From 0dd1324a73e404a2b02356c77088ec1f71beec11 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Tue, 20 Jun 2023 19:01:15 +0000 Subject: [PATCH] packfile: delete .idx files before .pack files When installing a packfile, we place the .pack file before the .idx file. The intention is that Git scans for .idx files in the pack directory and then loads the .pack files from that list. However, when we delete packfiles, we do not do this in the reverse order as we should. The unlink_pack_path() method deletes the .pack followed by the .idx. This creates a window where the process could be interrupted between the .pack deletion and the .idx deletion, leaving the repository in a state that looks strange, but isn't actually too problematic if we assume the pack was safe to delete. The .idx without a .pack will cause some overhead, but will not interrupt other Git processes. This ordering was introduced into the 'git repack' builtin by a1bbc6c0176 (repack: rewrite the shell script in C, 2013-09-15), though we must be careful to track history through the code move in 8434e85d5f9 (repack: refactor pack deletion for future use, 2019-06-10) to see that. This became more important after 73320e49add (builtin/repack.c: only collect fully-formed packs, 2023-06-07) changed how 'git repack' scanned for packfiles for use in the cruft pack process. It previously looked for .pack files, but that was problematic due to the order that packs are installed: repacks between the creation of a .pack and the creation of its .idx would result in hard failures. There is an independent proposal about what to do in the case of a .idx without a .pack during this 'git repack' scenario, but this change is focused on deleting .pack files more safely. Modify the order to delete the .idx before the .pack. The rest of the modifiers on the .pack should still come after the .pack so we know all of the presumed properties of the packfile as long as it exists in the filesystem, in case we wish to reinstate it by re-indexing the .pack file. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- packfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/packfile.c b/packfile.c index c0d7dd93f4..3a595a4efd 100644 --- a/packfile.c +++ b/packfile.c @@ -373,7 +373,7 @@ void close_object_store(struct raw_object_store *o) void unlink_pack_path(const char *pack_name, int force_delete) { - static const char *exts[] = {".pack", ".idx", ".rev", ".keep", ".bitmap", ".promisor", ".mtimes"}; + static const char *exts[] = {".idx", ".pack", ".rev", ".keep", ".bitmap", ".promisor", ".mtimes"}; int i; struct strbuf buf = STRBUF_INIT; size_t plen;