git-apply: prepare for upcoming GNU diff -u format change.

The latest GNU diff from CVS emits an empty line to express
an empty context line, instead of more traditional "single
white space followed by a newline".  Do not get broken by it.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

2 files changed, 64 insertions, 0 deletions

diff --git a/builtin-apply.c b/builtin-apply.c
index cbe597771..11a5277a6 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -934,6 +934,7 @@ static int parse_fragment(char *line, unsigned long size, struct patch *patch, s
 		switch (*line) {
 		default:
 			return -1;
+		case '\n': /* newer GNU diff, an empty context line */
 		case ' ':
 			oldlines--;
 			newlines--;
@@ -1623,6 +1624,14 @@ static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag, i
 				first = '-';
 		}
 		switch (first) {
+		case '\n':
+			/* Newer GNU diff, empty context line */
+			if (plen < 0)
+				/* ... followed by '\No newline'; nothing */
+				break;
+			old[oldsize++] = '\n';
+			new[newsize++] = '\n';
+			break;
 		case ' ':
 		case '-':
 			memcpy(old + oldsize, patch + 1, plen);
diff --git a/t/t4118-apply-empty-context.sh b/t/t4118-apply-empty-context.sh
new file mode 100755
index 000000000..7309422fe
--- /dev/null
+++ b/t/t4118-apply-empty-context.sh
@@ -0,0 +1,55 @@
+#!/bin/sh
+#
+# Copyright (c) 2006 Junio C Hamano
+#
+
+test_description='git-apply with new style GNU diff with empty context
+
+'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	{
+		echo; echo;
+		echo A; echo B; echo C;
+		echo;
+	} >file1 &&
+	cat file1 >file1.orig &&
+	{
+		cat file1 &&
+		echo Q | tr -d "\\012"
+	} >file2 &&
+	cat file2 >file2.orig
+	git add file1 file2 &&
+	sed -e "/^B/d" <file1.orig >file1 &&
+	sed -e "/^B/d" <file2.orig >file2 &&
+	cat file1 >file1.mods &&
+	cat file2 >file2.mods &&
+	git diff |
+	sed -e "s/^ \$//" >diff.output
+'
+
+test_expect_success 'apply --numstat' '
+
+	git apply --numstat diff.output >actual &&
+	{
+		echo "0	1	file1" &&
+		echo "0	1	file2"
+	} >expect &&
+	diff -u expect actual
+
+'
+
+test_expect_success 'apply --apply' '
+
+	cat file1.orig >file1 &&
+	cat file2.orig >file2 &&
+	git update-index file1 file2 &&
+	git apply --index diff.output &&
+	diff -u file1.mods file1 &&
+	diff -u file2.mods file2
+'
+
+test_done
+