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	/* 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	char FAST_FUNC bb_process_escape_sequence(const char **ptr)
20	{
21	/* 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
28	const char *p;
29	const char *q;
30	unsigned num_digits;
31	unsigned r;
32	unsigned n;
33	unsigned d;
34	unsigned base;
35
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	d = (unsigned char)(*q) - '0';
50	#ifdef WANT_HEX_ESCAPES
51	if (d >= 10) {
52	d = (unsigned char)(_tolower(*q)) - 'a' + 10;
53	}
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	n = *(p + (sizeof(charmap)/2));
84	}
85
86	*ptr = q;
87
88	return (char) n;
89	}