summaryrefslogtreecommitdiff
path: root/libdiskfs/filedev.c
blob: e0ae7f4c6576e419cd11fe9c5ac51efee33411ce (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
/* Get the mach device underlying a file

   Copyright (C) 1995, 1996 Free Software Foundation, Inc.

   Written by Miles Bader <miles@gnu.ai.mit.edu>

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include <errno.h>
#include <sys/fcntl.h>

#include <device/device.h>

#include "priv.h"

/* Returns the name and a send right for the mach device on which the file
   NAME is stored, and returns it in DEV_NAME (which is malloced) and PORT.
   Other values returned are START, the first valid offset, SIZE, the the
   number of blocks after START, and BLOCK_SIZE, the units in which the
   device is addressed.

   The device is opened for reading, and if the diskfs global variable
   DISKFS_READONLY is false, writing.  */
error_t
diskfs_get_file_device (char *name,
			char **dev_name, mach_port_t *port,
			off_t *start, off_t *size, size_t *block_size)
{
  int i;
  error_t err;
  mach_msg_type_number_t data_len = 100;
  mach_msg_type_number_t num_ints = 10, num_ports = 10, num_offsets = 10;
  int _ints[num_ints], *ints = _ints;
  mach_port_t _ports[num_ports], *ports = _ports;
  off_t _offsets[num_offsets], *offsets = _offsets;
  char _data[data_len], *data = _data;
  file_t node =
    file_name_lookup (name, diskfs_readonly ? O_RDONLY : O_RDWR, 0);

  if (node == MACH_PORT_NULL)
    return errno;

  *port = MACH_PORT_NULL;

  err = file_get_storage_info (node, &ports, &num_ports, &ints, &num_ints,
			       &offsets, &num_offsets, &data, &data_len);
  if (err)
    return err;

  /* See <hurd/store.h> for an explanation of what's in the vectors returned
     by file_get_storage_info.  */

  if (num_ints < 6)
    err = EGRATUITOUS;
  else if (ints[0] != STORAGE_DEVICE)
    err = ENODEV;

  if (!err && block_size)
    *block_size = ints[2];

  if (!err && (start || size))
    /* Extract the device block addresses.  */
    {
      size_t runs_len = ints[3];
      if (runs_len != 2)
	/* We can't handle anything but a contiguous set of blocks.  */
	err = ENODEV;		/* XXX */
      else
	{
	  if (start)
	    *start = offsets[0];
	  if (size)
	    *size = offsets[1];
	}
    }

  if (!err && dev_name)
    /* Extract the device name into DEV_NAME.  */
    {
      size_t name_len = ints[4];
      if (data && name_len > 0)
	if (data_len < name_len)
	  err = EGRATUITOUS;
	else
	  {
	    *dev_name = malloc (name_len);
	    if (*dev_name)
	      strcpy (*dev_name, data);
	    else
	      err = ENOMEM;
	  }
    }

  if (!err && port)
    /* Extract the device port.  */
    if (num_ports != 1)
      err = EGRATUITOUS;
    else
      *port = ports[0];

  /* Deallocate things we don't care about or that we've made copies of.  */

  for (i = 0; i < num_ports; i++)
    if (MACH_PORT_VALID (ports[i]))
      mach_port_deallocate (mach_task_self (), ports[i]);

#define DISCARD_MEM(v, vl, b)						    \
  if (v != b)							   	    \
    vm_deallocate (mach_task_self (), (vm_address_t)v, vl * sizeof *v);
  DISCARD_MEM (ports, num_ports, _ports);
  DISCARD_MEM (ints, num_ints, _ints);
  DISCARD_MEM (offsets, num_offsets, _offsets);
  DISCARD_MEM (data, data_len, _data);

  /* Note that we don't deallocate NODE unless we're returning an error,
     which should prevent the information returned by file_get_storage_info
     from changing.  */
  
  if (err)
    /* We got an error, deallocate everything.  */
    mach_port_deallocate (mach_task_self (), node);

  return err;
}