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builtin/repack.c: avoid dir traversal in collect_pack_filenames()

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When repacking, the function `collect_pack_filenames()` is responsible
for collecting the set of existing packs in the repository, and
partitioning them into "kept" (if the pack has a ".keep" file or was
given via `--keep-pack`) and "nonkept" (otherwise) lists.

This function comes from the original C port of git-repack.sh from back
in a1bbc6c017 (repack: rewrite the shell script in C, 2013-09-15),
where it first appears as `get_non_kept_pack_filenames()`. At the time,
the implementation was a fairly direct translation from the relevant
portion of git-repack.sh, which looped over the results of

    find "$PACKDIR" -type f -name '*.pack'

either ignoring the pack as kept, or adding it to the list of existing
packs.

So the choice to directly translate this function in terms of
`readdir()` in a1bbc6c017 made sense. At the time, it was possible to
refine the C version in terms of packed_git structs, but was never done.

However, manually enumerating a repository's packs via `readdir()` is
confusing and error-prone. It leads to frustrating inconsistencies
between which packs Git considers to be part of a repository (i.e.,
could be found in the list of packs from `get_all_packs()`), and which
packs `collect_pack_filenames()` considers to meet the same criteria.

This bit us in 73320e49ad (builtin/repack.c: only collect fully-formed
packs, 2023-06-07), and again in the previous commit.

Prevent these issues from biting us in the future by implementing the
`collect_pack_filenames()` function by looping over an array of pointers
to `packed_git` structs, ensuring that we use the same criteria to
determine the set of available packs.

One gotcha here is that we have to ignore non-local packs, since the
original version of `collect_pack_filenames()` only looks at the local
pack directory to collect existing packs.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau 2023-07-11 13:32:37 -04:00 committed by Junio C Hamano
parent 0af067276e
commit def390d593
1 changed files with 15 additions and 26 deletions
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41
builtin/repack.c
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@ -106,49 +106,38 @@ static void collect_pack_filenames(struct string_list *fname_nonkept_list,
struct string_list *fname_kept_list,
const struct string_list *extra_keep)
{
DIR *dir;
struct dirent *e;
char *fname;
struct packed_git *p;
struct strbuf buf = STRBUF_INIT;
if (!(dir = opendir(packdir)))
return;
while ((e = readdir(dir)) != NULL) {
size_t len;
for (p = get_all_packs(the_repository); p; p = p->next) {
int i;
const char *base;
if (!strip_suffix(e->d_name, ".idx", &len))
if (!p->pack_local)
continue;
strbuf_reset(&buf);
strbuf_add(&buf, e->d_name, len);
strbuf_addstr(&buf, ".pack");
if (!file_exists(mkpath("%s/%s", packdir, buf.buf)))
continue;
base = pack_basename(p);
for (i = 0; i < extra_keep->nr; i++)
if (!fspathcmp(buf.buf, extra_keep->items[i].string))
if (!fspathcmp(base, extra_keep->items[i].string))
break;
fname = xmemdupz(e->d_name, len);
strbuf_reset(&buf);
strbuf_addstr(&buf, base);
strbuf_strip_suffix(&buf, ".pack");
if ((extra_keep->nr > 0 && i < extra_keep->nr) ||
(file_exists(mkpath("%s/%s.keep", packdir, fname)))) {
string_list_append_nodup(fname_kept_list, fname);
} else {
if ((extra_keep->nr > 0 && i < extra_keep->nr) || p->pack_keep)
string_list_append(fname_kept_list, buf.buf);
else {
struct string_list_item *item;
item = string_list_append_nodup(fname_nonkept_list,
fname);
if (file_exists(mkpath("%s/%s.mtimes", packdir, fname)))
item = string_list_append(fname_nonkept_list, buf.buf);
if (p->is_cruft)
item->util = (void*)(uintptr_t)CRUFT_PACK;
}
}
closedir(dir);
strbuf_release(&buf);
string_list_sort(fname_kept_list);
strbuf_release(&buf);
}
static void remove_redundant_pack(const char *dir_name, const char *base_name)