1 /*- 2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen 3 * Copyright (c) 2001-2004 Mark R. V. Murray 4 * Copyright (c) 2014 Eitan Adler 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer 12 * in this position and unchanged. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include "opt_compat.h" 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/conf.h> 38 #include <sys/uio.h> 39 #include <sys/kernel.h> 40 #include <sys/malloc.h> 41 #include <sys/module.h> 42 #include <sys/disk.h> 43 #include <sys/bus.h> 44 #include <sys/filio.h> 45 46 #include <machine/bus.h> 47 #include <machine/vmparam.h> 48 49 /* For use with destroy_dev(9). */ 50 static struct cdev *full_dev; 51 static struct cdev *null_dev; 52 static struct cdev *zero_dev; 53 54 static d_write_t full_write; 55 static d_write_t null_write; 56 static d_ioctl_t null_ioctl; 57 static d_ioctl_t zero_ioctl; 58 static d_read_t zero_read; 59 60 static struct cdevsw full_cdevsw = { 61 .d_version = D_VERSION, 62 .d_read = zero_read, 63 .d_write = full_write, 64 .d_ioctl = zero_ioctl, 65 .d_name = "full", 66 }; 67 68 static struct cdevsw null_cdevsw = { 69 .d_version = D_VERSION, 70 .d_read = (d_read_t *)nullop, 71 .d_write = null_write, 72 .d_ioctl = null_ioctl, 73 .d_name = "null", 74 }; 75 76 static struct cdevsw zero_cdevsw = { 77 .d_version = D_VERSION, 78 .d_read = zero_read, 79 .d_write = null_write, 80 .d_ioctl = zero_ioctl, 81 .d_name = "zero", 82 .d_flags = D_MMAP_ANON, 83 }; 84 85 86 87 /* ARGSUSED */ 88 static int 89 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused) 90 { 91 92 return (ENOSPC); 93 } 94 95 /* ARGSUSED */ 96 static int 97 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 98 { 99 uio->uio_resid = 0; 100 101 return (0); 102 } 103 104 /* ARGSUSED */ 105 static int 106 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 107 int flags __unused, struct thread *td) 108 { 109 int error; 110 error = 0; 111 112 switch (cmd) { 113 #ifdef COMPAT_FREEBSD11 114 case DIOCSKERNELDUMP_FREEBSD11: 115 #endif 116 case DIOCSKERNELDUMP: 117 error = set_dumper(NULL, NULL, td, 0, 0, NULL, 0, NULL); 118 break; 119 case FIONBIO: 120 break; 121 case FIOASYNC: 122 if (*(int *)data != 0) 123 error = EINVAL; 124 break; 125 default: 126 error = ENOIOCTL; 127 } 128 return (error); 129 } 130 131 /* ARGSUSED */ 132 static int 133 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 134 int flags __unused, struct thread *td) 135 { 136 int error; 137 error = 0; 138 139 switch (cmd) { 140 case FIONBIO: 141 break; 142 case FIOASYNC: 143 if (*(int *)data != 0) 144 error = EINVAL; 145 break; 146 default: 147 error = ENOIOCTL; 148 } 149 return (error); 150 } 151 152 153 /* ARGSUSED */ 154 static int 155 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused) 156 { 157 void *zbuf; 158 ssize_t len; 159 int error = 0; 160 161 KASSERT(uio->uio_rw == UIO_READ, 162 ("Can't be in %s for write", __func__)); 163 zbuf = __DECONST(void *, zero_region); 164 while (uio->uio_resid > 0 && error == 0) { 165 len = uio->uio_resid; 166 if (len > ZERO_REGION_SIZE) 167 len = ZERO_REGION_SIZE; 168 error = uiomove(zbuf, len, uio); 169 } 170 171 return (error); 172 } 173 174 /* ARGSUSED */ 175 static int 176 null_modevent(module_t mod __unused, int type, void *data __unused) 177 { 178 switch(type) { 179 case MOD_LOAD: 180 if (bootverbose) 181 printf("null: <full device, null device, zero device>\n"); 182 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0, 183 NULL, UID_ROOT, GID_WHEEL, 0666, "full"); 184 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0, 185 NULL, UID_ROOT, GID_WHEEL, 0666, "null"); 186 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0, 187 NULL, UID_ROOT, GID_WHEEL, 0666, "zero"); 188 break; 189 190 case MOD_UNLOAD: 191 destroy_dev(full_dev); 192 destroy_dev(null_dev); 193 destroy_dev(zero_dev); 194 break; 195 196 case MOD_SHUTDOWN: 197 break; 198 199 default: 200 return (EOPNOTSUPP); 201 } 202 203 return (0); 204 } 205 206 DEV_MODULE(null, null_modevent, NULL); 207 MODULE_VERSION(null, 1); 208