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 <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/conf.h> 36 #include <sys/uio.h> 37 #include <sys/kernel.h> 38 #include <sys/malloc.h> 39 #include <sys/module.h> 40 #include <sys/priv.h> 41 #include <sys/disk.h> 42 #include <sys/bus.h> 43 #include <sys/filio.h> 44 45 #include <machine/bus.h> 46 #include <machine/vmparam.h> 47 48 /* For use with destroy_dev(9). */ 49 static struct cdev *full_dev; 50 static struct cdev *null_dev; 51 static struct cdev *zero_dev; 52 53 static d_write_t full_write; 54 static d_write_t null_write; 55 static d_ioctl_t null_ioctl; 56 static d_ioctl_t zero_ioctl; 57 static d_read_t zero_read; 58 59 static struct cdevsw full_cdevsw = { 60 .d_version = D_VERSION, 61 .d_read = zero_read, 62 .d_write = full_write, 63 .d_ioctl = zero_ioctl, 64 .d_name = "full", 65 }; 66 67 static struct cdevsw null_cdevsw = { 68 .d_version = D_VERSION, 69 .d_read = (d_read_t *)nullop, 70 .d_write = null_write, 71 .d_ioctl = null_ioctl, 72 .d_name = "null", 73 }; 74 75 static struct cdevsw zero_cdevsw = { 76 .d_version = D_VERSION, 77 .d_read = zero_read, 78 .d_write = null_write, 79 .d_ioctl = zero_ioctl, 80 .d_name = "zero", 81 .d_flags = D_MMAP_ANON, 82 }; 83 84 85 86 /* ARGSUSED */ 87 static int 88 full_write(struct cdev *dev __unused, struct uio *uio __unused, int flags __unused) 89 { 90 91 return (ENOSPC); 92 } 93 94 /* ARGSUSED */ 95 static int 96 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 97 { 98 uio->uio_resid = 0; 99 100 return (0); 101 } 102 103 /* ARGSUSED */ 104 static int 105 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 106 int flags __unused, struct thread *td) 107 { 108 int error; 109 error = 0; 110 111 switch (cmd) { 112 case DIOCSKERNELDUMP: 113 error = priv_check(td, PRIV_SETDUMPER); 114 if (error == 0) 115 error = set_dumper(NULL, NULL); 116 break; 117 case FIONBIO: 118 break; 119 case FIOASYNC: 120 if (*(int *)data != 0) 121 error = EINVAL; 122 break; 123 default: 124 error = ENOIOCTL; 125 } 126 return (error); 127 } 128 129 /* ARGSUSED */ 130 static int 131 zero_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 132 int flags __unused, struct thread *td) 133 { 134 int error; 135 error = 0; 136 137 switch (cmd) { 138 case FIONBIO: 139 break; 140 case FIOASYNC: 141 if (*(int *)data != 0) 142 error = EINVAL; 143 break; 144 default: 145 error = ENOIOCTL; 146 } 147 return (error); 148 } 149 150 151 /* ARGSUSED */ 152 static int 153 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused) 154 { 155 void *zbuf; 156 ssize_t len; 157 int error = 0; 158 159 KASSERT(uio->uio_rw == UIO_READ, 160 ("Can't be in %s for write", __func__)); 161 zbuf = __DECONST(void *, zero_region); 162 while (uio->uio_resid > 0 && error == 0) { 163 len = uio->uio_resid; 164 if (len > ZERO_REGION_SIZE) 165 len = ZERO_REGION_SIZE; 166 error = uiomove(zbuf, len, uio); 167 } 168 169 return (error); 170 } 171 172 /* ARGSUSED */ 173 static int 174 null_modevent(module_t mod __unused, int type, void *data __unused) 175 { 176 switch(type) { 177 case MOD_LOAD: 178 if (bootverbose) 179 printf("null: <full device, null device, zero device>\n"); 180 full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0, 181 NULL, UID_ROOT, GID_WHEEL, 0666, "full"); 182 null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0, 183 NULL, UID_ROOT, GID_WHEEL, 0666, "null"); 184 zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0, 185 NULL, UID_ROOT, GID_WHEEL, 0666, "zero"); 186 break; 187 188 case MOD_UNLOAD: 189 destroy_dev(full_dev); 190 destroy_dev(null_dev); 191 destroy_dev(zero_dev); 192 break; 193 194 case MOD_SHUTDOWN: 195 break; 196 197 default: 198 return (EOPNOTSUPP); 199 } 200 201 return (0); 202 } 203 204 DEV_MODULE(null, null_modevent, NULL); 205 MODULE_VERSION(null, 1); 206