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/*
* virt_mbrlen.c
*
* Platform-intependent clone of mbrlen - determine number of bytes in next multibyte character
*
* $Id$
*
* This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
* project.
*
* Copyright (C) 1998-2012 OpenLink Software
*
* This project 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; only version 2 of the License, dated June 1991.
*
* 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.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include "libutil.h"
size_t
virt_mbrlen (const char *s, size_t n, virt_mbstate_t *ps)
{
size_t used = 0;
static virt_mbstate_t internal;
if (ps == NULL)
ps = &internal;
if (s == NULL)
{
s = (unsigned char *) "";
n = 1;
}
if (n > 0)
{
if (ps->count == 0)
{
unsigned char byte = (unsigned char) *s++;
++used;
/* We must look for a possible first byte of a UTF8 sequence. */
if (!(byte & 0x80))
return byte ? used : 0;
if ((byte & 0xc0) == 0x80 || (byte & 0xfe) == 0xfe)
return (size_t) -1;
if ((byte & 0xe0) == 0xc0)
{
/* We expect two bytes. */
ps->count = 1;
ps->value = byte & 0x1f;
}
else if ((byte & 0xf0) == 0xe0)
{
/* We expect three bytes. */
ps->count = 2;
ps->value = byte & 0x0f;
}
else if ((byte & 0xf8) == 0xf0)
{
/* We expect four bytes. */
ps->count = 3;
ps->value = byte & 0x07;
}
else if ((byte & 0xfc) == 0xf8)
{
/* We expect five bytes. */
ps->count = 4;
ps->value = byte & 0x03;
}
else
{
/* We expect six bytes. */
ps->count = 5;
ps->value = byte & 0x01;
}
}
/* We know we have to handle a multibyte character and there are
some more bytes to read. */
while (used < n)
{
/* The second to sixths byte must be of the form 10xxxxxx. */
unsigned char byte = (unsigned char) *s++;
++used;
if ((byte & 0xc0) != 0x80)
{
return (size_t) -1;
}
ps->value <<= 6;
ps->value |= byte & 0x3f;
if (--ps->count == 0)
{
return ps->value ? used : 0;
}
}
}
return (size_t) -2;
}
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