1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen 5 * Copyright (c) 2001-2004 Mark R. V. Murray 6 * Copyright (c) 2014 Eitan Adler 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer 14 * in this position and unchanged. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 * 30 */ 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/conf.h> 35 #include <sys/uio.h> 36 #include <sys/kernel.h> 37 #include <sys/malloc.h> 38 #include <sys/module.h> 39 #include <sys/disk.h> 40 #include <sys/bus.h> 41 #include <sys/filio.h> 42 43 #include <machine/bus.h> 44 #include <machine/vmparam.h> 45 46 /* For use with destroy_dev(9). */ 47 static struct cdev *full_dev; 48 static struct cdev *null_dev; 49 static struct cdev *zero_dev; 50 51 static d_write_t full_write; 52 static d_write_t null_write; 53 static d_ioctl_t null_ioctl; 54 static d_ioctl_t zero_ioctl; 55 static d_read_t zero_read; 56 57 static struct cdevsw full_cdevsw = { 58 .d_version = D_VERSION, 59 .d_read = zero_read, 60 .d_write = full_write, 61 .d_ioctl = zero_ioctl, 62 .d_name = "full", 63 }; 64 65 static struct cdevsw null_cdevsw = { 66 .d_version = D_VERSION, 67 .d_read = (d_read_t *)nullop, 68 .d_write = null_write, 69 .d_ioctl = null_ioctl, 70 .d_name = "null", 71 }; 72 73 static struct cdevsw zero_cdevsw = { 74 .d_version = D_VERSION, 75 .d_read = zero_read, 76 .d_write = null_write, 77 .d_ioctl = zero_ioctl, 78 .d_name = "zero", 79 .d_flags = D_MMAP_ANON, 80 }; 81 82 /* ARGSUSED */ 83 static int 84 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused) 85 { 86 87 return (ENOSPC); 88 } 89 90 /* ARGSUSED */ 91 static int 92 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 93 { 94 uio->uio_resid = 0; 95 96 return (0); 97 } 98 99 /* ARGSUSED */ 100 static int 101 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 102 int flags __unused, struct thread *td) 103 { 104 struct diocskerneldump_arg kda; 105 int error; 106 107 error = 0; 108 switch (cmd) { 109 case DIOCSKERNELDUMP: 110 bzero(&kda, sizeof(kda)); 111 kda.kda_index = KDA_REMOVE_ALL; 112 error = dumper_remove(NULL, &kda); 113 break; 114 case FIONBIO: 115 break; 116 case FIOASYNC: 117 if (*(int *)data != 0) 118 error = EINVAL; 119 break; 120 default: 121 error = ENOIOCTL; 122 } 123 return (error); 124 } 125 126 /* ARGSUSED */ 127 static int 128 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 129 int flags __unused, struct thread *td) 130 { 131 int error; 132 error = 0; 133 134 switch (cmd) { 135 case FIONBIO: 136 break; 137 case FIOASYNC: 138 if (*(int *)data != 0) 139 error = EINVAL; 140 break; 141 default: 142 error = ENOIOCTL; 143 } 144 return (error); 145 } 146 147 /* ARGSUSED */ 148 static int 149 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused) 150 { 151 void *zbuf; 152 ssize_t len; 153 int error = 0; 154 155 KASSERT(uio->uio_rw == UIO_READ, 156 ("Can't be in %s for write", __func__)); 157 zbuf = __DECONST(void *, zero_region); 158 while (uio->uio_resid > 0 && error == 0) { 159 len = uio->uio_resid; 160 if (len > ZERO_REGION_SIZE) 161 len = ZERO_REGION_SIZE; 162 error = uiomove(zbuf, len, uio); 163 } 164 165 return (error); 166 } 167 168 /* ARGSUSED */ 169 static int 170 null_modevent(module_t mod __unused, int type, void *data __unused) 171 { 172 switch(type) { 173 case MOD_LOAD: 174 if (bootverbose) 175 printf("null: <full device, null device, zero device>\n"); 176 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0, 177 NULL, UID_ROOT, GID_WHEEL, 0666, "full"); 178 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0, 179 NULL, UID_ROOT, GID_WHEEL, 0666, "null"); 180 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0, 181 NULL, UID_ROOT, GID_WHEEL, 0666, "zero"); 182 break; 183 184 case MOD_UNLOAD: 185 destroy_dev(full_dev); 186 destroy_dev(null_dev); 187 destroy_dev(zero_dev); 188 break; 189 190 case MOD_SHUTDOWN: 191 break; 192 193 default: 194 return (EOPNOTSUPP); 195 } 196 197 return (0); 198 } 199 200 DEV_MODULE(null, null_modevent, NULL); 201 MODULE_VERSION(null, 1); 202