/*- * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen * 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 __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include /* For use with destroy_dev(9). */ static dev_t null_dev; static dev_t zero_dev; static d_write_t null_write; static d_ioctl_t null_ioctl; static d_read_t zero_read; static d_read_t null_read; #define CDEV_MAJOR 2 #define NULL_MINOR 2 #define ZERO_MINOR 12 static struct cdevsw null_cdevsw = { .d_open = nullopen, .d_close = nullclose, .d_read = null_read, .d_write = null_write, .d_ioctl = null_ioctl, .d_name = "null", .d_maj = CDEV_MAJOR, .d_flags = D_NOGIANT, }; static struct cdevsw zero_cdevsw = { .d_open = nullopen, .d_close = nullclose, .d_read = zero_read, .d_write = null_write, .d_name = "zero", .d_maj = CDEV_MAJOR, .d_flags = D_MMAP_ANON | D_NOGIANT, }; static void *zbuf; static int null_read(dev_t dev __unused, struct uio *uio, int flags __unused) { return 0; } /* ARGSUSED */ static int null_write(dev_t dev __unused, struct uio *uio, int flags __unused) { uio->uio_resid = 0; return 0; } static int null_ioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct thread *td) { int error; if (cmd != DIOCSKERNELDUMP) return (noioctl(dev, cmd, data, flags, td)); error = suser(td); if (error) return (error); return (set_dumper(NULL)); } /* ARGSUSED */ static int zero_read(dev_t dev __unused, struct uio *uio, int flags __unused) { int c; int error = 0; while (uio->uio_resid > 0 && error == 0) { c = uio->uio_resid < PAGE_SIZE ? uio->uio_resid : PAGE_SIZE; error = uiomove(zbuf, c, 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: \n"); zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO); zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT, GID_WHEEL, 0666, "zero"); null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT, GID_WHEEL, 0666, "null"); return 0; case MOD_UNLOAD: destroy_dev(null_dev); destroy_dev(zero_dev); free(zbuf, M_TEMP); return 0; case MOD_SHUTDOWN: return 0; default: return EOPNOTSUPP; } } DEV_MODULE(null, null_modevent, NULL);