summaryrefslogtreecommitdiff
path: root/libgfortran/io/unit.c
blob: b0ba3109b236f005439c1d351d56ea4b83bceb41 (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
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
   Contributed by Andy Vaught
   F2003 I/O support contributed by Jerry DeLisle

This file is part of the GNU Fortran runtime library (libgfortran).

Libgfortran 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 3, or (at your option)
any later version.

Libgfortran 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.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

#include "io.h"
#include "fbuf.h"
#include "format.h"
#include "unix.h"
#include <string.h>
#include <assert.h>


/* IO locking rules:
   UNIT_LOCK is a master lock, protecting UNIT_ROOT tree and UNIT_CACHE.
   Concurrent use of different units should be supported, so
   each unit has its own lock, LOCK.
   Open should be atomic with its reopening of units and list_read.c
   in several places needs find_unit another unit while holding stdin
   unit's lock, so it must be possible to acquire UNIT_LOCK while holding
   some unit's lock.  Therefore to avoid deadlocks, it is forbidden
   to acquire unit's private locks while holding UNIT_LOCK, except
   for freshly created units (where no other thread can get at their
   address yet) or when using just trylock rather than lock operation.
   In addition to unit's private lock each unit has a WAITERS counter
   and CLOSED flag.  WAITERS counter must be either only
   atomically incremented/decremented in all places (if atomic builtins
   are supported), or protected by UNIT_LOCK in all places (otherwise).
   CLOSED flag must be always protected by unit's LOCK.
   After finding a unit in UNIT_CACHE or UNIT_ROOT with UNIT_LOCK held,
   WAITERS must be incremented to avoid concurrent close from freeing
   the unit between unlocking UNIT_LOCK and acquiring unit's LOCK.
   Unit freeing is always done under UNIT_LOCK.  If close_unit sees any
   WAITERS, it doesn't free the unit but instead sets the CLOSED flag
   and the thread that decrements WAITERS to zero while CLOSED flag is
   set is responsible for freeing it (while holding UNIT_LOCK).
   flush_all_units operation is iterating over the unit tree with
   increasing UNIT_NUMBER while holding UNIT_LOCK and attempting to
   flush each unit (and therefore needs the unit's LOCK held as well).
   To avoid deadlocks, it just trylocks the LOCK and if unsuccessful,
   remembers the current unit's UNIT_NUMBER, unlocks UNIT_LOCK, acquires
   unit's LOCK and after flushing reacquires UNIT_LOCK and restarts with
   the smallest UNIT_NUMBER above the last one flushed.

   If find_unit/find_or_create_unit/find_file/get_unit routines return
   non-NULL, the returned unit has its private lock locked and when the
   caller is done with it, it must call either unlock_unit or close_unit
   on it.  unlock_unit or close_unit must be always called only with the
   private lock held.  */



/* Table of allocated newunit values.  A simple solution would be to
   map OS file descriptors (fd's) to unit numbers, e.g. with newunit =
   -fd - 2, however that doesn't work since Fortran allows an existing
   unit number to be reassociated with a new file. Thus the simple
   approach may lead to a situation where we'd try to assign a
   (negative) unit number which already exists. Hence we must keep
   track of allocated newunit values ourselves. This is the purpose of
   the newunits array. The indices map to newunit values as newunit =
   -index + NEWUNIT_FIRST. E.g. newunits[0] having the value true
   means that a unit with number NEWUNIT_FIRST exists. Similar to
   POSIX file descriptors, we always allocate the lowest (in absolute
   value) available unit number.
 */
static bool *newunits;
static int newunit_size; /* Total number of elements in the newunits array.  */
/* Low water indicator for the newunits array. Below the LWI all the
   units are allocated, above and equal to the LWI there may be both
   allocated and free units. */
static int newunit_lwi;
static void newunit_free (int);

/* Unit numbers assigned with NEWUNIT start from here.  */
#define NEWUNIT_START -10


#define NEWUNIT_STACK_SIZE 16

/* A stack to save previously used newunit-assigned unit numbers to
   allow them to be reused without reallocating the gfc_unit structure
   which is still in the treap.  */
static gfc_saved_unit newunit_stack[NEWUNIT_STACK_SIZE];
static int newunit_tos = 0; /* Index to Top of Stack.  */


#define CACHE_SIZE 3
static gfc_unit *unit_cache[CACHE_SIZE];
gfc_offset max_offset;
gfc_unit *unit_root;
#ifdef __GTHREAD_MUTEX_INIT
__gthread_mutex_t unit_lock = __GTHREAD_MUTEX_INIT;
#else
__gthread_mutex_t unit_lock;
#endif

/* We use these filenames for error reporting.  */

static char stdin_name[] = "stdin";
static char stdout_name[] = "stdout";
static char stderr_name[] = "stderr";


#ifdef HAVE_NEWLOCALE
locale_t c_locale;
#else
/* If we don't have POSIX 2008 per-thread locales, we need to use the
   traditional setlocale().  To prevent multiple concurrent threads
   doing formatted I/O from messing up the locale, we need to store a
   global old_locale, and a counter keeping track of how many threads
   are currently doing formatted I/O.  The first thread saves the old
   locale, and the last one restores it.  */
char *old_locale;
int old_locale_ctr;
#ifdef __GTHREAD_MUTEX_INIT
__gthread_mutex_t old_locale_lock = __GTHREAD_MUTEX_INIT;
#else
__gthread_mutex_t old_locale_lock;
#endif
#endif


/* This implementation is based on Stefan Nilsson's article in the
 * July 1997 Doctor Dobb's Journal, "Treaps in Java". */

/* pseudo_random()-- Simple linear congruential pseudorandom number
 * generator.  The period of this generator is 44071, which is plenty
 * for our purposes.  */

static int
pseudo_random (void)
{
  static int x0 = 5341;

  x0 = (22611 * x0 + 10) % 44071;
  return x0;
}


/* rotate_left()-- Rotate the treap left */

static gfc_unit *
rotate_left (gfc_unit * t)
{
  gfc_unit *temp;

  temp = t->right;
  t->right = t->right->left;
  temp->left = t;

  return temp;
}


/* rotate_right()-- Rotate the treap right */

static gfc_unit *
rotate_right (gfc_unit * t)
{
  gfc_unit *temp;

  temp = t->left;
  t->left = t->left->right;
  temp->right = t;

  return temp;
}


static int
compare (int a, int b)
{
  if (a < b)
    return -1;
  if (a > b)
    return 1;

  return 0;
}


/* insert()-- Recursive insertion function.  Returns the updated treap. */

static gfc_unit *
insert (gfc_unit *new, gfc_unit *t)
{
  int c;

  if (t == NULL)
    return new;

  c = compare (new->unit_number, t->unit_number);

  if (c < 0)
    {
      t->left = insert (new, t->left);
      if (t->priority < t->left->priority)
	t = rotate_right (t);
    }

  if (c > 0)
    {
      t->right = insert (new, t->right);
      if (t->priority < t->right->priority)
	t = rotate_left (t);
    }

  if (c == 0)
    internal_error (NULL, "insert(): Duplicate key found!");

  return t;
}


/* insert_unit()-- Create a new node, insert it into the treap.  */

static gfc_unit *
insert_unit (int n)
{
  gfc_unit *u = xcalloc (1, sizeof (gfc_unit));
  u->unit_number = n;
#ifdef __GTHREAD_MUTEX_INIT
  {
    __gthread_mutex_t tmp = __GTHREAD_MUTEX_INIT;
    u->lock = tmp;
  }
#else
  __GTHREAD_MUTEX_INIT_FUNCTION (&u->lock);
#endif
  __gthread_mutex_lock (&u->lock);
  u->priority = pseudo_random ();
  unit_root = insert (u, unit_root);
  return u;
}


/* destroy_unit_mutex()-- Destroy the mutex and free memory of unit.  */

static void
destroy_unit_mutex (gfc_unit * u)
{
  __gthread_mutex_destroy (&u->lock);
  free (u);
}


static gfc_unit *
delete_root (gfc_unit * t)
{
  gfc_unit *temp;

  if (t->left == NULL)
    return t->right;
  if (t->right == NULL)
    return t->left;

  if (t->left->priority > t->right->priority)
    {
      temp = rotate_right (t);
      temp->right = delete_root (t);
    }
  else
    {
      temp = rotate_left (t);
      temp->left = delete_root (t);
    }

  return temp;
}


/* delete_treap()-- Delete an element from a tree.  The 'old' value
 * does not necessarily have to point to the element to be deleted, it
 * must just point to a treap structure with the key to be deleted.
 * Returns the new root node of the tree. */

static gfc_unit *
delete_treap (gfc_unit * old, gfc_unit * t)
{
  int c;

  if (t == NULL)
    return NULL;

  c = compare (old->unit_number, t->unit_number);

  if (c < 0)
    t->left = delete_treap (old, t->left);
  if (c > 0)
    t->right = delete_treap (old, t->right);
  if (c == 0)
    t = delete_root (t);

  return t;
}


/* delete_unit()-- Delete a unit from a tree */

static void
delete_unit (gfc_unit * old)
{
  unit_root = delete_treap (old, unit_root);
}


/* get_gfc_unit()-- Given an integer, return a pointer to the unit
 * structure.  Returns NULL if the unit does not exist,
 * otherwise returns a locked unit. */

static gfc_unit *
get_gfc_unit (int n, int do_create)
{
  gfc_unit *p;
  int c, created = 0;

  __gthread_mutex_lock (&unit_lock);
retry:
  for (c = 0; c < CACHE_SIZE; c++)
    if (unit_cache[c] != NULL && unit_cache[c]->unit_number == n)
      {
	p = unit_cache[c];
	goto found;
      }

  p = unit_root;
  while (p != NULL)
    {
      c = compare (n, p->unit_number);
      if (c < 0)
	p = p->left;
      if (c > 0)
	p = p->right;
      if (c == 0)
	break;
    }

  if (p == NULL && do_create)
    {
      p = insert_unit (n);
      created = 1;
    }

  if (p != NULL)
    {
      for (c = 0; c < CACHE_SIZE - 1; c++)
	unit_cache[c] = unit_cache[c + 1];

      unit_cache[CACHE_SIZE - 1] = p;
    }

  if (created)
    {
      /* Newly created units have their lock held already
	 from insert_unit.  Just unlock UNIT_LOCK and return.  */
      __gthread_mutex_unlock (&unit_lock);
      return p;
    }

found:
  if (p != NULL && (p->child_dtio == 0))
    {
      /* Fast path.  */
      if (! __gthread_mutex_trylock (&p->lock))
	{
	  /* assert (p->closed == 0); */
	  __gthread_mutex_unlock (&unit_lock);
	  return p;
	}

      inc_waiting_locked (p);
    }


  __gthread_mutex_unlock (&unit_lock);

  if (p != NULL && (p->child_dtio == 0))
    {
      __gthread_mutex_lock (&p->lock);
      if (p->closed)
	{
	  __gthread_mutex_lock (&unit_lock);
	  __gthread_mutex_unlock (&p->lock);
	  if (predec_waiting_locked (p) == 0)
	    destroy_unit_mutex (p);
	  goto retry;
	}

      dec_waiting_unlocked (p);
    }
  return p;
}


gfc_unit *
find_unit (int n)
{
  return get_gfc_unit (n, 0);
}


gfc_unit *
find_or_create_unit (int n)
{
  return get_gfc_unit (n, 1);
}


/* Helper function to check rank, stride, format string, and namelist.
   This is used for optimization. You can't trim out blanks or shorten
   the string if trailing spaces are significant.  */
static bool
is_trim_ok (st_parameter_dt *dtp)
{
  /* Check rank and stride.  */
  if (dtp->internal_unit_desc)
    return false;
  /* Format strings can not have 'BZ' or '/'.  */
  if (dtp->common.flags & IOPARM_DT_HAS_FORMAT)
    {
      char *p = dtp->format;
      off_t i;
      if (dtp->common.flags & IOPARM_DT_HAS_BLANK)
	return false;
      for (i = 0; i < dtp->format_len; i++)
	{
	  if (p[i] == '/') return false;
	  if (p[i] == 'b' || p[i] == 'B')
	    if (p[i+1] == 'z' || p[i+1] == 'Z')
	      return false;
	}
    }
  if (dtp->u.p.ionml) /* A namelist.  */
    return false;
  return true;
}


gfc_unit *
set_internal_unit (st_parameter_dt *dtp, gfc_unit *iunit, int kind)
{
  gfc_offset start_record = 0;

  iunit->recl = dtp->internal_unit_len;
  iunit->internal_unit = dtp->internal_unit;
  iunit->internal_unit_len = dtp->internal_unit_len;
  iunit->internal_unit_kind = kind;

  /* As an optimization, adjust the unit record length to not
     include trailing blanks. This will not work under certain conditions
     where trailing blanks have significance.  */
  if (dtp->u.p.mode == READING && is_trim_ok (dtp))
    {
      int len;
      if (kind == 1)
	  len = string_len_trim (iunit->internal_unit_len,
						   iunit->internal_unit);
      else
	  len = string_len_trim_char4 (iunit->internal_unit_len,
			      (const gfc_char4_t*) iunit->internal_unit);
      iunit->internal_unit_len = len;
      iunit->recl = iunit->internal_unit_len;
    }

  /* Set up the looping specification from the array descriptor, if any.  */

  if (is_array_io (dtp))
    {
      iunit->rank = GFC_DESCRIPTOR_RANK (dtp->internal_unit_desc);
      iunit->ls = (array_loop_spec *)
	xmallocarray (iunit->rank, sizeof (array_loop_spec));
      iunit->internal_unit_len *=
	init_loop_spec (dtp->internal_unit_desc, iunit->ls, &start_record);

      start_record *= iunit->recl;
    }

  /* Set initial values for unit parameters.  */
  if (kind == 4)
    iunit->s = open_internal4 (iunit->internal_unit - start_record,
				 iunit->internal_unit_len, -start_record);
  else
    iunit->s = open_internal (iunit->internal_unit - start_record,
			      iunit->internal_unit_len, -start_record);

  iunit->bytes_left = iunit->recl;
  iunit->last_record=0;
  iunit->maxrec=0;
  iunit->current_record=0;
  iunit->read_bad = 0;
  iunit->endfile = NO_ENDFILE;

  /* Set flags for the internal unit.  */

  iunit->flags.access = ACCESS_SEQUENTIAL;
  iunit->flags.action = ACTION_READWRITE;
  iunit->flags.blank = BLANK_NULL;
  iunit->flags.form = FORM_FORMATTED;
  iunit->flags.pad = PAD_YES;
  iunit->flags.status = STATUS_UNSPECIFIED;
  iunit->flags.sign = SIGN_UNSPECIFIED;
  iunit->flags.decimal = DECIMAL_POINT;
  iunit->flags.delim = DELIM_UNSPECIFIED;
  iunit->flags.encoding = ENCODING_DEFAULT;
  iunit->flags.async = ASYNC_NO;
  iunit->flags.round = ROUND_UNSPECIFIED;

  /* Initialize the data transfer parameters.  */

  dtp->u.p.advance_status = ADVANCE_YES;
  dtp->u.p.seen_dollar = 0;
  dtp->u.p.skips = 0;
  dtp->u.p.pending_spaces = 0;
  dtp->u.p.max_pos = 0;
  dtp->u.p.at_eof = 0;
  return iunit;
}


/* stash_internal_unit()-- Push the internal unit number onto the
   avaialble stack.  */
void
stash_internal_unit (st_parameter_dt *dtp)
{
  __gthread_mutex_lock (&unit_lock);
  newunit_tos++;
  if (newunit_tos >= NEWUNIT_STACK_SIZE)
    internal_error (&dtp->common, "stash_internal_unit(): Stack Size Exceeded");
  newunit_stack[newunit_tos].unit_number = dtp->common.unit;
  newunit_stack[newunit_tos].unit = dtp->u.p.current_unit;
  __gthread_mutex_unlock (&unit_lock);
}



/* get_unit()-- Returns the unit structure associated with the integer
   unit or the internal file.  */

gfc_unit *
get_unit (st_parameter_dt *dtp, int do_create)
{
  gfc_unit * unit;

  if ((dtp->common.flags & IOPARM_DT_HAS_INTERNAL_UNIT) != 0)
    {
      int kind;
      if (dtp->common.unit == GFC_INTERNAL_UNIT)
        kind = 1;
      else if (dtp->common.unit == GFC_INTERNAL_UNIT4)
        kind = 4;
      else
	internal_error (&dtp->common, "get_unit(): Bad internal unit KIND");

      if ((dtp->common.flags & IOPARM_DT_HAS_UDTIO) != 0)
	{
	  dtp->u.p.unit_is_internal = 1;
	  dtp->common.unit = newunit_alloc ();
	  unit = get_gfc_unit (dtp->common.unit, do_create);
	  set_internal_unit (dtp, unit, kind);
	  fbuf_init (unit, 128);
	  return unit;
	}
      else
	{
	  if (newunit_tos)
	    {
	      dtp->common.unit = newunit_stack[newunit_tos].unit_number;
	      unit = newunit_stack[newunit_tos--].unit;
	      unit->fbuf->act = unit->fbuf->pos = 0;
	    }
	  else
	    {
	      dtp->common.unit = newunit_alloc ();
	      unit = xcalloc (1, sizeof (gfc_unit));
	      fbuf_init (unit, 128);
	    }
	  set_internal_unit (dtp, unit, kind);
	  return unit;
	}
    }
  /* Has to be an external unit.  */
  dtp->u.p.unit_is_internal = 0;
  dtp->internal_unit = NULL;
  dtp->internal_unit_desc = NULL;
  /* For an external unit with unit number < 0 creating it on the fly
     is not allowed, such units must be created with
     OPEN(NEWUNIT=...).  */
  if (dtp->common.unit < 0)
    return get_gfc_unit (dtp->common.unit, 0);
  return get_gfc_unit (dtp->common.unit, do_create);
}


/*************************/
/* Initialize everything.  */

void
init_units (void)
{
  gfc_unit *u;
  unsigned int i;

#ifdef HAVE_NEWLOCALE
  c_locale = newlocale (0, "C", 0);
#else
#ifndef __GTHREAD_MUTEX_INIT
  __GTHREAD_MUTEX_INIT_FUNCTION (&old_locale_lock);
#endif
#endif

#ifndef __GTHREAD_MUTEX_INIT
  __GTHREAD_MUTEX_INIT_FUNCTION (&unit_lock);
#endif

  if (options.stdin_unit >= 0)
    {				/* STDIN */
      u = insert_unit (options.stdin_unit);
      u->s = input_stream ();

      u->flags.action = ACTION_READ;

      u->flags.access = ACCESS_SEQUENTIAL;
      u->flags.form = FORM_FORMATTED;
      u->flags.status = STATUS_OLD;
      u->flags.blank = BLANK_NULL;
      u->flags.pad = PAD_YES;
      u->flags.position = POSITION_ASIS;
      u->flags.sign = SIGN_UNSPECIFIED;
      u->flags.decimal = DECIMAL_POINT;
      u->flags.delim = DELIM_UNSPECIFIED;
      u->flags.encoding = ENCODING_DEFAULT;
      u->flags.async = ASYNC_NO;
      u->flags.round = ROUND_UNSPECIFIED;
      u->flags.share = SHARE_UNSPECIFIED;
      u->flags.cc = CC_LIST;

      u->recl = options.default_recl;
      u->endfile = NO_ENDFILE;

      u->filename = strdup (stdin_name);

      fbuf_init (u, 0);

      __gthread_mutex_unlock (&u->lock);
    }

  if (options.stdout_unit >= 0)
    {				/* STDOUT */
      u = insert_unit (options.stdout_unit);
      u->s = output_stream ();

      u->flags.action = ACTION_WRITE;

      u->flags.access = ACCESS_SEQUENTIAL;
      u->flags.form = FORM_FORMATTED;
      u->flags.status = STATUS_OLD;
      u->flags.blank = BLANK_NULL;
      u->flags.position = POSITION_ASIS;
      u->flags.sign = SIGN_UNSPECIFIED;
      u->flags.decimal = DECIMAL_POINT;
      u->flags.delim = DELIM_UNSPECIFIED;
      u->flags.encoding = ENCODING_DEFAULT;
      u->flags.async = ASYNC_NO;
      u->flags.round = ROUND_UNSPECIFIED;
      u->flags.share = SHARE_UNSPECIFIED;
      u->flags.cc = CC_LIST;

      u->recl = options.default_recl;
      u->endfile = AT_ENDFILE;

      u->filename = strdup (stdout_name);

      fbuf_init (u, 0);

      __gthread_mutex_unlock (&u->lock);
    }

  if (options.stderr_unit >= 0)
    {				/* STDERR */
      u = insert_unit (options.stderr_unit);
      u->s = error_stream ();

      u->flags.action = ACTION_WRITE;

      u->flags.access = ACCESS_SEQUENTIAL;
      u->flags.form = FORM_FORMATTED;
      u->flags.status = STATUS_OLD;
      u->flags.blank = BLANK_NULL;
      u->flags.position = POSITION_ASIS;
      u->flags.sign = SIGN_UNSPECIFIED;
      u->flags.decimal = DECIMAL_POINT;
      u->flags.encoding = ENCODING_DEFAULT;
      u->flags.async = ASYNC_NO;
      u->flags.round = ROUND_UNSPECIFIED;
      u->flags.share = SHARE_UNSPECIFIED;
      u->flags.cc = CC_LIST;

      u->recl = options.default_recl;
      u->endfile = AT_ENDFILE;

      u->filename = strdup (stderr_name);

      fbuf_init (u, 256);  /* 256 bytes should be enough, probably not doing
                              any kind of exotic formatting to stderr.  */

      __gthread_mutex_unlock (&u->lock);
    }

  /* Calculate the maximum file offset in a portable manner.
     max will be the largest signed number for the type gfc_offset.
     set a 1 in the LSB and keep a running sum, stopping at MSB-1 bit.  */
  max_offset = 0;
  for (i = 0; i < sizeof (max_offset) * 8 - 1; i++)
    max_offset = max_offset + ((gfc_offset) 1 << i);

  /* Initialize the newunit stack.  */
  memset (newunit_stack, 0, NEWUNIT_STACK_SIZE * sizeof(gfc_saved_unit));
  newunit_tos = 0;
}


static int
close_unit_1 (gfc_unit *u, int locked)
{
  int i, rc;

  /* If there are previously written bytes from a write with ADVANCE="no"
     Reposition the buffer before closing.  */
  if (u->previous_nonadvancing_write)
    finish_last_advance_record (u);

  rc = (u->s == NULL) ? 0 : sclose (u->s) == -1;

  u->closed = 1;
  if (!locked)
    __gthread_mutex_lock (&unit_lock);

  for (i = 0; i < CACHE_SIZE; i++)
    if (unit_cache[i] == u)
      unit_cache[i] = NULL;

  delete_unit (u);

  free (u->filename);
  u->filename = NULL;

  free_format_hash_table (u);
  fbuf_destroy (u);

  if (u->unit_number <= NEWUNIT_START)
    newunit_free (u->unit_number);

  if (!locked)
    __gthread_mutex_unlock (&u->lock);

  /* If there are any threads waiting in find_unit for this unit,
     avoid freeing the memory, the last such thread will free it
     instead.  */
  if (u->waiting == 0)
    destroy_unit_mutex (u);

  if (!locked)
    __gthread_mutex_unlock (&unit_lock);

  return rc;
}

void
unlock_unit (gfc_unit *u)
{
  __gthread_mutex_unlock (&u->lock);
}

/* close_unit()-- Close a unit.  The stream is closed, and any memory
   associated with the stream is freed.  Returns nonzero on I/O error.
   Should be called with the u->lock locked. */

int
close_unit (gfc_unit *u)
{
  return close_unit_1 (u, 0);
}


/* close_units()-- Delete units on completion.  We just keep deleting
   the root of the treap until there is nothing left.
   Not sure what to do with locking here.  Some other thread might be
   holding some unit's lock and perhaps hold it indefinitely
   (e.g. waiting for input from some pipe) and close_units shouldn't
   delay the program too much.  */

void
close_units (void)
{
  __gthread_mutex_lock (&unit_lock);
  while (unit_root != NULL)
    close_unit_1 (unit_root, 1);
  __gthread_mutex_unlock (&unit_lock);

  while (newunit_tos != 0)
    if (newunit_stack[newunit_tos].unit)
      {
	fbuf_destroy (newunit_stack[newunit_tos].unit);
	free (newunit_stack[newunit_tos].unit->s);
	free (newunit_stack[newunit_tos--].unit);
      }

  free (newunits);

#ifdef HAVE_FREELOCALE
  freelocale (c_locale);
#endif
}


/* High level interface to truncate a file, i.e. flush format buffers,
   and generate an error or set some flags.  Just like POSIX
   ftruncate, returns 0 on success, -1 on failure.  */

int
unit_truncate (gfc_unit * u, gfc_offset pos, st_parameter_common * common)
{
  int ret;

  /* Make sure format buffer is flushed.  */
  if (u->flags.form == FORM_FORMATTED)
    {
      if (u->mode == READING)
	pos += fbuf_reset (u);
      else
	fbuf_flush (u, u->mode);
    }

  /* struncate() should flush the stream buffer if necessary, so don't
     bother calling sflush() here.  */
  ret = struncate (u->s, pos);

  if (ret != 0)
    generate_error (common, LIBERROR_OS, NULL);
  else
    {
      u->endfile = AT_ENDFILE;
      u->flags.position = POSITION_APPEND;
    }

  return ret;
}


/* filename_from_unit()-- If the unit_number exists, return a pointer to the
   name of the associated file, otherwise return the empty string.  The caller
   must free memory allocated for the filename string.  */

char *
filename_from_unit (int n)
{
  gfc_unit *u;
  int c;

  /* Find the unit.  */
  u = unit_root;
  while (u != NULL)
    {
      c = compare (n, u->unit_number);
      if (c < 0)
	u = u->left;
      if (c > 0)
	u = u->right;
      if (c == 0)
	break;
    }

  /* Get the filename.  */
  if (u != NULL && u->filename != NULL)
    return strdup (u->filename);
  else
    return (char *) NULL;
}

void
finish_last_advance_record (gfc_unit *u)
{

  if (u->saved_pos > 0)
    fbuf_seek (u, u->saved_pos, SEEK_CUR);

  if (!(u->unit_number == options.stdout_unit
	|| u->unit_number == options.stderr_unit))
    {
#ifdef HAVE_CRLF
      const int len = 2;
#else
      const int len = 1;
#endif
      char *p = fbuf_alloc (u, len);
      if (!p)
	os_error ("Completing record after ADVANCE_NO failed");
#ifdef HAVE_CRLF
      *(p++) = '\r';
#endif
      *p = '\n';
    }

  fbuf_flush (u, u->mode);
}


/* Assign a negative number for NEWUNIT in OPEN statements or for
   internal units.  */
int
newunit_alloc (void)
{
  __gthread_mutex_lock (&unit_lock);
  if (!newunits)
    {
      newunits = xcalloc (16, 1);
      newunit_size = 16;
    }

  /* Search for the next available newunit.  */
  for (int ii = newunit_lwi; ii < newunit_size; ii++)
    {
      if (!newunits[ii])
        {
          newunits[ii] = true;
          newunit_lwi = ii + 1;
	  __gthread_mutex_unlock (&unit_lock);
          return -ii + NEWUNIT_START;
        }
    }

  /* Search failed, bump size of array and allocate the first
     available unit.  */
  int old_size = newunit_size;
  newunit_size *= 2;
  newunits = xrealloc (newunits, newunit_size);
  memset (newunits + old_size, 0, old_size);
  newunits[old_size] = true;
  newunit_lwi = old_size + 1;
    __gthread_mutex_unlock (&unit_lock);
  return -old_size + NEWUNIT_START;
}


/* Free a previously allocated newunit= unit number.  unit_lock must
   be held when calling.  */

static void
newunit_free (int unit)
{
  int ind = -unit + NEWUNIT_START;
  assert(ind >= 0 && ind < newunit_size);
  newunits[ind] = false;
  if (ind < newunit_lwi)
    newunit_lwi = ind;
}