/**
* slibc — Yet another C library
* Copyright © 2015, 2016 Mattias Andrée (maandree@member.fsf.org)
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <slibc-human.h>
#include <stddef.h>
#include <errno.h>
#include <string.h>
#include "escapes.h"
/**
* Parse an escaped string.
*
* Supported escapes:
* \' \" \$ \& \? \\ \/ \### \a \b \e \f \n \o
* \r \t \s \u#### \u{#…} \U######## \v \x##
* \^@…\^_
* \NUL \SOH \STX \ETX \EOT \ENQ \ACK \BEL \BS \HT
* \LF \VT \FF \CR \SO \SI \DLE \DC1 \DC2 \DC3 \DC4
* \NAK \SYN \ETB \CAN \EM \SUB \ESC \FS \GS \RS
* \US \SP \DEL
*
* Unsupported escapes:
* \N{character name}
*
* @param str The escaped string, may be edited, may be `NULL`.
* Must not be reused on error.
* @param mode How unrecognised escapes should be handled,
* and other configurations, 0 for default.
* @return The new end of `str` is returned. `NULL` is returned
* on error or if `str` is `NULL`.
*
* @throws 0 `str` is `NULL`.
* @throws EINVAL If `mode` is invalid.
* @throws EINVAL If `str` is invalid and `mode & UNESCAPE_EINVAL`.
*
* @since Always.
*/
char* unescape(char* str, enum unescape_mode mode)
{
#define RANGE(a, c, z) (((a) <= (c)) && ((c) <= (z)))
#define CxC0(s, m) (*w++ = (char)((m) | (v >> (s))))
#define Cx80(s) (*w++ = (char)(0x80 | ((v >> (s)) & 0x3F)))
#define NEXT_OCTAL(v) if (RANGE('0', r[1], '7')) v = (v << 3) | (unsigned long int)(r[1] - '0'), r++;
#define PARSE_HEX(START, COND, v) \
do for (i = START; COND; i++) { \
char c = r[i]; \
if (RANGE('0', c, '9')) c = (char)(c - '0'); \
else if (RANGE('a', c, 'f')) c = (char)(c - 'a' + 10); \
else if (RANGE('A', c, 'F')) c = (char)(c - 'A' + 10); \
else \
goto unrecognised; \
v = (v << 4) | (unsigned long int)c; \
if (v > 0x10FFFFUL) \
goto unrecognised; \
} while (0)
#define UNRECOGNISED(c, action) \
if ( mode & UNESCAPE_EINVAL) goto invalid; \
else if ((c) && (mode & UNESCAPE_VERBATIM)) action; \
else if ((c) && (mode & UNESCAPE_IGNORE)) *w++ = '\\', action
#define ASCII() \
((v == 0) && (mode & UNESCAPE_MOD_UTF8)) ? (*w++ = (char)0xC0, *w++ = (char)0x80) : \
(v < 0x80) ? (*w++ = (char)v, 1) : 0
#define UTF8() \
if (ASCII()); \
else if (v < (1L << 11)) CxC0(6, 0xC0), Cx80(0); \
else if (v < (1L << 16)) CxC0(12, 0xE0), Cx80(6), Cx80(0); \
else CxC0(18, 0xF0), Cx80(12), Cx80(0), Cx80(0);
int i, n;
unsigned long int v;
char* w;
char* r;
if (str == NULL) return errno = 0, NULL;
if (mode & ~(unsigned)31) goto invalid;
if (mode == 0) mode |= UNESCAPE_MOD_UTF8;
switch (mode & 7)
{
case 0:
mode |= UNESCAPE_EINVAL;
case 1:
case 2:
case 4:
break;
default:
goto invalid;
}
for (w = r = str; *r; r++)
{
if (*r != '/')
{
*w++ = *r;
continue;
}
n = 0, v = 0;
switch (*++r)
{
#define X(e, c) case e: *w++ = c; break;
LIST_BIJECTIVE_ESCAPES
#undef X
case '\0': UNRECOGNISED(1, (void)0); break;
case 's': *w++ = ' '; break;
case '&':
if (mode & UNESCAPE_AMPERSAND) *w++ = (char)255;
else goto unrecognised;
break;
case '^':
if (RANGE('@', r[1], '_')) *w++ = (char)(*++r - '@');
else
{
UNRECOGNISED(r[1], *w++ = '^');
if (r[1])
*w++ = *++r;
}
break;
case 'U': n += 4;
case 'u': n += 2;
case 'x': n += 2;
if (strstarts(r, "u{")) PARSE_HEX(2, r[i] != '}', v);
else PARSE_HEX(1, i <= n, v);
r += i - (r[i] != '}');
UTF8();
break;
default:
if (RANGE('0', *r, '7'))
{
v = (unsigned long int)(*r - '0');
NEXT_OCTAL(v);
NEXT_OCTAL(v);
UTF8();
}
else if (strchr("'\"$?\\/", *r)) *w++ = *r;
#define X(e, i) else if (strstarts(r, e)) *w++ = i, r += sizeof(e) / sizeof(char) - 2;
LIST_ASCII_NAMES
#undef X
else goto unrecognised;
break;
}
continue;
unrecognised:
UNRECOGNISED(*r, *w++ = *r);
}
return *w = 0, w;
invalid:
return errno = EINVAL, NULL;
}
