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![Michael Haggerty](/assets/img/avatar_default.png)
Previously, the memory management of the object_array_entry::name
field was inconsistent and undocumented. object_array_entries are
ultimately created by a single function, add_object_array_with_mode(),
which has an argument "const char *name". This function used to
simply set the name field to reference the string pointed to by the
name parameter, and nobody on the object_array side ever freed the
memory. Thus, it assumed that the memory for the name field would be
managed by the caller, and that the lifetime of that string would be
at least as long as the lifetime of the object_array_entry. But
callers were inconsistent:
* Some passed pointers to constant strings or argv entries, which was
OK.
* Some passed pointers to newly-allocated memory, but didn't arrange
for the memory ever to be freed.
* Some passed the return value of sha1_to_hex(), which is a pointer to
a statically-allocated buffer that can be overwritten at any time.
* Some passed pointers to refnames that they received from a
for_each_ref()-type iteration, but the lifetimes of such refnames is
not guaranteed by the refs API.
Bring consistency to this mess by changing object_array to make its
own copy for the object_array_entry::name field and free this memory
when an object_array_entry is deleted from the array.
Many callers were passing the empty string as the name parameter, so
as a performance optimization, treat the empty string specially.
Instead of making a copy, store a pointer to a statically-allocated
empty string to object_array_entry::name. When deleting such an
entry, skip the free().
Change the callers that were already passing copies to
add_object_array_with_mode() to either skip the copy, or (if the
memory needed to be allocated anyway) freeing the memory itself.
A part of this commit effectively reverts
70d26c6e76
read_revisions_from_stdin: make copies for handle_revision_arg
because the copying introduced by that commit (which is still
necessary) is now done at a deeper level.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
356 lines
7.7 KiB
C
356 lines
7.7 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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static unsigned int hash_obj(struct object *obj, unsigned int n)
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{
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unsigned int hash;
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memcpy(&hash, obj->sha1, sizeof(unsigned int));
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return hash % n;
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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, 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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static unsigned int hashtable_index(const unsigned char *sha1)
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{
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unsigned int i;
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memcpy(&i, sha1, sizeof(unsigned int));
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return i % obj_hash_size;
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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;
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struct object *obj;
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if (!obj_hash)
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return NULL;
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i = hashtable_index(sha1);
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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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return obj;
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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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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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int eaten = 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 = 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 (!commit->buffer) {
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commit->buffer = buffer;
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eaten = 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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*eaten_p = eaten;
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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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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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/*
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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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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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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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array->nr = ++nr;
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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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