Add memrchr(3).

libc/Makefile

@@ -192,6 +192,7 @@ string/memchr.o \
 string/memcmp.o \
 string/memcpy.o \
 string/memmove.o \
+string/memrchr.o \
 string/memset.o \
 string/stpcpy.o \
 string/stpncpy.o \

libc/include/string.h

@@ -125,6 +125,7 @@ size_t strxfrm_l(char* __restrict, const char* __restrict, size_t, locale_t);
 /* Functions copied from elsewhere. */
 #if __USE_SORTIX
 int ffsl(long int);
+void* memrchr(const void*, int, size_t);
 /* TODO: strcasecmp_l */
 char* strchrnul(const char* str, int c);
 size_t strlcat(char* __restrict, const char* __restrict, size_t);

libc/string/memrchr.cpp

@@ -0,0 +1,35 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2014.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C 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.
+
+    The Sortix C 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 the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    string/memrchr.cpp
+    Scans memory in reverse directory for a character.
+
+*******************************************************************************/
+
+#include <stdint.h>
+#include <string.h>
+
+extern "C" void* memrchr(const void* ptr, int c, size_t n)
+{
+	const unsigned char* buf = (const unsigned char*) ptr;
+	for ( size_t i = n; i != 0; i-- )
+		if ( buf[i-1] == (unsigned char) c )
+			return (void*) (buf + i-1);
+	return NULL;
+}