diff(1): Implement -B/--ignore-blank-lines

As noted by cem in r338035, coccinelle invokes diff(1) with the -B flag.
This was not previously implemented here, so one was forced to create a link
for GNU diff to /usr/local/bin/diff

Implement the -B flag and add some primitive tests for it. It is implemented
in the same fashion that -I is implemented; each chunk's lines are scanned,
and if a non-blank line is encountered then the chunk will be output.
Otherwise, it's skipped.

MFC after:	2 weeks

5 files changed, 28 insertions, 0 deletions

diff --git a/usr.bin/diff/tests/Bflag_C.out b/usr.bin/diff/tests/Bflag_C.out
new file mode 100644
index 000000000000..c7f130aff396
--- /dev/null
+++ b/usr.bin/diff/tests/Bflag_C.out
@@ -0,0 +1,2 @@
+1a2
+>  
diff --git a/usr.bin/diff/tests/Bflag_D.out b/usr.bin/diff/tests/Bflag_D.out
new file mode 100644
index 000000000000..4c1170334935
--- /dev/null
+++ b/usr.bin/diff/tests/Bflag_D.out
@@ -0,0 +1,2 @@
+1a2
+> C
diff --git a/usr.bin/diff/tests/Bflag_F.out b/usr.bin/diff/tests/Bflag_F.out
new file mode 100644
index 000000000000..9dc5e5694048
--- /dev/null
+++ b/usr.bin/diff/tests/Bflag_F.out
@@ -0,0 +1,4 @@
+7c8
+< G
+---
+> X
diff --git a/usr.bin/diff/tests/Makefile b/usr.bin/diff/tests/Makefile
index 62a0ab5c6188..78744d3bed8e 100644
--- a/usr.bin/diff/tests/Makefile
+++ b/usr.bin/diff/tests/Makefile
@@ -5,6 +5,9 @@ PACKAGE=	tests
 ATF_TESTS_SH=	diff_test
 
 ${PACKAGE}FILES+=	\
+	Bflag_C.out \
+	Bflag_D.out \
+	Bflag_F.out \
 	input1.in \
 	input2.in \
 	input_c1.in \
diff --git a/usr.bin/diff/tests/diff_test.sh b/usr.bin/diff/tests/diff_test.sh
index 557eea049d4e..01942192e504 100755
--- a/usr.bin/diff/tests/diff_test.sh
+++ b/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 Bflag
 
 simple_body()
 {
@@ -150,6 +151,21 @@ brief_format_body()
 	    diff -Nrq A D
 }
 
+Bflag_body()
+{
+	atf_check -x 'printf "A\nB\n" > A'
+	atf_check -x 'printf "A\n\nB\n" > B'
+	atf_check -x 'printf "A\n \nB\n" > C'
+	atf_check -x 'printf "A\nC\nB\n" > D'
+	atf_check -x 'printf "A\nB\nC\nD\nE\nF\nG\nH" > E'
+	atf_check -x 'printf "A\n\nB\nC\nD\nE\nF\nX\nH" > F'
+
+	atf_check -s exit:0 -o inline:"" diff -B A B
+	atf_check -s exit:1 -o file:"$(atf_get_srcdir)/Bflag_C.out" diff -B A C
+	atf_check -s exit:1 -o file:"$(atf_get_srcdir)/Bflag_D.out" diff -B A D
+	atf_check -s exit:1 -o file:"$(atf_get_srcdir)/Bflag_F.out" diff -B E F
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case simple
@@ -161,4 +177,5 @@ 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 Bflag
 }