[GitHub] [incubator-nuttx] gustavonihei commented on a change in pull request #5837: libc: Implement getrandom on top of "/dev/[u]random"

[GitBox <gi...@apache.org>]

gustavonihei commented on a change in pull request #5837:
URL: https://github.com/apache/incubator-nuttx/pull/5837#discussion_r834558642



##########
File path: include/sys/random.h
##########
@@ -0,0 +1,79 @@
+/****************************************************************************
+ * include/sys/random.h
+ *
+ * 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.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_SYS_RANDOM_H
+#define __INCLUDE_SYS_RANDOM_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Flags for getrandom(2)
+ *
+ * GRND_NONBLOCK  Don't block and return EAGAIN instead
+ * GRND_RANDOM    Open /dev/random instead of /dev/urandom
+ * GRND_INSECURE  Return non-cryptographic random bytes
+ */
+
+#define GRND_NONBLOCK   (1 << 0)
+#define GRND_RANDOM     (1 << 1)
+#define GRND_INSECURE   (1 << 2)
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: getrandom
+ *
+ * Description:
+ *   Fill a buffer of arbitrary length with randomness. This is the
+ *   preferred interface for getting random numbers. The traditional
+ *   /dev/random approach is susceptible for things like the attacker
+ *   exhausting file descriptors on purpose.
+ *
+ *   Note that this function cannot fail, other than by asserting.
+ *
+ * Input Parameters:
+ *   bytes  - Buffer for returned random bytes
+ *   nbytes - Number of bytes requested.
+ *   flags  - Bit mask that can contain zero or more of the ORed values
+ *            together.
+ *
+ * Returned Value:
+ *   On success, getrandom() returns the number of bytes that were copied
+ *   to the buffer buf.  This may be less than the number of bytes
+ *   requested via buflen if either GRND_RANDOM was specified in flags and
+ *   insufficient entropy was present in the random source or the system
+ *   call was interrupted by a signal.

Review comment:
       ```suggestion
    *   On success, getrandom() returns the number of bytes that were copied
    *   to the buffer bytes.  This may be less than the number of bytes
    *   requested via nbytes if either GRND_RANDOM was specified in flags and
    *   insufficient entropy was present in the random source or the system
    *   call was interrupted by a signal.
   ```
   




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