
290 /* free directory entries */
291 for_each_hash(&istate->dir_hash, free_dir_entry, NULL);
293 free_hash(&istate->name_hash);
294 free_hash(&istate->dir_hash);