about summary refs log tree commit diff
path: root/libio/genops.c
blob: bd741ec66ea58ff584c30492abfe44595d2999e5 (plain) (blame)
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
/*
Copyright (C) 1993, 1995 Free Software Foundation

This file is part of the GNU IO Library.  This library 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 library 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 library; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

As a special exception, if you link this library with files
compiled with a GNU compiler to produce an executable, this does not cause
the resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why
the executable file might be covered by the GNU General Public License. */

/* Generic or default I/O operations. */

#include "libioP.h"
#ifdef __STDC__
#include <stdlib.h>
#endif
#include <string.h>

void
DEFUN(_IO_un_link, (fp),
      _IO_FILE *fp)
{
  if (fp->_flags & _IO_LINKED) {
    _IO_FILE **f;
    for (f = &_IO_list_all; *f != NULL; f = &(*f)->_chain) {
      if (*f == fp) {
	*f = fp->_chain;
	break;
      }
    }
    fp->_flags &= ~_IO_LINKED;
  }
}

void
DEFUN(_IO_link_in, (fp),
      _IO_FILE *fp)
{
    if ((fp->_flags & _IO_LINKED) == 0) {
	fp->_flags |= _IO_LINKED;
	fp->_chain = _IO_list_all;
	_IO_list_all = fp;
    }
}

/* Return minimum _pos markers
   Assumes the current get area is the main get area. */

_IO_size_t
DEFUN(_IO_least_marker, (fp),
      register _IO_FILE *fp)
{
  _IO_ssize_t least_so_far = fp->_IO_read_end - fp->_IO_read_base;
  register struct _IO_marker *mark;
  for (mark = fp->_markers; mark != NULL; mark = mark->_next)
    if (mark->_pos < least_so_far)
      least_so_far = mark->_pos;
  return least_so_far;
}

/* Switch current get area from backup buffer to (start of) main get area. */

void
DEFUN(_IO_switch_to_main_get_area, (fp),
      _IO_FILE *fp)
{
  char *tmp;
  fp->_flags &= ~_IO_IN_BACKUP;
  /* Swap _IO_read_end and _IO_save_end. */
  tmp = fp->_IO_read_end; fp->_IO_read_end= fp->_IO_save_end; fp->_IO_save_end= tmp;
  /* Swap _IO_read_base and _IO_save_base. */
  tmp = fp->_IO_read_base; fp->_IO_read_base = fp->_IO_save_base; fp->_IO_save_base = tmp;
  fp->_IO_read_ptr = fp->_IO_read_base;
}

/* Switch current get area from main get area to (end of) backup area. */

void
DEFUN(_IO_switch_to_backup_area, (fp),
     register _IO_FILE *fp)
{
  char *tmp;
  fp->_flags |= _IO_IN_BACKUP;
  /* Swap _IO_read_end and _IO_save_end. */
  tmp = fp->_IO_read_end; fp->_IO_read_end = fp->_IO_save_end; fp->_IO_save_end = tmp;
  /* Swap _gbase and _IO_save_base. */
  tmp = fp->_IO_read_base; fp->_IO_read_base = fp->_IO_save_base; fp->_IO_save_base = tmp;
  fp->_IO_read_ptr = fp->_IO_read_end;
}

int
DEFUN(_IO_switch_to_get_mode, (fp),
     register _IO_FILE *fp)
{
  if (fp->_IO_write_ptr > fp->_IO_write_base)
    if (_IO_OVERFLOW (fp, EOF) == EOF)
      return EOF;
  if (_IO_in_backup(fp))
    fp->_IO_read_base = fp->_IO_backup_base;
  else
    {
      fp->_IO_read_base = fp->_IO_buf_base;
      if (fp->_IO_write_ptr > fp->_IO_read_end)
	fp->_IO_read_end = fp->_IO_write_ptr;
    }
  fp->_IO_read_ptr = fp->_IO_write_ptr;

  fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_write_end = fp->_IO_read_ptr;

  fp->_flags &= ~_IO_CURRENTLY_PUTTING;
  return 0;
}

void
DEFUN(_IO_free_backup_area, (fp),
     register _IO_FILE *fp)
{
  if (_IO_in_backup (fp))
    _IO_switch_to_main_get_area(fp);  /* Just in case. */
  free (fp->_IO_save_base);
  fp->_IO_save_base = NULL;
  fp->_IO_save_end = NULL;
  fp->_IO_backup_base = NULL;
}

#if 0
int
DEFUN(_IO_switch_to_put_mode, (fp),
      register _IO_FILE *fp)
{
  fp->_IO_write_base = fp->_IO_read_ptr;
  fp->_IO_write_ptr = fp->_IO_read_ptr;
  /* Following is wrong if line- or un-buffered? */
  fp->_IO_write_end = fp->_flags & _IO_IN_BACKUP ? fp->_IO_read_end : fp->_IO_buf_end;

  fp->_IO_read_ptr = fp->_IO_read_end;
  fp->_IO_read_base = fp->_IO_read_end;

  fp->_flags |= _IO_CURRENTLY_PUTTING;
  return 0;
}
#endif

int
DEFUN(__overflow, (f, ch),
      _IO_FILE *f AND int ch)
{
  return _IO_OVERFLOW (f, ch);
}

static int
DEFUN(save_for_backup, (fp),
      _IO_FILE *fp)
{
  /* Append [_IO_read_base.._IO_read_end] to backup area. */
  int least_mark = _IO_least_marker(fp);
  /* needed_size is how much space we need in the backup area. */
  int needed_size = (fp->_IO_read_end - fp->_IO_read_base) - least_mark;
  int current_Bsize = fp->_IO_save_end - fp->_IO_save_base;
  int avail; /* Extra space available for future expansion. */
  int delta;
  struct _IO_marker *mark;
  if (needed_size > current_Bsize)
    {
      char *new_buffer;
      avail = 100;
      new_buffer = (char*)malloc(avail+needed_size);
      if (new_buffer == NULL)
	return EOF;		/* FIXME */
      if (least_mark < 0)
	{
	  memcpy(new_buffer + avail,
		 fp->_IO_save_end + least_mark,
		 -least_mark);
	  memcpy(new_buffer +avail - least_mark,
		 fp->_IO_read_base,
		 fp->_IO_read_end - fp->_IO_read_base);
	}
      else
	memcpy(new_buffer + avail,
	       fp->_IO_read_base + least_mark,
	       needed_size);
      if (fp->_IO_save_base)
	free (fp->_IO_save_base);
      fp->_IO_save_base = new_buffer;
      fp->_IO_save_end = new_buffer + avail + needed_size;
    }
  else
    {
      avail = current_Bsize - needed_size;
      if (least_mark < 0)
	{
	  memmove(fp->_IO_save_base + avail,
		  fp->_IO_save_end + least_mark,
		  -least_mark);
	  memcpy(fp->_IO_save_base + avail - least_mark,
		 fp->_IO_read_base,
		 fp->_IO_read_end - fp->_IO_read_base);
	}
      else if (needed_size > 0)
	memcpy(fp->_IO_save_base + avail,
	       fp->_IO_read_base + least_mark,
	       needed_size);
    }
  /* FIXME: Dubious arithmetic if pointers are NULL */
  fp->_IO_backup_base = fp->_IO_save_base + avail;
  /* Adjust all the streammarkers. */
  delta = fp->_IO_read_end - fp->_IO_read_base;
  for (mark = fp->_markers; mark != NULL; mark = mark->_next)
    mark->_pos -= delta;
  return 0;
}

int
DEFUN(__underflow, (fp),
      _IO_FILE *fp)
{
  if (_IO_in_put_mode(fp))
    if (_IO_switch_to_get_mode(fp) == EOF) return EOF;
  if (fp->_IO_read_ptr < fp->_IO_read_end)
    return *(unsigned char*)fp->_IO_read_ptr;
  if (_IO_in_backup(fp))
    {
      _IO_switch_to_main_get_area(fp);
      if (fp->_IO_read_ptr < fp->_IO_read_end)
	return *fp->_IO_read_ptr;
    }
  if (_IO_have_markers(fp))
    {
      if (save_for_backup (fp))
	return EOF;
    }
  else if (_IO_have_backup(fp))
    _IO_free_backup_area(fp);
  return _IO_UNDERFLOW (fp);
}

int
DEFUN(__uflow, (fp),
     _IO_FILE *fp)
{
  if (_IO_in_put_mode(fp))
    if (_IO_switch_to_get_mode(fp) == EOF) return EOF;
  if (fp->_IO_read_ptr < fp->_IO_read_end)
    return *(unsigned char*)fp->_IO_read_ptr++;
  if (_IO_in_backup(fp))
    {
      _IO_switch_to_main_get_area(fp);
      if (fp->_IO_read_ptr < fp->_IO_read_end)
	return *fp->_IO_read_ptr++;
    }
  if (_IO_have_markers(fp))
    {
      if (save_for_backup (fp))
	return EOF;
    }
  else if (_IO_have_backup(fp))
    _IO_free_backup_area(fp);
  return _IO_UFLOW (fp);
}

void
DEFUN(_IO_setb, (f, b, eb, a),
      _IO_FILE *f AND char *b AND char *eb AND int a)
{
  if (f->_IO_buf_base && !(f->_flags & _IO_USER_BUF))
    FREE_BUF(f->_IO_buf_base);
  f->_IO_buf_base = b;
  f->_IO_buf_end = eb;
  if (a)
    f->_flags &= ~_IO_USER_BUF;
  else
    f->_flags |= _IO_USER_BUF;
}

void
DEFUN(_IO_doallocbuf, (fp),
      register _IO_FILE *fp)
{
  if (fp->_IO_buf_base)
    return;
  if (!(fp->_flags & _IO_UNBUFFERED))
    if (_IO_DOALLOCATE (fp) != EOF)
      return;
  _IO_setb(fp, fp->_shortbuf, fp->_shortbuf+1, 0);
}

int
DEFUN(_IO_default_underflow, (fp),
      _IO_FILE *fp)
{
  return EOF;
}

int
DEFUN(_IO_default_uflow, (fp),
      _IO_FILE *fp)
{
  int ch = _IO_UNDERFLOW (fp);
  if (ch == EOF)
    return EOF;
  return *(unsigned char*)fp->_IO_read_ptr++;
}

_IO_size_t
DEFUN(_IO_default_xsputn, (f, data, n),
      register _IO_FILE *f AND const void *data AND _IO_size_t n)
{
  register const char *s = (char*) data;
  register _IO_size_t more = n;
  if (more <= 0)
    return 0;
  for (;;)
    {
      _IO_ssize_t count = f->_IO_write_end - f->_IO_write_ptr; /* Space available. */
      if (count > 0)
	{
	  if ((_IO_size_t) count > more)
	    count = more;
	  if (count > 20)
	    {
	      memcpy(f->_IO_write_ptr, s, count);
	      s += count;
	      f->_IO_write_ptr += count;
            }
	  else if (count <= 0)
	    count = 0;
	  else
	    {
	      register char *p = f->_IO_write_ptr;
	      register _IO_ssize_t i;
	      for (i = count; --i >= 0; ) *p++ = *s++;
	      f->_IO_write_ptr = p;
            }
	  more -= count;
        }
      if (more == 0 || __overflow(f, (unsigned char)*s++) == EOF)
	break;
      more--;
    }
  return n - more;
}

_IO_size_t
DEFUN(_IO_sgetn, (fp, data, n),
      _IO_FILE *fp AND void *data AND _IO_size_t n)
{
  /* FIXME handle putback buffer here! */
  return _IO_XSGETN (fp, data, n);
}

_IO_size_t
DEFUN(_IO_default_xsgetn, (fp, data, n),
      _IO_FILE *fp AND void *data AND _IO_size_t n)
{
  register _IO_size_t more = n;
  register char *s = (char*) data;
  for (;;)
    {
      _IO_ssize_t count = fp->_IO_read_end - fp->_IO_read_ptr; /* Data available. */
      if (count > 0)
	{
	  if ((_IO_size_t) count > more)
	    count = more;
	  if (count > 20)
	    {
	      memcpy(s, fp->_IO_read_ptr, count);
	      s += count;
	      fp->_IO_read_ptr += count;
	    }
	  else if (count <= 0)
	    count = 0;
	  else
	    {
	      register char *p = fp->_IO_read_ptr;
	      register int i = (int)count;
	      while (--i >= 0) *s++ = *p++;
	      fp->_IO_read_ptr = p;
            }
            more -= count;
        }
      if (more == 0 || __underflow(fp) == EOF)
	break;
    }
  return n - more;
}

int
DEFUN(_IO_sync, (fp),
      register _IO_FILE *fp)
{
  return 0;
}

_IO_FILE*
DEFUN(_IO_default_setbuf, (fp, p, len),
      register _IO_FILE *fp AND char* p AND _IO_ssize_t len)
{
    if (_IO_SYNC (fp) == EOF)
	return NULL;
    if (p == NULL || len == 0)
      {
	fp->_flags |= _IO_UNBUFFERED;
	_IO_setb(fp, fp->_shortbuf, fp->_shortbuf+1, 0);
      }
    else
      {
	fp->_flags &= ~_IO_UNBUFFERED;
	_IO_setb(fp, p, p+len, 0);
      }
    fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_write_end = 0;
    fp->_IO_read_base = fp->_IO_read_ptr = fp->_IO_read_end = 0;
    return fp;
}

_IO_pos_t
DEFUN(_IO_default_seekpos, (fp, pos, mode),
      _IO_FILE *fp AND _IO_pos_t pos AND int mode)
{
  return _IO_SEEKOFF (fp, _IO_pos_as_off(pos), 0, mode);
}

int
DEFUN(_IO_default_doallocate, (fp),
      _IO_FILE *fp)
{
  char *buf = ALLOC_BUF(_IO_BUFSIZ);
  if (buf == NULL)
    return EOF;
  _IO_setb(fp, buf, buf+_IO_BUFSIZ, 1);
  return 1;
}

void
DEFUN(_IO_init, (fp, flags),
      register _IO_FILE *fp AND int flags)
{
  fp->_flags = _IO_MAGIC|flags;
  fp->_IO_buf_base = NULL;
  fp->_IO_buf_end = NULL;
  fp->_IO_read_base = NULL;
  fp->_IO_read_ptr = NULL;
  fp->_IO_read_end = NULL;
  fp->_IO_write_base = NULL;
  fp->_IO_write_ptr = NULL;
  fp->_IO_write_end = NULL;
  fp->_chain = NULL; /* Not necessary. */

  fp->_IO_save_base = NULL;
  fp->_IO_backup_base = NULL;
  fp->_IO_save_end = NULL;
  fp->_markers = NULL;
  fp->_cur_column = 0;
#ifdef _IO_MTSAFE_IO
  __libc_lock_init (*fp->_lock);
#endif
}

int
DEFUN(_IO_default_sync, (fp),
      _IO_FILE *fp)
{
  return 0;
}

/* The way the C++ classes are mapped into the C functions in the
   current implementation, this function can get called twice! */

void
DEFUN(_IO_default_finish, (fp),
      _IO_FILE *fp)
{
  struct _IO_marker *mark;
  if (fp->_IO_buf_base && !(fp->_flags & _IO_USER_BUF))
    {
      FREE_BUF(fp->_IO_buf_base);
      fp->_IO_buf_base = fp->_IO_buf_end = NULL;
    }

  for (mark = fp->_markers; mark != NULL; mark = mark->_next)
    mark->_sbuf = NULL;

  if (fp->_IO_save_base)
    {
      free (fp->_IO_save_base);
      fp->_IO_save_base = NULL;
    }

#ifdef _IO_MTSAFE_IO
  __libc_lock_fini (*fp->_lock);
#endif

  _IO_un_link(fp);
}

_IO_pos_t
DEFUN(_IO_default_seekoff, (fp, offset, dir, mode),
      register _IO_FILE *fp AND _IO_off_t offset AND int dir AND int mode)
{
    return _IO_pos_BAD;
}

int
DEFUN(_IO_sputbackc, (fp, c),
      register _IO_FILE *fp AND int c)
{
  int result;

  if (fp->_IO_read_ptr > fp->_IO_read_base
      && (unsigned char)fp->_IO_read_ptr[-1] == (unsigned char)c)
    {
      fp->_IO_read_ptr--;
      result = (unsigned char)c;
    }
  else
    result = _IO_PBACKFAIL (fp, c);

  if (result != EOF)
    fp->_flags &= ~_IO_EOF_SEEN;

  return result;
}

int
DEFUN(_IO_sungetc, (fp),
      register _IO_FILE *fp)
{
  int result;

  if (fp->_IO_read_ptr > fp->_IO_read_base)
    {
      fp->_IO_read_ptr--;
      result = (unsigned char)*fp->_IO_read_ptr;
    }
  else
    result = _IO_PBACKFAIL (fp, EOF);

  if (result != EOF)
    fp->_flags &= ~_IO_EOF_SEEN;

  return result;
}

#if 0 /* Work in progress */
void
DEFUN(_IO_set_column, (fp, c),
      register _IO_FILE *fp AND int c)
{
  if (c == -1)
    fp->_column = -1;
  else
    fp->_column = c - (fp->_IO_write_ptr - fp->_IO_write_base);
}
#else
int
DEFUN(_IO_set_column, (fp, i),
      register _IO_FILE *fp AND int i)
{
  fp->_cur_column = i+1;
  return 0;
}
#endif


unsigned
DEFUN(_IO_adjust_column, (start, line, count),
      unsigned start AND const char *line AND int count)
{
  register const char *ptr = line + count;
  while (ptr > line)
    if (*--ptr == '\n')
      return line + count - ptr - 1;
  return start + count;
}

int
DEFUN(_IO_get_column, (fp),
      register _IO_FILE *fp)
{
  if (fp->_cur_column)
    return _IO_adjust_column(fp->_cur_column - 1,
			      fp->_IO_write_base,
			      fp->_IO_write_ptr - fp->_IO_write_base);
  return -1;
}

int
DEFUN_VOID(_IO_flush_all)
{
  int result = 0;
  _IO_FILE *fp;
  for (fp = _IO_list_all; fp != NULL; fp = fp->_chain)
    if (fp->_IO_write_ptr > fp->_IO_write_base
	&& _IO_OVERFLOW (fp, EOF) == EOF)
      result = EOF;
  return result;
}

void
DEFUN_VOID(_IO_flush_all_linebuffered)
{
  _IO_FILE *fp;
  for (fp = _IO_list_all; fp != NULL; fp = fp->_chain)
    if (fp->_flags & _IO_LINE_BUF)
      _IO_OVERFLOW (fp, EOF);
}

void
DEFUN_VOID(_IO_unbuffer_all)
{
  _IO_FILE *fp;
  for (fp = _IO_list_all; fp != NULL; fp = fp->_chain)
    if (! (fp->_flags & _IO_UNBUFFERED))
      _IO_SETBUF (fp, NULL, 0);
}

void
DEFUN_VOID(_IO_cleanup)
{
  _IO_flush_all ();

  /* We currently don't have a reliable mechanism for making sure that
     C++ static destructors are executed in the correct order.
     So it is possible that other static destructord might want to
     write to cout - and they're supposed to be able to do so.

     The following will make the standard streambufs be unbuffered,
     which forces any output from late destructors to be written out. */
  _IO_unbuffer_all ();
}

void
DEFUN(_IO_init_marker, (marker, fp),
      struct _IO_marker *marker AND _IO_FILE *fp)
{
  marker->_sbuf = fp;
  if (_IO_in_put_mode(fp))
    _IO_switch_to_get_mode(fp);
  if (_IO_in_backup(fp))
    marker->_pos = fp->_IO_read_ptr - fp->_IO_read_end;
  else
    marker->_pos = fp->_IO_read_ptr - fp->_IO_read_base;

  /* Should perhaps sort the chain? */
  marker->_next = fp->_markers;
  fp->_markers = marker;
}

void
DEFUN(_IO_remove_marker, (marker),
      register struct _IO_marker *marker)
{
  /* Unlink from sb's chain. */
  register struct _IO_marker **ptr = &marker->_sbuf->_markers;
  for (; ; ptr = &(*ptr)->_next)
    {
      if (*ptr == NULL)
	break;
      else if (*ptr == marker)
	{
	  *ptr = marker->_next;
	  return;
	}
    }
#if 0
    if _sbuf has a backup area that is no longer needed, should we delete
    it now, or wait until the next underflow?
#endif
}

#define BAD_DELTA EOF

int
DEFUN(_IO_marker_difference, (mark1, mark2),
      struct _IO_marker *mark1 AND struct _IO_marker *mark2)
{
  return mark1->_pos - mark2->_pos;
}

/* Return difference between MARK and current posistion of MARK's stream. */
int
DEFUN(_IO_marker_delta, (mark),
      struct _IO_marker *mark)
{
  int cur_pos;
  if (mark->_sbuf == NULL)
    return BAD_DELTA;
  if (_IO_in_backup(mark->_sbuf))
    cur_pos = mark->_sbuf->_IO_read_ptr - mark->_sbuf->_IO_read_end;
  else
    cur_pos = mark->_sbuf->_IO_read_ptr - mark->_sbuf->_IO_read_base;
  return mark->_pos - cur_pos;
}

int
DEFUN(_IO_seekmark, (fp, mark, delta),
      _IO_FILE *fp AND struct _IO_marker *mark AND int delta)
{
  if (mark->_sbuf != fp)
    return EOF;
 if (mark->_pos >= 0)
    {
      if (_IO_in_backup(fp))
	_IO_switch_to_main_get_area(fp);
      fp->_IO_read_ptr = fp->_IO_read_base + mark->_pos;
    }
  else
    {
      if (!_IO_in_backup(fp))
	_IO_switch_to_backup_area(fp);
      fp->_IO_read_ptr = fp->_IO_read_end + mark->_pos;
    }
  return 0;
}

void
DEFUN(_IO_unsave_markers, (fp),
     register _IO_FILE *fp)
{
  register struct _IO_marker *mark = fp->_markers;
  if (mark)
    {
#ifdef TODO
      streampos offset = seekoff(0, ios::cur, ios::in);
      if (offset != EOF)
	{
	  offset += eGptr() - Gbase();
	  for ( ; mark != NULL; mark = mark->_next)
	    mark->set_streampos(mark->_pos + offset);
	}
    else
      {
	for ( ; mark != NULL; mark = mark->_next)
	  mark->set_streampos(EOF);
      }
#endif
      fp->_markers = 0;
    }

  if (_IO_have_backup(fp))
    _IO_free_backup_area(fp);
}

int
DEFUN(_IO_nobackup_pbackfail, (fp, c),
     register _IO_FILE *fp AND int c)
{
  if (fp->_IO_read_ptr > fp->_IO_read_base)
	fp->_IO_read_ptr--;
  if (c != EOF && *fp->_IO_read_ptr != c)
      *fp->_IO_read_ptr = c;
  return (unsigned char)c;
}

int
DEFUN(_IO_default_pbackfail, (fp, c),
      register _IO_FILE *fp AND int c)
{
  if (fp->_IO_read_ptr <= fp->_IO_read_base)
      {
	/* Need to handle a filebuf in write mode (switch to read mode). FIXME!*/
	if (_IO_have_backup(fp) && !_IO_in_backup(fp))
	  _IO_switch_to_backup_area(fp);

	if (!_IO_have_backup(fp))
	  {
	    /* No backup buffer: allocate one. */
	    /* Use nshort buffer, if unused? (probably not)  FIXME */
	    int backup_size = 128;
	    char *bbuf = (char*)malloc(backup_size);
	    if (bbuf == NULL)
	      return EOF;
	    fp->_IO_save_base = bbuf;
	    fp->_IO_save_end = fp->_IO_save_base + backup_size;
	    fp->_IO_backup_base = fp->_IO_save_end;
	    _IO_switch_to_backup_area(fp);
	  }
	else if (fp->_IO_read_ptr <= fp->_IO_read_base)
	  {
	    /* Increase size of existing backup buffer. */
	    _IO_size_t new_size;
	    _IO_size_t old_size = fp->_IO_read_end - fp->_IO_read_base;
	    char *new_buf;
	    new_size = 2 * old_size;
	    new_buf = (char*)malloc(new_size);
	    if (new_buf == NULL)
	      return EOF;
	    memcpy(new_buf+(new_size-old_size), fp->_IO_read_base, old_size);
	    free (fp->_IO_read_base);
	    _IO_setg(fp,
		     new_buf, new_buf+(new_size-old_size), new_buf+new_size);
	    fp->_IO_backup_base = fp->_IO_read_ptr;
	  }
      }
  fp->_IO_read_ptr--;
  if (c != EOF && *fp->_IO_read_ptr != c)
    *fp->_IO_read_ptr = c;
  return (unsigned char)*fp->_IO_read_ptr;
}

_IO_pos_t
DEFUN(_IO_default_seek, (fp, offset, dir),
      _IO_FILE *fp AND _IO_off_t offset AND int dir)
{
  return _IO_pos_BAD;
}

int
DEFUN(_IO_default_stat, (fp, st),
      _IO_FILE *fp AND void* st)
{
  return EOF;
}

_IO_ssize_t
DEFUN(_IO_default_read, (fp, data, n),
      register _IO_FILE* fp AND void* data AND _IO_ssize_t n)
{
  return -1;
}

_IO_ssize_t
DEFUN(_IO_default_write, (fp, data, n),
      register _IO_FILE* fp AND const void* data AND _IO_ssize_t n)
{
  return 0;
}


#ifdef TODO
#if defined(linux)
#define IO_CLEANUP ;
#endif

#ifdef IO_CLEANUP
  IO_CLEANUP
#else
struct __io_defs {
    __io_defs() { }
    ~__io_defs() { _IO_cleanup(); }
};
__io_defs io_defs__;
#endif

#endif /* TODO */

#ifdef weak_alias
weak_alias (_IO_cleanup, _cleanup)
#endif