com32/lib/sys/opendev.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2003-2008 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 }