add object_as_type helper for casting objects
[git/git.git] / object.c
1 #include "cache.h"
2 #include "object.h"
3 #include "blob.h"
4 #include "tree.h"
5 #include "commit.h"
6 #include "tag.h"
7
8 static struct object **obj_hash;
9 static int nr_objs, obj_hash_size;
10
11 unsigned int get_max_object_index(void)
12 {
13 return obj_hash_size;
14 }
15
16 struct object *get_indexed_object(unsigned int idx)
17 {
18 return obj_hash[idx];
19 }
20
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 */
27 };
28
29 const char *typename(unsigned int type)
30 {
31 if (type >= ARRAY_SIZE(object_type_strings))
32 return NULL;
33 return object_type_strings[type];
34 }
35
36 int type_from_string(const char *str)
37 {
38 int i;
39
40 for (i = 1; i < ARRAY_SIZE(object_type_strings); i++)
41 if (!strcmp(str, object_type_strings[i]))
42 return i;
43 die("invalid object type \"%s\"", str);
44 }
45
46 /*
47 * Return a numerical hash value between 0 and n-1 for the object with
48 * the specified sha1. n must be a power of 2. Please note that the
49 * return value is *not* consistent across computer architectures.
50 */
51 static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
52 {
53 unsigned int hash;
54
55 /*
56 * Since the sha1 is essentially random, we just take the
57 * required number of bits directly from the first
58 * sizeof(unsigned int) bytes of sha1. First we have to copy
59 * the bytes into a properly aligned integer. If we cared
60 * about getting consistent results across architectures, we
61 * would have to call ntohl() here, too.
62 */
63 memcpy(&hash, sha1, sizeof(unsigned int));
64 return hash & (n - 1);
65 }
66
67 /*
68 * Insert obj into the hash table hash, which has length size (which
69 * must be a power of 2). On collisions, simply overflow to the next
70 * empty bucket.
71 */
72 static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
73 {
74 unsigned int j = hash_obj(obj->sha1, size);
75
76 while (hash[j]) {
77 j++;
78 if (j >= size)
79 j = 0;
80 }
81 hash[j] = obj;
82 }
83
84 /*
85 * Look up the record for the given sha1 in the hash map stored in
86 * obj_hash. Return NULL if it was not found.
87 */
88 struct object *lookup_object(const unsigned char *sha1)
89 {
90 unsigned int i, first;
91 struct object *obj;
92
93 if (!obj_hash)
94 return NULL;
95
96 first = i = hash_obj(sha1, obj_hash_size);
97 while ((obj = obj_hash[i]) != NULL) {
98 if (!hashcmp(sha1, obj->sha1))
99 break;
100 i++;
101 if (i == obj_hash_size)
102 i = 0;
103 }
104 if (obj && i != first) {
105 /*
106 * Move object to where we started to look for it so
107 * that we do not need to walk the hash table the next
108 * time we look for it.
109 */
110 struct object *tmp = obj_hash[i];
111 obj_hash[i] = obj_hash[first];
112 obj_hash[first] = tmp;
113 }
114 return obj;
115 }
116
117 /*
118 * Increase the size of the hash map stored in obj_hash to the next
119 * power of 2 (but at least 32). Copy the existing values to the new
120 * hash map.
121 */
122 static void grow_object_hash(void)
123 {
124 int i;
125 /*
126 * Note that this size must always be power-of-2 to match hash_obj
127 * above.
128 */
129 int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
130 struct object **new_hash;
131
132 new_hash = xcalloc(new_hash_size, sizeof(struct object *));
133 for (i = 0; i < obj_hash_size; i++) {
134 struct object *obj = obj_hash[i];
135 if (!obj)
136 continue;
137 insert_obj_hash(obj, new_hash, new_hash_size);
138 }
139 free(obj_hash);
140 obj_hash = new_hash;
141 obj_hash_size = new_hash_size;
142 }
143
144 void *create_object(const unsigned char *sha1, void *o)
145 {
146 struct object *obj = o;
147
148 obj->parsed = 0;
149 obj->used = 0;
150 obj->flags = 0;
151 hashcpy(obj->sha1, sha1);
152
153 if (obj_hash_size - 1 <= nr_objs * 2)
154 grow_object_hash();
155
156 insert_obj_hash(obj, obj_hash, obj_hash_size);
157 nr_objs++;
158 return obj;
159 }
160
161 void *object_as_type(struct object *obj, enum object_type type, int quiet)
162 {
163 if (obj->type == type)
164 return obj;
165 else if (obj->type == OBJ_NONE) {
166 obj->type = type;
167 return obj;
168 }
169 else {
170 if (!quiet)
171 error("object %s is a %s, not a %s",
172 sha1_to_hex(obj->sha1),
173 typename(obj->type), typename(type));
174 return NULL;
175 }
176 }
177
178 struct object *lookup_unknown_object(const unsigned char *sha1)
179 {
180 struct object *obj = lookup_object(sha1);
181 if (!obj)
182 obj = create_object(sha1, alloc_object_node());
183 return obj;
184 }
185
186 struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
187 {
188 struct object *obj;
189 *eaten_p = 0;
190
191 obj = NULL;
192 if (type == OBJ_BLOB) {
193 struct blob *blob = lookup_blob(sha1);
194 if (blob) {
195 if (parse_blob_buffer(blob, buffer, size))
196 return NULL;
197 obj = &blob->object;
198 }
199 } else if (type == OBJ_TREE) {
200 struct tree *tree = lookup_tree(sha1);
201 if (tree) {
202 obj = &tree->object;
203 if (!tree->buffer)
204 tree->object.parsed = 0;
205 if (!tree->object.parsed) {
206 if (parse_tree_buffer(tree, buffer, size))
207 return NULL;
208 *eaten_p = 1;
209 }
210 }
211 } else if (type == OBJ_COMMIT) {
212 struct commit *commit = lookup_commit(sha1);
213 if (commit) {
214 if (parse_commit_buffer(commit, buffer, size))
215 return NULL;
216 if (!get_cached_commit_buffer(commit, NULL)) {
217 set_commit_buffer(commit, buffer, size);
218 *eaten_p = 1;
219 }
220 obj = &commit->object;
221 }
222 } else if (type == OBJ_TAG) {
223 struct tag *tag = lookup_tag(sha1);
224 if (tag) {
225 if (parse_tag_buffer(tag, buffer, size))
226 return NULL;
227 obj = &tag->object;
228 }
229 } else {
230 warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
231 obj = NULL;
232 }
233 return obj;
234 }
235
236 struct object *parse_object_or_die(const unsigned char *sha1,
237 const char *name)
238 {
239 struct object *o = parse_object(sha1);
240 if (o)
241 return o;
242
243 die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
244 }
245
246 struct object *parse_object(const unsigned char *sha1)
247 {
248 unsigned long size;
249 enum object_type type;
250 int eaten;
251 const unsigned char *repl = lookup_replace_object(sha1);
252 void *buffer;
253 struct object *obj;
254
255 obj = lookup_object(sha1);
256 if (obj && obj->parsed)
257 return obj;
258
259 if ((obj && obj->type == OBJ_BLOB) ||
260 (!obj && has_sha1_file(sha1) &&
261 sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
262 if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
263 error("sha1 mismatch %s", sha1_to_hex(repl));
264 return NULL;
265 }
266 parse_blob_buffer(lookup_blob(sha1), NULL, 0);
267 return lookup_object(sha1);
268 }
269
270 buffer = read_sha1_file(sha1, &type, &size);
271 if (buffer) {
272 if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
273 free(buffer);
274 error("sha1 mismatch %s", sha1_to_hex(repl));
275 return NULL;
276 }
277
278 obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
279 if (!eaten)
280 free(buffer);
281 return obj;
282 }
283 return NULL;
284 }
285
286 struct object_list *object_list_insert(struct object *item,
287 struct object_list **list_p)
288 {
289 struct object_list *new_list = xmalloc(sizeof(struct object_list));
290 new_list->item = item;
291 new_list->next = *list_p;
292 *list_p = new_list;
293 return new_list;
294 }
295
296 int object_list_contains(struct object_list *list, struct object *obj)
297 {
298 while (list) {
299 if (list->item == obj)
300 return 1;
301 list = list->next;
302 }
303 return 0;
304 }
305
306 /*
307 * A zero-length string to which object_array_entry::name can be
308 * initialized without requiring a malloc/free.
309 */
310 static char object_array_slopbuf[1];
311
312 static void add_object_array_with_mode_context(struct object *obj, const char *name,
313 struct object_array *array,
314 unsigned mode,
315 struct object_context *context)
316 {
317 unsigned nr = array->nr;
318 unsigned alloc = array->alloc;
319 struct object_array_entry *objects = array->objects;
320 struct object_array_entry *entry;
321
322 if (nr >= alloc) {
323 alloc = (alloc + 32) * 2;
324 objects = xrealloc(objects, alloc * sizeof(*objects));
325 array->alloc = alloc;
326 array->objects = objects;
327 }
328 entry = &objects[nr];
329 entry->item = obj;
330 if (!name)
331 entry->name = NULL;
332 else if (!*name)
333 /* Use our own empty string instead of allocating one: */
334 entry->name = object_array_slopbuf;
335 else
336 entry->name = xstrdup(name);
337 entry->mode = mode;
338 entry->context = context;
339 array->nr = ++nr;
340 }
341
342 void add_object_array(struct object *obj, const char *name, struct object_array *array)
343 {
344 add_object_array_with_mode(obj, name, array, S_IFINVALID);
345 }
346
347 void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
348 {
349 add_object_array_with_mode_context(obj, name, array, mode, NULL);
350 }
351
352 void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context)
353 {
354 if (context)
355 add_object_array_with_mode_context(obj, name, array, context->mode, context);
356 else
357 add_object_array_with_mode_context(obj, name, array, S_IFINVALID, context);
358 }
359
360 void object_array_filter(struct object_array *array,
361 object_array_each_func_t want, void *cb_data)
362 {
363 unsigned nr = array->nr, src, dst;
364 struct object_array_entry *objects = array->objects;
365
366 for (src = dst = 0; src < nr; src++) {
367 if (want(&objects[src], cb_data)) {
368 if (src != dst)
369 objects[dst] = objects[src];
370 dst++;
371 } else {
372 if (objects[src].name != object_array_slopbuf)
373 free(objects[src].name);
374 }
375 }
376 array->nr = dst;
377 }
378
379 /*
380 * Return true iff array already contains an entry with name.
381 */
382 static int contains_name(struct object_array *array, const char *name)
383 {
384 unsigned nr = array->nr, i;
385 struct object_array_entry *object = array->objects;
386
387 for (i = 0; i < nr; i++, object++)
388 if (!strcmp(object->name, name))
389 return 1;
390 return 0;
391 }
392
393 void object_array_remove_duplicates(struct object_array *array)
394 {
395 unsigned nr = array->nr, src;
396 struct object_array_entry *objects = array->objects;
397
398 array->nr = 0;
399 for (src = 0; src < nr; src++) {
400 if (!contains_name(array, objects[src].name)) {
401 if (src != array->nr)
402 objects[array->nr] = objects[src];
403 array->nr++;
404 } else {
405 if (objects[src].name != object_array_slopbuf)
406 free(objects[src].name);
407 }
408 }
409 }
410
411 void clear_object_flags(unsigned flags)
412 {
413 int i;
414
415 for (i=0; i < obj_hash_size; i++) {
416 struct object *obj = obj_hash[i];
417 if (obj)
418 obj->flags &= ~flags;
419 }
420 }