gnu: introduce memmem(3)

Implementation imported from OpenBSD

Change-Id: If2620dc7ed373650bb3dabb0f22c2cd84b9e0ef9

headers/compatibility/gnu/string.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2018 Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _GNU_STRING_H_
+#define _GNU_STRING_H_
+
+
+#include_next <string.h>
+
+
+#ifdef _GNU_SOURCE
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern void *memmem(const void *source, size_t sourceLength,
+	const void *search, size_t searchLength);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif
+
+
+#endif	/* _GNU_STRING_H_ */

src/libs/gnu/Jamfile

@@ -3,10 +3,14 @@ SubDir HAIKU_TOP src libs gnu ;
 UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility gnu ] : true ;
 UsePrivateHeaders shared ;
 
+SubDirCcFlags [ FDefines _GNU_SOURCE=1 ] ;
+SubDirC++Flags [ FDefines _GNU_SOURCE=1 ] ;
+
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {
 	on $(architectureObject) {
 		SharedLibrary [ MultiArchDefaultGristFiles libgnu.so ] :
+			memmem.c
 			xattr.cpp
 			;
 	}

src/libs/gnu/memmem.c

@@ -0,0 +1,63 @@
+/*	$OpenBSD: memmem.c,v 1.4 2015/08/31 02:53:57 guenther Exp $ */
+/*-
+ * Copyright (c) 2005 Pascal Gloor <[email protected]>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <string.h>
+
+/*
+ * Find the first occurrence of the byte string s in byte string l.
+ */
+
+void *
+memmem(const void *l, size_t l_len, const void *s, size_t s_len)
+{
+	const char *cur, *last;
+	const char *cl = l;
+	const char *cs = s;
+
+	/* a zero length needle should just return the haystack */
+	if (s_len == 0)
+		return (void *)cl;
+
+	/* "s" must be smaller or equal to "l" */
+	if (l_len < s_len)
+		return NULL;
+
+	/* special case where s_len == 1 */
+	if (s_len == 1)
+		return memchr(l, *cs, l_len);
+
+	/* the last position where its possible to find "s" in "l" */
+	last = cl + l_len - s_len;
+
+	for (cur = cl; cur <= last; cur++)
+		if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0)
+			return (void *)cur;
+
+	return NULL;
+}