sys/rump/librump/rumpvfs/devnull.c

   1 /*      $NetBSD$        */
   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, "$NetBSD$");
  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 devmajor_t null_bmaj, null_cmaj;
  46
  47 static dev_type_open(rump_devnullopen);
  48 static dev_type_read(rump_devnullrw);
  49
  50 static struct cdevsw null_cdevsw = {
  51         rump_devnullopen, nullclose, rump_devnullrw, rump_devnullrw, noioctl,
  52         nostop, notty, nopoll, nommap, nokqfilter, D_OTHER | D_MPSAFE,
  53 };
  54
  55 int
  56 rump_devnull_init()
  57 {
  58         int error;
  59
  60         null_bmaj = null_cmaj = NODEVMAJOR;
  61         error = devsw_attach("null", NULL, &null_bmaj, &null_cdevsw,&null_cmaj);
  62         if (error != 0)
  63                 return error;
  64
  65         return rump_vfs_makeonedevnode(S_IFCHR, "/dev/null", null_cmaj, 0);
  66 }
  67
  68 static int
  69 rump_devnullopen(dev_t dev, int flag, int mode, struct lwp *l)
  70 {
  71
  72         return 0;
  73 }
  74
  75 static int
  76 rump_devnullrw(dev_t dev, struct uio *uio, int flags)
  77 {
  78
  79         if (uio->uio_rw == UIO_WRITE)
  80                 uio->uio_resid = 0;
  81         return 0;
  82 }