[PATCH] diff: bugfix: binary file permission regression

[Nazri Ramliy <ayiehere@gmail.com>]

Regression at 3e97c7c6af2901cec63bf35fcd43ae3472e24af8
"No diff -b/-w output for all-whitespace changes"

When a binary file's permission is modified, git status
reports the file as modified, but git diff shows nothing.

Add a test file too.
---
 diff.c                            |    4 ++--
 t/t4043-diff-binary-permission.sh |   26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100755 t/t4043-diff-binary-permission.sh

diff --git a/diff.c b/diff.c
index 494f560..0aa1a2d 100644
--- a/diff.c
+++ b/diff.c
@@ -1745,12 +1745,12 @@ static void builtin_diff(const char *name_a,
 	      (!textconv_two && diff_filespec_is_binary(two)) )) {
 		if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
 			die("unable to read files to diff");
+		fprintf(o->file, "%s", header.buf);
+		strbuf_reset(&header);
 		/* Quite common confusing case */
 		if (mf1.size == mf2.size &&
 		    !memcmp(mf1.ptr, mf2.ptr, mf1.size))
 			goto free_ab_and_return;
-		fprintf(o->file, "%s", header.buf);
-		strbuf_reset(&header);
 		if (DIFF_OPT_TST(o, BINARY))
 			emit_binary_diff(o->file, &mf1, &mf2);
 		else
diff --git a/t/t4043-diff-binary-permission.sh b/t/t4043-diff-binary-permission.sh
new file mode 100755
index 0000000..7b77fb3
--- /dev/null
+++ b/t/t4043-diff-binary-permission.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Nazri Ramliy
+#
+
+test_description='Test permission change on binary files
+
+'
+. ./test-lib.sh
+
+/bin/echo -e "\0\0\0\0" > a.bin
+chmod 644 a.bin
+git update-index --add a.bin
+chmod 755 a.bin
+
+cat << EOF > expect
+diff --git a/a.bin b/a.bin
+old mode 100644
+new mode 100755
+EOF
+
+git diff > out
+
+test_expect_success 'diff-binary-permission' 'test_cmp expect out'
+
+test_done
-- 
1.7.1.245.g7c42e.dirty