libc: Implement strlcpy function

Reference:
http://www.delorie.com/djgpp/doc/libc/libc_763.html

Signed-off-by: chao.an <anchao@xiaomi.com>

include/string.h

@@ -1,7 +1,8 @@
 /****************************************************************************
  * include/string.h
  *
- *   Copyright (C) 2007-2012, 2014, 2016-2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2012, 2014, 2016-2017, 2020 Gregory Nutt.
+ *   All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -76,6 +77,7 @@ int        strncmp(FAR const char *, FAR const char *, size_t);
 int        strcoll(FAR const char *, FAR const char *s2);
 FAR char  *strcpy(FAR char *dest, FAR const char *src);
 FAR char  *stpcpy(FAR char *dest, FAR const char *src);
+size_t     strlcpy(FAR char *dst, FAR const char *src, size_t siz);
 FAR char  *strncpy(FAR char *, FAR const char *, size_t);
 FAR char  *stpncpy(FAR char *, FAR const char *, size_t);
 FAR char  *strpbrk(FAR const char *, FAR const char *);

libs/libc/machine/Kconfig

@@ -72,6 +72,10 @@ config LIBC_ARCH_STRCPY
 	bool
 	default n
 
+config LIBC_ARCH_STRLCPY
+	bool
+	default n
+
 config LIBC_ARCH_STRNCPY
 	bool
 	default n

libs/libc/string/Make.defs

@@ -48,7 +48,7 @@ CSRCS += lib_strspn.c lib_strstr.c lib_strtok.c lib_strtokr.c
 CSRCS += lib_strsep.c lib_strerrorr.c lib_explicit_bzero.c lib_strsignal.c
 CSRCS += lib_anbstr2cstr.c lib_ancstr2bstr.c lib_bmem2cmem.c
 CSRCS += lib_bstrnlen.c lib_cmem2bmem.c lib_nbstr2cstr.c lib_ncstr2bstr.c
-CSRCS += lib_index.c lib_rindex.c
+CSRCS += lib_index.c lib_rindex.c lib_strlcpy.c
 
 ifneq ($(CONFIG_LIBC_ARCH_MEMCPY),y)
 ifeq ($(CONFIG_MEMCPY_VIK),y)

libs/libc/string/lib_strlcpy.c

@@ -0,0 +1,75 @@
+/****************************************************************************
+ * libs/libc/string/lib_strlcpy.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <string.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: strlcpy
+ *
+ * Description:
+ *   Copy src to string dst of size dsize.  At most dsize-1 characters
+ *   will be copied.  Always NUL terminates (unless dsize == 0).
+ *
+ * Returned Value:
+ *   Returns strlen(src); if retval >= dsize, truncation occurred.
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_LIBC_ARCH_STRLCPY
+size_t strlcpy(FAR char *dst, FAR const char *src, size_t dsize)
+{
+  FAR const char *osrc = src;
+  size_t nleft = dsize;
+
+  if (nleft != 0)
+    {
+      while (--nleft != 0)
+        {
+          if ((*dst++ = *src++) == '\0')
+            {
+              break;
+            }
+        }
+    }
+
+  if (nleft == 0)
+    {
+      if (dsize != 0)
+        {
+          *dst = '\0';
+        }
+
+      while (*src++);
+    }
+
+  return (src - osrc - 1);
+}
+#endif