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/*
* Copyright (c) 2025 Ian Marco Moffett and L5 engineers
* All rights reserved.
*
* 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 of the project 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.
*/
#include <sys/syslog.h>
#include <os/module.h>
#include <fs/devfs.h>
static struct cdevsw null_cdev;
/*
* Lie to the user and make them think they are
* reading data but give them nothing
*/
static ssize_t
null_read(struct devfs_node *dnp, struct dev_iobuf *io, int flags)
{
/* We give you a whole lot of nothing! */
return io->count;
}
/*
* Take the users carefully crafted bytes made with love
* and throw it in the trash
*/
static ssize_t
null_write(struct devfs_node *dnp, struct dev_iobuf *io, int flags)
{
return io->count;
}
static int
init_devnull(struct module *modp)
{
int error;
error = devfs_register(
"null",
DEVFS_CDEV,
&null_cdev,
0
);
if (error < 0) {
printf("null: could not create /dev/null\n");
return error;
}
return 0;
}
static struct cdevsw null_cdev = {
.read = null_read,
.write = null_write
};
MODULE_EXPORT("null", MODTYPE_GENERIC, init_devnull);
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