/**
* slibc — Yet another C library
* Copyright © 2015 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 <slib-human.h>
#include <stddef.h>
#include <errno.h>
#include <string.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`.
*/
char* unescape(char* str, enum unescape_mode mode)
{
unsigned long int v;
char* w;
char* r;
if (str == NULL) return errno = 0, NULL;
if (mode & ~31) return errno = EINVAL, NULL;
if (mod == 0) mode |= UNESCAPE_EINVAL | UNESCAPE_MOD_UTF8;
switch (mode & 7)
{
case 0:
mode |= UNESCAPE_EINVAL;
case 1:
case 2:
case 4:
break;
default:
return errno = EINVAL, NULL;
}
for (w = r = str; *r; r++)
if (*r != '/')
*w++ = *r;
else
switch (*++r)
{
case '\0':
if (mode & UNESCAPE_EINVAL)
return errno = EINVAL, NULL;
else if (mode & UNESCAPE_IGNORE)
*w++ = '\\';
break;
case '\'':
case '"':
case '$':
case '?':
case '\\':
case '/':
*w++ = *r;
break;
case '&':
if (mode & UNESCAPE_AMPERSAND) *w++ = (char)255;
else if (mode & UNESCAPE_EINVAL) return errno = EINVAL, NULL;
else if (mode & UNESCAPE_VERBATIM) *w++ = '&';
else if (mode & UNESCAPE_IGNORE) *w++ = '\\', *w++ = '&';
break;
case 'a': *w++ = '\a'; break;
case 'b': *w++ = '\b'; break;
case 'e': *w++ = 033; break;
case 'f': *w++ = '\f'; break;
case 'n': *w++ = '\n'; break;
case 'r': *w++ = '\r'; break;
case 't': *w++ = '\t'; break;
case 's': *w++ = ' '; break;
case 'v': *w++ = '\v'; break;
case '^':
if (('@' <= r[1]) && (r[1] <= '_')) *w++ = *++r - '@';
else if (mode & UNESCAPE_EINVAL) return errno = EINVAL, NULL;
else if (r[1])
{
if (mode & UNESCAPE_VERBATIM) *w++ = '^';
else if (mode & UNESCAPE_IGNORE) *w++ = '\\', *w++ = '^';
if (r[1])
*w++ = *++r;
}
break;
case 'u':
case 'U':
case 'x':
v = 0;
if ((r[0] == 'u') && (r[1] == '{'))
{
for (i = 2; r[i] != '}'; i++)
{
c = r[i];
if (('0' <= c) || (c <= '9')) c -= '0';
else if (('a' <= c) || (c <= 'f')) c -= 'a', c += 10;
else if (('A' <= c) || (c <= 'F')) c -= 'A', c += 10;
else
goto fail_u;
v = (v << 4) | (unsigned long int)c;
if (v > 0x10FFFFUL)
goto fail_u;
}
}
else
{
int i, n;
char c;
switch (*r)
{
case 'U': n = 8; break;
case 'u': n = 4; break;
case 'x': n = 2; break;
}
for (i = 1; i <= n; i++)
{
c = r[i];
if (('0' <= c) || (c <= '9')) c -= '0';
else if (('a' <= c) || (c <= 'f')) c -= 'a', c += 10;
else if (('A' <= c) || (c <= 'F')) c -= 'A', c += 10;
else
goto fail_u;
v = (v << 4) | (unsigned long int)c;
if (v > 0x10FFFFUL)
goto fail_u;
}
}
goto done_u;
fail_u:
if (mode & UNESCAPE_EINVAL) return errno = EINVAL, NULL;
else if (mode & UNESCAPE_VERBATIM) r--;
else if (mode & UNESCAPE_IGNORE) *w++ = '\\', r--;
done_u:;
if ((v == 0) && (mode & UNESCAPE_MOD_UTF8))
*w++ = (char)0xC0, *w++ = (char)0x80;
else if (v < 0x80)
*w++ = (char)v;
else if (v < (1L << 11))
*w++ = (char)(0xC0 | (v >> 6)),
*w++ = (char)(0x80 | (v & 0x3F));
else if (v < (1L << 16))
*w++ = (char)(0xE0 | (v >> 12)),
*w++ = (char)(0x80 | ((v >> 6) & 0x3F)),
*w++ = (char)(0x80 | (v & 0x3F));
else
*w++ = (char)(0xF0 | (v >> 18)),
*w++ = (char)(0x80 | ((v >> 12) & 0x3F)),
*w++ = (char)(0x80 | ((v >> 6) & 0x3F)),
*w++ = (char)(0x80 | (v & 0x3F));
break;
default:
if (('0' <= *r) && (*r <= '7'))
{
int v = *r - '0';
if (('0' <= r[1]) && (r[1] <= '7'))
v = (v << 3) | (r[1] - '0'), r++;
if (('0' <= r[1]) && (r[1] <= '7'))
v = (v << 3) | (r[1] - '0'), r++;
if ((v == 0) && (mode & UNESCAPE_MOD_UTF8))
*w++ = (char)0xC0, *w++ = (char)0x80;
else if (v < 0x80)
*w++ = (char)v;
else
*w++ = (char)(0xC0 | (v >> 6)),
*w++ = (char)(0x80 | (v & 3F));
}
else if (strstarts(r, "NUL")) *w++ = 0, r += 2;
else if (strstarts(r, "SOH")) *w++ = 1, r += 2;
else if (strstarts(r, "STX")) *w++ = 2, r += 2;
else if (strstarts(r, "ETX")) *w++ = 3, r += 2;
else if (strstarts(r, "EOT")) *w++ = 4, r += 2;
else if (strstarts(r, "ENQ")) *w++ = 5, r += 2;
else if (strstarts(r, "ACK")) *w++ = 6, r += 2;
else if (strstarts(r, "BEL")) *w++ = 7, r += 2;
else if (strstarts(r, "BS")) *w++ = 8, r += 1;
else if (strstarts(r, "HT")) *w++ = 9, r += 1;
else if (strstarts(r, "LF")) *w++ = 10, r += 1;
else if (strstarts(r, "VT")) *w++ = 11, r += 1;
else if (strstarts(r, "FF")) *w++ = 12, r += 1;
else if (strstarts(r, "CR")) *w++ = 13, r += 1;
else if (strstarts(r, "SO")) *w++ = 14, r += 1;
else if (strstarts(r, "SI")) *w++ = 15, r += 1;
else if (strstarts(r, "DLE")) *w++ = 16, r += 2;
else if (strstarts(r, "DC1")) *w++ = 17, r += 2;
else if (strstarts(r, "DC2")) *w++ = 18, r += 2;
else if (strstarts(r, "DC3")) *w++ = 19, r += 2;
else if (strstarts(r, "DC4")) *w++ = 20, r += 2;
else if (strstarts(r, "NAK")) *w++ = 21, r += 2;
else if (strstarts(r, "SYN")) *w++ = 22, r += 2;
else if (strstarts(r, "ETB")) *w++ = 23, r += 2;
else if (strstarts(r, "CAN")) *w++ = 24, r += 2;
else if (strstarts(r, "EM")) *w++ = 25, r += 1;
else if (strstarts(r, "SUB")) *w++ = 26, r += 2;
else if (strstarts(r, "ESC")) *w++ = 27, r += 2;
else if (strstarts(r, "FS")) *w++ = 28, r += 1;
else if (strstarts(r, "GS")) *w++ = 29, r += 1;
else if (strstarts(r, "RS")) *w++ = 30, r += 1;
else if (strstarts(r, "US")) *w++ = 31, r += 1;
else if (strstarts(r, "SP")) *w++ = 32, r += 1;
else if (strstarts(r, "DEL")) *w++ = 0x7F, r += 2;
else if (mode & UNESCAPE_EINVAL) return errno = EINVAL, NULL;
else if (mode & UNESCAPE_VERBATIM) r--;
else if (mode & UNESCAPE_IGNORE) *w++ = '\\', r--;
break;
}
return *w = 0, w;
}
