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From: Taylor Blau <me@ttaylorr•com>
To: git@vger•kernel.org
Cc: Jeff King <peff@peff•net>, Elijah Newren <newren@gmail•com>,
	Patrick Steinhardt <ps@pks•im>,
	Junio C Hamano <gitster@pobox•com>
Subject: [PATCH v2 16/18] t/helper/test-read-midx.c: plug memory leak when selecting layer
Date: Wed, 14 Jan 2026 14:55:07 -0500	[thread overview]
Message-ID: <dbbcb49456385265eceb6dd77e054df1e26677c8.1768420450.git.me@ttaylorr.com> (raw)
In-Reply-To: <cover.1768420450.git.me@ttaylorr.com>

Though our 'read-midx' test tool is capable of printing information
about a single MIDX layer identified by its checksum, no caller in our
test suite exercises this path.

Unfortunately, there is a memory leak lurking in this (currently) unused
path that would otherwise be exposed by the following commit.

This occurs when providing a MIDX layer checksum other than the tip. As
we walk over the MIDX chain trying to find the matching layer, we drop
our reference to the top-most MIDX layer. Thus, our call to
'close_midx()' later on leaks memory between the top-most MIDX layer and
the MIDX layer immediately following the specified one.

Plug this leak by holding a reference to the tip of the MIDX chain, and
ensure that we call `close_midx()` before terminating the test tool.

Signed-off-by: Taylor Blau <me@ttaylorr•com>
---
 t/helper/test-read-midx.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/t/helper/test-read-midx.c b/t/helper/test-read-midx.c
index 9d42c587564..388d29e2b53 100644
--- a/t/helper/test-read-midx.c
+++ b/t/helper/test-read-midx.c
@@ -26,9 +26,10 @@ static int read_midx_file(const char *object_dir, const char *checksum,
 			  int show_objects)
 {
 	uint32_t i;
-	struct multi_pack_index *m;
+	struct multi_pack_index *m, *tip;
+	int ret = 0;
 
-	m = setup_midx(object_dir);
+	m = tip = setup_midx(object_dir);
 
 	if (!m)
 		return 1;
@@ -36,8 +37,11 @@ static int read_midx_file(const char *object_dir, const char *checksum,
 	if (checksum) {
 		while (m && strcmp(midx_get_checksum_hex(m), checksum))
 			m = m->base_midx;
-		if (!m)
-			return 1;
+		if (!m) {
+			ret = error(_("could not find MIDX with checksum %s"),
+				    checksum);
+			goto out;
+		}
 	}
 
 	printf("header: %08x %d %d %d %d\n",
@@ -82,9 +86,10 @@ static int read_midx_file(const char *object_dir, const char *checksum,
 		}
 	}
 
-	close_midx(m);
+out:
+	close_midx(tip);
 
-	return 0;
+	return ret;
 }
 
 static int read_midx_checksum(const char *object_dir)
-- 
2.52.0.457.gb599f1ad4b0


  parent reply	other threads:[~2026-01-14 19:55 UTC|newest]

Thread overview: 99+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-06 20:30 [PATCH 00/17] midx: incremental MIDX/bitmap layer compaction Taylor Blau
2025-12-06 20:31 ` [PATCH 01/17] midx: mark `get_midx_checksum()` arguments as const Taylor Blau
2025-12-08 18:26   ` Patrick Steinhardt
2025-12-09  1:41     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 02/17] midx: split `get_midx_checksum()` by adding `get_midx_hash()` Taylor Blau
2025-12-08 18:25   ` Patrick Steinhardt
2025-12-09  1:42     ` Taylor Blau
2025-12-09  1:50       ` Taylor Blau
2025-12-09  6:27         ` Patrick Steinhardt
2026-01-13 22:46           ` Taylor Blau
2025-12-06 20:31 ` [PATCH 03/17] builtin/multi-pack-index.c: make '--progress' a common option Taylor Blau
2025-12-06 20:31 ` [PATCH 04/17] git-multi-pack-index(1): remove non-existent incompatibility Taylor Blau
2025-12-06 20:31 ` [PATCH 05/17] git-multi-pack-index(1): align SYNOPSIS with 'git multi-pack-index -h' Taylor Blau
2025-12-06 20:31 ` [PATCH 06/17] t/t5319-multi-pack-index.sh: fix copy-and-paste error in t5319.39 Taylor Blau
2025-12-06 20:31 ` [PATCH 07/17] midx-write.c: don't use `pack_perm` when assigning `bitmap_pos` Taylor Blau
2025-12-08 18:26   ` Patrick Steinhardt
2025-12-09  1:59     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 08/17] midx-write.c: introduce `struct write_midx_opts` Taylor Blau
2025-12-08 18:26   ` Patrick Steinhardt
2025-12-09  2:04     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 09/17] midx: do not require packs to be sorted in lexicographic order Taylor Blau
2025-12-08 18:26   ` Patrick Steinhardt
2025-12-09  2:07     ` Taylor Blau
2025-12-09  2:11       ` Taylor Blau
2025-12-06 20:31 ` [PATCH 10/17] git-compat-util.h: introduce `u32_add()` Taylor Blau
2025-12-08 18:27   ` Patrick Steinhardt
2025-12-09  2:13     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 11/17] midx-write.c: introduce `midx_pack_perm()` helper Taylor Blau
2025-12-06 20:31 ` [PATCH 12/17] midx-write.c: extract `fill_pack_from_midx()` Taylor Blau
2025-12-06 20:31 ` [PATCH 13/17] midx-write.c: enumerate `pack_int_id` values directly Taylor Blau
2025-12-08 18:27   ` Patrick Steinhardt
2025-12-09  2:14     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 14/17] midx-write.c: factor fanout layering from `compute_sorted_entries()` Taylor Blau
2025-12-06 20:31 ` [PATCH 15/17] t/helper/test-read-midx.c: plug memory leak when selecting layer Taylor Blau
2025-12-08 18:27   ` Patrick Steinhardt
2025-12-09  2:16     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 16/17] midx: implement MIDX compaction Taylor Blau
2025-12-09  7:21   ` Patrick Steinhardt
2026-01-13 23:32     ` Taylor Blau
2025-12-06 20:31 ` [PATCH 17/17] midx: enable reachability bitmaps during " Taylor Blau
2025-12-09  7:21   ` Patrick Steinhardt
2026-01-13 23:47     ` Taylor Blau
2026-01-14 19:54 ` [PATCH v2 00/18] midx: incremental MIDX/bitmap layer compaction Taylor Blau
2026-01-14 19:54   ` [PATCH v2 01/18] midx: mark `get_midx_checksum()` arguments as const Taylor Blau
2026-01-14 19:54   ` [PATCH v2 02/18] midx: rename `get_midx_checksum()` to `midx_get_checksum_hash()` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 03/18] midx: introduce `midx_get_checksum_hex()` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 04/18] builtin/multi-pack-index.c: make '--progress' a common option Taylor Blau
2026-01-14 19:54   ` [PATCH v2 05/18] git-multi-pack-index(1): remove non-existent incompatibility Taylor Blau
2026-01-14 19:54   ` [PATCH v2 06/18] git-multi-pack-index(1): align SYNOPSIS with 'git multi-pack-index -h' Taylor Blau
2026-01-14 19:54   ` [PATCH v2 07/18] t/t5319-multi-pack-index.sh: fix copy-and-paste error in t5319.39 Taylor Blau
2026-01-14 19:54   ` [PATCH v2 08/18] midx-write.c: don't use `pack_perm` when assigning `bitmap_pos` Taylor Blau
2026-01-14 21:13     ` Junio C Hamano
2026-01-14 21:40       ` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 09/18] midx-write.c: introduce `struct write_midx_opts` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 10/18] midx: do not require packs to be sorted in lexicographic order Taylor Blau
2026-01-14 21:28     ` Junio C Hamano
2026-01-14 21:44       ` Taylor Blau
2026-01-27  7:34     ` Patrick Steinhardt
2026-02-24 18:47       ` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 11/18] git-compat-util.h: introduce `u32_add()` Taylor Blau
2026-01-14 21:49     ` Junio C Hamano
2026-01-14 22:03       ` Taylor Blau
2026-01-15  0:11         ` Taylor Blau
2026-01-21  8:51           ` Patrick Steinhardt
2026-01-21 23:55             ` Taylor Blau
2026-01-22  2:26               ` rsbecker
2026-01-22 17:07                 ` Junio C Hamano
2026-02-23 13:49               ` Jeff King
2026-02-24 18:53                 ` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 12/18] midx-write.c: introduce `midx_pack_perm()` helper Taylor Blau
2026-01-14 19:54   ` [PATCH v2 13/18] midx-write.c: extract `fill_pack_from_midx()` Taylor Blau
2026-01-14 19:54   ` [PATCH v2 14/18] midx-write.c: enumerate `pack_int_id` values directly Taylor Blau
2026-01-14 19:55   ` [PATCH v2 15/18] midx-write.c: factor fanout layering from `compute_sorted_entries()` Taylor Blau
2026-01-14 19:55   ` Taylor Blau [this message]
2026-01-14 19:55   ` [PATCH v2 17/18] midx: implement MIDX compaction Taylor Blau
2026-01-27  7:35     ` Patrick Steinhardt
2026-01-27 22:13       ` Taylor Blau
2026-01-14 19:55   ` [PATCH v2 18/18] midx: enable reachability bitmaps during " Taylor Blau
2026-02-20 22:24   ` [PATCH v2 00/18] midx: incremental MIDX/bitmap layer compaction Junio C Hamano
2026-02-23 14:08     ` Jeff King
2026-02-24  5:25       ` Taylor Blau
2026-02-24 18:59 ` [PATCH v3 00/17] " Taylor Blau
2026-02-24 18:59   ` [PATCH v3 01/17] midx: mark `get_midx_checksum()` arguments as const Taylor Blau
2026-02-24 18:59   ` [PATCH v3 02/17] midx: rename `get_midx_checksum()` to `midx_get_checksum_hash()` Taylor Blau
2026-02-24 18:59   ` [PATCH v3 03/17] midx: introduce `midx_get_checksum_hex()` Taylor Blau
2026-02-24 18:59   ` [PATCH v3 04/17] builtin/multi-pack-index.c: make '--progress' a common option Taylor Blau
2026-02-24 18:59   ` [PATCH v3 05/17] git-multi-pack-index(1): remove non-existent incompatibility Taylor Blau
2026-02-24 18:59   ` [PATCH v3 06/17] git-multi-pack-index(1): align SYNOPSIS with 'git multi-pack-index -h' Taylor Blau
2026-02-24 19:00   ` [PATCH v3 07/17] t/t5319-multi-pack-index.sh: fix copy-and-paste error in t5319.39 Taylor Blau
2026-02-24 19:00   ` [PATCH v3 08/17] midx-write.c: don't use `pack_perm` when assigning `bitmap_pos` Taylor Blau
2026-02-24 19:00   ` [PATCH v3 09/17] midx-write.c: introduce `struct write_midx_opts` Taylor Blau
2026-02-24 19:00   ` [PATCH v3 10/17] midx: do not require packs to be sorted in lexicographic order Taylor Blau
2026-02-24 19:00   ` [PATCH v3 11/17] midx-write.c: introduce `midx_pack_perm()` helper Taylor Blau
2026-02-24 19:00   ` [PATCH v3 12/17] midx-write.c: extract `fill_pack_from_midx()` Taylor Blau
2026-02-24 19:00   ` [PATCH v3 13/17] midx-write.c: enumerate `pack_int_id` values directly Taylor Blau
2026-02-24 19:00   ` [PATCH v3 14/17] midx-write.c: factor fanout layering from `compute_sorted_entries()` Taylor Blau
2026-02-24 19:00   ` [PATCH v3 15/17] t/helper/test-read-midx.c: plug memory leak when selecting layer Taylor Blau
2026-02-24 19:00   ` [PATCH v3 16/17] midx: implement MIDX compaction Taylor Blau
2026-02-24 19:00   ` [PATCH v3 17/17] midx: enable reachability bitmaps during " Taylor Blau

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