150 lines
3.7 KiB
C
150 lines
3.7 KiB
C
/*-
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* Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
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* All rights reserved.
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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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* 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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* in this position and unchanged.
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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 the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/uio.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/disk.h>
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#include <sys/bus.h>
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#include <machine/bus.h>
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/* For use with destroy_dev(9). */
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static dev_t null_dev;
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static dev_t zero_dev;
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static d_write_t null_write;
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static d_ioctl_t null_ioctl;
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static d_read_t zero_read;
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static d_read_t null_read;
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#define CDEV_MAJOR 2
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#define NULL_MINOR 2
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#define ZERO_MINOR 12
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static struct cdevsw null_cdevsw = {
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.d_open = nullopen,
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.d_close = nullclose,
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.d_read = null_read,
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.d_write = null_write,
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.d_ioctl = null_ioctl,
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.d_name = "null",
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.d_maj = CDEV_MAJOR,
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.d_flags = D_NOGIANT,
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};
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static struct cdevsw zero_cdevsw = {
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.d_open = nullopen,
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.d_close = nullclose,
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.d_read = zero_read,
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.d_write = null_write,
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.d_name = "zero",
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.d_maj = CDEV_MAJOR,
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.d_flags = D_MMAP_ANON | D_NOGIANT,
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};
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static void *zbuf;
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static int
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null_read(dev_t dev __unused, struct uio *uio, int flags __unused)
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{
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return 0;
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}
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/* ARGSUSED */
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static int
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null_write(dev_t dev __unused, struct uio *uio, int flags __unused)
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{
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uio->uio_resid = 0;
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return 0;
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}
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static int
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null_ioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct thread *td)
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{
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int error;
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if (cmd != DIOCSKERNELDUMP)
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return (noioctl(dev, cmd, data, flags, td));
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error = suser(td);
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if (error)
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return (error);
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return (set_dumper(NULL));
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}
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/* ARGSUSED */
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static int
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zero_read(dev_t dev __unused, struct uio *uio, int flags __unused)
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{
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int c;
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int error = 0;
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while (uio->uio_resid > 0 && error == 0) {
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c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE;
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error = uiomove(zbuf, c, uio);
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}
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return error;
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}
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/* ARGSUSED */
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static int
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null_modevent(module_t mod __unused, int type, void *data __unused)
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{
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switch(type) {
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case MOD_LOAD:
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if (bootverbose)
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printf("null: <null device, zero device>\n");
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zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO);
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zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
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GID_WHEEL, 0666, "zero");
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null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT,
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GID_WHEEL, 0666, "null");
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return 0;
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case MOD_UNLOAD:
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destroy_dev(null_dev);
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destroy_dev(zero_dev);
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free(zbuf, M_TEMP);
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return 0;
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case MOD_SHUTDOWN:
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return 0;
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default:
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return EOPNOTSUPP;
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}
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}
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DEV_MODULE(null, null_modevent, NULL);
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