diff: don't output carriage returns that were stripped on input

--strip-trailing-cr worked as intended for comparison between files,
but the characters were still present in final output.

usr.bin/diff/diffreg.c

@@ -1273,7 +1273,16 @@ fetch(long *f, int a, int b, FILE *lb, int ch, int oldfile, int flags)
 		}
 		col = 0;
 		for (j = 0, lastc = '\0'; j < nc; j++, lastc = c) {
-			if ((c = getc(lb)) == EOF) {
+			c = getc(lb);
+			if (flags & D_STRIPCR && c == '\r') {
+				if ((c = getc(lb)) == '\n')
+					j++;
+				else {
+					ungetc(c, lb);
+					c = '\r';
+				}
+			}
+			if (c == EOF) {
 				if (diff_format == D_EDIT ||
 				    diff_format == D_REVERSE ||
 				    diff_format == D_NREVERSE)

usr.bin/diff/tests/Makefile

@@ -26,7 +26,8 @@ ${PACKAGE}FILES+=	\
 	header.out \
 	header_ns.out \
 	ifdef.out \
-	group-format.out
+	group-format.out \
+	strip_o.out
 
 NETBSD_ATF_TESTS_SH+=	netbsd_diff_test
 

usr.bin/diff/tests/diff_test.sh

@@ -9,6 +9,7 @@ atf_test_case group_format
 atf_test_case side_by_side
 atf_test_case brief_format
 atf_test_case b230049
+atf_test_case stripcr_o
 atf_test_case b252515
 atf_test_case Bflag
 atf_test_case Nflag
@@ -68,6 +69,14 @@ b230049_body()
 		    b230049_a.in b230049_b.in
 }
 
+stripcr_o_body()
+{
+	printf 'a\nX\nc\n' > stripcr_o_X.in
+	printf 'a\r\nY\r\nc\r\n' > stripcr_o_Y.in
+	atf_check -o "file:$(atf_get_srcdir)/strip_o.out" -s eq:1 \
+		diff -L1 -L2 -u --strip-trailing-cr stripcr_o_X.in stripcr_o_Y.in
+}
+
 b252515_body()
 {
 	printf 'a b\n' > b252515_a.in
@@ -267,6 +276,7 @@ atf_init_test_cases()
 	atf_add_test_case side_by_side
 	atf_add_test_case brief_format
 	atf_add_test_case b230049
+	atf_add_test_case stripcr_o
 	atf_add_test_case b252515
 	atf_add_test_case Bflag
 	atf_add_test_case Nflag

usr.bin/diff/tests/strip_o.out

@@ -0,0 +1,7 @@
+--- 1
++++ 2
+@@ -1,3 +1,3 @@
+ a
+-X
++Y
+ c