xmemmem.c

/*
 * ryshttpd -- simple filesharing http server.
 *
 * ryshttpd is copyrighted:
 * Copyright (C) 2018 Andrey Rys. All rights reserved.
 *
 * ryshttpd is licensed to you under the terms of std. MIT/X11 license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "httpd.h"

/* simple, all cases portable memmem implementation. Lynx. */
void *rh_memmem(const void *hs, size_t hsn, const void *ne, size_t nen)
{
	const unsigned char *bhs, *shs;

	if (nen == 0) return (void *)hs;
	if (hsn < nen) return NULL;
	if (hsn == nen && !memcmp(hs, ne, hsn)) return (void *)hs;
	if (nen == sizeof(unsigned char)) return memchr(hs, *(unsigned char *)ne, hsn);

	bhs = shs = hs;
	do {
		if (!memcmp(shs, ne, nen)) return (void *)shs;
		shs++;
	} while (shs-bhs <= hsn-nen);

	return NULL;
}