git/object.c
Jeff King 75a9549047 avoid segfaults on parse_object failure
Many call-sites of parse_object assume that they will get a
non-NULL return value; this is not the case if we encounter
an error while parsing the object.

This patch adds a wrapper function around parse_object that
handles dying automatically, and uses it anywhere we
immediately try to access the return value as a non-NULL
pointer (i.e., anywhere that we would currently segfault).

This wrapper may also be useful in other places. The most
obvious one is code like:

  o = parse_object(sha1);
  if (!o)
	  die(...);

However, these should not be mechanically converted to
parse_object_or_die, as the die message is sometimes
customized. Later patches can address these sites on a
case-by-case basis.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-17 12:49:03 -07:00

310 lines
6.6 KiB
C

#include "cache.h"
#include "object.h"
#include "blob.h"
#include "tree.h"
#include "commit.h"
#include "tag.h"
static struct object **obj_hash;
static int nr_objs, obj_hash_size;
unsigned int get_max_object_index(void)
{
return obj_hash_size;
}
struct object *get_indexed_object(unsigned int idx)
{
return obj_hash[idx];
}
static const char *object_type_strings[] = {
NULL, /* OBJ_NONE = 0 */
"commit", /* OBJ_COMMIT = 1 */
"tree", /* OBJ_TREE = 2 */
"blob", /* OBJ_BLOB = 3 */
"tag", /* OBJ_TAG = 4 */
};
const char *typename(unsigned int type)
{
if (type >= ARRAY_SIZE(object_type_strings))
return NULL;
return object_type_strings[type];
}
int type_from_string(const char *str)
{
int i;
for (i = 1; i < ARRAY_SIZE(object_type_strings); i++)
if (!strcmp(str, object_type_strings[i]))
return i;
die("invalid object type \"%s\"", str);
}
static unsigned int hash_obj(struct object *obj, unsigned int n)
{
unsigned int hash;
memcpy(&hash, obj->sha1, sizeof(unsigned int));
return hash % n;
}
static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
{
unsigned int j = hash_obj(obj, size);
while (hash[j]) {
j++;
if (j >= size)
j = 0;
}
hash[j] = obj;
}
static unsigned int hashtable_index(const unsigned char *sha1)
{
unsigned int i;
memcpy(&i, sha1, sizeof(unsigned int));
return i % obj_hash_size;
}
struct object *lookup_object(const unsigned char *sha1)
{
unsigned int i;
struct object *obj;
if (!obj_hash)
return NULL;
i = hashtable_index(sha1);
while ((obj = obj_hash[i]) != NULL) {
if (!hashcmp(sha1, obj->sha1))
break;
i++;
if (i == obj_hash_size)
i = 0;
}
return obj;
}
static void grow_object_hash(void)
{
int i;
int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
struct object **new_hash;
new_hash = xcalloc(new_hash_size, sizeof(struct object *));
for (i = 0; i < obj_hash_size; i++) {
struct object *obj = obj_hash[i];
if (!obj)
continue;
insert_obj_hash(obj, new_hash, new_hash_size);
}
free(obj_hash);
obj_hash = new_hash;
obj_hash_size = new_hash_size;
}
void *create_object(const unsigned char *sha1, int type, void *o)
{
struct object *obj = o;
obj->parsed = 0;
obj->used = 0;
obj->type = type;
obj->flags = 0;
hashcpy(obj->sha1, sha1);
if (obj_hash_size - 1 <= nr_objs * 2)
grow_object_hash();
insert_obj_hash(obj, obj_hash, obj_hash_size);
nr_objs++;
return obj;
}
struct object *lookup_unknown_object(const unsigned char *sha1)
{
struct object *obj = lookup_object(sha1);
if (!obj)
obj = create_object(sha1, OBJ_NONE, alloc_object_node());
return obj;
}
struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
{
struct object *obj;
int eaten = 0;
obj = NULL;
if (type == OBJ_BLOB) {
struct blob *blob = lookup_blob(sha1);
if (blob) {
if (parse_blob_buffer(blob, buffer, size))
return NULL;
obj = &blob->object;
}
} else if (type == OBJ_TREE) {
struct tree *tree = lookup_tree(sha1);
if (tree) {
obj = &tree->object;
if (!tree->buffer)
tree->object.parsed = 0;
if (!tree->object.parsed) {
if (parse_tree_buffer(tree, buffer, size))
return NULL;
eaten = 1;
}
}
} else if (type == OBJ_COMMIT) {
struct commit *commit = lookup_commit(sha1);
if (commit) {
if (parse_commit_buffer(commit, buffer, size))
return NULL;
if (!commit->buffer) {
commit->buffer = buffer;
eaten = 1;
}
obj = &commit->object;
}
} else if (type == OBJ_TAG) {
struct tag *tag = lookup_tag(sha1);
if (tag) {
if (parse_tag_buffer(tag, buffer, size))
return NULL;
obj = &tag->object;
}
} else {
warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
obj = NULL;
}
if (obj && obj->type == OBJ_NONE)
obj->type = type;
*eaten_p = eaten;
return obj;
}
struct object *parse_object_or_die(const unsigned char *sha1,
const char *name)
{
struct object *o = parse_object(sha1);
if (o)
return o;
die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
}
struct object *parse_object(const unsigned char *sha1)
{
unsigned long size;
enum object_type type;
int eaten;
const unsigned char *repl = lookup_replace_object(sha1);
void *buffer;
struct object *obj;
obj = lookup_object(sha1);
if (obj && obj->parsed)
return obj;
if ((obj && obj->type == OBJ_BLOB) ||
(!obj && has_sha1_file(sha1) &&
sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
error("sha1 mismatch %s", sha1_to_hex(repl));
return NULL;
}
parse_blob_buffer(lookup_blob(sha1), NULL, 0);
return lookup_object(sha1);
}
buffer = read_sha1_file(sha1, &type, &size);
if (buffer) {
if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
free(buffer);
error("sha1 mismatch %s", sha1_to_hex(repl));
return NULL;
}
obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
if (!eaten)
free(buffer);
return obj;
}
return NULL;
}
struct object_list *object_list_insert(struct object *item,
struct object_list **list_p)
{
struct object_list *new_list = xmalloc(sizeof(struct object_list));
new_list->item = item;
new_list->next = *list_p;
*list_p = new_list;
return new_list;
}
int object_list_contains(struct object_list *list, struct object *obj)
{
while (list) {
if (list->item == obj)
return 1;
list = list->next;
}
return 0;
}
void add_object_array(struct object *obj, const char *name, struct object_array *array)
{
add_object_array_with_mode(obj, name, array, S_IFINVALID);
}
void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
{
unsigned nr = array->nr;
unsigned alloc = array->alloc;
struct object_array_entry *objects = array->objects;
if (nr >= alloc) {
alloc = (alloc + 32) * 2;
objects = xrealloc(objects, alloc * sizeof(*objects));
array->alloc = alloc;
array->objects = objects;
}
objects[nr].item = obj;
objects[nr].name = name;
objects[nr].mode = mode;
array->nr = ++nr;
}
void object_array_remove_duplicates(struct object_array *array)
{
unsigned int ref, src, dst;
struct object_array_entry *objects = array->objects;
for (ref = 0; ref + 1 < array->nr; ref++) {
for (src = ref + 1, dst = src;
src < array->nr;
src++) {
if (!strcmp(objects[ref].name, objects[src].name))
continue;
if (src != dst)
objects[dst] = objects[src];
dst++;
}
array->nr = dst;
}
}
void clear_object_flags(unsigned flags)
{
int i;
for (i=0; i < obj_hash_size; i++) {
struct object *obj = obj_hash[i];
if (obj)
obj->flags &= ~flags;
}
}