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![Jeff King](/assets/img/avatar_default.png)
Most callsites which use the commit buffer try to use the cached version attached to the commit, rather than re-reading from disk. Unfortunately, that interface provides only a pointer to the NUL-terminated buffer, with no indication of the original length. For the most part, this doesn't matter. People do not put NULs in their commit messages, and the log code is happy to treat it all as a NUL-terminated string. However, some code paths do care. For example, when checking signatures, we want to be very careful that we verify all the bytes to avoid malicious trickery. This patch just adds an optional "size" out-pointer to get_commit_buffer and friends. The existing callers all pass NULL (there did not seem to be any obvious sites where we could avoid an immediate strlen() call, though perhaps with some further refactoring we could). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
407 lines
9.6 KiB
C
407 lines
9.6 KiB
C
#include "cache.h"
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#include "object.h"
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#include "blob.h"
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#include "tree.h"
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#include "commit.h"
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#include "tag.h"
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static struct object **obj_hash;
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static int nr_objs, obj_hash_size;
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unsigned int get_max_object_index(void)
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{
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return obj_hash_size;
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}
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struct object *get_indexed_object(unsigned int idx)
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{
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return obj_hash[idx];
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}
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static const char *object_type_strings[] = {
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NULL, /* OBJ_NONE = 0 */
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"commit", /* OBJ_COMMIT = 1 */
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"tree", /* OBJ_TREE = 2 */
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"blob", /* OBJ_BLOB = 3 */
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"tag", /* OBJ_TAG = 4 */
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};
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const char *typename(unsigned int type)
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{
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if (type >= ARRAY_SIZE(object_type_strings))
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return NULL;
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return object_type_strings[type];
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}
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int type_from_string(const char *str)
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{
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int i;
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for (i = 1; i < ARRAY_SIZE(object_type_strings); i++)
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if (!strcmp(str, object_type_strings[i]))
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return i;
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die("invalid object type \"%s\"", str);
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}
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/*
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* Return a numerical hash value between 0 and n-1 for the object with
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* the specified sha1. n must be a power of 2. Please note that the
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* return value is *not* consistent across computer architectures.
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*/
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static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
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{
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unsigned int hash;
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/*
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* Since the sha1 is essentially random, we just take the
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* required number of bits directly from the first
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* sizeof(unsigned int) bytes of sha1. First we have to copy
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* the bytes into a properly aligned integer. If we cared
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* about getting consistent results across architectures, we
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* would have to call ntohl() here, too.
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*/
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memcpy(&hash, sha1, sizeof(unsigned int));
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return hash & (n - 1);
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}
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/*
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* Insert obj into the hash table hash, which has length size (which
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* must be a power of 2). On collisions, simply overflow to the next
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* empty bucket.
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*/
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static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
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{
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unsigned int j = hash_obj(obj->sha1, size);
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while (hash[j]) {
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j++;
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if (j >= size)
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j = 0;
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}
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hash[j] = obj;
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}
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/*
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* Look up the record for the given sha1 in the hash map stored in
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* obj_hash. Return NULL if it was not found.
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*/
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struct object *lookup_object(const unsigned char *sha1)
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{
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unsigned int i, first;
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struct object *obj;
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if (!obj_hash)
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return NULL;
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first = i = hash_obj(sha1, obj_hash_size);
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while ((obj = obj_hash[i]) != NULL) {
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if (!hashcmp(sha1, obj->sha1))
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break;
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i++;
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if (i == obj_hash_size)
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i = 0;
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}
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if (obj && i != first) {
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/*
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* Move object to where we started to look for it so
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* that we do not need to walk the hash table the next
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* time we look for it.
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*/
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struct object *tmp = obj_hash[i];
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obj_hash[i] = obj_hash[first];
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obj_hash[first] = tmp;
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}
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return obj;
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}
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/*
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* Increase the size of the hash map stored in obj_hash to the next
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* power of 2 (but at least 32). Copy the existing values to the new
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* hash map.
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*/
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static void grow_object_hash(void)
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{
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int i;
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/*
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* Note that this size must always be power-of-2 to match hash_obj
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* above.
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*/
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int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
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struct object **new_hash;
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new_hash = xcalloc(new_hash_size, sizeof(struct object *));
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for (i = 0; i < obj_hash_size; i++) {
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struct object *obj = obj_hash[i];
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if (!obj)
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continue;
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insert_obj_hash(obj, new_hash, new_hash_size);
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}
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free(obj_hash);
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obj_hash = new_hash;
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obj_hash_size = new_hash_size;
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}
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void *create_object(const unsigned char *sha1, int type, void *o)
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{
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struct object *obj = o;
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obj->parsed = 0;
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obj->used = 0;
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obj->type = type;
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obj->flags = 0;
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hashcpy(obj->sha1, sha1);
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if (obj_hash_size - 1 <= nr_objs * 2)
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grow_object_hash();
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insert_obj_hash(obj, obj_hash, obj_hash_size);
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nr_objs++;
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return obj;
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}
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struct object *lookup_unknown_object(const unsigned char *sha1)
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{
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struct object *obj = lookup_object(sha1);
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if (!obj)
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obj = create_object(sha1, OBJ_NONE, alloc_object_node());
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return obj;
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}
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struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
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{
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struct object *obj;
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*eaten_p = 0;
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obj = NULL;
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if (type == OBJ_BLOB) {
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struct blob *blob = lookup_blob(sha1);
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if (blob) {
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if (parse_blob_buffer(blob, buffer, size))
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return NULL;
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obj = &blob->object;
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}
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} else if (type == OBJ_TREE) {
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struct tree *tree = lookup_tree(sha1);
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if (tree) {
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obj = &tree->object;
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if (!tree->buffer)
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tree->object.parsed = 0;
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if (!tree->object.parsed) {
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if (parse_tree_buffer(tree, buffer, size))
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return NULL;
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*eaten_p = 1;
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}
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}
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} else if (type == OBJ_COMMIT) {
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struct commit *commit = lookup_commit(sha1);
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if (commit) {
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if (parse_commit_buffer(commit, buffer, size))
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return NULL;
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if (!get_cached_commit_buffer(commit, NULL)) {
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set_commit_buffer(commit, buffer, size);
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*eaten_p = 1;
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}
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obj = &commit->object;
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}
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} else if (type == OBJ_TAG) {
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struct tag *tag = lookup_tag(sha1);
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if (tag) {
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if (parse_tag_buffer(tag, buffer, size))
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return NULL;
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obj = &tag->object;
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}
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} else {
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warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
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obj = NULL;
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}
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if (obj && obj->type == OBJ_NONE)
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obj->type = type;
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return obj;
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}
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struct object *parse_object_or_die(const unsigned char *sha1,
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const char *name)
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{
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struct object *o = parse_object(sha1);
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if (o)
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return o;
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die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
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}
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struct object *parse_object(const unsigned char *sha1)
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{
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unsigned long size;
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enum object_type type;
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int eaten;
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const unsigned char *repl = lookup_replace_object(sha1);
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void *buffer;
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struct object *obj;
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obj = lookup_object(sha1);
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if (obj && obj->parsed)
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return obj;
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if ((obj && obj->type == OBJ_BLOB) ||
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(!obj && has_sha1_file(sha1) &&
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sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
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if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
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error("sha1 mismatch %s", sha1_to_hex(repl));
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return NULL;
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}
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parse_blob_buffer(lookup_blob(sha1), NULL, 0);
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return lookup_object(sha1);
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}
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buffer = read_sha1_file(sha1, &type, &size);
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if (buffer) {
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if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
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free(buffer);
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error("sha1 mismatch %s", sha1_to_hex(repl));
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return NULL;
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}
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obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
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if (!eaten)
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free(buffer);
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return obj;
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}
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return NULL;
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}
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struct object_list *object_list_insert(struct object *item,
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struct object_list **list_p)
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{
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struct object_list *new_list = xmalloc(sizeof(struct object_list));
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new_list->item = item;
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new_list->next = *list_p;
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*list_p = new_list;
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return new_list;
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}
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int object_list_contains(struct object_list *list, struct object *obj)
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{
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while (list) {
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if (list->item == obj)
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return 1;
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list = list->next;
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}
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return 0;
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}
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/*
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* A zero-length string to which object_array_entry::name can be
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* initialized without requiring a malloc/free.
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*/
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static char object_array_slopbuf[1];
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static void add_object_array_with_mode_context(struct object *obj, const char *name,
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struct object_array *array,
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unsigned mode,
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struct object_context *context)
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{
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unsigned nr = array->nr;
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unsigned alloc = array->alloc;
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struct object_array_entry *objects = array->objects;
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struct object_array_entry *entry;
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if (nr >= alloc) {
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alloc = (alloc + 32) * 2;
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objects = xrealloc(objects, alloc * sizeof(*objects));
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array->alloc = alloc;
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array->objects = objects;
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}
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entry = &objects[nr];
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entry->item = obj;
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if (!name)
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entry->name = NULL;
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else if (!*name)
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/* Use our own empty string instead of allocating one: */
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entry->name = object_array_slopbuf;
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else
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entry->name = xstrdup(name);
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entry->mode = mode;
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entry->context = context;
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array->nr = ++nr;
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}
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void add_object_array(struct object *obj, const char *name, struct object_array *array)
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{
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add_object_array_with_mode(obj, name, array, S_IFINVALID);
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}
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void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
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{
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add_object_array_with_mode_context(obj, name, array, mode, NULL);
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}
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void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context)
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{
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if (context)
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add_object_array_with_mode_context(obj, name, array, context->mode, context);
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else
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add_object_array_with_mode_context(obj, name, array, S_IFINVALID, context);
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}
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void object_array_filter(struct object_array *array,
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object_array_each_func_t want, void *cb_data)
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{
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unsigned nr = array->nr, src, dst;
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struct object_array_entry *objects = array->objects;
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for (src = dst = 0; src < nr; src++) {
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if (want(&objects[src], cb_data)) {
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if (src != dst)
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objects[dst] = objects[src];
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dst++;
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} else {
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if (objects[src].name != object_array_slopbuf)
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free(objects[src].name);
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}
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}
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array->nr = dst;
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}
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/*
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* Return true iff array already contains an entry with name.
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*/
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static int contains_name(struct object_array *array, const char *name)
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{
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unsigned nr = array->nr, i;
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struct object_array_entry *object = array->objects;
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for (i = 0; i < nr; i++, object++)
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if (!strcmp(object->name, name))
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return 1;
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return 0;
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}
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void object_array_remove_duplicates(struct object_array *array)
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{
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unsigned nr = array->nr, src;
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struct object_array_entry *objects = array->objects;
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array->nr = 0;
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for (src = 0; src < nr; src++) {
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if (!contains_name(array, objects[src].name)) {
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if (src != array->nr)
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objects[array->nr] = objects[src];
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array->nr++;
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} else {
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if (objects[src].name != object_array_slopbuf)
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free(objects[src].name);
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}
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}
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}
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void clear_object_flags(unsigned flags)
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{
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int i;
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for (i=0; i < obj_hash_size; i++) {
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struct object *obj = obj_hash[i];
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if (obj)
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obj->flags &= ~flags;
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}
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}
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