[PATCH v2] diff --no-index: reset temporary buffer lengths on directory iteration

[Bobby Powers <bobbypowers@gmail.com>]

Commit 875b91b3 introduced a regression when using diff --no-index
with directories.  When iterating through a directory, the switch to
strbuf from heap-allocated char arrays caused paths to form like
'dir/file1', 'dir/file1file2', rather than 'dir/file1', 'dir/file2' as
expected.  By resetting the length on each iteration (but not
buf.alloc), we avoid this.

Signed-off-by: Bobby Powers <bobbypowers@gmail.com>
---
 diff-no-index.c          |  6 ++++++
 t/t4053-diff-no-index.sh | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100755 t/t4053-diff-no-index.sh

diff --git a/diff-no-index.c b/diff-no-index.c
index b44473e..3080b66 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -68,6 +68,7 @@ static int queue_diff(struct diff_options *o,
 		struct string_list p1 = STRING_LIST_INIT_DUP;
 		struct string_list p2 = STRING_LIST_INIT_DUP;
 		int i1, i2, ret = 0;
+		size_t len1 = 0, len2 = 0;
 
 		if (name1 && read_directory(name1, &p1))
 			return -1;
@@ -80,18 +81,23 @@ static int queue_diff(struct diff_options *o,
 			strbuf_addstr(&buffer1, name1);
 			if (buffer1.len && buffer1.buf[buffer1.len - 1] != '/')
 				strbuf_addch(&buffer1, '/');
+			len1 = buffer1.len;
 		}
 
 		if (name2) {
 			strbuf_addstr(&buffer2, name2);
 			if (buffer2.len && buffer2.buf[buffer2.len - 1] != '/')
 				strbuf_addch(&buffer2, '/');
+			len2 = buffer2.len;
 		}
 
 		for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
 			const char *n1, *n2;
 			int comp;
 
+			strbuf_setlen(&buffer1, len1);
+			strbuf_setlen(&buffer2, len2);
+
 			if (i1 == p1.nr)
 				comp = 1;
 			else if (i2 == p2.nr)
diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
new file mode 100755
index 0000000..4dc8c67
--- /dev/null
+++ b/t/t4053-diff-no-index.sh
@@ -0,0 +1,19 @@
+#!/bin/sh
+
+test_description='diff --no-index'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	mkdir a &&
+	mkdir b &&
+	echo 1 >a/1 &&
+	echo 2 >a/2
+'
+
+test_expect_success 'git diff --no-index directories' '
+	git diff --no-index a b >cnt
+	test $? = 1 && test_line_count = 14 cnt
+'
+
+test_done
-- 
1.7.10.2.521.g8ddb639