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 struct object *lookup_unknown_object(const unsigned char *sha1)
 162 {
 163         struct object *obj = lookup_object(sha1);
 164         if (!obj)
 165                 obj = create_object(sha1, alloc_object_node());
 166         return obj;
 167 }
 168
 169 struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
 170 {
 171         struct object *obj;
 172         *eaten_p = 0;
 173
 174         obj = NULL;
 175         if (type == OBJ_BLOB) {
 176                 struct blob *blob = lookup_blob(sha1);
 177                 if (blob) {
 178                         if (parse_blob_buffer(blob, buffer, size))
 179                                 return NULL;
 180                         obj = &blob->object;
 181                 }
 182         } else if (type == OBJ_TREE) {
 183                 struct tree *tree = lookup_tree(sha1);
 184                 if (tree) {
 185                         obj = &tree->object;
 186                         if (!tree->buffer)
 187                                 tree->object.parsed = 0;
 188                         if (!tree->object.parsed) {
 189                                 if (parse_tree_buffer(tree, buffer, size))
 190                                         return NULL;
 191                                 *eaten_p = 1;
 192                         }
 193                 }
 194         } else if (type == OBJ_COMMIT) {
 195                 struct commit *commit = lookup_commit(sha1);
 196                 if (commit) {
 197                         if (parse_commit_buffer(commit, buffer, size))
 198                                 return NULL;
 199                         if (!get_cached_commit_buffer(commit, NULL)) {
 200                                 set_commit_buffer(commit, buffer, size);
 201                                 *eaten_p = 1;
 202                         }
 203                         obj = &commit->object;
 204                 }
 205         } else if (type == OBJ_TAG) {
 206                 struct tag *tag = lookup_tag(sha1);
 207                 if (tag) {
 208                         if (parse_tag_buffer(tag, buffer, size))
 209                                return NULL;
 210                         obj = &tag->object;
 211                 }
 212         } else {
 213                 warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
 214                 obj = NULL;
 215         }
 216         return obj;
 217 }
 218
 219 struct object *parse_object_or_die(const unsigned char *sha1,
 220                                    const char *name)
 221 {
 222         struct object *o = parse_object(sha1);
 223         if (o)
 224                 return o;
 225
 226         die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
 227 }
 228
 229 struct object *parse_object(const unsigned char *sha1)
 230 {
 231         unsigned long size;
 232         enum object_type type;
 233         int eaten;
 234         const unsigned char *repl = lookup_replace_object(sha1);
 235         void *buffer;
 236         struct object *obj;
 237
 238         obj = lookup_object(sha1);
 239         if (obj && obj->parsed)
 240                 return obj;
 241
 242         if ((obj && obj->type == OBJ_BLOB) ||
 243             (!obj && has_sha1_file(sha1) &&
 244              sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
 245                 if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
 246                         error("sha1 mismatch %s", sha1_to_hex(repl));
 247                         return NULL;
 248                 }
 249                 parse_blob_buffer(lookup_blob(sha1), NULL, 0);
 250                 return lookup_object(sha1);
 251         }
 252
 253         buffer = read_sha1_file(sha1, &type, &size);
 254         if (buffer) {
 255                 if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
 256                         free(buffer);
 257                         error("sha1 mismatch %s", sha1_to_hex(repl));
 258                         return NULL;
 259                 }
 260
 261                 obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
 262                 if (!eaten)
 263                         free(buffer);
 264                 return obj;
 265         }
 266         return NULL;
 267 }
 268
 269 struct object_list *object_list_insert(struct object *item,
 270                                        struct object_list **list_p)
 271 {
 272         struct object_list *new_list = xmalloc(sizeof(struct object_list));
 273         new_list->item = item;
 274         new_list->next = *list_p;
 275         *list_p = new_list;
 276         return new_list;
 277 }
 278
 279 int object_list_contains(struct object_list *list, struct object *obj)
 280 {
 281         while (list) {
 282                 if (list->item == obj)
 283                         return 1;
 284                 list = list->next;
 285         }
 286         return 0;
 287 }
 288
 289 /*
 290  * A zero-length string to which object_array_entry::name can be
 291  * initialized without requiring a malloc/free.
 292  */
 293 static char object_array_slopbuf[1];
 294
 295 static void add_object_array_with_mode_context(struct object *obj, const char *name,
 296                                                struct object_array *array,
 297                                                unsigned mode,
 298                                                struct object_context *context)
 299 {
 300         unsigned nr = array->nr;
 301         unsigned alloc = array->alloc;
 302         struct object_array_entry *objects = array->objects;
 303         struct object_array_entry *entry;
 304
 305         if (nr >= alloc) {
 306                 alloc = (alloc + 32) * 2;
 307                 objects = xrealloc(objects, alloc * sizeof(*objects));
 308                 array->alloc = alloc;
 309                 array->objects = objects;
 310         }
 311         entry = &objects[nr];
 312         entry->item = obj;
 313         if (!name)
 314                 entry->name = NULL;
 315         else if (!*name)
 316                 /* Use our own empty string instead of allocating one: */
 317                 entry->name = object_array_slopbuf;
 318         else
 319                 entry->name = xstrdup(name);
 320         entry->mode = mode;
 321         entry->context = context;
 322         array->nr = ++nr;
 323 }
 324
 325 void add_object_array(struct object *obj, const char *name, struct object_array *array)
 326 {
 327         add_object_array_with_mode(obj, name, array, S_IFINVALID);
 328 }
 329
 330 void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
 331 {
 332         add_object_array_with_mode_context(obj, name, array, mode, NULL);
 333 }
 334
 335 void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context)
 336 {
 337         if (context)
 338                 add_object_array_with_mode_context(obj, name, array, context->mode, context);
 339         else
 340                 add_object_array_with_mode_context(obj, name, array, S_IFINVALID, context);
 341 }
 342
 343 void object_array_filter(struct object_array *array,
 344                          object_array_each_func_t want, void *cb_data)
 345 {
 346         unsigned nr = array->nr, src, dst;
 347         struct object_array_entry *objects = array->objects;
 348
 349         for (src = dst = 0; src < nr; src++) {
 350                 if (want(&objects[src], cb_data)) {
 351                         if (src != dst)
 352                                 objects[dst] = objects[src];
 353                         dst++;
 354                 } else {
 355                         if (objects[src].name != object_array_slopbuf)
 356                                 free(objects[src].name);
 357                 }
 358         }
 359         array->nr = dst;
 360 }
 361
 362 /*
 363  * Return true iff array already contains an entry with name.
 364  */
 365 static int contains_name(struct object_array *array, const char *name)
 366 {
 367         unsigned nr = array->nr, i;
 368         struct object_array_entry *object = array->objects;
 369
 370         for (i = 0; i < nr; i++, object++)
 371                 if (!strcmp(object->name, name))
 372                         return 1;
 373         return 0;
 374 }
 375
 376 void object_array_remove_duplicates(struct object_array *array)
 377 {
 378         unsigned nr = array->nr, src;
 379         struct object_array_entry *objects = array->objects;
 380
 381         array->nr = 0;
 382         for (src = 0; src < nr; src++) {
 383                 if (!contains_name(array, objects[src].name)) {
 384                         if (src != array->nr)
 385                                 objects[array->nr] = objects[src];
 386                         array->nr++;
 387                 } else {
 388                         if (objects[src].name != object_array_slopbuf)
 389                                 free(objects[src].name);
 390                 }
 391         }
 392 }
 393
 394 void clear_object_flags(unsigned flags)
 395 {
 396         int i;
 397
 398         for (i=0; i < obj_hash_size; i++) {
 399                 struct object *obj = obj_hash[i];
 400                 if (obj)
 401                         obj->flags &= ~flags;
 402         }
 403 }