From 246959346f3407cb047c3d46ed9c44da84bd0b29 Mon Sep 17 00:00:00 2001
From: Jinoh Kang <luke1337@theori.io>
Date: Fri, 6 Nov 2020 17:14:52 +0000
Subject: diff: allow passing NULL to diff_free_filespec_data()

Commit 3aef54e8b8 ("diff: munmap() file contents before running external
diff") introduced calls to diff_free_filespec_data in
run_external_diff, which may pass NULL pointers.

Fix this and prevent any such bugs in the future by making
`diff_free_filespec_data(NULL)` a no-op.

Fixes: 3aef54e8b8 ("diff: munmap() file contents before running external diff")
Signed-off-by: Jinoh Kang <luke1337@theori.io>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 2bb2f8f..ffdb08d 100644
--- a/diff.c
+++ b/diff.c
@@ -4111,6 +4111,9 @@ void diff_free_filespec_blob(struct diff_filespec *s)
 
 void diff_free_filespec_data(struct diff_filespec *s)
 {
+	if (!s)
+		return;
+
 	diff_free_filespec_blob(s);
 	FREE_AND_NULL(s->cnt_data);
 }
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index 524f30f..e9391ab 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -728,6 +728,29 @@ test_expect_success 'add -N and difftool -d' '
 	git difftool --dir-diff --extcmd ls
 '
 
+test_expect_success 'difftool --cached with unmerged files' '
+	test_when_finished git reset --hard &&
+	echo base >file &&
+	git add file &&
+	git commit -m base &&
+	git checkout -B conflict-a &&
+	git checkout -B conflict-b &&
+	git checkout conflict-a &&
+	echo conflict-a >>file &&
+	git add file &&
+	git commit -m conflict-a &&
+	git checkout conflict-b &&
+	echo conflict-b >>file &&
+	git add file &&
+	git commit -m conflict-b &&
+	git checkout master &&
+	git merge conflict-a &&
+	test_must_fail git merge conflict-b &&
+	: >expect &&
+	git difftool --cached --no-prompt >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'outside worktree' '
 	echo 1 >1 &&
 	echo 2 >2 &&
-- 
cgit v0.10.2-6-g49f6


From d66851806ff25c6afdb4650d8292a50d5ca0ea6d Mon Sep 17 00:00:00 2001
From: Jinoh Kang <luke1337@theori.io>
Date: Fri, 6 Nov 2020 17:14:52 +0000
Subject: t7800: simplify difftool test

The new test added by the previous commit can be simplified a lot.
Let's do so.

Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Jinoh Kang <luke1337@theori.io>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index e9391ab..a578b35 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -730,25 +730,15 @@ test_expect_success 'add -N and difftool -d' '
 
 test_expect_success 'difftool --cached with unmerged files' '
 	test_when_finished git reset --hard &&
-	echo base >file &&
-	git add file &&
-	git commit -m base &&
-	git checkout -B conflict-a &&
-	git checkout -B conflict-b &&
-	git checkout conflict-a &&
-	echo conflict-a >>file &&
-	git add file &&
-	git commit -m conflict-a &&
-	git checkout conflict-b &&
-	echo conflict-b >>file &&
-	git add file &&
-	git commit -m conflict-b &&
-	git checkout master &&
-	git merge conflict-a &&
-	test_must_fail git merge conflict-b &&
-	: >expect &&
-	git difftool --cached --no-prompt >actual &&
-	test_cmp expect actual
+
+	test_commit conflicting &&
+	test_commit conflict-a conflict.t a &&
+	git reset --hard conflicting &&
+	test_commit conflict-b conflict.t b &&
+	test_must_fail git merge conflict-a &&
+
+	git difftool --cached --no-prompt >output &&
+	test_must_be_empty output
 '
 
 test_expect_success 'outside worktree' '
-- 
cgit v0.10.2-6-g49f6