1 /* $NetBSD: devnull.c,v 1.8 2018/09/03 16:29:37 riastradh 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 1.8 2018/09/03 16:29:37 riastradh 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-sys/vfs.h> 44 45 static dev_type_open(rump_devnullopen); 46 static dev_type_read(rump_devnullrw); 47 48 static struct cdevsw null_cdevsw = { 49 .d_open = rump_devnullopen, 50 .d_close = nullclose, 51 .d_read = rump_devnullrw, 52 .d_write = rump_devnullrw, 53 .d_ioctl = noioctl, 54 .d_stop = nostop, 55 .d_tty = notty, 56 .d_poll = nopoll, 57 .d_mmap = nommap, 58 .d_kqfilter = nokqfilter, 59 .d_discard = nodiscard, 60 .d_flag = D_OTHER | D_MPSAFE 61 }; 62 63 int 64 rump_devnull_init() 65 { 66 devmajor_t null_bmaj, null_cmaj; 67 int error; 68 69 null_bmaj = null_cmaj = NODEVMAJOR; 70 error = devsw_attach("null", NULL, &null_bmaj, &null_cdevsw,&null_cmaj); 71 KASSERT(error || null_cmaj == 2); 72 73 error = rump_vfs_makeonedevnode(S_IFCHR, 74 "/dev/null", null_cmaj, DEV_NULL); 75 if (error) 76 return error; 77 return rump_vfs_makeonedevnode(S_IFCHR, 78 "/dev/zero", null_cmaj, DEV_ZERO); 79 } 80 81 static int 82 rump_devnullopen(dev_t dev, int flag, int mode, struct lwp *l) 83 { 84 85 if (minor(dev) == DEV_ZERO || minor(dev) == DEV_NULL) 86 return 0; 87 return ENXIO; 88 } 89 90 static int 91 rump_devnullrw(dev_t dev, struct uio *uio, int flags) 92 { 93 char zeros[512]; 94 int error; 95 96 switch (minor(dev)) { 97 case DEV_NULL: 98 if (uio->uio_rw == UIO_WRITE) 99 uio->uio_resid = 0; 100 break; 101 case DEV_ZERO: 102 if (uio->uio_rw == UIO_WRITE) { 103 uio->uio_resid = 0; 104 break; 105 } 106 memset(zeros, 0, sizeof(zeros)); 107 while (uio->uio_resid > 0) { 108 error = uiomove(zeros, 109 uimin(sizeof(zeros), uio->uio_resid), uio); 110 if (error) 111 return error; 112 } 113 break; 114 default: 115 return ENXIO; /* how? */ 116 } 117 118 return 0; 119 } 120