summaryrefslogtreecommitdiff
path: root/trans/mtab.c
blob: 5207c1ea06d361a00cb51e0e2919b2b8de015811 (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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
/* This is an mtab translator.

   Copyright (C) 2013,14 Free Software Foundation, Inc.

   Written by Justus Winter <4winter@informatik.uni-hamburg.de>

   This file is part of the GNU Hurd.

   The GNU Hurd 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.

   The GNU Hurd 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 the GNU Hurd.  If not, see <http://www.gnu.org/licenses/>.  */

#include <argp.h>
#include <argz.h>
#include <error.h>
#include <fcntl.h>
#include <hurd.h>
#include <hurd/trivfs.h>
#include <inttypes.h>
#include <mntent.h>
#include <nullauth.h>
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <version.h>

#include "libtrivfs/trivfs_io_S.h"
#include "fs_U.h"

static char *target_path = NULL;
static int insecure = 0;
static int all_translators = 0;

/* Our control port.  */
struct trivfs_control *control;

/* These kind of objects are created and populated in the open_hook.
   They keep track of the content and file position of the client.  */
struct mtab
{
  pthread_mutex_t lock;
  char *contents;
  size_t contents_len;
  off_t offs;
};

const char *argp_program_version = STANDARD_HURD_VERSION (mtab);

static const struct argp_option options[] =
{
  {"insecure", 'I', 0, 0,
   "Follow translators not bound to nodes owned by you or root"},
  {"all-translators", 'A', 0, 0,
   "List all translators, even those that are probably not "
   "filesystem translators"},
  {}
};

/* Parse a command line option.	 */
error_t parse_opt (int key, char *arg, struct argp_state *state)
{
  switch (key)
    {
    case 'I':
      insecure = 1;
      break;

    case 'A':
      all_translators = 1;
      break;

    case ARGP_KEY_ARG:
      target_path = realpath (arg, NULL);
      if (! target_path)
	argp_error (state, "Error while canonicalizing path");
      break;

    case ARGP_KEY_NO_ARGS:
      argp_usage (state);
      return EINVAL;

    default:
      return ARGP_ERR_UNKNOWN;
    }
  return 0;
}

static struct argp argp =
  {
    options,
    parse_opt,
    "TARGET\tFile name of a node with an active translator",
    "A translator providing mtab compatible information about active "
    "and passive translators below TARGET.",
  };

/* This will be called from libtrivfs to help construct the answer
   to an fsys_get_options RPC.	*/
error_t
trivfs_append_args (struct trivfs_control *fsys,
		    char **argz, size_t *argz_len)
{
  error_t err;

  if (insecure)
    {
      err = argz_add (argz, argz_len, target_path);
      if (err)
	return err;
    }

  err = argz_add (argz, argz_len, target_path);
  return err;
}

/* Setting this variable makes libtrivfs use our argp to
   parse options passed in an fsys_set_options RPC.  */
struct argp *trivfs_runtime_argp = &argp;

/* Authentication of the current process.  */
uid_t *uids;
gid_t *gids;
size_t uids_len, gids_len;

/* Initialize and populate the uids and gids vectors.  */
error_t
get_credentials (void)
{
  /* Fetch uids...  */
  uids_len = geteuids (0, 0);
  if (uids_len < 0)
    return errno;

  uids = malloc (uids_len * sizeof (uid_t));
  if (! uids)
    return ENOMEM;

  uids_len = geteuids (uids_len, uids);
  if (uids_len < 0)
    return errno;

  /* ... and gids.  */
  gids_len = getgroups (0, 0);
  if (gids_len < 0)
    return errno;

  gids = malloc (gids_len * sizeof (gid_t));
  if (! uids)
    return ENOMEM;

  gids_len = getgroups (gids_len, gids);
  if (gids_len < 0)
    return errno;

  return 0;
}

/* Check if the given struct stat describes a node owned by the
   current user.  */
int
is_owner (io_statbuf_t *st)
{
  int found = 0;
  for (size_t i = 0; i < uids_len; i++)
    if (uids[i] == st->st_uid)
      {
	found = 1;
	break;
      }

  if (! found)
    return 0;

  found = 0;
  for (size_t i = 0; i < gids_len; i++)
    if (gids[i] == st->st_gid)
      {
	found = 1;
	break;
      }

  return found;
}

error_t
mtab_populate (struct mtab *mtab, const char *path, int insecure);

error_t
argz_add_device (char **options, size_t *options_len, const char *device);

error_t
map_device_to_path (const char *device, char **path);

int
main (int argc, char *argv[])
{
  error_t err;

  err = argp_parse (&argp, argc, argv, ARGP_IN_ORDER, 0, 0);
  if (err)
    error (1, err, "argument parsing");

  err = get_credentials ();
  if (err)
    error (2, err, "getting credentials");

  mach_port_t bootstrap;
  task_get_bootstrap_port (mach_task_self (), &bootstrap);
  if (bootstrap != MACH_PORT_NULL)
    {
      /* Started as a translator.  */
      err = setnullauth ();
      if (err)
        error (3, err, "dropping credentials");

      /* Reply to our parent.  */
      err = trivfs_startup (bootstrap, 0, 0, 0, 0, 0, &control);
      mach_port_deallocate (mach_task_self (), bootstrap);
      if (err)
	error (4, err, "trivfs_startup");

      /* Launch.  */
      ports_manage_port_operations_multithread (control->pi.bucket,
                                                trivfs_demuxer,
                                                /* idle thread timeout */
                                                30 * 1000,
                                                /* idle server timeout */
                                                0,
                                                NULL);
    }
  else
    {
      /* One-shot mode.	 */
      struct mtab mtab = { .lock = PTHREAD_MUTEX_INITIALIZER };
      err = mtab_populate (&mtab, target_path, insecure);
      if (err)
	error (5, err, "%s", target_path);

      if (mtab.contents)
	printf ("%s", mtab.contents);
    }

  return 0;
}

error_t
mtab_add_entry (struct mtab *mtab, const char *entry, size_t length)
{
  char *p = realloc (mtab->contents, mtab->contents_len + length + 1);
  if (! p)
    return ENOMEM;

  memcpy (&p[mtab->contents_len], entry, length);

  mtab->contents = p;
  mtab->contents_len += length;

  /* Zero-terminate contents so that we can also interpret it as
     string.  */
  mtab->contents[mtab->contents_len] = '\0';

  return 0;
}

/* Check whether the given NODE is a directory on a filesystem
   translator.  */
static boolean_t
is_filesystem_translator (file_t node)
{
  error_t err;
  char *data = NULL;
  size_t datacnt = 0;
  int amount;
  err = dir_readdir (node, &data, &datacnt, 0, 1, 0, &amount);
  if (data != NULL && datacnt > 0)
    vm_deallocate (mach_task_self (), (vm_address_t) data, datacnt);

  /* Filesystem translators return either no error, or, if NODE has
     not been looked up with O_READ, EBADF to dir_readdir
     requests.  */
  switch (err)
    {
    case 0:
    case EBADF:
      return TRUE;
    default:
      return FALSE;
    }
}

/* Populates the given MTAB object with the information for PATH.  If
   INSECURE is given, also follow translators bound to nodes not owned
   by root or the current user.  */
/* XXX split up */
error_t
mtab_populate (struct mtab *mtab, const char *path, int insecure)
{
  error_t err = 0;

  /* These resources are freed in the epilogue.	 */
  file_t node = MACH_PORT_NULL;
  char *argz = NULL;
  size_t argz_len = 0;
  char **argv = NULL;
  char *type = NULL;
  char *options = NULL;
  size_t options_len = 0;
  char *src = NULL;
  char *entry = NULL;
  size_t entry_len = 0;
  char *children = NULL;
  size_t children_len = 0;

  if (! insecure)
    {
      /* Get the underlying node.  */
      node = file_name_lookup (path, O_NOTRANS, 0666);
      if (node == MACH_PORT_NULL)
        {
          err = errno;
          goto errout;
        }

      /* Check who owns the node the translator is bound to.  */
      io_statbuf_t st;
      err = io_stat (node, &st);
      if (err)
	goto errout;

      if (st.st_uid != 0 && st.st_gid != 0 && ! is_owner (&st))
	{
	  err = EPERM;
	  goto errout;
	}

      mach_port_deallocate (mach_task_self (), node);
    }

  /* (Re-)do the lookup without O_NOTRANS to get the root node.  */
  node = file_name_lookup (path, 0, 0666);
  if (node == MACH_PORT_NULL)
    {
      err = errno;
      goto errout;
    }

  if (! (all_translators || is_filesystem_translator (node)))
    {
      err = 0;
      goto errout;
    }

  /* Query its options.	 */
  err = file_get_fs_options (node, &argz, &argz_len);
  if (err)
    {
      if (err == EOPNOTSUPP)
	err = 0; /* There's not much we could do then.	*/

      goto errout;
    }

  size_t count = argz_count (argz, argz_len);
  argv = malloc ((count + 1) * sizeof (char *));
  if (! argv)
    {
      err = ENOMEM;
      goto errout;
    }

  argz_extract (argz, argz_len, argv);

  type = strdup (argv[0]);
  if (! type)
    {
      err = ENOMEM;
      goto errout;
    }

  for (int i = 1; i < count - 1; i++)
    {
      char *v = argv[i];

      if (*v == '-')
	v++;
      if (*v == '-')
	v++;

      err = argz_add (&options, &options_len, v);
      if (err)
	goto errout;
    }

  err = argz_add_device (&options, &options_len, argv[count - 1]);
  if (err)
    goto errout;

  argz_stringify (options, options_len, ',');

  string_t source;
  err = file_get_source (node, source);
  if (err)
    goto errout;

  /* Guess based on the last argument.	*/
  err = map_device_to_path (source, &src);
  if (err)
    goto errout;

  entry_len = asprintf (&entry, "%s %s %s %s 0 0\n", src, path, type,
			options? options: MNTOPT_DEFAULTS);
  if (! entry)
    {
      err = ENOMEM;
      goto errout;
    }

  err = mtab_add_entry (mtab, entry, entry_len);
  if (err)
    goto errout;

  /* path has an active translator, query its children.	 */
  err = file_get_children (node, &children, &children_len);
  if (err == EOPNOTSUPP)
    {
      err = 0;
      children_len = 0;
    }

  if (err)
    goto errout;

  if (children_len)
    for (char *c = children; c; c = argz_next (children, children_len, c))
      {
	char *p = NULL;
	asprintf (&p, "%s%s%s",
		  path,
		  path[strlen (path) - 1] == '/'? "": "/",
		  c);
	if (! p)
	  {
	    err = ENOMEM;
	    goto errout;
	  }

	err = mtab_populate (mtab, p, insecure);
	if (err)
	  {
	    /* There is really not much we can do about errors here.  */
	    error (0, err, "%s", p);
	    err = 0;
	  }

	free (p);
      }

 errout:
  if (node != MACH_PORT_NULL)
    mach_port_deallocate (mach_task_self (), node);

  if (argz)
    vm_deallocate (mach_task_self (), (vm_address_t) argz, argz_len);

  free (argv);
  free (type);
  free (options);

  if (src != source)
    free (src);

  free (entry);

  if (children)
    vm_deallocate (mach_task_self (), (vm_address_t) children, children_len);

  return err;
}

/* Decodes the DEVICE string into appropriate OPTIONS.  Currently only
   tmpfs-style size declarations are supported.  */
error_t
argz_add_device (char **options, size_t *options_len, const char *device)
{
  error_t err;
  char *end = NULL;
  intmax_t size = strtoimax (device, &end, 0);
  if (end == NULL || end == device)
    return 0;

  if (size < 0)
    return 0;

  switch (*end)
    {
      case 'g':
      case 'G':
      case 'm':
      case 'M':
      case 'k':
      case 'K':
	break;
    default:
      return 0;
    }

  /* device specifies a size.  */
  char *arg = NULL;
  asprintf (&arg, "size=%s", device);
  if (! arg)
    return ENOMEM;

  err = argz_add (options, options_len, arg);

  free (arg);
  return err;
}

/* Matches [hs]d\ds\d\d?.  */
int
looks_like_block_device (const char *s)
{
  size_t len = strlen (s);
  if (len != 3 && len != 5 && len != 6)
    return 0;

  return ((s[0] == 'h' || s[0] == 's') && s[1] == 'd' && isdigit (s[2]) &&
          (len == 3 || (s[3] == 's' && isdigit (s[4]) &&
                        (len == 5 || isdigit (s[5])))));
}

/* Map a device string to a file name referencing the appropriate
   device file.	 */
error_t
map_device_to_path (const char *device, char **path)
{
  if (strncmp (device, "device:", 7) == 0)
    asprintf (path, "/dev/%s", &device[7]);
  else if (strncmp (device, "/dev/", 5) == 0)
    *path = strdup (device);
  else if (looks_like_block_device (device))
    asprintf (path, "/dev/%s", device);
  else
    *path = strdup (device);

  if (! *path)
    return ENOMEM;

  return 0;
}

/* Trivfs hooks.  */
int trivfs_fstype = FSTYPE_MISC;
int trivfs_fsid = 0;

int trivfs_allow_open = O_READ;

int trivfs_support_read = 1;
int trivfs_support_write = 0;
int trivfs_support_exec = 0;

void
trivfs_modify_stat (struct trivfs_protid *cred, struct stat *st)
{
  /* Mark the node as a read-only plain file.  */
  st->st_mode &= ~(S_IFMT | ALLPERMS);
  st->st_mode |= (S_IFREG | S_IRUSR | S_IRGRP | S_IROTH);
  st->st_size = ((struct mtab *) cred->po->hook)->contents_len;
}

error_t
trivfs_goaway (struct trivfs_control *cntl, int flags)
{
  exit (EXIT_SUCCESS);
}

static error_t
open_hook (struct trivfs_peropen *peropen)
{
  struct mtab *mtab = malloc (sizeof (struct mtab));
  if (mtab == NULL)
    return ENOMEM;

  /* Hook! */
  peropen->hook = mtab;

  /* Initialize the fields.  */
  pthread_mutex_init (&mtab->lock, NULL);
  mtab->offs = 0;
  mtab->contents = NULL;
  mtab->contents_len = 0;

  /* The mtab object is initialized, but not yet populated.  We delay
     that until that data is really needed.  This avoids the following
     problems:

     Suppose you have

     settrans -ac /foo /hurd/mtab /

     If you now access /foo, the mtab translator will walk the tree of
     all active translators starting from /.  If it visits /foo, it
     will talk to itself.  Previously the translator migitated this by
     comparing the control port of the translator with its own.  This
     does not work if you got two mtab translators like this:

     settrans -ac /foo /hurd/mtab /
     settrans -ac /bar /hurd/mtab /

     With a single-threaded mtab server this results in a dead-lock,
     with a multi-threaded server this will create more and more
     threads.

     Delaying the data generation until it is really needed cleanly
     avoids these kind of problems.  */
  return 0;
}

static void
close_hook (struct trivfs_peropen *peropen)
{
  struct mtab *op = peropen->hook;
  pthread_mutex_destroy (&op->lock);
  free (op->contents);
  free (op);
}

/* Read data from an IO object.	 If offset is -1, read from the object
   maintained file pointer.  If the object is not seekable, offset is
   ignored.  The amount desired to be read is in AMOUNT.  */
error_t
trivfs_S_io_read (struct trivfs_protid *cred,
		  mach_port_t reply, mach_msg_type_name_t reply_type,
		  char **data, mach_msg_type_number_t *data_len,
		  loff_t offs, mach_msg_type_number_t amount)
{
  error_t err = 0;
  struct mtab *op;

  /* Deny access if they have bad credentials.	*/
  if (! cred)
    return EOPNOTSUPP;

  if (! (cred->po->openmodes & O_READ))
    return EBADF;

  /* Get the offset.  */
  op = cred->po->hook;
  pthread_mutex_lock (&op->lock);

  if (op->contents == NULL)
    {
      err = mtab_populate (op, target_path, insecure);
      if (err)
	goto out;
    }

  if (offs == -1)
    offs = op->offs;

  /* Prune the amount they want to read.  */
  if (offs > op->contents_len)
    offs = op->contents_len;
  if (offs + amount > op->contents_len)
    amount = op->contents_len - offs;

  if (amount > 0)
    {
      /* Possibly allocate a new buffer.  */
      if (*data_len < amount)
	{
	  *data = mmap (0, amount, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0);
	  if (*data == MAP_FAILED)
	    {
	      err = ENOMEM;
	      goto out;
	    }
	}

      /* Copy the constant data into the buffer.  */
      memcpy ((char *) *data, op->contents + offs, amount);

      /* Update the saved offset.  */
      op->offs += amount;
    }

  *data_len = amount;
 out:
  pthread_mutex_unlock (&op->lock);
  return err;
}


/* Change current read/write offset */
error_t
trivfs_S_io_seek (struct trivfs_protid *cred,
		  mach_port_t reply, mach_msg_type_name_t reply_type,
		  off_t offs, int whence, off_t *new_offs)
{
  error_t err = 0;
  if (! cred)
    return EOPNOTSUPP;

  struct mtab *op = cred->po->hook;
  pthread_mutex_lock (&op->lock);

  if (op->contents == NULL)
    {
      err = mtab_populate (op, target_path, insecure);
      if (err)
	goto out;
    }

  switch (whence)
    {
    case SEEK_CUR:
      offs += op->offs;
      goto check;
    case SEEK_END:
      offs += op->contents_len;
    case SEEK_SET:
    check:
      if (offs >= 0)
	{
	  *new_offs = op->offs = offs;
	  break;
	}
    default:
      err = EINVAL;
    }

 out:
  pthread_mutex_unlock (&op->lock);
  return err;
}

/* If this variable is set, it is called every time a new peropen
   structure is created and initialized.  */
error_t (*trivfs_peropen_create_hook)(struct trivfs_peropen *) = open_hook;

/* If this variable is set, it is called every time a peropen structure
   is about to be destroyed.  */
void (*trivfs_peropen_destroy_hook) (struct trivfs_peropen *) = close_hook;

/* Tell how much data can be read from the object without blocking for
   a "long time" (this should be the same meaning of "long time" used
   by the nonblocking flag.  */
kern_return_t
trivfs_S_io_readable (struct trivfs_protid *cred,
		      mach_port_t reply, mach_msg_type_name_t replytype,
		      mach_msg_type_number_t *amount)
{
  error_t err = 0;
  if (!cred)
    return EOPNOTSUPP;

  if (!(cred->po->openmodes & O_READ))
    return EINVAL;

  struct mtab *op = cred->po->hook;
  pthread_mutex_lock (&op->lock);

  if (op->contents == NULL)
    {
      error_t err = mtab_populate (op, target_path, insecure);
      if (err)
	goto out;
    }

  *amount = op->contents_len - op->offs;
 out:
  pthread_mutex_unlock (&op->lock);
  return err;
}

/* SELECT_TYPE is the bitwise OR of SELECT_READ, SELECT_WRITE, and SELECT_URG.
   Block until one of the indicated types of i/o can be done "quickly", and
   return the types that are then available.  ID_TAG is returned as passed; it
   is just for the convenience of the user in matching up reply messages with
   specific requests sent.  */
kern_return_t
trivfs_S_io_select (struct trivfs_protid *cred,
		    mach_port_t reply, mach_msg_type_name_t replytype,
		    int *type)
{
  if (!cred)
    return EOPNOTSUPP;

  if (((*type & SELECT_READ) && !(cred->po->openmodes & O_READ))
      || ((*type & SELECT_WRITE) && !(cred->po->openmodes & O_WRITE)))
    return EBADF;

  *type &= ~SELECT_URG;
  return 0;
}

kern_return_t
trivfs_S_io_select_timeout (struct trivfs_protid *cred,
			    mach_port_t reply, mach_msg_type_name_t replytype,
			    struct timespec ts,
			    int *type)
{
  return trivfs_S_io_select (cred, reply, replytype, type);
}

/* These four routines modify the O_APPEND, O_ASYNC, O_FSYNC, and
   O_NONBLOCK bits for the IO object. In addition, io_get_openmodes
   will tell you which of O_READ, O_WRITE, and O_EXEC the object can
   be used for.	 The O_ASYNC bit affects icky async I/O; good async
   I/O is done through io_async which is orthogonal to these calls. */

kern_return_t
trivfs_S_io_get_openmodes (struct trivfs_protid *cred,
			   mach_port_t reply, mach_msg_type_name_t replytype,
			   int *bits)
{
  if (!cred)
    return EOPNOTSUPP;

  *bits = cred->po->openmodes;
  return 0;
}

error_t
trivfs_S_io_set_all_openmodes(struct trivfs_protid *cred,
			      mach_port_t reply,
			      mach_msg_type_name_t replytype,
			      int mode)
{
  if (!cred)
    return EOPNOTSUPP;

  return 0;
}

kern_return_t
trivfs_S_io_set_some_openmodes (struct trivfs_protid *cred,
				mach_port_t reply,
				mach_msg_type_name_t replytype,
				int bits)
{
  if (!cred)
    return EOPNOTSUPP;

  return 0;
}

kern_return_t
trivfs_S_io_clear_some_openmodes (struct trivfs_protid *cred,
				  mach_port_t reply,
				  mach_msg_type_name_t replytype,
				  int bits)
{
  if (!cred)
    return EOPNOTSUPP;

  return 0;
}