1 /*- 2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen 3 * Copyright (c) 2001-2004 Mark R. V. Murray 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer 11 * in this position and unchanged. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 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 <machine/bus.h> 42 43 /* For use with destroy_dev(9). */ 44 static struct cdev *null_dev; 45 static struct cdev *zero_dev; 46 47 static d_write_t null_write; 48 static d_ioctl_t null_ioctl; 49 static d_read_t zero_read; 50 51 #define NULL_MINOR 2 52 #define ZERO_MINOR 12 53 54 static struct cdevsw null_cdevsw = { 55 .d_version = D_VERSION, 56 .d_read = (d_read_t *)nullop, 57 .d_write = null_write, 58 .d_ioctl = null_ioctl, 59 .d_name = "null", 60 }; 61 62 static struct cdevsw zero_cdevsw = { 63 .d_version = D_VERSION, 64 .d_read = zero_read, 65 .d_write = null_write, 66 .d_name = "zero", 67 .d_flags = D_MMAP_ANON, 68 }; 69 70 static void *zbuf; 71 72 /* ARGSUSED */ 73 static int 74 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 75 { 76 uio->uio_resid = 0; 77 78 return (0); 79 } 80 81 /* ARGSUSED */ 82 static int 83 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 84 int flags __unused, struct thread *td) 85 { 86 int error; 87 88 if (cmd != DIOCSKERNELDUMP) 89 return (ENOIOCTL); 90 error = suser(td); 91 if (error) 92 return (error); 93 return (set_dumper(NULL)); 94 } 95 96 /* ARGSUSED */ 97 static int 98 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused) 99 { 100 int error = 0; 101 102 while (uio->uio_resid > 0 && error == 0) 103 error = uiomove(zbuf, MIN(uio->uio_resid, PAGE_SIZE), uio); 104 105 return (error); 106 } 107 108 /* ARGSUSED */ 109 static int 110 null_modevent(module_t mod __unused, int type, void *data __unused) 111 { 112 switch(type) { 113 case MOD_LOAD: 114 if (bootverbose) 115 printf("null: <null device, zero device>\n"); 116 zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO); 117 null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT, 118 GID_WHEEL, 0666, "null"); 119 zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT, 120 GID_WHEEL, 0666, "zero"); 121 break; 122 123 case MOD_UNLOAD: 124 destroy_dev(null_dev); 125 destroy_dev(zero_dev); 126 free(zbuf, M_TEMP); 127 break; 128 129 case MOD_SHUTDOWN: 130 break; 131 132 default: 133 return (EOPNOTSUPP); 134 } 135 136 return (0); 137 } 138 139 DEV_MODULE(null, null_modevent, NULL); 140 MODULE_VERSION(null, 1); 141