63 lines
2.2 KiB
C
63 lines
2.2 KiB
C
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/* -*-comment-start: "//";comment-end:""-*-
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* GNU Mes --- Maxwell Equations of Software
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* Copyright © 1997--2015,2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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* Copyright (C) 1997--2015,2018 Han-Wen Nienhuys <hanwen@xs4all.nl>
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*
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* This file is part of GNU Mes.
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*
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* GNU Mes is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* GNU Mes is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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/** locate a substring. #memmem# finds the first occurrence of
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#needle# in #haystack#. This is not ANSI-C.
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The prototype is not in accordance with the Linux Programmer's
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Manual v1.15, but it is with /usr/include/string.h */
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unsigned char *
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_memmem (unsigned char const *haystack, int haystack_len,
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unsigned char const *needle, int needle_len)
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{
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unsigned char const *end_haystack = haystack + haystack_len - needle_len + 1;
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unsigned char const *end_needle = needle + needle_len;
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/* Ahhh ... Some minimal lowlevel stuff. This *is* nice; Varation
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is the spice of life */
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while (haystack < end_haystack)
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{
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unsigned char const *subneedle = needle;
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unsigned char const *subhaystack = haystack;
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while (subneedle < end_needle)
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if (*subneedle++ != *subhaystack++)
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goto next;
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/* Completed the needle. Gotcha. */
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return (unsigned char *) haystack;
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next:
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haystack++;
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}
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return 0;
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}
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void *
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memmem (void const *haystack, int haystack_len,
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void const *needle, int needle_len)
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{
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unsigned char const *haystack_byte_c = (unsigned char const *)haystack;
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unsigned char const *needle_byte_c = (unsigned char const *)needle;
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return _memmem (haystack_byte_c, haystack_len, needle_byte_c, needle_len);
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}
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