1/*	$OpenBSD: vis.c,v 1.26 2022/05/04 18:57:50 deraadt Exp $ */
2/*-
3 * Copyright (c) 1989, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/types.h>
32#include <errno.h>
33#include <ctype.h>
34#include <limits.h>
35#include <string.h>
36#include <stdlib.h>
37#include <vis.h>
38
39static int
40isoctal(int c)
41{
42	u_char uc = c;
43
44	return uc >= '0' && uc <= '7';
45}
46
47static int
48isvisible(int c, int flag)
49{
50	int vis_sp = flag & VIS_SP;
51	int vis_tab = flag & VIS_TAB;
52	int vis_nl = flag & VIS_NL;
53	int vis_safe = flag & VIS_SAFE;
54	int vis_glob = flag & VIS_GLOB;
55	int vis_all = flag & VIS_ALL;
56	u_char uc = c;
57
58	if (c == '\\' || !vis_all) {
59		if ((u_int)c <= UCHAR_MAX && isascii(uc) &&
60		    ((c != '*' && c != '?' && c != '[' && c != '#') || !vis_glob) &&
61		    isgraph(uc))
62			return 1;
63		if (!vis_sp && c == ' ')
64			return 1;
65		if (!vis_tab && c == '\t')
66			return 1;
67		if (!vis_nl && c == '\n')
68			return 1;
69		if (vis_safe && (c == '\b' || c == '\007' || c == '\r' || isgraph(uc)))
70			return 1;
71	}
72	return 0;
73}
74
75/*
76 * vis - visually encode characters
77 */
78char *
79vis(char *dst, int c, int flag, int nextc)
80{
81	int vis_dq = flag & VIS_DQ;
82	int vis_noslash = flag & VIS_NOSLASH;
83	int vis_cstyle = flag & VIS_CSTYLE;
84	int vis_octal = flag & VIS_OCTAL;
85	int vis_glob = flag & VIS_GLOB;
86
87	if (isvisible(c, flag)) {
88		if ((c == '"' && vis_dq) ||
89		    (c == '\\' && !vis_noslash))
90			*dst++ = '\\';
91		*dst++ = c;
92		*dst = '\0';
93		return (dst);
94	}
95
96	if (vis_cstyle) {
97		switch (c) {
98		case '\n':
99			*dst++ = '\\';
100			*dst++ = 'n';
101			goto done;
102		case '\r':
103			*dst++ = '\\';
104			*dst++ = 'r';
105			goto done;
106		case '\b':
107			*dst++ = '\\';
108			*dst++ = 'b';
109			goto done;
110		case '\a':
111			*dst++ = '\\';
112			*dst++ = 'a';
113			goto done;
114		case '\v':
115			*dst++ = '\\';
116			*dst++ = 'v';
117			goto done;
118		case '\t':
119			*dst++ = '\\';
120			*dst++ = 't';
121			goto done;
122		case '\f':
123			*dst++ = '\\';
124			*dst++ = 'f';
125			goto done;
126		case ' ':
127			*dst++ = '\\';
128			*dst++ = 's';
129			goto done;
130		case '\0':
131			*dst++ = '\\';
132			*dst++ = '0';
133			if (isoctal(nextc)) {
134				*dst++ = '0';
135				*dst++ = '0';
136			}
137			goto done;
138		}
139	}
140	if (((c & 0177) == ' ') || vis_octal ||
141	    (vis_glob && (c == '*' || c == '?' || c == '[' || c == '#'))) {
142		*dst++ = '\\';
143		*dst++ = ((u_char)c >> 6 & 07) + '0';
144		*dst++ = ((u_char)c >> 3 & 07) + '0';
145		*dst++ = ((u_char)c & 07) + '0';
146		goto done;
147	}
148	if (!vis_noslash)
149		*dst++ = '\\';
150	if (c & 0200) {
151		c &= 0177;
152		*dst++ = 'M';
153	}
154	if (iscntrl((u_char)c)) {
155		*dst++ = '^';
156		if (c == 0177)
157			*dst++ = '?';
158		else
159			*dst++ = c + '@';
160	} else {
161		*dst++ = '-';
162		*dst++ = c;
163	}
164done:
165	*dst = '\0';
166	return (dst);
167}
168DEF_WEAK(vis);
169
170/*
171 * strvis, strnvis, strvisx - visually encode characters from src into dst
172 *
173 *	Dst must be 4 times the size of src to account for possible
174 *	expansion.  The length of dst, not including the trailing NULL,
175 *	is returned.
176 *
177 *	Strnvis will write no more than siz-1 bytes (and will NULL terminate).
178 *	The number of bytes needed to fully encode the string is returned.
179 *
180 *	Strvisx encodes exactly len bytes from src into dst.
181 *	This is useful for encoding a block of data.
182 */
183int
184strvis(char *dst, const char *src, int flag)
185{
186	char c;
187	char *start;
188
189	for (start = dst; (c = *src);)
190		dst = vis(dst, c, flag, *++src);
191	*dst = '\0';
192	return (dst - start);
193}
194DEF_WEAK(strvis);
195
196int
197strnvis(char *dst, const char *src, size_t siz, int flag)
198{
199	int vis_dq = flag & VIS_DQ;
200	int vis_noslash = flag & VIS_NOSLASH;
201	char *start, *end;
202	char tbuf[5];
203	int c, i;
204
205	i = 0;
206	for (start = dst, end = start + siz - 1; (c = *src) && dst < end; ) {
207		if (isvisible(c, flag)) {
208			if ((c == '"' && vis_dq) ||
209			    (c == '\\' && !vis_noslash)) {
210				/* need space for the extra '\\' */
211				if (dst + 1 >= end) {
212					i = 2;
213					break;
214				}
215				*dst++ = '\\';
216			}
217			i = 1;
218			*dst++ = c;
219			src++;
220		} else {
221			i = vis(tbuf, c, flag, *++src) - tbuf;
222			if (dst + i <= end) {
223				memcpy(dst, tbuf, i);
224				dst += i;
225			} else {
226				src--;
227				break;
228			}
229		}
230	}
231	if (siz > 0)
232		*dst = '\0';
233	if (dst + i > end) {
234		/* adjust return value for truncation */
235		while ((c = *src))
236			dst += vis(tbuf, c, flag, *++src) - tbuf;
237	}
238	return (dst - start);
239}
240
241int
242stravis(char **outp, const char *src, int flag)
243{
244	char *buf;
245	int len, serrno;
246
247	buf = reallocarray(NULL, 4, strlen(src) + 1);
248	if (buf == NULL)
249		return -1;
250	len = strvis(buf, src, flag);
251	serrno = errno;
252	*outp = realloc(buf, len + 1);
253	if (*outp == NULL) {
254		*outp = buf;
255		errno = serrno;
256	}
257	return (len);
258}
259
260int
261strvisx(char *dst, const char *src, size_t len, int flag)
262{
263	char c;
264	char *start;
265
266	for (start = dst; len > 1; len--) {
267		c = *src;
268		dst = vis(dst, c, flag, *++src);
269	}
270	if (len)
271		dst = vis(dst, *src, flag, '\0');
272	*dst = '\0';
273	return (dst - start);
274}
275