1 files changed, 99 insertions, 0 deletions

diff --git a/src/lib/libc/string/memcpy.c b/src/lib/libc/string/memcpy.c
new file mode 100644
index 0000000000..1b9715e471
--- /dev/null
+++ b/src/lib/libc/string/memcpy.c
@@ -0,0 +1,99 @@
+/*      $OpenBSD: memcpy.c,v 1.1 2014/11/30 19:43:56 deraadt Exp $ */
+/*-
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * 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. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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>
+#include <stdlib.h>
+#include <syslog.h>
+
+/*
+ * sizeof(word) MUST BE A POWER OF TWO
+ * SO THAT wmask BELOW IS ALL ONES
+ */
+typedef long word;              /* "word" used for optimal copy speed */
+
+#define wsize   sizeof(word)
+#define wmask   (wsize - 1)
+
+/*
+ * Copy a block of memory, not handling overlap.
+ */
+void *
+memcpy(void *dst0, const void *src0, size_t length)
+{
+        char *dst = dst0;
+        const char *src = src0;
+        size_t t;
+
+        if (length == 0 || dst == src)          /* nothing to do */
+                goto done;
+
+        if ((dst < src && dst + length > src) ||
+            (src < dst && src + length > dst)) {
+                struct syslog_data sdata = SYSLOG_DATA_INIT;
+
+                syslog_r(LOG_CRIT, &sdata, "backwards memcpy");
+                abort();
+        }
+
+        /*
+         * Macros: loop-t-times; and loop-t-times, t>0
+         */
+#define TLOOP(s) if (t) TLOOP1(s)
+#define TLOOP1(s) do { s; } while (--t)
+
+        /*
+         * Copy forward.
+         */
+        t = (long)src;  /* only need low bits */
+        if ((t | (long)dst) & wmask) {
+                /*
+                 * Try to align operands.  This cannot be done
+                 * unless the low bits match.
+                 */
+                if ((t ^ (long)dst) & wmask || length < wsize)
+                        t = length;
+                else
+                        t = wsize - (t & wmask);
+                length -= t;
+                TLOOP1(*dst++ = *src++);
+        }
+        /*
+         * Copy whole words, then mop up any trailing bytes.
+         */
+        t = length / wsize;
+        TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
+        t = length & wmask;
+        TLOOP(*dst++ = *src++);
+done:
+        return (dst0);
+}