From 027e2eed282aa09d1c522c05f81b3ad65b11b7ab Mon Sep 17 00:00:00 2001
From: Xiang Xiao <xiaoxiang@xiaomi.com>
Date: Mon, 14 Sep 2020 14:20:13 +0800
Subject: [PATCH] libc: Implement umask function

Here is the spec:
https://pubs.opengroup.org/onlinepubs/009695399/functions/umask.html
Note: The simple implementaton is enough since
      NuttX doesn't really support the permission

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
---
 include/sys/stat.h         |  2 ++
 libs/libc/misc/Make.defs   |  2 +-
 libs/libc/misc/lib_umask.c | 57 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 libs/libc/misc/lib_umask.c

diff --git a/include/sys/stat.h b/include/sys/stat.h
index 2939189598..891c341639 100644
--- a/include/sys/stat.h
+++ b/include/sys/stat.h
@@ -168,6 +168,8 @@ int fstat(int fd, FAR struct stat *buf);
 int chmod(FAR const char *path, mode_t mode);
 int fchmod(int fd, mode_t mode);
 
+mode_t umask(mode_t mask);
+
 #undef EXTERN
 #if defined(__cplusplus)
 }
diff --git a/libs/libc/misc/Make.defs b/libs/libc/misc/Make.defs
index 1cf29072bf..0f34be1b0f 100644
--- a/libs/libc/misc/Make.defs
+++ b/libs/libc/misc/Make.defs
@@ -36,7 +36,7 @@
 
 # Add the internal C files to the build
 
-CSRCS += lib_stream.c lib_utsname.c
+CSRCS += lib_stream.c lib_umask.c lib_utsname.c
 CSRCS += lib_xorshift128.c lib_tea_encrypt.c lib_tea_decrypt.c
 
 ifneq ($(CONFIG_STDIO_DISABLE_BUFFERING),y)
diff --git a/libs/libc/misc/lib_umask.c b/libs/libc/misc/lib_umask.c
new file mode 100644
index 0000000000..6cf6214979
--- /dev/null
+++ b/libs/libc/misc/lib_umask.c
@@ -0,0 +1,57 @@
+/****************************************************************************
+ * libs/libc/misc/lib_umask.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 <sys/stat.h>
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static mode_t g_mask;
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: umask
+ *
+ * Description:
+ *    Set and get the file mode creation mask
+ *
+ * Input Parameters:
+ *   mask - The process' file mode creation mask
+ *
+ * Returned Value:
+ *   The previous value of the mask.
+ *
+ ****************************************************************************/
+
+mode_t umask(mode_t mask)
+{
+  mode_t prev = g_mask;
+
+  g_mask = mask & 0777;
+  return prev;
+}