Documentation/describe: improve one-line summary
[git.git] / object.c
blob23d6c9671904cfe273fc16de8a4d2db56b91c3b4
1 #include "cache.h"
2 #include "object.h"
3 #include "blob.h"
4 #include "tree.h"
5 #include "commit.h"
6 #include "tag.h"
8 static struct object **obj_hash;
9 static int nr_objs, obj_hash_size;
11 unsigned int get_max_object_index(void)
13 return obj_hash_size;
16 struct object *get_indexed_object(unsigned int idx)
18 return obj_hash[idx];
21 static const char *object_type_strings[] = {
22 NULL, /* OBJ_NONE = 0 */
23 "commit", /* OBJ_COMMIT = 1 */
24 "tree", /* OBJ_TREE = 2 */
25 "blob", /* OBJ_BLOB = 3 */
26 "tag", /* OBJ_TAG = 4 */
29 const char *typename(unsigned int type)
31 if (type >= ARRAY_SIZE(object_type_strings))
32 return NULL;
33 return object_type_strings[type];
36 int type_from_string_gently(const char *str, ssize_t len, int gentle)
38 int i;
40 if (len < 0)
41 len = strlen(str);
43 for (i = 1; i < ARRAY_SIZE(object_type_strings); i++)
44 if (!strncmp(str, object_type_strings[i], len))
45 return i;
47 if (gentle)
48 return -1;
50 die("invalid object type \"%s\"", str);
54 * Return a numerical hash value between 0 and n-1 for the object with
55 * the specified sha1. n must be a power of 2. Please note that the
56 * return value is *not* consistent across computer architectures.
58 static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
60 return sha1hash(sha1) & (n - 1);
64 * Insert obj into the hash table hash, which has length size (which
65 * must be a power of 2). On collisions, simply overflow to the next
66 * empty bucket.
68 static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
70 unsigned int j = hash_obj(obj->sha1, size);
72 while (hash[j]) {
73 j++;
74 if (j >= size)
75 j = 0;
77 hash[j] = obj;
81 * Look up the record for the given sha1 in the hash map stored in
82 * obj_hash. Return NULL if it was not found.
84 struct object *lookup_object(const unsigned char *sha1)
86 unsigned int i, first;
87 struct object *obj;
89 if (!obj_hash)
90 return NULL;
92 first = i = hash_obj(sha1, obj_hash_size);
93 while ((obj = obj_hash[i]) != NULL) {
94 if (!hashcmp(sha1, obj->sha1))
95 break;
96 i++;
97 if (i == obj_hash_size)
98 i = 0;
100 if (obj && i != first) {
102 * Move object to where we started to look for it so
103 * that we do not need to walk the hash table the next
104 * time we look for it.
106 struct object *tmp = obj_hash[i];
107 obj_hash[i] = obj_hash[first];
108 obj_hash[first] = tmp;
110 return obj;
114 * Increase the size of the hash map stored in obj_hash to the next
115 * power of 2 (but at least 32). Copy the existing values to the new
116 * hash map.
118 static void grow_object_hash(void)
120 int i;
122 * Note that this size must always be power-of-2 to match hash_obj
123 * above.
125 int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
126 struct object **new_hash;
128 new_hash = xcalloc(new_hash_size, sizeof(struct object *));
129 for (i = 0; i < obj_hash_size; i++) {
130 struct object *obj = obj_hash[i];
131 if (!obj)
132 continue;
133 insert_obj_hash(obj, new_hash, new_hash_size);
135 free(obj_hash);
136 obj_hash = new_hash;
137 obj_hash_size = new_hash_size;
140 void *create_object(const unsigned char *sha1, void *o)
142 struct object *obj = o;
144 obj->parsed = 0;
145 obj->used = 0;
146 obj->flags = 0;
147 hashcpy(obj->sha1, sha1);
149 if (obj_hash_size - 1 <= nr_objs * 2)
150 grow_object_hash();
152 insert_obj_hash(obj, obj_hash, obj_hash_size);
153 nr_objs++;
154 return obj;
157 void *object_as_type(struct object *obj, enum object_type type, int quiet)
159 if (obj->type == type)
160 return obj;
161 else if (obj->type == OBJ_NONE) {
162 if (type == OBJ_COMMIT)
163 ((struct commit *)obj)->index = alloc_commit_index();
164 obj->type = type;
165 return obj;
167 else {
168 if (!quiet)
169 error("object %s is a %s, not a %s",
170 sha1_to_hex(obj->sha1),
171 typename(obj->type), typename(type));
172 return NULL;
176 struct object *lookup_unknown_object(const unsigned char *sha1)
178 struct object *obj = lookup_object(sha1);
179 if (!obj)
180 obj = create_object(sha1, alloc_object_node());
181 return obj;
184 struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
186 struct object *obj;
187 *eaten_p = 0;
189 obj = NULL;
190 if (type == OBJ_BLOB) {
191 struct blob *blob = lookup_blob(sha1);
192 if (blob) {
193 if (parse_blob_buffer(blob, buffer, size))
194 return NULL;
195 obj = &blob->object;
197 } else if (type == OBJ_TREE) {
198 struct tree *tree = lookup_tree(sha1);
199 if (tree) {
200 obj = &tree->object;
201 if (!tree->buffer)
202 tree->object.parsed = 0;
203 if (!tree->object.parsed) {
204 if (parse_tree_buffer(tree, buffer, size))
205 return NULL;
206 *eaten_p = 1;
209 } else if (type == OBJ_COMMIT) {
210 struct commit *commit = lookup_commit(sha1);
211 if (commit) {
212 if (parse_commit_buffer(commit, buffer, size))
213 return NULL;
214 if (!get_cached_commit_buffer(commit, NULL)) {
215 set_commit_buffer(commit, buffer, size);
216 *eaten_p = 1;
218 obj = &commit->object;
220 } else if (type == OBJ_TAG) {
221 struct tag *tag = lookup_tag(sha1);
222 if (tag) {
223 if (parse_tag_buffer(tag, buffer, size))
224 return NULL;
225 obj = &tag->object;
227 } else {
228 warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
229 obj = NULL;
231 return obj;
234 struct object *parse_object_or_die(const unsigned char *sha1,
235 const char *name)
237 struct object *o = parse_object(sha1);
238 if (o)
239 return o;
241 die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
244 struct object *parse_object(const unsigned char *sha1)
246 unsigned long size;
247 enum object_type type;
248 int eaten;
249 const unsigned char *repl = lookup_replace_object(sha1);
250 void *buffer;
251 struct object *obj;
253 obj = lookup_object(sha1);
254 if (obj && obj->parsed)
255 return obj;
257 if ((obj && obj->type == OBJ_BLOB) ||
258 (!obj && has_sha1_file(sha1) &&
259 sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
260 if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
261 error("sha1 mismatch %s", sha1_to_hex(repl));
262 return NULL;
264 parse_blob_buffer(lookup_blob(sha1), NULL, 0);
265 return lookup_object(sha1);
268 buffer = read_sha1_file(sha1, &type, &size);
269 if (buffer) {
270 if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
271 free(buffer);
272 error("sha1 mismatch %s", sha1_to_hex(repl));
273 return NULL;
276 obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
277 if (!eaten)
278 free(buffer);
279 return obj;
281 return NULL;
284 struct object_list *object_list_insert(struct object *item,
285 struct object_list **list_p)
287 struct object_list *new_list = xmalloc(sizeof(struct object_list));
288 new_list->item = item;
289 new_list->next = *list_p;
290 *list_p = new_list;
291 return new_list;
294 int object_list_contains(struct object_list *list, struct object *obj)
296 while (list) {
297 if (list->item == obj)
298 return 1;
299 list = list->next;
301 return 0;
305 * A zero-length string to which object_array_entry::name can be
306 * initialized without requiring a malloc/free.
308 static char object_array_slopbuf[1];
310 void add_object_array_with_path(struct object *obj, const char *name,
311 struct object_array *array,
312 unsigned mode, const char *path)
314 unsigned nr = array->nr;
315 unsigned alloc = array->alloc;
316 struct object_array_entry *objects = array->objects;
317 struct object_array_entry *entry;
319 if (nr >= alloc) {
320 alloc = (alloc + 32) * 2;
321 REALLOC_ARRAY(objects, alloc);
322 array->alloc = alloc;
323 array->objects = objects;
325 entry = &objects[nr];
326 entry->item = obj;
327 if (!name)
328 entry->name = NULL;
329 else if (!*name)
330 /* Use our own empty string instead of allocating one: */
331 entry->name = object_array_slopbuf;
332 else
333 entry->name = xstrdup(name);
334 entry->mode = mode;
335 if (path)
336 entry->path = xstrdup(path);
337 else
338 entry->path = NULL;
339 array->nr = ++nr;
342 void add_object_array(struct object *obj, const char *name, struct object_array *array)
344 add_object_array_with_path(obj, name, array, S_IFINVALID, NULL);
348 * Free all memory associated with an entry; the result is
349 * in an unspecified state and should not be examined.
351 static void object_array_release_entry(struct object_array_entry *ent)
353 if (ent->name != object_array_slopbuf)
354 free(ent->name);
355 free(ent->path);
358 void object_array_filter(struct object_array *array,
359 object_array_each_func_t want, void *cb_data)
361 unsigned nr = array->nr, src, dst;
362 struct object_array_entry *objects = array->objects;
364 for (src = dst = 0; src < nr; src++) {
365 if (want(&objects[src], cb_data)) {
366 if (src != dst)
367 objects[dst] = objects[src];
368 dst++;
369 } else {
370 object_array_release_entry(&objects[src]);
373 array->nr = dst;
376 void object_array_clear(struct object_array *array)
378 int i;
379 for (i = 0; i < array->nr; i++)
380 object_array_release_entry(&array->objects[i]);
381 free(array->objects);
382 array->objects = NULL;
383 array->nr = array->alloc = 0;
387 * Return true iff array already contains an entry with name.
389 static int contains_name(struct object_array *array, const char *name)
391 unsigned nr = array->nr, i;
392 struct object_array_entry *object = array->objects;
394 for (i = 0; i < nr; i++, object++)
395 if (!strcmp(object->name, name))
396 return 1;
397 return 0;
400 void object_array_remove_duplicates(struct object_array *array)
402 unsigned nr = array->nr, src;
403 struct object_array_entry *objects = array->objects;
405 array->nr = 0;
406 for (src = 0; src < nr; src++) {
407 if (!contains_name(array, objects[src].name)) {
408 if (src != array->nr)
409 objects[array->nr] = objects[src];
410 array->nr++;
411 } else {
412 object_array_release_entry(&objects[src]);
417 void clear_object_flags(unsigned flags)
419 int i;
421 for (i=0; i < obj_hash_size; i++) {
422 struct object *obj = obj_hash[i];
423 if (obj)
424 obj->flags &= ~flags;