[PATCH v2 2/2] t5333: test memory leak when use pseudo-merge in boundary traversal

From: Lidong Yan via GitGitGadget <gitgitgadget@gmail.com>
Date: May 30, 2025, 18:14 UTC
Message-ID: <56b24d681cbcedaf5c03c89eee582d554a0894b7.1748628847.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1977.v2.git.git.1748628846.gitgitgadget@gmail.com>

From: Lidong Yan <502024330056@smail.nju.edu.cn>

In pack-bitmap.c:find_boundary_objects(), the roots_bitmap is only freed if cascade_pseudo_merges_1() fails. Otherwise, it leaks, leading to a memory leak that currently lacks a dedicated test to detect it.

To trigger this leak, we need a pseudo-merge whose size is equal to or smaller than roots_bitmap (which corresponds to the set of "haves" commits in prepare_bitmap_walk()). To do this, we can create two commits: A and B. Add A to the pseudo-merge list and perform a traversal over the range A..B. In this scenario, the "haves" set will be {A}, and cascade_pseudo_merges_1() will succeed — thereby exposing the leak due to the missing roots_bitmap cleanup.

Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn>
---
 t/t5333-pseudo-merge-bitmaps.sh | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/t/t5333-pseudo-merge-bitmaps.sh b/t/t5333-pseudo-merge-bitmaps.sh
index 56674db562f9..5e263fce50a7 100755
--- a/t/t5333-pseudo-merge-bitmaps.sh
+++ b/t/t5333-pseudo-merge-bitmaps.sh
@@ -445,4 +445,24 @@ test_expect_success 'pseudo-merge closure' '
 	)
 '
 
+test_expect_success 'use pseudo-merge in boundary traversal' '
+	git init pseudo-merge-boundary-traversal &&
+	(
+		cd pseudo-merge-boundary-traversal &&
+
+		git config bitmapPseudoMerge.test.pattern refs/ &&
+		git config bitmapPseudoMerge.test.threshold now &&
+		git config bitmapPseudoMerge.test.stableThreshold now &&
+		export GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL=1 &&
+
+		test_commit A &&
+		git repack -adb &&
+		test_commit B &&
+
+		echo '1' >expect &&
+		git rev-list --count --use-bitmap-index HEAD~1..HEAD >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done

-- 
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