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/*
* Copyright (c) 2002-2012 Balabit
* Copyright (c) 1998-2012 Balázs Scheidler
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* As an additional exemption you are allowed to compile & link against the
* OpenSSL libraries as published by the OpenSSL project. See the file
* COPYING for details.
*
*/
#include "find-crlf.h"
#include <string.h>
/**
* This is an optimized version of finding either a CR or LF or NUL
* character in a buffer. It is used to find these line terminators in
* syslog traffic.
*
* It uses an algorithm very similar to what there's in libc memchr/strchr.
**/
gchar *
find_cr_or_lf_or_nul(gchar *s, gsize n)
{
gchar *char_ptr;
gulong *longword_ptr;
gulong longword, magic_bits, cr_charmask, lf_charmask;
const char CR = '\r';
const char LF = '\n';
/* align input to long boundary */
for (char_ptr = s; n > 0 && ((gulong) char_ptr & (sizeof(longword) - 1)) != 0; ++char_ptr, n--)
{
if (*char_ptr == CR || *char_ptr == LF || *char_ptr == 0)
return char_ptr;
}
longword_ptr = (gulong *) char_ptr;
#if GLIB_SIZEOF_LONG == 8
magic_bits = 0x7efefefefefefeffL;
#elif GLIB_SIZEOF_LONG == 4
magic_bits = 0x7efefeffL;
#else
#error "unknown architecture"
#endif
memset(&cr_charmask, CR, sizeof(cr_charmask));
memset(&lf_charmask, LF, sizeof(lf_charmask));
while (n > sizeof(longword))
{
longword = *longword_ptr++;
if ((((longword + magic_bits) ^ ~longword) & ~magic_bits) != 0 ||
((((longword ^ cr_charmask) + magic_bits) ^ ~(longword ^ cr_charmask)) & ~magic_bits) != 0 ||
((((longword ^ lf_charmask) + magic_bits) ^ ~(longword ^ lf_charmask)) & ~magic_bits) != 0)
{
gint i;
char_ptr = (gchar *) (longword_ptr - 1);
for (i = 0; i < sizeof(longword); i++)
{
if (*char_ptr == CR || *char_ptr == LF || *char_ptr == 0)
return char_ptr;
char_ptr++;
}
}
n -= sizeof(longword);
}
char_ptr = (gchar *) longword_ptr;
while (n-- > 0)
{
if (*char_ptr == CR || *char_ptr == LF || *char_ptr == 0)
return char_ptr;
++char_ptr;
}
return NULL;
}
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