development/git
development/git
1
0
Fork 0
mirror of https://github.com/git/git synced 2024-07-17 02:57:48 +00:00
Code Issues Actions 9 Packages Projects Releases Wiki Activity

prepare_packed_git_one: refactor duplicate-pack check

Browse source 
When we are reloading the list of packs, we check whether a
particular pack has been loaded. This is slightly tricky,
because we load packs based on the presence of their ".idx"
files, but record the name of the matching ".pack" file.
Therefore we want to compare their bases.

The existing code stripped off ".idx" from a file we found,
then compared that whole base length to strings containing
the ".pack" version. This meant we could end up comparing
bytes past what the ".pack" string contained, if the ".idx"
file name was much longer.

In practice, it worked OK because memcmp would end up seeing
a difference in the two strings and would return early
before hitting the full length. However, memcmp may
sometimes read extra bytes past a difference (e.g., because
it is comparing 64-bit words), or is even free to compare in
reverse order.

Furthermore, our memcmp made no guarantees that we matched
the whole pack name, up to ".pack". So "foo.idx" would match
"foo-bar.pack", which is wrong (but does not typically
happen, because our pack names have a fixed size).

We can fix both issues, avoid magic numbers, and document
that we expect to compare against a string with ".pack" by
using strip_suffix.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2014-06-30 13:04:03 -04:00 committed by Junio C Hamano
parent d6cd00c768
commit 47bf4b0fc5
1 changed files with 7 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
sha1_file.c
View file

@ -1197,6 +1197,7 @@ static void prepare_packed_git_one(char *objdir, int local)
dirnamelen = path.len;
while ((de = readdir(dir)) != NULL) {
struct packed_git *p;
size_t base_len;
if (is_dot_or_dotdot(de->d_name))
continue;
@ -1204,10 +1205,14 @@ static void prepare_packed_git_one(char *objdir, int local)
strbuf_setlen(&path, dirnamelen);
strbuf_addstr(&path, de->d_name);
if (ends_with(de->d_name, ".idx")) {
base_len = path.len;
if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
/* Don't reopen a pack we already have. */
for (p = packed_git; p; p = p->next) {
if (!memcmp(path.buf, p->pack_name, path.len - 4))
size_t len;
if (strip_suffix(p->pack_name, ".pack", &len) &&
len == base_len &&
!memcmp(p->pack_name, path.buf, len))
break;
}
if (p == NULL &&