busybox/libbb/process_escape_sequence.c
2006-01-25 00:08:53 +00:00

113 lines
2.2 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) Manuel Novoa III <mjn3@codepoet.org>
* and Vladimir Oleynik <dzo@simtreas.ru>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
*/
#include <stdio.h>
#include <limits.h>
#include <ctype.h>
#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 bb_process_escape_sequence(const char **ptr)
{
static const char charmap[] = {
'a', 'b', 'f', 'n', 'r', 't', 'v', '\\', 0,
'\a', '\b', '\f', '\n', '\r', '\t', '\v', '\\', '\\' };
const char *p;
const char *q;
unsigned int num_digits;
unsigned int r;
unsigned int n;
unsigned int d;
unsigned int 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 int)(*q - '0');
#ifdef WANT_HEX_ESCAPES
if (d >= 10) {
d = ((unsigned int)(_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;
}
/* END CODE */
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/