Fix strnvis() and strnunvis() NetBSD ABI break

The NetBSD implementations have different prototypes to the ones coming
from OpenBSD, which will break builds, and have caused segfaults at
run-time. We provide now both interfaces with different prototypes as
different version nodes allow selecting them at compile-time, defaulting
for now to the OpenBSD one to avoid build-time breakage, while emitting
a compile-time warning. Later on, in 0.10.0, we will be switching the
compile-time default to the NetBSD version.

Ref: http://gnats.netbsd.org/44977
Fixes: https://bugs.debian.org/899282

test/.gitignore

@@ -19,3 +19,5 @@ setmode
 strl
 strmode
 strnstr
+vis
+vis-openbsd

test/Makefile.am

@@ -47,6 +47,8 @@ check_PROGRAMS = \
 	strl \
 	strmode \
 	strnstr \
+	vis \
+	vis-openbsd \
 	$(nil)
 
 if HAVE_LIBTESTU01

test/vis-openbsd.c

@@ -0,0 +1,47 @@
+/*
+ * Copyright © 2018 Guillem Jover <guillem@hadrons.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <assert.h>
+#include <string.h>
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcpp"
+#include <vis.h>
+#pragma GCC diagnostic pop
+
+int
+main(int argc, char **argv)
+{
+	char str[200];
+	char unstr[200];
+
+	strnvis(str, "0123456789abcdef", 10, 0);
+	assert(strcmp(str, "0123456789") == 0);
+
+	strnunvis(unstr, str, 100);
+	assert(strcmp(unstr, "0123456789") == 0);
+
+	return 0;
+}

test/vis.c

@@ -0,0 +1,46 @@
+/*
+ * Copyright © 2018 Guillem Jover <guillem@hadrons.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define LIBBSD_NETBSD_VIS 1
+
+#include <assert.h>
+#include <string.h>
+#include <vis.h>
+
+int
+main(int argc, char **argv)
+{
+	char str[200];
+	char unstr[200];
+
+	strnvis(str, 10, "0123456789abcdef", 0);
+	assert(strcmp(str, "0123456789") == 0);
+
+	strnunvis(unstr, 100, str);
+	assert(strcmp(unstr, "0123456789") == 0);
+
+	return 0;
+}