busybox/libbb/process_escape_sequence.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) Manuel Novoa III <mjn3@codepoet.org>
 * and Vladimir Oleynik <dzo@simtreas.ru>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"

#define WANT_HEX_ESCAPES 1

/* Usual "this only works for ascii compatible encodings" disclaimer. */
#undef _tolower
#define _tolower(X) ((X)|((char) 0x20))

char FAST_FUNC bb_process_escape_sequence(const char **ptr)
{
	/* bash builtin "echo -e '\ec'" interprets \e as ESC,
	 * but coreutils "/bin/echo -e '\ec'" does not.
	 * manpages tend to support coreutils way. */
	static const char charmap[] ALIGN1 = {
		'a',  'b', /*'e',*/ 'f',  'n',  'r',  't',  'v',  '\\', 0,
		'\a', '\b', /*27,*/ '\f', '\n', '\r', '\t', '\v', '\\', '\\' };

	const char *p;
	const char *q;
	unsigned num_digits;
	unsigned r;
	unsigned n;
	unsigned d;
	unsigned base;

	num_digits = n = 0;
	base = 8;
	q = *ptr;

#ifdef WANT_HEX_ESCAPES
	if (*q == 'x') {
		++q;
		base = 16;
		++num_digits;
	}
#endif

	do {
		d = (unsigned char)(*q) - '0';
#ifdef WANT_HEX_ESCAPES
		if (d >= 10) {
			d = (unsigned char)(_tolower(*q)) - 'a' + 10;
		}
#endif

		if (d >= base) {
#ifdef WANT_HEX_ESCAPES
			if ((base == 16) && (!--num_digits)) {
/*				return '\\'; */
				--q;
			}
#endif
			break;
		}

		r = n * base + d;
		if (r > UCHAR_MAX) {
			break;
		}

		n = r;
		++q;
	} while (++num_digits < 3);

	if (num_digits == 0) {	/* mnemonic escape sequence? */
		p = charmap;
		do {
			if (*p == *q) {
				q++;
				break;
			}
		} while (*++p);
		n = *(p + (sizeof(charmap)/2));
	}

	*ptr = q;

	return (char) n;
}
1	niro	532	/* vi: set sw=4 ts=4: */
2			/*
3			* Utility routines.
4			*
5			* Copyright (C) Manuel Novoa III <mjn3@codepoet.org>
6			* and Vladimir Oleynik <dzo@simtreas.ru>
7			*
8			* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
9			*/
10
11			#include "libbb.h"
12
13			#define WANT_HEX_ESCAPES 1
14
15			/* Usual "this only works for ascii compatible encodings" disclaimer. */
16			#undef _tolower
17			#define _tolower(X) ((X)\|((char) 0x20))
18
19	niro	816	char FAST_FUNC bb_process_escape_sequence(const char **ptr)
20	niro	532	{
21	niro	816	/* bash builtin "echo -e '\ec'" interprets \e as ESC,
22			* but coreutils "/bin/echo -e '\ec'" does not.
23			* manpages tend to support coreutils way. */
24			static const char charmap[] ALIGN1 = {
25			'a', 'b', /'e',/ 'f', 'n', 'r', 't', 'v', '\\', 0,
26			'\a', '\b', /27,/ '\f', '\n', '\r', '\t', '\v', '\\', '\\' };
27	niro	532
28			const char *p;
29			const char *q;
30	niro	816	unsigned num_digits;
31			unsigned r;
32			unsigned n;
33			unsigned d;
34			unsigned base;
35	niro	532
36			num_digits = n = 0;
37			base = 8;
38			q = *ptr;
39
40			#ifdef WANT_HEX_ESCAPES
41			if (*q == 'x') {
42			++q;
43			base = 16;
44			++num_digits;
45			}
46			#endif
47
48			do {
49	niro	816	d = (unsigned char)(*q) - '0';
50	niro	532	#ifdef WANT_HEX_ESCAPES
51			if (d >= 10) {
52	niro	816	d = (unsigned char)(_tolower(*q)) - 'a' + 10;
53	niro	532	}
54			#endif
55
56			if (d >= base) {
57			#ifdef WANT_HEX_ESCAPES
58			if ((base == 16) && (!--num_digits)) {
59			/* return '\\'; */
60			--q;
61			}
62			#endif
63			break;
64			}
65
66			r = n * base + d;
67			if (r > UCHAR_MAX) {
68			break;
69			}
70
71			n = r;
72			++q;
73			} while (++num_digits < 3);
74
75			if (num_digits == 0) { /* mnemonic escape sequence? */
76			p = charmap;
77			do {
78			if (p == q) {
79			q++;
80			break;
81			}
82			} while (*++p);
83	niro	816	n = *(p + (sizeof(charmap)/2));
84	niro	532	}
85
86			*ptr = q;
87
88			return (char) n;
89			}