[PATCH] midx.c: clear auxiliary MIDX files first

From: Taylor Blau <me@ttaylorr.com>
Date: Oct 25, 2022, 18:25 UTC
Message-ID: <bf36093cd6d7ac83b16241b0199b3a8c904e6774.1666722316.git.me@ttaylorr.com>

Since they were added in c528e17966 (pack-bitmap: write multi-pack bitmaps, 2021-08-31), the routine to remove MIDXs removed the multi-pack-index file itself before removing its associated .bitmap and .rev file(s), if any.

This creates a window where a MIDX's .bitmap file exists without its corresponding MIDX. If a reader tries to load a MIDX bitmap during that time, they will get a warning, and the MIDX bitmap code will gracefully degrade.

Remove this window entirely by removing the MIDX last, and removing its auxiliary files first.

The order here is important, too. We remove the MIDX's .bitmap file ahead of its .rev, since callers try and read the .bitmap first. The .rev file is no longer generated by modern versions of Git, but cleaning up old ones generated by previous versions of Git is still important to do.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 midx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/midx.c b/midx.c
index 3a8dcfe98e..994129aecd 100644
--- a/midx.c
+++ b/midx.c
@@ -1619,12 +1619,12 @@ void clear_midx_file(struct repository *r)
 		r->objects->multi_pack_index = NULL;
 	}
 
-	if (remove_path(midx.buf))
-		die(_("failed to clear multi-pack-index at %s"), midx.buf);
-
 	clear_midx_files_ext(r->objects->odb->path, ".bitmap", NULL);
 	clear_midx_files_ext(r->objects->odb->path, ".rev", NULL);
 
+	if (remove_path(midx.buf))
+		die(_("failed to clear multi-pack-index at %s"), midx.buf);
+
 	strbuf_release(&midx);
 }

-- 
2.38.0.16.g393fd4c6db