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 CDEV_MAJOR 2 52 #define NULL_MINOR 2 53 #define ZERO_MINOR 12 54 55 static struct cdevsw null_cdevsw = { 56 .d_version = D_VERSION, 57 .d_read = (d_read_t *)nullop, 58 .d_write = null_write, 59 .d_ioctl = null_ioctl, 60 .d_name = "null", 61 .d_maj = CDEV_MAJOR, 62 }; 63 64 static struct cdevsw zero_cdevsw = { 65 .d_version = D_VERSION, 66 .d_read = zero_read, 67 .d_write = null_write, 68 .d_name = "zero", 69 .d_maj = CDEV_MAJOR, 70 .d_flags = D_MMAP_ANON, 71 }; 72 73 static void *zbuf; 74 75 /* ARGSUSED */ 76 static int 77 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused) 78 { 79 uio->uio_resid = 0; 80 81 return (0); 82 } 83 84 /* ARGSUSED */ 85 static int 86 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused, 87 int flags __unused, struct thread *td) 88 { 89 int error; 90 91 if (cmd != DIOCSKERNELDUMP) 92 return (ENOIOCTL); 93 error = suser(td); 94 if (error) 95 return (error); 96 return (set_dumper(NULL)); 97 } 98 99 /* ARGSUSED */ 100 static int 101 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused) 102 { 103 int error = 0; 104 105 while (uio->uio_resid > 0 && error == 0) 106 error = uiomove(zbuf, MIN(uio->uio_resid, PAGE_SIZE), uio); 107 108 return (error); 109 } 110 111 /* ARGSUSED */ 112 static int 113 null_modevent(module_t mod __unused, int type, void *data __unused) 114 { 115 switch(type) { 116 case MOD_LOAD: 117 if (bootverbose) 118 printf("null: <null device, zero device>\n"); 119 zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO); 120 null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT, 121 GID_WHEEL, 0666, "null"); 122 zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT, 123 GID_WHEEL, 0666, "zero"); 124 break; 125 126 case MOD_UNLOAD: 127 destroy_dev(null_dev); 128 destroy_dev(zero_dev); 129 free(zbuf, M_TEMP); 130 break; 131 132 case MOD_SHUTDOWN: 133 break; 134 135 default: 136 return (EOPNOTSUPP); 137 } 138 139 return (0); 140 } 141 142 DEV_MODULE(null, null_modevent, NULL); 143 MODULE_VERSION(null, 1); 144