1/* See LICENSE file for copyright and license details. */
 2#include <ctype.h>
 3#include <string.h>
 4
 5#include "../util.h"
 6
 7#define is_odigit(c)  ('0' <= c && c <= '7')
 8
 9size_t
10unescape(char *s)
11{
12	static const char escapes[256] = {
13		['"'] = '"',
14		['\''] = '\'',
15		['\\'] = '\\',
16		['a'] = '\a',
17		['b'] = '\b',
18		['E'] = 033,
19		['e'] = 033,
20		['f'] = '\f',
21		['n'] = '\n',
22		['r'] = '\r',
23		['t'] = '\t',
24		['v'] = '\v'
25	};
26	size_t m, q;
27	char *r, *w;
28
29	for (r = w = s; *r;) {
30		if (*r != '\\') {
31			*w++ = *r++;
32			continue;
33		}
34		r++;
35		if (!*r) {
36			eprintf("null escape sequence\n");
37		} else if (escapes[(unsigned char)*r]) {
38			*w++ = escapes[(unsigned char)*r++];
39		} else if (is_odigit(*r)) {
40			for (q = 0, m = 3; m && is_odigit(*r); m--, r++)
41				q = q * 8 + (*r - '0');
42			*w++ = MIN(q, (size_t)255);
43		} else if (*r == 'x' && isxdigit(r[1])) {
44			r++;
45			for (q = 0, m = 2; m && isxdigit(*r); m--, r++)
46				if (isdigit(*r))
47					q = q * 16 + (*r - '0');
48				else
49					q = q * 16 + (tolower(*r) - 'a' + 10);
50			*w++ = q;
51		} else {
52			eprintf("invalid escape sequence '\\%c'\n", *r);
53		}
54	}
55	*w = '\0';
56
57	return w - s;
58}