address the strnvis(3) portability fiasco

strnvis originates on OpenBSD.  When NetBSD added it to their libc
they decided to swap the argument.  Without starting a holy war on
the "best" argument order, adding an implementation of a function
that's widely available and making its signature purposefully
incompatible is beyond justification.  FreeBSD (and so macos too?)
followed NetBSD in this, so we end up with *two* major and incompatible
strnvis implementations.  libbsd is in a limbo, they started with
the OpenBSD version but they'll probably switch to the NetBSD version
in the future.

That's why we can't have nice things.

Do the right thing(tm) and check for the presence of the original
strnvis(3), if not available or broken use the bundled one.

3 files changed, 366 insertions, 1 deletions

diff --git a/compat/Makefile b/compat/Makefile
index f820f71..65ec3ef 100644
--- a/compat/Makefile
+++ b/compat/Makefile
@@ -19,7 +19,8 @@ DISTFILES =	Makefile \
 		strlcpy.c \
 		strtonum.c \
 		tree.h \
-		vasprintf.c
+		vasprintf.c \
+		vis.c
 
 all:
 	false
@@ -27,6 +28,8 @@ all:
 dist: ${DISTFILES}
 	mkdir -p ${DESTDIR}/
 	${INSTALL} -m 0644 ${DISTFILES} ${DESTDIR}/
+	mkdir -p ${DESTDIR}/vis
+	${INSTALL} -m 0644 vis/vis.h ${DESTDIR}/vis
 
 .PHONY: all dist
 include ../config.mk
diff --git a/compat/vis.c b/compat/vis.c
new file mode 100644
index 0000000..9ebdc72
--- /dev/null
+++ b/compat/vis.c
@@ -0,0 +1,272 @@
+/*	$OpenBSD: vis.c,v 1.26 2022/05/04 18:57:50 deraadt Exp $ */
+/*-
+ * Copyright (c) 1989, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * 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. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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 <sys/types.h>
+#include <errno.h>
+#include <ctype.h>
+#include <limits.h>
+#include <string.h>
+#include <stdlib.h>
+#include <vis.h>
+
+static int
+isoctal(int c)
+{
+	u_char uc = c;
+
+	return uc >= '0' && uc <= '7';
+}
+
+static int
+isvisible(int c, int flag)
+{
+	int vis_sp = flag & VIS_SP;
+	int vis_tab = flag & VIS_TAB;
+	int vis_nl = flag & VIS_NL;
+	int vis_safe = flag & VIS_SAFE;
+	int vis_glob = flag & VIS_GLOB;
+	int vis_all = flag & VIS_ALL;
+	u_char uc = c;
+
+	if (c == '\\' || !vis_all) {
+		if ((u_int)c <= UCHAR_MAX && isascii(uc) &&
+		    ((c != '*' && c != '?' && c != '[' && c != '#') || !vis_glob) &&
+		    isgraph(uc))
+			return 1;
+		if (!vis_sp && c == ' ')
+			return 1;
+		if (!vis_tab && c == '\t')
+			return 1;
+		if (!vis_nl && c == '\n')
+			return 1;
+		if (vis_safe && (c == '\b' || c == '\007' || c == '\r' || isgraph(uc)))
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * vis - visually encode characters
+ */
+char *
+vis(char *dst, int c, int flag, int nextc)
+{
+	int vis_dq = flag & VIS_DQ;
+	int vis_noslash = flag & VIS_NOSLASH;
+	int vis_cstyle = flag & VIS_CSTYLE;
+	int vis_octal = flag & VIS_OCTAL;
+	int vis_glob = flag & VIS_GLOB;
+
+	if (isvisible(c, flag)) {
+		if ((c == '"' && vis_dq) ||
+		    (c == '\\' && !vis_noslash))
+			*dst++ = '\\';
+		*dst++ = c;
+		*dst = '\0';
+		return (dst);
+	}
+
+	if (vis_cstyle) {
+		switch (c) {
+		case '\n':
+			*dst++ = '\\';
+			*dst++ = 'n';
+			goto done;
+		case '\r':
+			*dst++ = '\\';
+			*dst++ = 'r';
+			goto done;
+		case '\b':
+			*dst++ = '\\';
+			*dst++ = 'b';
+			goto done;
+		case '\a':
+			*dst++ = '\\';
+			*dst++ = 'a';
+			goto done;
+		case '\v':
+			*dst++ = '\\';
+			*dst++ = 'v';
+			goto done;
+		case '\t':
+			*dst++ = '\\';
+			*dst++ = 't';
+			goto done;
+		case '\f':
+			*dst++ = '\\';
+			*dst++ = 'f';
+			goto done;
+		case ' ':
+			*dst++ = '\\';
+			*dst++ = 's';
+			goto done;
+		case '\0':
+			*dst++ = '\\';
+			*dst++ = '0';
+			if (isoctal(nextc)) {
+				*dst++ = '0';
+				*dst++ = '0';
+			}
+			goto done;
+		}
+	}
+	if (((c & 0177) == ' ') || vis_octal ||
+	    (vis_glob && (c == '*' || c == '?' || c == '[' || c == '#'))) {
+		*dst++ = '\\';
+		*dst++ = ((u_char)c >> 6 & 07) + '0';
+		*dst++ = ((u_char)c >> 3 & 07) + '0';
+		*dst++ = ((u_char)c & 07) + '0';
+		goto done;
+	}
+	if (!vis_noslash)
+		*dst++ = '\\';
+	if (c & 0200) {
+		c &= 0177;
+		*dst++ = 'M';
+	}
+	if (iscntrl((u_char)c)) {
+		*dst++ = '^';
+		if (c == 0177)
+			*dst++ = '?';
+		else
+			*dst++ = c + '@';
+	} else {
+		*dst++ = '-';
+		*dst++ = c;
+	}
+done:
+	*dst = '\0';
+	return (dst);
+}
+
+/*
+ * strvis, strnvis, strvisx - visually encode characters from src into dst
+ *	
+ *	Dst must be 4 times the size of src to account for possible
+ *	expansion.  The length of dst, not including the trailing NULL,
+ *	is returned. 
+ *
+ *	Strnvis will write no more than siz-1 bytes (and will NULL terminate).
+ *	The number of bytes needed to fully encode the string is returned.
+ *
+ *	Strvisx encodes exactly len bytes from src into dst.
+ *	This is useful for encoding a block of data.
+ */
+int
+strvis(char *dst, const char *src, int flag)
+{
+	char c;
+	char *start;
+
+	for (start = dst; (c = *src);)
+		dst = vis(dst, c, flag, *++src);
+	*dst = '\0';
+	return (dst - start);
+}
+
+int
+strnvis(char *dst, const char *src, size_t siz, int flag)
+{
+	int vis_dq = flag & VIS_DQ;
+	int vis_noslash = flag & VIS_NOSLASH;
+	char *start, *end;
+	char tbuf[5];
+	int c, i;
+
+	i = 0;
+	for (start = dst, end = start + siz - 1; (c = *src) && dst < end; ) {
+		if (isvisible(c, flag)) {
+			if ((c == '"' && vis_dq) ||
+			    (c == '\\' && !vis_noslash)) {
+				/* need space for the extra '\\' */
+				if (dst + 1 >= end) {
+					i = 2;
+					break;
+				}
+				*dst++ = '\\';
+			}
+			i = 1;
+			*dst++ = c;
+			src++;
+		} else {
+			i = vis(tbuf, c, flag, *++src) - tbuf;
+			if (dst + i <= end) {
+				memcpy(dst, tbuf, i);
+				dst += i;
+			} else {
+				src--;
+				break;
+			}
+		}
+	}
+	if (siz > 0)
+		*dst = '\0';
+	if (dst + i > end) {
+		/* adjust return value for truncation */
+		while ((c = *src))
+			dst += vis(tbuf, c, flag, *++src) - tbuf;
+	}
+	return (dst - start);
+}
+
+int
+stravis(char **outp, const char *src, int flag)
+{
+	char *buf;
+	int len, serrno;
+
+	buf = reallocarray(NULL, 4, strlen(src) + 1);
+	if (buf == NULL)
+		return -1;
+	len = strvis(buf, src, flag);
+	serrno = errno;
+	*outp = realloc(buf, len + 1);
+	if (*outp == NULL) {
+		*outp = buf;
+		errno = serrno;
+	}
+	return (len);
+}
+
+int
+strvisx(char *dst, const char *src, size_t len, int flag)
+{
+	char c;
+	char *start;
+
+	for (start = dst; len > 1; len--) {
+		c = *src;
+		dst = vis(dst, c, flag, *++src);
+	}
+	if (len)
+		dst = vis(dst, *src, flag, '\0');
+	*dst = '\0';
+	return (dst - start);
+}
diff --git a/compat/vis/vis.h b/compat/vis/vis.h
new file mode 100644
index 0000000..59b7d6b
--- /dev/null
+++ b/compat/vis/vis.h
@@ -0,0 +1,90 @@
+/*	$OpenBSD: vis.h,v 1.15 2015/07/20 01:52:27 millert Exp $	*/
+/*	$NetBSD: vis.h,v 1.4 1994/10/26 00:56:41 cgd Exp $	*/
+
+/*-
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * 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. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
+ *
+ *	@(#)vis.h	5.9 (Berkeley) 4/3/91
+ */
+
+#ifndef _VIS_H_
+#define	_VIS_H_
+
+/*
+ * to select alternate encoding format
+ */
+#define	VIS_OCTAL	0x01	/* use octal \ddd format */
+#define	VIS_CSTYLE	0x02	/* use \[nrft0..] where appropriate */
+
+/*
+ * to alter set of characters encoded (default is to encode all
+ * non-graphic except space, tab, and newline).
+ */
+#define	VIS_SP		0x04	/* also encode space */
+#define	VIS_TAB		0x08	/* also encode tab */
+#define	VIS_NL		0x10	/* also encode newline */
+#define	VIS_WHITE	(VIS_SP | VIS_TAB | VIS_NL)
+#define	VIS_SAFE	0x20	/* only encode "unsafe" characters */
+#define	VIS_DQ		0x200	/* backslash-escape double quotes */
+#define	VIS_ALL		0x400	/* encode all characters */
+
+/*
+ * other
+ */
+#define	VIS_NOSLASH	0x40	/* inhibit printing '\' */
+#define	VIS_GLOB	0x100	/* encode glob(3) magics and '#' */
+
+/*
+ * unvis return codes
+ */
+#define	UNVIS_VALID	 1	/* character valid */
+#define	UNVIS_VALIDPUSH	 2	/* character valid, push back passed char */
+#define	UNVIS_NOCHAR	 3	/* valid sequence, no character produced */
+#define	UNVIS_SYNBAD	-1	/* unrecognized escape sequence */
+#define	UNVIS_ERROR	-2	/* decoder in unknown state (unrecoverable) */
+
+/*
+ * unvis flags
+ */
+#define	UNVIS_END	1	/* no more characters */
+
+#include <sys/cdefs.h>
+
+char	*vis(char *, int, int, int);
+int	strvis(char *, const char *, int);
+int	stravis(char **, const char *, int);
+int	strnvis(char *, const char *, size_t, int)
+		__attribute__ ((__bounded__(__string__,1,3)));
+int	strvisx(char *, const char *, size_t, int)
+		__attribute__ ((__bounded__(__string__,1,3)));
+int	strunvis(char *, const char *);
+int	unvis(char *, char, int *, int);
+ssize_t strnunvis(char *, const char *, size_t)
+		__attribute__ ((__bounded__(__string__,1,3)));
+
+#endif /* !_VIS_H_ */