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 }