diff options
Diffstat (limited to 'nuttx/drivers/dev_null.c')
-rw-r--r-- | nuttx/drivers/dev_null.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/nuttx/drivers/dev_null.c b/nuttx/drivers/dev_null.c new file mode 100644 index 000000000..c70370e1e --- /dev/null +++ b/nuttx/drivers/dev_null.c @@ -0,0 +1,135 @@ +/**************************************************************************** + * drivers/dev_null.c + * + * Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <sys/types.h> +#include <stdbool.h> +#include <string.h> +#include <poll.h> +#include <errno.h> +#include <nuttx/fs/fs.h> + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +static ssize_t devnull_read(FAR struct file *, FAR char *, size_t); +static ssize_t devnull_write(FAR struct file *, FAR const char *, size_t); +#ifndef CONFIG_DISABLE_POLL +static int devnull_poll(FAR struct file *filp, FAR struct pollfd *fds, + bool setup); +#endif + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +static const struct file_operations devnull_fops = +{ + 0, /* open */ + 0, /* close */ + devnull_read, /* read */ + devnull_write, /* write */ + 0, /* seek */ + 0 /* ioctl */ +#ifndef CONFIG_DISABLE_POLL + , devnull_poll /* poll */ +#endif +}; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: devnull_read + ****************************************************************************/ + +static ssize_t devnull_read(FAR struct file *filp, FAR char *buffer, size_t len) +{ + return 0; /* Return EOF */ +} + +/**************************************************************************** + * Name: devnull_write + ****************************************************************************/ + +static ssize_t devnull_write(FAR struct file *filp, FAR const char *buffer, size_t len) +{ + return len; /* Say that everything was written */ +} + +/**************************************************************************** + * Name: devnull_poll + ****************************************************************************/ + +#ifndef CONFIG_DISABLE_POLL +static int devnull_poll(FAR struct file *filp, FAR struct pollfd *fds, + bool setup) +{ + if (setup) + { + fds->revents |= (fds->events & (POLLIN|POLLOUT)); + if (fds->revents != 0) + { + sem_post(fds->sem); + } + } + + return OK; +} +#endif + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: devnull_register + * + * Description: + * Register /dev/null + * + ****************************************************************************/ + +void devnull_register(void) +{ + (void)register_driver("/dev/null", &devnull_fops, 0666, NULL); +} |