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index-pack: use streaming interface for collision test on large blobs

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When putting whole objects in core is unavoidable, try match object
type and size first before actually inflating.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nguyễn Thái Ngọc Duy 2012-05-24 20:55:44 +07:00 committed by Junio C Hamano
parent 8a2e163ccd
commit 4614043c8f
2 changed files with 82 additions and 5 deletions
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82
builtin/index-pack.c
View file

@ -9,6 +9,7 @@
#include "progress.h"
#include "fsck.h"
#include "exec_cmd.h"
#include "streaming.h"
#include "thread-utils.h"
static const char index_pack_usage[] =
@ -621,31 +622,102 @@ static void find_delta_children(const union delta_base *base,
*last_index = last;
}
struct compare_data {
struct object_entry *entry;
struct git_istream *st;
unsigned char *buf;
unsigned long buf_size;
};
static int compare_objects(const unsigned char *buf, unsigned long size,
void *cb_data)
{
struct compare_data *data = cb_data;
if (data->buf_size < size) {
free(data->buf);
data->buf = xmalloc(size);
data->buf_size = size;
}
while (size) {
ssize_t len = read_istream(data->st, data->buf, size);
if (len == 0)
die(_("SHA1 COLLISION FOUND WITH %s !"),
sha1_to_hex(data->entry->idx.sha1));
if (len < 0)
die(_("unable to read %s"),
sha1_to_hex(data->entry->idx.sha1));
if (memcmp(buf, data->buf, len))
die(_("SHA1 COLLISION FOUND WITH %s !"),
sha1_to_hex(data->entry->idx.sha1));
size -= len;
buf += len;
}
return 0;
}
static int check_collison(struct object_entry *entry)
{
struct compare_data data;
enum object_type type;
unsigned long size;
if (entry->size <= big_file_threshold || entry->type != OBJ_BLOB)
return -1;
memset(&data, 0, sizeof(data));
data.entry = entry;
data.st = open_istream(entry->idx.sha1, &type, &size, NULL);
if (!data.st)
return -1;
if (size != entry->size || type != entry->type)
die(_("SHA1 COLLISION FOUND WITH %s !"),
sha1_to_hex(entry->idx.sha1));
unpack_data(entry, compare_objects, &data);
close_istream(data.st);
free(data.buf);
return 0;
}
static void sha1_object(const void *data, struct object_entry *obj_entry,
unsigned long size, enum object_type type,
const unsigned char *sha1)
{
void *new_data = NULL;
int collision_test_needed;
assert(data || obj_entry);
read_lock();
if (has_sha1_file(sha1)) {
collision_test_needed = has_sha1_file(sha1);
read_unlock();
if (collision_test_needed && !data) {
read_lock();
if (!check_collison(obj_entry))
collision_test_needed = 0;
read_unlock();
}
if (collision_test_needed) {
void *has_data;
enum object_type has_type;
unsigned long has_size;
if (!data)
data = new_data = get_data_from_pack(obj_entry);
read_lock();
has_type = sha1_object_info(sha1, &has_size);
if (has_type != type || has_size != size)
die(_("SHA1 COLLISION FOUND WITH %s !"), sha1_to_hex(sha1));
has_data = read_sha1_file(sha1, &has_type, &has_size);
read_unlock();
if (!data)
data = new_data = get_data_from_pack(obj_entry);
if (!has_data)
die(_("cannot read existing object %s"), sha1_to_hex(sha1));
if (size != has_size || type != has_type ||
memcmp(data, has_data, size) != 0)
die(_("SHA1 COLLISION FOUND WITH %s !"), sha1_to_hex(sha1));
free(has_data);
} else
read_unlock();
}
if (strict) {
read_lock();

5
t/t5300-pack-object.sh
View file

@ -418,4 +418,9 @@ test_expect_success \
'test_must_fail git index-pack -o bad.idx test-3.pack 2>msg &&
grep "SHA1 COLLISION FOUND" msg'
test_expect_success \
'make sure index-pack detects the SHA1 collision (large blobs)' \
'test_must_fail git -c core.bigfilethreshold=1 index-pack -o bad.idx test-3.pack 2>msg &&
grep "SHA1 COLLISION FOUND" msg'
test_done