com32/lib/sys/opendev.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2003-2004 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 #include <errno.h>
  29 #include <com32.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32 #include "file.h"
  33
  34 /*
  35  * opendev.c
  36  *
  37  * Open a special device
  38  */
  39
  40 int opendev(const struct input_dev *idev,
  41             const struct output_dev *odev, int flags)
  42 {
  43   int fd;
  44   struct file_info *fp;
  45   int okflags;
  46   int e;
  47
  48   okflags = (idev ? idev->fileflags : 0) | (odev ? odev->fileflags : 0);
  49
  50   if ( !(flags & 3) || (flags & ~okflags) ) {
  51     errno = EINVAL;
  52     return -1;
  53   }
  54
  55   for ( fd = 0, fp = __file_info ; fd < NFILES ; fd++, fp++ )
  56     if ( !fp->iop && !fp->oop )
  57       break;
  58
  59   if ( fd >= NFILES ) {
  60     errno = EMFILE;
  61     return -1;
  62   }
  63
  64   /* The file structure is already zeroed */
  65   fp->iop         = &dev_error_r;
  66   fp->oop         = &dev_error_w;
  67   fp->i.datap     = fp->i.buf;
  68
  69   if (idev) {
  70     if (idev->open && (e = idev->open(fp))) {
  71       errno = e;
  72       goto puke;
  73     }
  74     fp->iop = idev;
  75   }
  76
  77   while (odev) {
  78     if (odev->open && (e = odev->open(fp))) {
  79       if (e == EAGAIN) {
  80         if (odev->fallback) {
  81           odev = odev->fallback;
  82           continue;
  83         } else {
  84           e = EIO;
  85         }
  86       }
  87       errno = e;
  88       goto puke;
  89     }
  90     fp->oop = odev;
  91     break;
  92   }
  93
  94   return fd;
  95
  96  puke:
  97   close(fd);
  98   return -1;
  99 }