1 /* $NetBSD: devnull.c,v 1.4 2013/04/04 01:29:55 pooka Exp $ */ 2 3 /* 4 * Copyright (c) 2009 Antti Kantee. 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 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * /dev/null, the infamous bytesink. 30 * 31 * I can't imagine it being very different in the rump kernel than in 32 * the host kernel. But nonetheless it serves as a simple example. 33 */ 34 35 #include <sys/cdefs.h> 36 __KERNEL_RCSID(0, "$NetBSD: devnull.c,v 1.4 2013/04/04 01:29:55 pooka Exp $"); 37 38 #include <sys/param.h> 39 #include <sys/conf.h> 40 #include <sys/device.h> 41 #include <sys/stat.h> 42 43 #include "rump_vfs_private.h" 44 45 static dev_type_open(rump_devnullopen); 46 static dev_type_read(rump_devnullrw); 47 48 static struct cdevsw null_cdevsw = { 49 rump_devnullopen, nullclose, rump_devnullrw, rump_devnullrw, noioctl, 50 nostop, notty, nopoll, nommap, nokqfilter, D_OTHER | D_MPSAFE, 51 }; 52 53 int 54 rump_devnull_init() 55 { 56 devmajor_t null_bmaj, null_cmaj; 57 int error; 58 59 null_bmaj = null_cmaj = NODEVMAJOR; 60 error = devsw_attach("null", NULL, &null_bmaj, &null_cdevsw,&null_cmaj); 61 KASSERT(error || null_cmaj == 2); 62 63 error = rump_vfs_makeonedevnode(S_IFCHR, 64 "/dev/null", null_cmaj, DEV_NULL); 65 if (error) 66 return error; 67 return rump_vfs_makeonedevnode(S_IFCHR, 68 "/dev/zero", null_cmaj, DEV_ZERO); 69 } 70 71 static int 72 rump_devnullopen(dev_t dev, int flag, int mode, struct lwp *l) 73 { 74 75 if (minor(dev) == DEV_ZERO || minor(dev) == DEV_NULL) 76 return 0; 77 return ENXIO; 78 } 79 80 static int 81 rump_devnullrw(dev_t dev, struct uio *uio, int flags) 82 { 83 char zeros[512]; 84 int error; 85 86 switch (minor(dev)) { 87 case DEV_NULL: 88 if (uio->uio_rw == UIO_WRITE) 89 uio->uio_resid = 0; 90 break; 91 case DEV_ZERO: 92 if (uio->uio_rw == UIO_WRITE) { 93 uio->uio_resid = 0; 94 break; 95 } 96 memset(zeros, 0, sizeof(zeros)); 97 while (uio->uio_resid > 0) { 98 error = uiomove(zeros, 99 min(sizeof(zeros), uio->uio_resid), uio); 100 if (error) 101 return error; 102 } 103 break; 104 default: 105 return ENXIO; /* how? */ 106 } 107 108 return 0; 109 } 110