merge-tree: handle directory/empty conflict correctly

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>
Tested-by: Andreas Jacobsen <andreas@andreasjacobsen.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index ec49917a3686233548afb0f959208e2561fc1374..61cbde4094bf27ea9dfaba158233ba7f4613f2ee 100644 (file)
--- 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 2defb422e8813c1ca314939aedba1d33c40dd388..9015e476541dafdd6a82efcd4ace6038461d8522 100755 (executable)
--- 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 &&