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null.c
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/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen * Copyright (c) 2001-2004 Mark R. V. Murray * Copyright (c) 2014 Eitan Adler * 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 * in this position and unchanged. * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHOR 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/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/systm.h> #include <sys/conf.h> #include <sys/uio.h> #include <sys/kernel.h> #include <sys/malloc.h> #include <sys/module.h> #include <sys/disk.h> #include <sys/bus.h> #include <sys/filio.h> #include <machine/bus.h> #include <machine/vmparam.h> /* For use with destroy_dev(9). */ static struct cdev *full_dev; static struct cdev *null_dev; static struct cdev *zero_dev; static d_write_t full_write; static d_write_t null_write; static d_ioctl_t null_ioctl; static d_ioctl_t zero_ioctl; static d_read_t zero_read; static struct cdevsw full_cdevsw = { .d_version = D_VERSION, .d_read = zero_read, .d_write = full_write, .d_ioctl = zero_ioctl, .d_name = "full", }; static struct cdevsw null_cdevsw = { .d_version = D_VERSION, .d_read = (d_read_t *)nullop, .d_write = null_write, .d_ioctl = null_ioctl, .d_name = "null", }; static struct cdevsw zero_cdevsw = { .d_version = D_VERSION, .d_read = zero_read, .d_write = null_write, .d_ioctl = zero_ioctl, .d_name = "zero", .d_flags = D_MMAP_ANON, }; /* ARGSUSED */ static int full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused) { return (ENOSPC); } /* ARGSUSED */ static int null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) { uio->uio_resid = 0; return (0); } /* ARGSUSED */ static int null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, int flags __unused, struct thread *td) { struct diocskerneldump_arg kda; int error; error = 0; switch (cmd) { #ifdef COMPAT_FREEBSD11 case DIOCSKERNELDUMP_FREEBSD11: gone_in(13, "FreeBSD 11.x ABI compat"); /* FALLTHROUGH */ #endif #ifdef COMPAT_FREEBSD12 case DIOCSKERNELDUMP_FREEBSD12: if (cmd == DIOCSKERNELDUMP_FREEBSD12) gone_in(14, "FreeBSD 12.x ABI compat"); /* FALLTHROUGH */ #endif case DIOCSKERNELDUMP: bzero(&kda, sizeof(kda)); kda.kda_index = KDA_REMOVE_ALL; error = dumper_remove(NULL, &kda); break; case FIONBIO: break; case FIOASYNC: if (*(int *)data != 0) error = EINVAL; break; default: error = ENOIOCTL; } return (error); } /* ARGSUSED */ static int zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, int flags __unused, struct thread *td) { int error; error = 0; switch (cmd) { case FIONBIO: break; case FIOASYNC: if (*(int *)data != 0) error = EINVAL; break; default: error = ENOIOCTL; } return (error); } /* ARGSUSED */ static int zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused) { void *zbuf; ssize_t len; int error = 0; KASSERT(uio->uio_rw == UIO_READ, ("Can't be in %s for write", __func__)); zbuf = __DECONST(void *, zero_region); while (uio->uio_resid > 0 && error == 0) { len = uio->uio_resid; if (len > ZERO_REGION_SIZE) len = ZERO_REGION_SIZE; error = uiomove(zbuf, len, uio); } return (error); } /* ARGSUSED */ static int null_modevent(module_t mod __unused, int type, void *data __unused) { switch(type) { case MOD_LOAD: if (bootverbose) printf("null: <full device, null device, zero device>\n"); full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0666, "full"); null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0666, "null"); zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0666, "zero"); break; case MOD_UNLOAD: destroy_dev(full_dev); destroy_dev(null_dev); destroy_dev(zero_dev); break; case MOD_SHUTDOWN: break; default: return (EOPNOTSUPP); } return (0); } DEV_MODULE(null, null_modevent, NULL); MODULE_VERSION(null, 1);
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