unvis.c
1/* $OpenBSD: unvis.c,v 1.17 2015/09/13 11:32:51 guenther 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 "pconfig.h"
32
33#ifndef HAVE_STRUNVIS
34
35#include <sys/types.h>
36#include <ctype.h>
37
38#include "vis.h"
39
40/*
41 * decode driven by state machine
42 */
43#define S_GROUND 0 /* haven't seen escape char */
44#define S_START 1 /* start decoding special sequence */
45#define S_META 2 /* metachar started (M) */
46#define S_META1 3 /* metachar more, regular char (-) */
47#define S_CTRL 4 /* control char started (^) */
48#define S_OCTAL2 5 /* octal digit 2 */
49#define S_OCTAL3 6 /* octal digit 3 */
50
51#define isoctal(c) (((u_char)(c)) >= '0' && ((u_char)(c)) <= '7')
52
53/*
54 * unvis - decode characters previously encoded by vis
55 */
56static int
57eunvis(char *cp, char c, int *astate, int flag)
58{
59
60 if (flag & UNVIS_END) {
61 if (*astate == S_OCTAL2 || *astate == S_OCTAL3) {
62 *astate = S_GROUND;
63 return (UNVIS_VALID);
64 }
65 return (*astate == S_GROUND ? UNVIS_NOCHAR : UNVIS_SYNBAD);
66 }
67
68 switch (*astate) {
69
70 case S_GROUND:
71 *cp = 0;
72 if (c == '\\') {
73 *astate = S_START;
74 return (0);
75 }
76 *cp = c;
77 return (UNVIS_VALID);
78
79 case S_START:
80 switch(c) {
81 case '-':
82 *cp = 0;
83 *astate = S_GROUND;
84 return (0);
85 case '\\':
86 case '"':
87 *cp = c;
88 *astate = S_GROUND;
89 return (UNVIS_VALID);
90 case '0': case '1': case '2': case '3':
91 case '4': case '5': case '6': case '7':
92 *cp = (c - '0');
93 *astate = S_OCTAL2;
94 return (0);
95 case 'M':
96 *cp = (char) 0200;
97 *astate = S_META;
98 return (0);
99 case '^':
100 *astate = S_CTRL;
101 return (0);
102 case 'n':
103 *cp = '\n';
104 *astate = S_GROUND;
105 return (UNVIS_VALID);
106 case 'r':
107 *cp = '\r';
108 *astate = S_GROUND;
109 return (UNVIS_VALID);
110 case 'b':
111 *cp = '\b';
112 *astate = S_GROUND;
113 return (UNVIS_VALID);
114 case 'a':
115 *cp = '\007';
116 *astate = S_GROUND;
117 return (UNVIS_VALID);
118 case 'v':
119 *cp = '\v';
120 *astate = S_GROUND;
121 return (UNVIS_VALID);
122 case 't':
123 *cp = '\t';
124 *astate = S_GROUND;
125 return (UNVIS_VALID);
126 case 'f':
127 *cp = '\f';
128 *astate = S_GROUND;
129 return (UNVIS_VALID);
130 case 's':
131 *cp = ' ';
132 *astate = S_GROUND;
133 return (UNVIS_VALID);
134 case 'E':
135 *cp = '\033';
136 *astate = S_GROUND;
137 return (UNVIS_VALID);
138 case '\n':
139 /*
140 * hidden newline
141 */
142 *astate = S_GROUND;
143 return (UNVIS_NOCHAR);
144 case '$':
145 /*
146 * hidden marker
147 */
148 *astate = S_GROUND;
149 return (UNVIS_NOCHAR);
150 }
151 *astate = S_GROUND;
152 return (UNVIS_SYNBAD);
153
154 case S_META:
155 if (c == '-')
156 *astate = S_META1;
157 else if (c == '^')
158 *astate = S_CTRL;
159 else {
160 *astate = S_GROUND;
161 return (UNVIS_SYNBAD);
162 }
163 return (0);
164
165 case S_META1:
166 *astate = S_GROUND;
167 *cp |= c;
168 return (UNVIS_VALID);
169
170 case S_CTRL:
171 if (c == '?')
172 *cp |= 0177;
173 else
174 *cp |= c & 037;
175 *astate = S_GROUND;
176 return (UNVIS_VALID);
177
178 case S_OCTAL2: /* second possible octal digit */
179 if (isoctal(c)) {
180 /*
181 * yes - and maybe a third
182 */
183 *cp = (*cp << 3) + (c - '0');
184 *astate = S_OCTAL3;
185 return (0);
186 }
187 /*
188 * no - done with current sequence, push back passed char
189 */
190 *astate = S_GROUND;
191 return (UNVIS_VALIDPUSH);
192
193 case S_OCTAL3: /* third possible octal digit */
194 *astate = S_GROUND;
195 if (isoctal(c)) {
196 *cp = (*cp << 3) + (c - '0');
197 return (UNVIS_VALID);
198 }
199 /*
200 * we were done, push back passed char
201 */
202 return (UNVIS_VALIDPUSH);
203
204 default:
205 /*
206 * decoder in unknown state - (probably uninitialized)
207 */
208 *astate = S_GROUND;
209 return (UNVIS_SYNBAD);
210 }
211}
212
213/*
214 * strunvis - decode src into dst
215 *
216 * Number of chars decoded into dst is returned, -1 on error.
217 * Dst is null terminated.
218 */
219
220int
221strunvis(char *dst, const char *src)
222{
223 char c;
224 char *start = dst;
225 int state = 0;
226
227 while ((c = *src++)) {
228 again:
229 switch (eunvis(dst, c, &state, 0)) {
230 case UNVIS_VALID:
231 dst++;
232 break;
233 case UNVIS_VALIDPUSH:
234 dst++;
235 goto again;
236 case 0:
237 case UNVIS_NOCHAR:
238 break;
239 default:
240 *dst = '\0';
241 return (-1);
242 }
243 }
244 if (eunvis(dst, c, &state, UNVIS_END) == UNVIS_VALID)
245 dst++;
246 *dst = '\0';
247 return (dst - start);
248}
249
250#endif /* !HAVE_STRUNVIS */
