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[/] [openrisc/] [trunk/] [gnu-old/] [binutils-2.18.50/] [bfd/] [cache.c] - Blame information for rev 824

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/* BFD library -- caching of file descriptors.
2
 
3
   Copyright 1990, 1991, 1992, 1993, 1994, 1996, 2000, 2001, 2002,
4
   2003, 2004, 2005, 2007 Free Software Foundation, Inc.
5
 
6
   Hacked by Steve Chamberlain of Cygnus Support (steve@cygnus.com).
7
 
8
   This file is part of BFD, the Binary File Descriptor library.
9
 
10
   This program is free software; you can redistribute it and/or modify
11
   it under the terms of the GNU General Public License as published by
12
   the Free Software Foundation; either version 3 of the License, or
13
   (at your option) any later version.
14
 
15
   This program is distributed in the hope that it will be useful,
16
   but WITHOUT ANY WARRANTY; without even the implied warranty of
17
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18
   GNU General Public License for more details.
19
 
20
   You should have received a copy of the GNU General Public License
21
   along with this program; if not, write to the Free Software
22
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
23
   MA 02110-1301, USA.  */
24
 
25
/*
26
SECTION
27
        File caching
28
 
29
        The file caching mechanism is embedded within BFD and allows
30
        the application to open as many BFDs as it wants without
31
        regard to the underlying operating system's file descriptor
32
        limit (often as low as 20 open files).  The module in
33
        <<cache.c>> maintains a least recently used list of
34
        <<BFD_CACHE_MAX_OPEN>> files, and exports the name
35
        <<bfd_cache_lookup>>, which runs around and makes sure that
36
        the required BFD is open. If not, then it chooses a file to
37
        close, closes it and opens the one wanted, returning its file
38
        handle.
39
 
40
SUBSECTION
41
        Caching functions
42
*/
43
 
44
#include "sysdep.h"
45
#include "bfd.h"
46
#include "libbfd.h"
47
#include "libiberty.h"
48
 
49
/* In some cases we can optimize cache operation when reopening files.
50
   For instance, a flush is entirely unnecessary if the file is already
51
   closed, so a flush would use CACHE_NO_OPEN.  Similarly, a seek using
52
   SEEK_SET or SEEK_END need not first seek to the current position.
53
   For stat we ignore seek errors, just in case the file has changed
54
   while we weren't looking.  If it has, then it's possible that the
55
   file is shorter and we don't want a seek error to prevent us doing
56
   the stat.  */
57
enum cache_flag {
58
  CACHE_NORMAL = 0,
59
  CACHE_NO_OPEN = 1,
60
  CACHE_NO_SEEK = 2,
61
  CACHE_NO_SEEK_ERROR = 4
62
};
63
 
64
/* The maximum number of files which the cache will keep open at
65
   one time.  */
66
 
67
#define BFD_CACHE_MAX_OPEN 10
68
 
69
/* The number of BFD files we have open.  */
70
 
71
static int open_files;
72
 
73
/* Zero, or a pointer to the topmost BFD on the chain.  This is
74
   used by the <<bfd_cache_lookup>> macro in @file{libbfd.h} to
75
   determine when it can avoid a function call.  */
76
 
77
static bfd *bfd_last_cache = NULL;
78
 
79
/* Insert a BFD into the cache.  */
80
 
81
static void
82
insert (bfd *abfd)
83
{
84
  if (bfd_last_cache == NULL)
85
    {
86
      abfd->lru_next = abfd;
87
      abfd->lru_prev = abfd;
88
    }
89
  else
90
    {
91
      abfd->lru_next = bfd_last_cache;
92
      abfd->lru_prev = bfd_last_cache->lru_prev;
93
      abfd->lru_prev->lru_next = abfd;
94
      abfd->lru_next->lru_prev = abfd;
95
    }
96
  bfd_last_cache = abfd;
97
}
98
 
99
/* Remove a BFD from the cache.  */
100
 
101
static void
102
snip (bfd *abfd)
103
{
104
  abfd->lru_prev->lru_next = abfd->lru_next;
105
  abfd->lru_next->lru_prev = abfd->lru_prev;
106
  if (abfd == bfd_last_cache)
107
    {
108
      bfd_last_cache = abfd->lru_next;
109
      if (abfd == bfd_last_cache)
110
        bfd_last_cache = NULL;
111
    }
112
}
113
 
114
/* Close a BFD and remove it from the cache.  */
115
 
116
static bfd_boolean
117
bfd_cache_delete (bfd *abfd)
118
{
119
  bfd_boolean ret;
120
 
121
  if (fclose ((FILE *) abfd->iostream) == 0)
122
    ret = TRUE;
123
  else
124
    {
125
      ret = FALSE;
126
      bfd_set_error (bfd_error_system_call);
127
    }
128
 
129
  snip (abfd);
130
 
131
  abfd->iostream = NULL;
132
  --open_files;
133
 
134
  return ret;
135
}
136
 
137
/* We need to open a new file, and the cache is full.  Find the least
138
   recently used cacheable BFD and close it.  */
139
 
140
static bfd_boolean
141
close_one (void)
142
{
143
  register bfd *kill;
144
 
145
  if (bfd_last_cache == NULL)
146
    kill = NULL;
147
  else
148
    {
149
      for (kill = bfd_last_cache->lru_prev;
150
           ! kill->cacheable;
151
           kill = kill->lru_prev)
152
        {
153
          if (kill == bfd_last_cache)
154
            {
155
              kill = NULL;
156
              break;
157
            }
158
        }
159
    }
160
 
161
  if (kill == NULL)
162
    {
163
      /* There are no open cacheable BFD's.  */
164
      return TRUE;
165
    }
166
 
167
  kill->where = real_ftell ((FILE *) kill->iostream);
168
 
169
  return bfd_cache_delete (kill);
170
}
171
 
172
/* Check to see if the required BFD is the same as the last one
173
   looked up. If so, then it can use the stream in the BFD with
174
   impunity, since it can't have changed since the last lookup;
175
   otherwise, it has to perform the complicated lookup function.  */
176
 
177
#define bfd_cache_lookup(x, flag) \
178
  ((x) == bfd_last_cache                        \
179
   ? (FILE *) (bfd_last_cache->iostream)        \
180
   : bfd_cache_lookup_worker (x, flag))
181
 
182
/* Called when the macro <<bfd_cache_lookup>> fails to find a
183
   quick answer.  Find a file descriptor for @var{abfd}.  If
184
   necessary, it open it.  If there are already more than
185
   <<BFD_CACHE_MAX_OPEN>> files open, it tries to close one first, to
186
   avoid running out of file descriptors.  It will return NULL
187
   if it is unable to (re)open the @var{abfd}.  */
188
 
189
static FILE *
190
bfd_cache_lookup_worker (bfd *abfd, enum cache_flag flag)
191
{
192
  bfd *orig_bfd = abfd;
193
  if ((abfd->flags & BFD_IN_MEMORY) != 0)
194
    abort ();
195
 
196
  if (abfd->my_archive)
197
    abfd = abfd->my_archive;
198
 
199
  if (abfd->iostream != NULL)
200
    {
201
      /* Move the file to the start of the cache.  */
202
      if (abfd != bfd_last_cache)
203
        {
204
          snip (abfd);
205
          insert (abfd);
206
        }
207
      return (FILE *) abfd->iostream;
208
    }
209
 
210
  if (flag & CACHE_NO_OPEN)
211
    return NULL;
212
 
213
  if (bfd_open_file (abfd) == NULL)
214
    ;
215
  else if (!(flag & CACHE_NO_SEEK)
216
           && real_fseek ((FILE *) abfd->iostream, abfd->where, SEEK_SET) != 0
217
           && !(flag & CACHE_NO_SEEK_ERROR))
218
    bfd_set_error (bfd_error_system_call);
219
  else
220
    return (FILE *) abfd->iostream;
221
 
222
  (*_bfd_error_handler) (_("reopening %B: %s\n"),
223
                         orig_bfd, bfd_errmsg (bfd_get_error ()));
224
  return NULL;
225
}
226
 
227
static file_ptr
228
cache_btell (struct bfd *abfd)
229
{
230
  FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN);
231
  if (f == NULL)
232
    return abfd->where;
233
  return real_ftell (f);
234
}
235
 
236
static int
237
cache_bseek (struct bfd *abfd, file_ptr offset, int whence)
238
{
239
  FILE *f = bfd_cache_lookup (abfd, whence != SEEK_CUR ? CACHE_NO_SEEK : 0);
240
  if (f == NULL)
241
    return -1;
242
  return real_fseek (f, offset, whence);
243
}
244
 
245
/* Note that archive entries don't have streams; they share their parent's.
246
   This allows someone to play with the iostream behind BFD's back.
247
 
248
   Also, note that the origin pointer points to the beginning of a file's
249
   contents (0 for non-archive elements).  For archive entries this is the
250
   first octet in the file, NOT the beginning of the archive header.  */
251
 
252
static file_ptr
253
cache_bread_1 (struct bfd *abfd, void *buf, file_ptr nbytes)
254
{
255
  FILE *f;
256
  file_ptr nread;
257
  /* FIXME - this looks like an optimization, but it's really to cover
258
     up for a feature of some OSs (not solaris - sigh) that
259
     ld/pe-dll.c takes advantage of (apparently) when it creates BFDs
260
     internally and tries to link against them.  BFD seems to be smart
261
     enough to realize there are no symbol records in the "file" that
262
     doesn't exist but attempts to read them anyway.  On Solaris,
263
     attempting to read zero bytes from a NULL file results in a core
264
     dump, but on other platforms it just returns zero bytes read.
265
     This makes it to something reasonable. - DJ */
266
  if (nbytes == 0)
267
    return 0;
268
 
269
  f = bfd_cache_lookup (abfd, 0);
270
  if (f == NULL)
271
    return 0;
272
 
273
#if defined (__VAX) && defined (VMS)
274
  /* Apparently fread on Vax VMS does not keep the record length
275
     information.  */
276
  nread = read (fileno (f), buf, nbytes);
277
  /* Set bfd_error if we did not read as much data as we expected.  If
278
     the read failed due to an error set the bfd_error_system_call,
279
     else set bfd_error_file_truncated.  */
280
  if (nread == (file_ptr)-1)
281
    {
282
      bfd_set_error (bfd_error_system_call);
283
      return -1;
284
    }
285
#else
286
  nread = fread (buf, 1, nbytes, f);
287
  /* Set bfd_error if we did not read as much data as we expected.  If
288
     the read failed due to an error set the bfd_error_system_call,
289
     else set bfd_error_file_truncated.  */
290
  if (nread < nbytes && ferror (f))
291
    {
292
      bfd_set_error (bfd_error_system_call);
293
      return -1;
294
    }
295
#endif
296
  if (nread < nbytes)
297
    /* This may or may not be an error, but in case the calling code
298
       bails out because of it, set the right error code.  */
299
    bfd_set_error (bfd_error_file_truncated);
300
  return nread;
301
}
302
 
303
static file_ptr
304
cache_bread (struct bfd *abfd, void *buf, file_ptr nbytes)
305
{
306
  file_ptr nread = 0;
307
 
308
  /* Some filesystems are unable to handle reads that are too large
309
     (for instance, NetApp shares with oplocks turned off).  To avoid
310
     hitting this limitation, we read the buffer in chunks of 8MB max.  */
311
  while (nread < nbytes)
312
    {
313
      const file_ptr max_chunk_size = 0x800000;
314
      file_ptr chunk_size = nbytes - nread;
315
      file_ptr chunk_nread;
316
 
317
      if (chunk_size > max_chunk_size)
318
        chunk_size = max_chunk_size;
319
 
320
      chunk_nread = cache_bread_1 (abfd, buf + nread, chunk_size);
321
 
322
      /* Update the nread count.
323
 
324
         We just have to be careful of the case when cache_bread_1 returns
325
         a negative count:  If this is our first read, then set nread to
326
         that negative count in order to return that negative value to the
327
         caller.  Otherwise, don't add it to our total count, or we would
328
         end up returning a smaller number of bytes read than we actually
329
         did.  */
330
      if (nread == 0 || chunk_nread > 0)
331
        nread += chunk_nread;
332
 
333
      if (chunk_nread < chunk_size)
334
        break;
335
    }
336
 
337
  return nread;
338
}
339
 
340
static file_ptr
341
cache_bwrite (struct bfd *abfd, const void *where, file_ptr nbytes)
342
{
343
  file_ptr nwrite;
344
  FILE *f = bfd_cache_lookup (abfd, 0);
345
  if (f == NULL)
346
    return 0;
347
  nwrite = fwrite (where, 1, nbytes, f);
348
  if (nwrite < nbytes && ferror (f))
349
    {
350
      bfd_set_error (bfd_error_system_call);
351
      return -1;
352
    }
353
  return nwrite;
354
}
355
 
356
static int
357
cache_bclose (struct bfd *abfd)
358
{
359
  return bfd_cache_close (abfd);
360
}
361
 
362
static int
363
cache_bflush (struct bfd *abfd)
364
{
365
  int sts;
366
  FILE *f = bfd_cache_lookup (abfd, CACHE_NO_OPEN);
367
  if (f == NULL)
368
    return 0;
369
  sts = fflush (f);
370
  if (sts < 0)
371
    bfd_set_error (bfd_error_system_call);
372
  return sts;
373
}
374
 
375
static int
376
cache_bstat (struct bfd *abfd, struct stat *sb)
377
{
378
  int sts;
379
  FILE *f = bfd_cache_lookup (abfd, CACHE_NO_SEEK_ERROR);
380
  if (f == NULL)
381
    return -1;
382
  sts = fstat (fileno (f), sb);
383
  if (sts < 0)
384
    bfd_set_error (bfd_error_system_call);
385
  return sts;
386
}
387
 
388
static const struct bfd_iovec cache_iovec = {
389
  &cache_bread, &cache_bwrite, &cache_btell, &cache_bseek,
390
  &cache_bclose, &cache_bflush, &cache_bstat
391
};
392
 
393
/*
394
INTERNAL_FUNCTION
395
        bfd_cache_init
396
 
397
SYNOPSIS
398
        bfd_boolean bfd_cache_init (bfd *abfd);
399
 
400
DESCRIPTION
401
        Add a newly opened BFD to the cache.
402
*/
403
 
404
bfd_boolean
405
bfd_cache_init (bfd *abfd)
406
{
407
  BFD_ASSERT (abfd->iostream != NULL);
408
  if (open_files >= BFD_CACHE_MAX_OPEN)
409
    {
410
      if (! close_one ())
411
        return FALSE;
412
    }
413
  abfd->iovec = &cache_iovec;
414
  insert (abfd);
415
  ++open_files;
416
  return TRUE;
417
}
418
 
419
/*
420
INTERNAL_FUNCTION
421
        bfd_cache_close
422
 
423
SYNOPSIS
424
        bfd_boolean bfd_cache_close (bfd *abfd);
425
 
426
DESCRIPTION
427
        Remove the BFD @var{abfd} from the cache. If the attached file is open,
428
        then close it too.
429
 
430
RETURNS
431
        <<FALSE>> is returned if closing the file fails, <<TRUE>> is
432
        returned if all is well.
433
*/
434
 
435
bfd_boolean
436
bfd_cache_close (bfd *abfd)
437
{
438
  if (abfd->iovec != &cache_iovec)
439
    return TRUE;
440
 
441
  if (abfd->iostream == NULL)
442
    /* Previously closed.  */
443
    return TRUE;
444
 
445
  return bfd_cache_delete (abfd);
446
}
447
 
448
/*
449
FUNCTION
450
        bfd_cache_close_all
451
 
452
SYNOPSIS
453
        bfd_boolean bfd_cache_close_all (void);
454
 
455
DESCRIPTION
456
        Remove all BFDs from the cache. If the attached file is open,
457
        then close it too.
458
 
459
RETURNS
460
        <<FALSE>> is returned if closing one of the file fails, <<TRUE>> is
461
        returned if all is well.
462
*/
463
 
464
bfd_boolean
465
bfd_cache_close_all ()
466
{
467
  bfd_boolean ret = TRUE;
468
 
469
  while (bfd_last_cache != NULL)
470
    ret &= bfd_cache_close (bfd_last_cache);
471
 
472
  return ret;
473
}
474
 
475
/*
476
INTERNAL_FUNCTION
477
        bfd_open_file
478
 
479
SYNOPSIS
480
        FILE* bfd_open_file (bfd *abfd);
481
 
482
DESCRIPTION
483
        Call the OS to open a file for @var{abfd}.  Return the <<FILE *>>
484
        (possibly <<NULL>>) that results from this operation.  Set up the
485
        BFD so that future accesses know the file is open. If the <<FILE *>>
486
        returned is <<NULL>>, then it won't have been put in the
487
        cache, so it won't have to be removed from it.
488
*/
489
 
490
FILE *
491
bfd_open_file (bfd *abfd)
492
{
493
  abfd->cacheable = TRUE;       /* Allow it to be closed later.  */
494
 
495
  if (open_files >= BFD_CACHE_MAX_OPEN)
496
    {
497
      if (! close_one ())
498
        return NULL;
499
    }
500
 
501
  switch (abfd->direction)
502
    {
503
    case read_direction:
504
    case no_direction:
505
      abfd->iostream = (PTR) real_fopen (abfd->filename, FOPEN_RB);
506
      break;
507
    case both_direction:
508
    case write_direction:
509
      if (abfd->opened_once)
510
        {
511
          abfd->iostream = (PTR) real_fopen (abfd->filename, FOPEN_RUB);
512
          if (abfd->iostream == NULL)
513
            abfd->iostream = (PTR) real_fopen (abfd->filename, FOPEN_WUB);
514
        }
515
      else
516
        {
517
          /* Create the file.
518
 
519
             Some operating systems won't let us overwrite a running
520
             binary.  For them, we want to unlink the file first.
521
 
522
             However, gcc 2.95 will create temporary files using
523
             O_EXCL and tight permissions to prevent other users from
524
             substituting other .o files during the compilation.  gcc
525
             will then tell the assembler to use the newly created
526
             file as an output file.  If we unlink the file here, we
527
             open a brief window when another user could still
528
             substitute a file.
529
 
530
             So we unlink the output file if and only if it has
531
             non-zero size.  */
532
#ifndef __MSDOS__
533
          /* Don't do this for MSDOS: it doesn't care about overwriting
534
             a running binary, but if this file is already open by
535
             another BFD, we will be in deep trouble if we delete an
536
             open file.  In fact, objdump does just that if invoked with
537
             the --info option.  */
538
          struct stat s;
539
 
540
          if (stat (abfd->filename, &s) == 0 && s.st_size != 0)
541
            unlink_if_ordinary (abfd->filename);
542
#endif
543
          abfd->iostream = (PTR) real_fopen (abfd->filename, FOPEN_WUB);
544
          abfd->opened_once = TRUE;
545
        }
546
      break;
547
    }
548
 
549
  if (abfd->iostream == NULL)
550
    bfd_set_error (bfd_error_system_call);
551
  else
552
    {
553
      if (! bfd_cache_init (abfd))
554
        return NULL;
555
    }
556
 
557
  return (FILE *) abfd->iostream;
558
}

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