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         return sha1hash(sha1) & (n - 1);
  54 }
  55
  56 /*
  57  * Insert obj into the hash table hash, which has length size (which
  58  * must be a power of 2).  On collisions, simply overflow to the next
  59  * empty bucket.
  60  */
  61 static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
  62 {
  63         unsigned int j = hash_obj(obj->sha1, size);
  64
  65         while (hash[j]) {
  66                 j++;
  67                 if (j >= size)
  68                         j = 0;
  69         }
  70         hash[j] = obj;
  71 }
  72
  73 /*
  74  * Look up the record for the given sha1 in the hash map stored in
  75  * obj_hash.  Return NULL if it was not found.
  76  */
  77 struct object *lookup_object(const unsigned char *sha1)
  78 {
  79         unsigned int i, first;
  80         struct object *obj;
  81
  82         if (!obj_hash)
  83                 return NULL;
  84
  85         first = i = hash_obj(sha1, obj_hash_size);
  86         while ((obj = obj_hash[i]) != NULL) {
  87                 if (!hashcmp(sha1, obj->sha1))
  88                         break;
  89                 i++;
  90                 if (i == obj_hash_size)
  91                         i = 0;
  92         }
  93         if (obj && i != first) {
  94                 /*
  95                  * Move object to where we started to look for it so
  96                  * that we do not need to walk the hash table the next
  97                  * time we look for it.
  98                  */
  99                 struct object *tmp = obj_hash[i];
 100                 obj_hash[i] = obj_hash[first];
 101                 obj_hash[first] = tmp;
 102         }
 103         return obj;
 104 }
 105
 106 /*
 107  * Increase the size of the hash map stored in obj_hash to the next
 108  * power of 2 (but at least 32).  Copy the existing values to the new
 109  * hash map.
 110  */
 111 static void grow_object_hash(void)
 112 {
 113         int i;
 114         /*
 115          * Note that this size must always be power-of-2 to match hash_obj
 116          * above.
 117          */
 118         int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
 119         struct object **new_hash;
 120
 121         new_hash = xcalloc(new_hash_size, sizeof(struct object *));
 122         for (i = 0; i < obj_hash_size; i++) {
 123                 struct object *obj = obj_hash[i];
 124                 if (!obj)
 125                         continue;
 126                 insert_obj_hash(obj, new_hash, new_hash_size);
 127         }
 128         free(obj_hash);
 129         obj_hash = new_hash;
 130         obj_hash_size = new_hash_size;
 131 }
 132
 133 void *create_object(const unsigned char *sha1, int type, void *o)
 134 {
 135         struct object *obj = o;
 136
 137         obj->parsed = 0;
 138         obj->used = 0;
 139         obj->type = type;
 140         obj->flags = 0;
 141         hashcpy(obj->sha1, sha1);
 142
 143         if (obj_hash_size - 1 <= nr_objs * 2)
 144                 grow_object_hash();
 145
 146         insert_obj_hash(obj, obj_hash, obj_hash_size);
 147         nr_objs++;
 148         return obj;
 149 }
 150
 151 struct object *lookup_unknown_object(const unsigned char *sha1)
 152 {
 153         struct object *obj = lookup_object(sha1);
 154         if (!obj)
 155                 obj = create_object(sha1, OBJ_NONE, alloc_object_node());
 156         return obj;
 157 }
 158
 159 struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
 160 {
 161         struct object *obj;
 162         *eaten_p = 0;
 163
 164         obj = NULL;
 165         if (type == OBJ_BLOB) {
 166                 struct blob *blob = lookup_blob(sha1);
 167                 if (blob) {
 168                         if (parse_blob_buffer(blob, buffer, size))
 169                                 return NULL;
 170                         obj = &blob->object;
 171                 }
 172         } else if (type == OBJ_TREE) {
 173                 struct tree *tree = lookup_tree(sha1);
 174                 if (tree) {
 175                         obj = &tree->object;
 176                         if (!tree->buffer)
 177                                 tree->object.parsed = 0;
 178                         if (!tree->object.parsed) {
 179                                 if (parse_tree_buffer(tree, buffer, size))
 180                                         return NULL;
 181                                 *eaten_p = 1;
 182                         }
 183                 }
 184         } else if (type == OBJ_COMMIT) {
 185                 struct commit *commit = lookup_commit(sha1);
 186                 if (commit) {
 187                         if (parse_commit_buffer(commit, buffer, size))
 188                                 return NULL;
 189                         if (!get_cached_commit_buffer(commit, NULL)) {
 190                                 set_commit_buffer(commit, buffer, size);
 191                                 *eaten_p = 1;
 192                         }
 193                         obj = &commit->object;
 194                 }
 195         } else if (type == OBJ_TAG) {
 196                 struct tag *tag = lookup_tag(sha1);
 197                 if (tag) {
 198                         if (parse_tag_buffer(tag, buffer, size))
 199                                return NULL;
 200                         obj = &tag->object;
 201                 }
 202         } else {
 203                 warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
 204                 obj = NULL;
 205         }
 206         if (obj && obj->type == OBJ_NONE)
 207                 obj->type = type;
 208         return obj;
 209 }
 210
 211 struct object *parse_object_or_die(const unsigned char *sha1,
 212                                    const char *name)
 213 {
 214         struct object *o = parse_object(sha1);
 215         if (o)
 216                 return o;
 217
 218         die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
 219 }
 220
 221 struct object *parse_object(const unsigned char *sha1)
 222 {
 223         unsigned long size;
 224         enum object_type type;
 225         int eaten;
 226         const unsigned char *repl = lookup_replace_object(sha1);
 227         void *buffer;
 228         struct object *obj;
 229
 230         obj = lookup_object(sha1);
 231         if (obj && obj->parsed)
 232                 return obj;
 233
 234         if ((obj && obj->type == OBJ_BLOB) ||
 235             (!obj && has_sha1_file(sha1) &&
 236              sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
 237                 if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
 238                         error("sha1 mismatch %s", sha1_to_hex(repl));
 239                         return NULL;
 240                 }
 241                 parse_blob_buffer(lookup_blob(sha1), NULL, 0);
 242                 return lookup_object(sha1);
 243         }
 244
 245         buffer = read_sha1_file(sha1, &type, &size);
 246         if (buffer) {
 247                 if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
 248                         free(buffer);
 249                         error("sha1 mismatch %s", sha1_to_hex(repl));
 250                         return NULL;
 251                 }
 252
 253                 obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
 254                 if (!eaten)
 255                         free(buffer);
 256                 return obj;
 257         }
 258         return NULL;
 259 }
 260
 261 struct object_list *object_list_insert(struct object *item,
 262                                        struct object_list **list_p)
 263 {
 264         struct object_list *new_list = xmalloc(sizeof(struct object_list));
 265         new_list->item = item;
 266         new_list->next = *list_p;
 267         *list_p = new_list;
 268         return new_list;
 269 }
 270
 271 int object_list_contains(struct object_list *list, struct object *obj)
 272 {
 273         while (list) {
 274                 if (list->item == obj)
 275                         return 1;
 276                 list = list->next;
 277         }
 278         return 0;
 279 }
 280
 281 /*
 282  * A zero-length string to which object_array_entry::name can be
 283  * initialized without requiring a malloc/free.
 284  */
 285 static char object_array_slopbuf[1];
 286
 287 static void add_object_array_with_mode_context(struct object *obj, const char *name,
 288                                                struct object_array *array,
 289                                                unsigned mode,
 290                                                struct object_context *context)
 291 {
 292         unsigned nr = array->nr;
 293         unsigned alloc = array->alloc;
 294         struct object_array_entry *objects = array->objects;
 295         struct object_array_entry *entry;
 296
 297         if (nr >= alloc) {
 298                 alloc = (alloc + 32) * 2;
 299                 objects = xrealloc(objects, alloc * sizeof(*objects));
 300                 array->alloc = alloc;
 301                 array->objects = objects;
 302         }
 303         entry = &objects[nr];
 304         entry->item = obj;
 305         if (!name)
 306                 entry->name = NULL;
 307         else if (!*name)
 308                 /* Use our own empty string instead of allocating one: */
 309                 entry->name = object_array_slopbuf;
 310         else
 311                 entry->name = xstrdup(name);
 312         entry->mode = mode;
 313         entry->context = context;
 314         array->nr = ++nr;
 315 }
 316
 317 void add_object_array(struct object *obj, const char *name, struct object_array *array)
 318 {
 319         add_object_array_with_mode(obj, name, array, S_IFINVALID);
 320 }
 321
 322 void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
 323 {
 324         add_object_array_with_mode_context(obj, name, array, mode, NULL);
 325 }
 326
 327 void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context)
 328 {
 329         if (context)
 330                 add_object_array_with_mode_context(obj, name, array, context->mode, context);
 331         else
 332                 add_object_array_with_mode_context(obj, name, array, S_IFINVALID, context);
 333 }
 334
 335 void object_array_filter(struct object_array *array,
 336                          object_array_each_func_t want, void *cb_data)
 337 {
 338         unsigned nr = array->nr, src, dst;
 339         struct object_array_entry *objects = array->objects;
 340
 341         for (src = dst = 0; src < nr; src++) {
 342                 if (want(&objects[src], cb_data)) {
 343                         if (src != dst)
 344                                 objects[dst] = objects[src];
 345                         dst++;
 346                 } else {
 347                         if (objects[src].name != object_array_slopbuf)
 348                                 free(objects[src].name);
 349                 }
 350         }
 351         array->nr = dst;
 352 }
 353
 354 /*
 355  * Return true iff array already contains an entry with name.
 356  */
 357 static int contains_name(struct object_array *array, const char *name)
 358 {
 359         unsigned nr = array->nr, i;
 360         struct object_array_entry *object = array->objects;
 361
 362         for (i = 0; i < nr; i++, object++)
 363                 if (!strcmp(object->name, name))
 364                         return 1;
 365         return 0;
 366 }
 367
 368 void object_array_remove_duplicates(struct object_array *array)
 369 {
 370         unsigned nr = array->nr, src;
 371         struct object_array_entry *objects = array->objects;
 372
 373         array->nr = 0;
 374         for (src = 0; src < nr; src++) {
 375                 if (!contains_name(array, objects[src].name)) {
 376                         if (src != array->nr)
 377                                 objects[array->nr] = objects[src];
 378                         array->nr++;
 379                 } else {
 380                         if (objects[src].name != object_array_slopbuf)
 381                                 free(objects[src].name);
 382                 }
 383         }
 384 }
 385
 386 void clear_object_flags(unsigned flags)
 387 {
 388         int i;
 389
 390         for (i=0; i < obj_hash_size; i++) {
 391                 struct object *obj = obj_hash[i];
 392                 if (obj)
 393                         obj->flags &= ~flags;
 394         }
 395 }