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[PATCH] merge-tree: handle directory/empty conflict correctly

From
John Keeping <john@keeping.me.uk>
Date
May 6, 2013, 15:20 UTC
Message-ID
<20130506152054.GE25912@serenity.lan>
In-Reply-To
<20130506144958.GD25912@serenity.lan>

git-merge-tree causes a null pointer dereference when a directory entry exists in only one or two of the three trees being compared with no corresponding entry in the other tree(s).

When this happens, we want to handle the entry as a directory and not attempt to mark it as a file merge. Do this by setting the entries bit in the directory mask when the entry is missing or when it is a directory, only performing the file comparison when we know that a file entry exists.

Reported-by: Andreas Jacobsen <andreas@andreasjacobsen.com>
Signed-off-by: John Keeping <john@keeping.me.uk>
---
Andreas, can you try this patch and see if it fixes your test case?
 builtin/merge-tree.c  |  6 +++++-
 t/t4300-merge-tree.sh | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index ec49917..61cbde4 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -251,7 +251,11 @@ static void unresolved(const struct traverse_info *info, struct name_entry n[3])
 
 	for (i = 0; i < 3; i++) {
 		mask |= (1 << i);
-		if (n[i].mode && S_ISDIR(n[i].mode))
+		/*
+		 * Treat missing entries as directories so that we return
+		 * after unresolved_directory has handled this.
+		 */
+		if (!n[i].mode || S_ISDIR(n[i].mode))
 			dirmask |= (1 << i);
 	}
 
diff --git a/t/t4300-merge-tree.sh b/t/t4300-merge-tree.sh
index 2defb42..9015e47 100755
--- a/t/t4300-merge-tree.sh
+++ b/t/t4300-merge-tree.sh
@@ -259,6 +259,57 @@ EXPECTED
 	test_cmp expected actual
 '
 
+test_expect_success 'tree add A, B (same)' '
+	cat >expect <<-\EOF &&
+	EOF
+	git reset --hard initial &&
+	mkdir sub &&
+	test_commit "add sub/file" "sub/file" "file" add-tree-A &&
+	git merge-tree initial add-tree-A add-tree-A >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'tree add A, B (different)' '
+	cat >expect <<-\EOF &&
+	added in both
+	  our    100644 43d5a8ed6ef6c00ff775008633f95787d088285d sub/file
+	  their  100644 ba629238ca89489f2b350e196ca445e09d8bb834 sub/file
+	@@ -1 +1,5 @@
+	+<<<<<<< .our
+	 AAA
+	+=======
+	+BBB
+	+>>>>>>> .their
+	EOF
+	git reset --hard initial &&
+	mkdir sub &&
+	test_commit "add sub/file" "sub/file" "AAA" add-tree-a-b-A &&
+	git reset --hard initial &&
+	mkdir sub &&
+	test_commit "add sub/file" "sub/file" "BBB" add-tree-a-b-B &&
+	git merge-tree initial add-tree-a-b-A add-tree-a-b-B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'tree unchanged A, removed B' '
+	cat >expect <<-\EOF &&
+	removed in remote
+	  base   100644 43d5a8ed6ef6c00ff775008633f95787d088285d sub/file
+	  our    100644 43d5a8ed6ef6c00ff775008633f95787d088285d sub/file
+	@@ -1 +0,0 @@
+	-AAA
+	EOF
+	git reset --hard initial &&
+	mkdir sub &&
+	test_commit "add sub/file" "sub/file" "AAA" tree-remove-b-initial &&
+	git rm sub/file &&
+	test_tick &&
+	git commit -m "remove sub/file" &&
+	git tag tree-remove-b-B &&
+	git merge-tree tree-remove-b-initial tree-remove-b-initial tree-remove-b-B >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'turn file to tree' '
 	git reset --hard initial &&
 	rm initial-file &&
-- 
1.8.3.rc0.149.g98a72f2.dirty
Previous: John KeepingNext: Andreas Jacobsen
Message 6 of 8 in “Segfault in git merge-tree (1.8.2.2)”
  1. Andreas JacobsenMay 6, 2013
  2. John KeepingMay 6, 2013
  3. Andreas JacobsenMay 6, 2013
  4. John KeepingMay 6, 2013
  5. John KeepingMay 6, 2013
  6. merge-tree: handle directory/empty conflict correctlyJohn Keeping, May 6, 2013
  7. Andreas JacobsenMay 7, 2013
  8. Junio C HamanoMay 7, 2013

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