aboutsummaryrefslogtreecommitdiff
path: root/bfd/compress.c
blob: d06f2fe28fac4df0bbbf1ca47622c3f5aa22996a (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
/* Compressed section support (intended for debug sections).
   Copyright (C) 2008-2017 Free Software Foundation, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

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

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

#include "sysdep.h"
#include <zlib.h>
#include "bfd.h"
#include "libbfd.h"
#include "safe-ctype.h"

#define MAX_COMPRESSION_HEADER_SIZE 24

static bfd_boolean
decompress_contents (bfd_byte *compressed_buffer,
		     bfd_size_type compressed_size,
		     bfd_byte *uncompressed_buffer,
		     bfd_size_type uncompressed_size)
{
  z_stream strm;
  int rc;

  /* It is possible the section consists of several compressed
     buffers concatenated together, so we uncompress in a loop.  */
  /* PR 18313: The state field in the z_stream structure is supposed
     to be invisible to the user (ie us), but some compilers will
     still complain about it being used without initialisation.  So
     we first zero the entire z_stream structure and then set the fields
     that we need.  */
  memset (& strm, 0, sizeof strm);
  strm.avail_in = compressed_size;
  strm.next_in = (Bytef*) compressed_buffer;
  strm.avail_out = uncompressed_size;

  BFD_ASSERT (Z_OK == 0);
  rc = inflateInit (&strm);
  while (strm.avail_in > 0 && strm.avail_out > 0)
    {
      if (rc != Z_OK)
	break;
      strm.next_out = ((Bytef*) uncompressed_buffer
                       + (uncompressed_size - strm.avail_out));
      rc = inflate (&strm, Z_FINISH);
      if (rc != Z_STREAM_END)
	break;
      rc = inflateReset (&strm);
    }
  rc |= inflateEnd (&strm);
  return rc == Z_OK && strm.avail_out == 0;
}

/* Compress data of the size specified in @var{uncompressed_size}
   and pointed to by @var{uncompressed_buffer} using zlib and store
   as the contents field.  This function assumes the contents
   field was allocated using bfd_malloc() or equivalent.

   Return the uncompressed size if the full section contents is
   compressed successfully.  Otherwise return 0.  */

static bfd_size_type
bfd_compress_section_contents (bfd *abfd, sec_ptr sec,
			       bfd_byte *uncompressed_buffer,
			       bfd_size_type uncompressed_size)
{
  uLong compressed_size;
  bfd_byte *buffer;
  bfd_size_type buffer_size;
  bfd_boolean decompress;
  int zlib_size = 0;
  int orig_compression_header_size;
  bfd_size_type orig_uncompressed_size;
  int header_size = bfd_get_compression_header_size (abfd, NULL);
  bfd_boolean compressed
    = bfd_is_section_compressed_with_header (abfd, sec,
					     &orig_compression_header_size,
					     &orig_uncompressed_size);

  /* Either ELF compression header or the 12-byte, "ZLIB" + 8-byte size,
     overhead in .zdebug* section.  */
  if (!header_size)
     header_size = 12;

  if (compressed)
    {
      /* We shouldn't decompress unsupported compressed section.  */
      if (orig_compression_header_size < 0)
	abort ();

      /* Different compression schemes.  Just move the compressed section
	 contents to the right position. */
      if (orig_compression_header_size == 0)
	{
	  /* Convert it from .zdebug* section.  Get the uncompressed
	     size first.  We need to subtract the 12-byte overhead in
	     .zdebug* section.  Set orig_compression_header_size to
	     the 12-bye overhead.  */
	  orig_compression_header_size = 12;
	  zlib_size = uncompressed_size - 12;
	}
      else
	{
	  /* Convert it to .zdebug* section.  */
	  zlib_size = uncompressed_size - orig_compression_header_size;
	}

      /* Add the header size.  */
      compressed_size = zlib_size + header_size;
    }
  else
    compressed_size = compressBound (uncompressed_size) + header_size;

  /* Uncompress if it leads to smaller size.  */
  if (compressed && compressed_size > orig_uncompressed_size)
    {
      decompress = TRUE;
      buffer_size = orig_uncompressed_size;
    }
  else
    {
      decompress = FALSE;
      buffer_size = compressed_size;
    }
  buffer = (bfd_byte *) bfd_alloc (abfd, buffer_size);
  if (buffer == NULL)
    return 0;

  if (compressed)
    {
      sec->size = orig_uncompressed_size;
      if (decompress)
	{
	  if (!decompress_contents (uncompressed_buffer
				    + orig_compression_header_size,
				    zlib_size, buffer, buffer_size))
	    {
	      bfd_set_error (bfd_error_bad_value);
	      bfd_release (abfd, buffer);
	      return 0;
	    }
	  free (uncompressed_buffer);
	  sec->contents = buffer;
	  sec->compress_status = COMPRESS_SECTION_DONE;
	  return orig_uncompressed_size;
	}
      else
	{
	  bfd_update_compression_header (abfd, buffer, sec);
	  memmove (buffer + header_size,
		   uncompressed_buffer + orig_compression_header_size,
		   zlib_size);
	}
    }
  else
    {
      if (compress ((Bytef*) buffer + header_size,
		    &compressed_size,
		    (const Bytef*) uncompressed_buffer,
		    uncompressed_size) != Z_OK)
	{
	  bfd_release (abfd, buffer);
	  bfd_set_error (bfd_error_bad_value);
	  return 0;
	}

      compressed_size += header_size;
      /* PR binutils/18087: If compression didn't make the section smaller,
	 just keep it uncompressed.  */
      if (compressed_size < uncompressed_size)
	bfd_update_compression_header (abfd, buffer, sec);
      else
	{
	  /* NOTE: There is a small memory leak here since
	     uncompressed_buffer is malloced and won't be freed.  */
	  bfd_release (abfd, buffer);
	  sec->contents = uncompressed_buffer;
	  sec->compress_status = COMPRESS_SECTION_NONE;
	  return uncompressed_size;
	}
    }

  free (uncompressed_buffer);
  sec->contents = buffer;
  sec->size = compressed_size;
  sec->compress_status = COMPRESS_SECTION_DONE;

  return uncompressed_size;
}

/*
FUNCTION
	bfd_get_full_section_contents

SYNOPSIS
	bfd_boolean bfd_get_full_section_contents
	  (bfd *abfd, asection *section, bfd_byte **ptr);

DESCRIPTION
	Read all data from @var{section} in BFD @var{abfd}, decompress
	if needed, and store in @var{*ptr}.  If @var{*ptr} is NULL,
	return @var{*ptr} with memory malloc'd by this function.

	Return @code{TRUE} if the full section contents is retrieved
	successfully.  If the section has no contents then this function
	returns @code{TRUE} but @var{*ptr} is set to NULL.
*/

bfd_boolean
bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
{
  bfd_size_type sz;
  bfd_byte *p = *ptr;
  bfd_boolean ret;
  bfd_size_type save_size;
  bfd_size_type save_rawsize;
  bfd_byte *compressed_buffer;
  unsigned int compression_header_size;

  if (abfd->direction != write_direction && sec->rawsize != 0)
    sz = sec->rawsize;
  else
    sz = sec->size;
  if (sz == 0)
    {
      *ptr = NULL;
      return TRUE;
    }

  switch (sec->compress_status)
    {
    case COMPRESS_SECTION_NONE:
      if (p == NULL)
	{
	  p = (bfd_byte *) bfd_malloc (sz);
	  if (p == NULL)
	    {
	      /* PR 20801: Provide a more helpful error message.  */
	      if (bfd_get_error () == bfd_error_no_memory)
		_bfd_error_handler
		  /* xgettext:c-format */
		  (_("error: %B(%A) is too large (%#Lx bytes)"),
		  abfd, sec, sz);
	      return FALSE;
	    }
	}

      if (!bfd_get_section_contents (abfd, sec, p, 0, sz))
	{
	  if (*ptr != p)
	    free (p);
	  return FALSE;
	}
      *ptr = p;
      return TRUE;

    case DECOMPRESS_SECTION_SIZED:
      /* Read in the full compressed section contents.  */
      compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
      if (compressed_buffer == NULL)
	return FALSE;
      save_rawsize = sec->rawsize;
      save_size = sec->size;
      /* Clear rawsize, set size to compressed size and set compress_status
	 to COMPRESS_SECTION_NONE.  If the compressed size is bigger than
	 the uncompressed size, bfd_get_section_contents will fail.  */
      sec->rawsize = 0;
      sec->size = sec->compressed_size;
      sec->compress_status = COMPRESS_SECTION_NONE;
      ret = bfd_get_section_contents (abfd, sec, compressed_buffer,
				      0, sec->compressed_size);
      /* Restore rawsize and size.  */
      sec->rawsize = save_rawsize;
      sec->size = save_size;
      sec->compress_status = DECOMPRESS_SECTION_SIZED;
      if (!ret)
	goto fail_compressed;

      if (p == NULL)
	p = (bfd_byte *) bfd_malloc (sz);
      if (p == NULL)
	goto fail_compressed;

      compression_header_size = bfd_get_compression_header_size (abfd, sec);
      if (compression_header_size == 0)
	/* Set header size to the zlib header size if it is a
	   SHF_COMPRESSED section.  */
	compression_header_size = 12;
      if (!decompress_contents (compressed_buffer + compression_header_size,
				sec->compressed_size - compression_header_size, p, sz))
	{
	  bfd_set_error (bfd_error_bad_value);
	  if (p != *ptr)
	    free (p);
	fail_compressed:
	  free (compressed_buffer);
	  return FALSE;
	}

      free (compressed_buffer);
      *ptr = p;
      return TRUE;

    case COMPRESS_SECTION_DONE:
      if (sec->contents == NULL)
	return FALSE;
      if (p == NULL)
	{
	  p = (bfd_byte *) bfd_malloc (sz);
	  if (p == NULL)
	    return FALSE;
	  *ptr = p;
	}
      /* PR 17512; file: 5bc29788.  */
      if (p != sec->contents)
	memcpy (p, sec->contents, sz);
      return TRUE;

    default:
      abort ();
    }
}

/*
FUNCTION
	bfd_cache_section_contents

SYNOPSIS
	void bfd_cache_section_contents
	  (asection *sec, void *contents);

DESCRIPTION
	Stash @var(contents) so any following reads of @var(sec) do
	not need to decompress again.
*/

void
bfd_cache_section_contents (asection *sec, void *contents)
{
  if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
    sec->compress_status = COMPRESS_SECTION_DONE;
  sec->contents = contents;
  sec->flags |= SEC_IN_MEMORY;
}

/*
FUNCTION
	bfd_is_section_compressed_with_header

SYNOPSIS
	bfd_boolean bfd_is_section_compressed_with_header
	  (bfd *abfd, asection *section,
	  int *compression_header_size_p,
	  bfd_size_type *uncompressed_size_p);

DESCRIPTION
	Return @code{TRUE} if @var{section} is compressed.  Compression
	header size is returned in @var{compression_header_size_p} and
	uncompressed size is returned in @var{uncompressed_size_p}.  If
	compression is unsupported, compression header size is returned
	with -1 and uncompressed size is returned with 0.
*/

bfd_boolean
bfd_is_section_compressed_with_header (bfd *abfd, sec_ptr sec,
				       int *compression_header_size_p,
				       bfd_size_type *uncompressed_size_p)
{
  bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];
  int compression_header_size;
  int header_size;
  unsigned int saved = sec->compress_status;
  bfd_boolean compressed;

  compression_header_size = bfd_get_compression_header_size (abfd, sec);
  if (compression_header_size > MAX_COMPRESSION_HEADER_SIZE)
    abort ();
  header_size = compression_header_size ? compression_header_size : 12;

  /* Don't decompress the section.  */
  sec->compress_status = COMPRESS_SECTION_NONE;

  /* Read the header.  */
  if (bfd_get_section_contents (abfd, sec, header, 0, header_size))
    {
      if (compression_header_size == 0)
        /* In this case, it should be "ZLIB" followed by the uncompressed
	   section size, 8 bytes in big-endian order.  */
	compressed = CONST_STRNEQ ((char*) header , "ZLIB");
      else
	compressed = TRUE;
    }
  else
    compressed = FALSE;

  *uncompressed_size_p = sec->size;
  if (compressed)
    {
      if (compression_header_size != 0)
	{
	  if (!bfd_check_compression_header (abfd, header, sec,
					     uncompressed_size_p))
	    compression_header_size = -1;
	}
      /* Check for the pathalogical case of a debug string section that
	 contains the string ZLIB.... as the first entry.  We assume that
	 no uncompressed .debug_str section would ever be big enough to
	 have the first byte of its (big-endian) size be non-zero.  */
      else if (strcmp (sec->name, ".debug_str") == 0
	       && ISPRINT (header[4]))
	compressed = FALSE;
      else
	*uncompressed_size_p = bfd_getb64 (header + 4);
    }

  /* Restore compress_status.  */
  sec->compress_status = saved;
  *compression_header_size_p = compression_header_size;
  return compressed;
}

/*
FUNCTION
	bfd_is_section_compressed

SYNOPSIS
	bfd_boolean bfd_is_section_compressed
	  (bfd *abfd, asection *section);

DESCRIPTION
	Return @code{TRUE} if @var{section} is compressed.
*/

bfd_boolean
bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
{
  int compression_header_size;
  bfd_size_type uncompressed_size;
  return (bfd_is_section_compressed_with_header (abfd, sec,
						 &compression_header_size,
						 &uncompressed_size)
	  && compression_header_size >= 0
	  && uncompressed_size > 0);
}

/*
FUNCTION
	bfd_init_section_decompress_status

SYNOPSIS
	bfd_boolean bfd_init_section_decompress_status
	  (bfd *abfd, asection *section);

DESCRIPTION
	Record compressed section size, update section size with
	decompressed size and set compress_status to
	DECOMPRESS_SECTION_SIZED.

	Return @code{FALSE} if the section is not a valid compressed
	section.  Otherwise, return @code{TRUE}.
*/

bfd_boolean
bfd_init_section_decompress_status (bfd *abfd, sec_ptr sec)
{
  bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];
  int compression_header_size;
  int header_size;
  bfd_size_type uncompressed_size;

  compression_header_size = bfd_get_compression_header_size (abfd, sec);
  if (compression_header_size > MAX_COMPRESSION_HEADER_SIZE)
    abort ();
  header_size = compression_header_size ? compression_header_size : 12;

  /* Read the header.  */
  if (sec->rawsize != 0
      || sec->contents != NULL
      || sec->compress_status != COMPRESS_SECTION_NONE
      || !bfd_get_section_contents (abfd, sec, header, 0, header_size))
    {
      bfd_set_error (bfd_error_invalid_operation);
      return FALSE;
    }

  if (compression_header_size == 0)
    {
      /* In this case, it should be "ZLIB" followed by the uncompressed
	 section size, 8 bytes in big-endian order.  */
      if (! CONST_STRNEQ ((char*) header, "ZLIB"))
	{
	  bfd_set_error (bfd_error_wrong_format);
	  return FALSE;
	}
      uncompressed_size = bfd_getb64 (header + 4);
    }
  else if (!bfd_check_compression_header (abfd, header, sec,
					 &uncompressed_size))
    {
      bfd_set_error (bfd_error_wrong_format);
      return FALSE;
    }

  sec->compressed_size = sec->size;
  sec->size = uncompressed_size;
  sec->compress_status = DECOMPRESS_SECTION_SIZED;

  return TRUE;
}

/*
FUNCTION
	bfd_init_section_compress_status

SYNOPSIS
	bfd_boolean bfd_init_section_compress_status
	  (bfd *abfd, asection *section);

DESCRIPTION
	If open for read, compress section, update section size with
	compressed size and set compress_status to COMPRESS_SECTION_DONE.

	Return @code{FALSE} if the section is not a valid compressed
	section.  Otherwise, return @code{TRUE}.
*/

bfd_boolean
bfd_init_section_compress_status (bfd *abfd, sec_ptr sec)
{
  bfd_size_type uncompressed_size;
  bfd_byte *uncompressed_buffer;

  /* Error if not opened for read.  */
  if (abfd->direction != read_direction
      || sec->size == 0
      || sec->rawsize != 0
      || sec->contents != NULL
      || sec->compress_status != COMPRESS_SECTION_NONE)
    {
      bfd_set_error (bfd_error_invalid_operation);
      return FALSE;
    }

  /* Read in the full section contents and compress it.  */
  uncompressed_size = sec->size;
  uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
  /* PR 21431 */
  if (uncompressed_buffer == NULL)
    return FALSE;

  if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
				 0, uncompressed_size))
    return FALSE;

  uncompressed_size = bfd_compress_section_contents (abfd, sec,
						     uncompressed_buffer,
						     uncompressed_size);
  return uncompressed_size != 0;
}

/*
FUNCTION
	bfd_compress_section

SYNOPSIS
	bfd_boolean bfd_compress_section
	  (bfd *abfd, asection *section, bfd_byte *uncompressed_buffer);

DESCRIPTION
	If open for write, compress section, update section size with
	compressed size and set compress_status to COMPRESS_SECTION_DONE.

	Return @code{FALSE} if compression fail.  Otherwise, return
	@code{TRUE}.
*/

bfd_boolean
bfd_compress_section (bfd *abfd, sec_ptr sec, bfd_byte *uncompressed_buffer)
{
  bfd_size_type uncompressed_size = sec->size;

  /* Error if not opened for write.  */
  if (abfd->direction != write_direction
      || uncompressed_size == 0
      || uncompressed_buffer == NULL
      || sec->contents != NULL
      || sec->compressed_size != 0
      || sec->compress_status != COMPRESS_SECTION_NONE)
    {
      bfd_set_error (bfd_error_invalid_operation);
      return FALSE;
    }

  /* Compress it.  */
  return bfd_compress_section_contents (abfd, sec, uncompressed_buffer,
					uncompressed_size) != 0;
}