cstrcasestr.c
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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 1999, 2000, 2001, 2002, 2003, 2005, 2006, 2007, 2009,
2010, 2011 Free Software Foundation, Inc.
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 3 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, see
<http://www.gnu.org/licenses/>. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <unistd.h>
#include <mailutils/cctype.h>
/* Based on strstr from GNU libc (Stephen R. van den Berg,
berg@pool.informatik.rwth-aachen.de) */
char *
mu_c_strcasestr (const char *a_haystack, const char *a_needle)
{
register const unsigned char *haystack = (unsigned char*) a_haystack,
*needle = (unsigned char*) a_needle;
register unsigned int b, c;
#define U(c) mu_toupper (c)
if ((b = U (*needle)))
{
haystack--;
do
{
if (!(c = *++haystack))
goto ret0;
}
while (U (c) != b);
if (!(c = *++needle))
goto foundneedle;
c = U (c);
++needle;
goto jin;
for (;;)
{
register unsigned int a;
register const unsigned char *rhaystack, *rneedle;
do
{
if (!(a = *++haystack))
goto ret0;
if (U (a) == b)
break;
if (!(a = *++haystack))
goto ret0;
shloop: ;
}
while (U (a) != b);
jin: if (!(a = *++haystack))
goto ret0;
if (U (a) != c)
goto shloop;
if (U (*(rhaystack = haystack-- + 1)) ==
(a = U (*(rneedle = needle))))
do
{
if (!a)
goto foundneedle;
if (U (*++rhaystack) != (a = U (*++needle)))
break;
if (!a)
goto foundneedle;
}
while (U (*++rhaystack) == (a = U (*++needle)));
needle = rneedle;
if (!a)
break;
}
}
foundneedle:
return (char*)haystack;
ret0:
return NULL;
#undef U
}