From 2898ec916cff65f7c1199dfb5705a2eaefae3928 Mon Sep 17 00:00:00 2001
From: Romain Goyet <romain@goyet.com>
Date: Sun, 30 Jul 2017 22:11:05 +0200
Subject: [PATCH] [liba] Add memmove to string.h

Change-Id: I99b412dc7404e2711dbf7753f0d619694dee3d19
---
 liba/Makefile         |  1 +
 liba/include/string.h |  1 +
 liba/src/memmove.c    | 21 +++++++++++++++++++++
 3 files changed, 23 insertions(+)
 create mode 100644 liba/src/memmove.c

diff --git a/liba/Makefile b/liba/Makefile
index 1e01c0def..761b90772 100644
--- a/liba/Makefile
+++ b/liba/Makefile
@@ -12,6 +12,7 @@ objs += $(addprefix liba/src/, \
   isinff.o \
   malloc.o \
   memcpy.o \
+  memmove.o \
   memset.o \
   strcmp.o \
   strlcpy.o \
diff --git a/liba/include/string.h b/liba/include/string.h
index 6c00070c0..bc3852626 100644
--- a/liba/include/string.h
+++ b/liba/include/string.h
@@ -7,6 +7,7 @@
 LIBA_BEGIN_DECLS
 
 void * memcpy(void * dst, const void * src, size_t n);
+void * memmove(void * dst, const void * src, size_t n);
 void * memset(void * b, int c, size_t len);
 size_t strlen(const char * s);
 int strcmp(const char *s1, const char *s2);
diff --git a/liba/src/memmove.c b/liba/src/memmove.c
new file mode 100644
index 000000000..cfb5a7c01
--- /dev/null
+++ b/liba/src/memmove.c
@@ -0,0 +1,21 @@
+#include <string.h>
+
+void * memmove(void * dst, const void * src, size_t n) {
+  char * destination = (char *)dst;
+  char * source = (char *)src;
+
+  if (source < destination && destination < source + n) {
+    /* Copy backwards to avoid overwrites */
+    source += n;
+    destination += n;
+    while (n--) {
+      *--destination = *--source;
+    }
+  } else {
+    while (n--) {
+      *destination++ = *source++;
+    }
+  }
+
+  return dst;
+}