mirror of
https://github.com/apache/nuttx.git
synced 2026-05-20 04:16:35 +08:00
This change provides an option to add /dev/urandom to all architectures. The pseudo-random algorithm I choose strikes an arguably-good balance between being "random" and small/fast enough for 8/16 bit MCUs. It’s the well-documented xorshift128 algorithm. It has an internal state of 128 bits that can be [re-]seeded with a write.
This commit is contained in:
David Alessio
committed by
Gregory Nutt
Gregory Nutt
parent
91ba0be667
commit
6cefbc0c3f
@@ -198,6 +198,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -239,6 +239,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -165,6 +165,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -167,6 +167,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -53,6 +53,8 @@
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#include <nuttx/sched.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/arch.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/sched_note.h>
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#include <nuttx/serial/pty.h>
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#include <nuttx/syslog/syslog.h>
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#include <nuttx/crypto/crypto.h>
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@@ -131,6 +133,32 @@ void up_initialize(void)
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syslog_initialize(SYSLOG_INIT_EARLY);
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/* Register devices */
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#if CONFIG_NFILE_DESCRIPTORS > 0
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#if defined(CONFIG_DEV_NULL)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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#if defined(CONFIG_DEV_LOOP)
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loop_register(); /* Standard /dev/loop */
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#endif
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#endif /* CONFIG_NFILE_DESCRIPTORS */
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#if defined(CONFIG_SCHED_INSTRUMENTATION_BUFFER) && \
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defined(CONFIG_DRIVER_NOTE)
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note_register(); /* Non-standard /dev/note */
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#endif
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#if defined(CONFIG_CRYPTO)
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/* Initialize the HW crypto and /dev/crypto */
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@@ -156,6 +156,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -153,6 +153,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -167,6 +167,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -167,6 +167,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -164,6 +164,10 @@ void up_initialize(void)
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devnull_register(); /* Standard /dev/null */
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#endif
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#if defined(CONFIG_DEV_URANDOM)
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devurandom_register(); /* Standard /dev/urandom */
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#endif
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#if defined(CONFIG_DEV_ZERO)
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devzero_register(); /* Standard /dev/zero */
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#endif
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@@ -30,6 +30,13 @@ config DEV_RANDOM
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default y
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depends on ARCH_HAVE_RNG
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config DEV_URANDOM
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bool "Enable /dev/urandom"
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default n
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---help---
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xorshift128 is a pseudorandom number generator that's simple,
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portable, and can also be used on 8-bit and 16-bit MCUs.
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source drivers/loop/Kconfig
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menu "Buffering"
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@@ -98,6 +98,10 @@ endif
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ifeq ($(CONFIG_PWM),y)
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CSRCS += pwm.c
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endif
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ifeq ($(CONFIG_DEV_URANDOM),y)
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CSRCS += dev_urandom.c
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endif
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endif
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AOBJS = $(ASRCS:.S=$(OBJEXT))
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@@ -0,0 +1,245 @@
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/****************************************************************************
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* drivers/dev_urandom.c
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*
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* Copyright (C) 2016 Gregory Nutt. All rights reserved.
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* Author: David S. Alessio
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/* This random number generator is simple, fast and portable.
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* Ref: https://en.wikipedia.org/wiki/Xorshift
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*/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdbool.h>
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#include <string.h>
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#include <poll.h>
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#include <errno.h>
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#include <nuttx/fs/fs.h>
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/****************************************************************************
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* Private Types
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****************************************************************************/
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typedef union
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{
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struct
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{
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uint32_t x;
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uint32_t y;
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uint32_t z;
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uint32_t w;
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};
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uint8_t u[16];
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} xorshift128_state_t;
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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#define min(a, b) (((a) < (b)) ? (a) : (b))
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static ssize_t devurand_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t devurand_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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#ifndef CONFIG_DISABLE_POLL
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static int devurand_poll(FAR struct file *filep, FAR struct pollfd *fds,
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bool setup);
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#endif
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations devurand_fops =
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{
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NULL, /* open */
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NULL, /* close */
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devurand_read, /* read */
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devurand_write, /* write */
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NULL, /* seek */
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NULL /* ioctl */
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#ifndef CONFIG_DISABLE_POLL
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, devurand_poll /* poll */
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#endif
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, NULL /* unlink */
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#endif
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};
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static xorshift128_state_t prng;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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static uint32_t xorshift128(void)
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{
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uint32_t t = prng.x;
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t ^= t << 11;
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t ^= t >> 8;
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prng.x = prng.y;
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prng.y = prng.z;
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prng.z = prng.w;
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prng.w ^= prng.w >> 19;
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prng.w ^= t;
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return prng.w;
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}
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/****************************************************************************
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* Name: devurand_read
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****************************************************************************/
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static ssize_t devurand_read(FAR struct file *filep, FAR char *buffer,
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size_t len)
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{
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size_t n;
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uint32_t rnd;
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n = len;
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/* Align buffer pointer to 4-byte boundry */
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if ((unsigned)buffer & 0x03)
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{
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/* Generate a pseudo random number */
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rnd = xorshift128();
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while ((unsigned)buffer & 0x03)
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{
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if (n <= 0)
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{
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return len;
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}
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*buffer++ = rnd & 0xFF;
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rnd >>= 8;
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--n;
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}
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}
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/* Stuff buffer with PRNGs 4 bytes at a time */
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while (n >= 4)
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{
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*(uint32_t *) buffer = xorshift128();
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buffer += 4;
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n -= 4;
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}
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/* Stuff remaining 1, 2, or 3 bytes */
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if (n > 0)
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{
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/* Generate a pseudo random number */
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rnd = xorshift128();
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do
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{
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*buffer++ = rnd & 0xFF;
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rnd >>= 8;
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}
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while (--n > 0);
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}
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return len;
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}
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/****************************************************************************
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* Name: devurand_write
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****************************************************************************/
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static ssize_t devurand_write(FAR struct file *filep, FAR const char *buffer,
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size_t len)
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{
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/* Write can be used to seed the PRNG state */
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len = min(len, sizeof(prng.u));
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memcpy(&prng.u, buffer, len);
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return len;
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}
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/****************************************************************************
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* Name: devurand_poll
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****************************************************************************/
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#ifndef CONFIG_DISABLE_POLL
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static int devurand_poll(FAR struct file *filep, FAR struct pollfd *fds,
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bool setup)
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{
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if (setup)
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{
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fds->revents |= (fds->events & (POLLIN | POLLOUT));
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if (fds->revents != 0)
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{
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sem_post(fds->sem);
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}
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}
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return OK;
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}
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: devurandom_register
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*
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* Description:
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* Register /dev/urandom
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*
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****************************************************************************/
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void devurandom_register(void)
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{
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/* Seed the PRNG */
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prng.w = 97;
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prng.x = 101;
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prng.y = prng.w << 17;
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prng.z = prng.x << 25;
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(void)register_driver("/dev/urandom", &devurand_fops, 0666, NULL);
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}
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@@ -1013,6 +1013,16 @@ int fdesc_poll(int fd, FAR struct pollfd *fds, bool setup);
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void devnull_register(void);
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/****************************************************************************
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* Name: devurandom_register
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*
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* Description:
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* Register /dev/urandom
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*
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****************************************************************************/
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void devurandom_register(void);
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/****************************************************************************
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* Name: devcrypto_register
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*
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