aboutsummaryrefslogtreecommitdiff
path: root/bfd/compress.c
blob: 844328b27a965f71295adb6d510b402cfdb565fa (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
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
/* Compressed section support (intended for debug sections).
   Copyright (C) 2008-2023 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>
#ifdef HAVE_ZSTD
#include <zstd.h>
#endif
#include "bfd.h"
#include "elf-bfd.h"
#include "libbfd.h"
#include "safe-ctype.h"
#include "libiberty.h"

#define MAX_COMPRESSION_HEADER_SIZE 24

/*
CODE_FRAGMENT
.{* Types of compressed DWARF debug sections.  *}
.enum compressed_debug_section_type
.{
.  COMPRESS_DEBUG_NONE = 0,
.  COMPRESS_DEBUG_GNU_ZLIB = 1 << 1,
.  COMPRESS_DEBUG_GABI_ZLIB = 1 << 2,
.  COMPRESS_DEBUG_ZSTD = 1 << 3,
.  COMPRESS_UNKNOWN = 1 << 4
.};
.
.{* Tuple for compressed_debug_section_type and their name.  *}
.struct compressed_type_tuple
.{
.  enum compressed_debug_section_type type;
.  const char *name;
.};
.
.{* Compression header ch_type values.  *}
.enum compression_type
.{
.  ch_none = 0,
.  ch_compress_zlib = 1	,	{* Compressed with zlib.  *}
.  ch_compress_zstd = 2		{* Compressed with zstd (www.zstandard.org).  *}
.};
.
.static inline char *
.bfd_debug_name_to_zdebug (bfd *abfd, const char *name)
.{
.  size_t len = strlen (name);
.  char *new_name = (char *) bfd_alloc (abfd, len + 2);
.  if (new_name == NULL)
.    return NULL;
.  new_name[0] = '.';
.  new_name[1] = 'z';
.  memcpy (new_name + 2, name + 1, len);
.  return new_name;
.}
.
.static inline char *
.bfd_zdebug_name_to_debug (bfd *abfd, const char *name)
.{
.  size_t len = strlen (name);
.  char *new_name = (char *) bfd_alloc (abfd, len);
.  if (new_name == NULL)
.    return NULL;
.  new_name[0] = '.';
.  memcpy (new_name + 1, name + 2, len - 1);
.  return new_name;
.}
.
*/

/* Display texts for type of compressed DWARF debug sections.  */
static const struct compressed_type_tuple compressed_debug_section_names[] =
{
  { COMPRESS_DEBUG_NONE, "none" },
  { COMPRESS_DEBUG_GABI_ZLIB, "zlib" },
  { COMPRESS_DEBUG_GNU_ZLIB, "zlib-gnu" },
  { COMPRESS_DEBUG_GABI_ZLIB, "zlib-gabi" },
  { COMPRESS_DEBUG_ZSTD, "zstd" },
};

/*
FUNCTION
	bfd_get_compression_algorithm
SYNOPSIS
	enum compressed_debug_section_type
	  bfd_get_compression_algorithm (const char *name);
DESCRIPTION
	Return compressed_debug_section_type from a string representation.
*/
enum compressed_debug_section_type
bfd_get_compression_algorithm (const char *name)
{
  for (unsigned i = 0; i < ARRAY_SIZE (compressed_debug_section_names); ++i)
    if (strcasecmp (compressed_debug_section_names[i].name, name) == 0)
      return compressed_debug_section_names[i].type;

  return COMPRESS_UNKNOWN;
}

/*
FUNCTION
	bfd_get_compression_algorithm_name
SYNOPSIS
	const char *bfd_get_compression_algorithm_name
	  (enum compressed_debug_section_type type);
DESCRIPTION
	Return compression algorithm name based on the type.
*/
const char *
bfd_get_compression_algorithm_name (enum compressed_debug_section_type type)
{
  for (unsigned i = 0; i < ARRAY_SIZE (compressed_debug_section_names); ++i)
    if (type == compressed_debug_section_names[i].type)
      return compressed_debug_section_names[i].name;

  return NULL;
}

/*
FUNCTION
	bfd_update_compression_header

SYNOPSIS
	void bfd_update_compression_header
	  (bfd *abfd, bfd_byte *contents, asection *sec);

DESCRIPTION
	Set the compression header at CONTENTS of SEC in ABFD and update
	elf_section_flags for compression.
*/

void
bfd_update_compression_header (bfd *abfd, bfd_byte *contents,
			       asection *sec)
{
  if ((abfd->flags & BFD_COMPRESS) == 0)
    abort ();

  switch (bfd_get_flavour (abfd))
    {
    case bfd_target_elf_flavour:
      if ((abfd->flags & BFD_COMPRESS_GABI) != 0)
	{
	  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
	  struct bfd_elf_section_data * esd = elf_section_data (sec);
	  enum compression_type ch_type = (abfd->flags & BFD_COMPRESS_ZSTD
					   ? ch_compress_zstd
					   : ch_compress_zlib);

	  /* Set the SHF_COMPRESSED bit.  */
	  elf_section_flags (sec) |= SHF_COMPRESSED;

	  if (bed->s->elfclass == ELFCLASS32)
	    {
	      Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;
	      bfd_put_32 (abfd, ch_type, &echdr->ch_type);
	      bfd_put_32 (abfd, sec->size, &echdr->ch_size);
	      bfd_put_32 (abfd, 1u << sec->alignment_power,
			  &echdr->ch_addralign);
	      /* bfd_log2 (alignof (Elf32_Chdr)) */
	      bfd_set_section_alignment (sec, 2);
	      esd->this_hdr.sh_addralign = 4;
	    }
	  else
	    {
	      Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;
	      bfd_put_32 (abfd, ch_type, &echdr->ch_type);
	      bfd_put_32 (abfd, 0, &echdr->ch_reserved);
	      bfd_put_64 (abfd, sec->size, &echdr->ch_size);
	      bfd_put_64 (abfd, UINT64_C (1) << sec->alignment_power,
			  &echdr->ch_addralign);
	      /* bfd_log2 (alignof (Elf64_Chdr)) */
	      bfd_set_section_alignment (sec, 3);
	      esd->this_hdr.sh_addralign = 8;
	    }
	  break;
	}

      /* Clear the SHF_COMPRESSED bit.  */
      elf_section_flags (sec) &= ~SHF_COMPRESSED;
      /* Fall through.  */

    default:
      /* Write the zlib header.  It should be "ZLIB" followed by
	 the uncompressed section size, 8 bytes in big-endian
	 order.  */
      memcpy (contents, "ZLIB", 4);
      bfd_putb64 (sec->size, contents + 4);
      /* No way to keep the original alignment, just use 1 always. */
      bfd_set_section_alignment (sec, 0);
      break;
    }
}

/* Check the compression header at CONTENTS of SEC in ABFD and store the
   ch_type in CH_TYPE, uncompressed size in UNCOMPRESSED_SIZE, and the
   uncompressed data alignment in UNCOMPRESSED_ALIGNMENT_POWER if the
   compression header is valid.  */

static bool
bfd_check_compression_header (bfd *abfd, bfd_byte *contents,
			      asection *sec,
			      enum compression_type *ch_type,
			      bfd_size_type *uncompressed_size,
			      unsigned int *uncompressed_alignment_power)
{
  if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
      && (elf_section_flags (sec) & SHF_COMPRESSED) != 0)
    {
      Elf_Internal_Chdr chdr;
      const struct elf_backend_data *bed = get_elf_backend_data (abfd);
      if (bed->s->elfclass == ELFCLASS32)
	{
	  Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;
	  chdr.ch_type = bfd_get_32 (abfd, &echdr->ch_type);
	  chdr.ch_size = bfd_get_32 (abfd, &echdr->ch_size);
	  chdr.ch_addralign = bfd_get_32 (abfd, &echdr->ch_addralign);
	}
      else
	{
	  Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;
	  chdr.ch_type = bfd_get_32 (abfd, &echdr->ch_type);
	  chdr.ch_size = bfd_get_64 (abfd, &echdr->ch_size);
	  chdr.ch_addralign = bfd_get_64 (abfd, &echdr->ch_addralign);
	}
      *ch_type = chdr.ch_type;
      if ((chdr.ch_type == ch_compress_zlib
	   || chdr.ch_type == ch_compress_zstd)
	  && chdr.ch_addralign == (chdr.ch_addralign & -chdr.ch_addralign))
	{
	  *uncompressed_size = chdr.ch_size;
	  *uncompressed_alignment_power = bfd_log2 (chdr.ch_addralign);
	  return true;
	}
    }

  return false;
}

/*
FUNCTION
	bfd_get_compression_header_size

SYNOPSIS
	int bfd_get_compression_header_size (bfd *abfd, asection *sec);

DESCRIPTION
	Return the size of the compression header of SEC in ABFD.
*/

int
bfd_get_compression_header_size (bfd *abfd, asection *sec)
{
  if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
    {
      if (sec == NULL)
	{
	  if (!(abfd->flags & BFD_COMPRESS_GABI))
	    return 0;
	}
      else if (!(elf_section_flags (sec) & SHF_COMPRESSED))
	return 0;

      if (get_elf_backend_data (abfd)->s->elfclass == ELFCLASS32)
	return sizeof (Elf32_External_Chdr);
      else
	return sizeof (Elf64_External_Chdr);
    }

  return 0;
}

/*
FUNCTION
	bfd_convert_section_setup

SYNOPSIS
	bool bfd_convert_section_setup
	  (bfd *ibfd, asection *isec, bfd *obfd,
	   const char **new_name, bfd_size_type *new_size);

DESCRIPTION
	Do early setup for objcopy, when copying @var{isec} in input
	BFD @var{ibfd} to output BFD @var{obfd}.  Returns the name and
	size of the output section.
*/

bool
bfd_convert_section_setup (bfd *ibfd, asection *isec, bfd *obfd,
			   const char **new_name, bfd_size_type *new_size)
{
  bfd_size_type hdr_size;

  if ((isec->flags & SEC_DEBUGGING) != 0
      && (isec->flags & SEC_HAS_CONTENTS) != 0)
    {
      const char *name = *new_name;

      if ((obfd->flags & (BFD_DECOMPRESS | BFD_COMPRESS_GABI)) != 0)
	{
	  /* When we decompress or compress with SHF_COMPRESSED,
	     convert section name from .zdebug_* to .debug_*.  */
	  if (startswith (name, ".zdebug_"))
	    {
	      name = bfd_zdebug_name_to_debug (obfd, name);
	      if (name == NULL)
		return false;
	    }
	}

      /* PR binutils/18087: Compression does not always make a
	 section smaller.  So only rename the section when
	 compression has actually taken place.  If input section
	 name is .zdebug_*, we should never compress it again.  */
      else if (isec->compress_status == COMPRESS_SECTION_DONE
	       && startswith (name, ".debug_"))
	{
	  name = bfd_debug_name_to_zdebug (obfd, name);
	  if (name == NULL)
	    return false;
	}
      *new_name = name;
    }
  *new_size = bfd_section_size (isec);

  /* Do nothing if either input or output aren't ELF.  */
  if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
      || bfd_get_flavour (obfd) != bfd_target_elf_flavour)
    return true;

  /* Do nothing if ELF classes of input and output are the same. */
  if (get_elf_backend_data (ibfd)->s->elfclass
      == get_elf_backend_data (obfd)->s->elfclass)
    return true;

  /* Convert GNU property size.  */
  if (startswith (isec->name, NOTE_GNU_PROPERTY_SECTION_NAME))
    {
      *new_size = _bfd_elf_convert_gnu_property_size (ibfd, obfd);
      return true;
    }

  /* Do nothing if input file will be decompressed.  */
  if ((ibfd->flags & BFD_DECOMPRESS))
    return true;

  /* Do nothing if the input section isn't a SHF_COMPRESSED section. */
  hdr_size = bfd_get_compression_header_size (ibfd, isec);
  if (hdr_size == 0)
    return true;

  /* Adjust the size of the output SHF_COMPRESSED section.  */
  if (hdr_size == sizeof (Elf32_External_Chdr))
    *new_size += sizeof (Elf64_External_Chdr) - sizeof (Elf32_External_Chdr);
  else
    *new_size -= sizeof (Elf64_External_Chdr) - sizeof (Elf32_External_Chdr);
  return true;
}

/*
FUNCTION
	bfd_convert_section_contents

SYNOPSIS
	bool bfd_convert_section_contents
	  (bfd *ibfd, asection *isec, bfd *obfd,
	   bfd_byte **ptr, bfd_size_type *ptr_size);

DESCRIPTION
	Convert the contents, stored in @var{*ptr}, of the section
	@var{isec} in input BFD @var{ibfd} to output BFD @var{obfd}
	if needed.  The original buffer pointed to by @var{*ptr} may
	be freed and @var{*ptr} is returned with memory malloc'd by this
	function, and the new size written to @var{ptr_size}.
*/

bool
bfd_convert_section_contents (bfd *ibfd, sec_ptr isec, bfd *obfd,
			      bfd_byte **ptr, bfd_size_type *ptr_size)
{
  bfd_byte *contents;
  bfd_size_type ihdr_size, ohdr_size, size;
  Elf_Internal_Chdr chdr;
  bool use_memmove;

  /* Do nothing if either input or output aren't ELF.  */
  if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
      || bfd_get_flavour (obfd) != bfd_target_elf_flavour)
    return true;

  /* Do nothing if ELF classes of input and output are the same.  */
  if (get_elf_backend_data (ibfd)->s->elfclass
      == get_elf_backend_data (obfd)->s->elfclass)
    return true;

  /* Convert GNU properties.  */
  if (startswith (isec->name, NOTE_GNU_PROPERTY_SECTION_NAME))
    return _bfd_elf_convert_gnu_properties (ibfd, isec, obfd, ptr,
					    ptr_size);

  /* Do nothing if input file will be decompressed.  */
  if ((ibfd->flags & BFD_DECOMPRESS))
    return true;

  /* Do nothing if the input section isn't a SHF_COMPRESSED section.  */
  ihdr_size = bfd_get_compression_header_size (ibfd, isec);
  if (ihdr_size == 0)
    return true;

  /* PR 25221.  Check for corrupt input sections.  */
  if (ihdr_size > bfd_get_section_limit (ibfd, isec))
    /* FIXME: Issue a warning about a corrupt
       compression header size field ?  */
    return false;

  contents = *ptr;

  /* Convert the contents of the input SHF_COMPRESSED section to
     output.  Get the input compression header and the size of the
     output compression header.  */
  if (ihdr_size == sizeof (Elf32_External_Chdr))
    {
      Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;
      chdr.ch_type = bfd_get_32 (ibfd, &echdr->ch_type);
      chdr.ch_size = bfd_get_32 (ibfd, &echdr->ch_size);
      chdr.ch_addralign = bfd_get_32 (ibfd, &echdr->ch_addralign);

      ohdr_size = sizeof (Elf64_External_Chdr);

      use_memmove = false;
    }
  else if (ihdr_size != sizeof (Elf64_External_Chdr))
    {
      /* FIXME: Issue a warning about a corrupt
	 compression header size field ?  */
      return false;
    }
  else
    {
      Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;
      chdr.ch_type = bfd_get_32 (ibfd, &echdr->ch_type);
      chdr.ch_size = bfd_get_64 (ibfd, &echdr->ch_size);
      chdr.ch_addralign = bfd_get_64 (ibfd, &echdr->ch_addralign);

      ohdr_size = sizeof (Elf32_External_Chdr);
      use_memmove = true;
    }

  size = bfd_section_size (isec) - ihdr_size + ohdr_size;
  if (!use_memmove)
    {
      contents = (bfd_byte *) bfd_malloc (size);
      if (contents == NULL)
	return false;
    }

  /* Write out the output compression header.  */
  if (ohdr_size == sizeof (Elf32_External_Chdr))
    {
      Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;
      bfd_put_32 (obfd, chdr.ch_type, &echdr->ch_type);
      bfd_put_32 (obfd, chdr.ch_size, &echdr->ch_size);
      bfd_put_32 (obfd, chdr.ch_addralign, &echdr->ch_addralign);
    }
  else
    {
      Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;
      bfd_put_32 (obfd, chdr.ch_type, &echdr->ch_type);
      bfd_put_32 (obfd, 0, &echdr->ch_reserved);
      bfd_put_64 (obfd, chdr.ch_size, &echdr->ch_size);
      bfd_put_64 (obfd, chdr.ch_addralign, &echdr->ch_addralign);
    }

  /* Copy the compressed contents.  */
  if (use_memmove)
    memmove (contents + ohdr_size, *ptr + ihdr_size, size - ohdr_size);
  else
    {
      memcpy (contents + ohdr_size, *ptr + ihdr_size, size - ohdr_size);
      free (*ptr);
      *ptr = contents;
    }

  *ptr_size = size;
  return true;
}

static bool
decompress_contents (bool is_zstd, bfd_byte *compressed_buffer,
		     bfd_size_type compressed_size,
		     bfd_byte *uncompressed_buffer,
		     bfd_size_type uncompressed_size)
{
  if (is_zstd)
    {
#ifdef HAVE_ZSTD
      size_t ret = ZSTD_decompress (uncompressed_buffer, uncompressed_size,
				    compressed_buffer, compressed_size);
      return !ZSTD_isError (ret);
#endif
    }

  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;
  /* FIXME: strm.avail_in and strm.avail_out are typically unsigned
     int.  Supporting sizes that don't fit in an unsigned int is
     possible but will require some rewriting of this function.  */
  if (strm.avail_in != compressed_size || strm.avail_out != uncompressed_size)
    return false;

  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);
    }
  return inflateEnd (&strm) == Z_OK && rc == Z_OK && strm.avail_out == 0;
}

/* Compress section contents using zlib/zstd 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 *input_buffer;
  uLong compressed_size;
  bfd_byte *buffer;
  bfd_size_type buffer_size;
  int zlib_size = 0;
  int orig_header_size;
  bfd_size_type uncompressed_size;
  unsigned int uncompressed_alignment_pow;
  enum compression_type ch_type = ch_none;
  int new_header_size = bfd_get_compression_header_size (abfd, NULL);
  bool compressed
    = bfd_is_section_compressed_info (abfd, sec,
				      &orig_header_size,
				      &uncompressed_size,
				      &uncompressed_alignment_pow,
				      &ch_type);
  bool update = false;

  /* We shouldn't be trying to decompress unsupported compressed sections.  */
  if (compressed && orig_header_size < 0)
    abort ();

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

  input_buffer = sec->contents;
  if (compressed)
    {
      zlib_size = sec->size - orig_header_size;
      compressed_size = zlib_size + new_header_size;

      /* If we are converting between zlib-gnu and zlib-gabi then the
	 compressed contents just need to be moved.  */
      update = (ch_type < ch_compress_zstd
		&& (abfd->flags & BFD_COMPRESS_ZSTD) == 0);

      /* Uncompress when not just moving contents or when compressed
	 is not smaller than uncompressed.  */
      if (!update || compressed_size >= uncompressed_size)
	{
	  buffer_size = uncompressed_size;
	  buffer = bfd_malloc (buffer_size);
	  if (buffer == NULL)
	    return 0;

	  if (!decompress_contents (ch_type == ch_compress_zstd,
				    input_buffer + orig_header_size,
				    zlib_size, buffer, buffer_size))
	    {
	      bfd_set_error (bfd_error_bad_value);
	      free (buffer);
	      return 0;
	    }
	  free (input_buffer);
	  bfd_set_section_alignment (sec, uncompressed_alignment_pow);
	  sec->contents = buffer;
	  sec->flags |= SEC_IN_MEMORY;
	  sec->compress_status = COMPRESS_SECTION_NONE;
	  sec->size = uncompressed_size;
	  input_buffer = buffer;
	}
    }

  if (!update)
    compressed_size = compressBound (uncompressed_size) + new_header_size;

  buffer_size = compressed_size;
  buffer = bfd_alloc (abfd, buffer_size);
  if (buffer == NULL)
    return 0;

  if (update)
    {
      if (compressed_size < uncompressed_size)
	memcpy (buffer + new_header_size,
		input_buffer + orig_header_size,
		zlib_size);
    }
  else
    {
      if (abfd->flags & BFD_COMPRESS_ZSTD)
	{
#if HAVE_ZSTD
	  compressed_size = ZSTD_compress (buffer + new_header_size,
					   compressed_size,
					   input_buffer,
					   uncompressed_size,
					   ZSTD_CLEVEL_DEFAULT);
	  if (ZSTD_isError (compressed_size))
	    {
	      bfd_release (abfd, buffer);
	      bfd_set_error (bfd_error_bad_value);
	      return 0;
	    }
#endif
	}
      else if (compress ((Bytef *) buffer + new_header_size, &compressed_size,
			 (const Bytef *) input_buffer, uncompressed_size)
	       != Z_OK)
	{
	  bfd_release (abfd, buffer);
	  bfd_set_error (bfd_error_bad_value);
	  return 0;
	}

      compressed_size += new_header_size;
    }

  /* If compression didn't make the section smaller, keep it uncompressed.  */
  if (compressed_size >= uncompressed_size)
    {
      memcpy (buffer, input_buffer, uncompressed_size);
      if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
	elf_section_flags (sec) &= ~SHF_COMPRESSED;
      sec->compress_status = COMPRESS_SECTION_NONE;
    }
  else
    {
      sec->size = uncompressed_size;
      bfd_update_compression_header (abfd, buffer, sec);
      sec->size = compressed_size;
      sec->compress_status = COMPRESS_SECTION_DONE;
    }
  sec->contents = buffer;
  sec->flags |= SEC_IN_MEMORY;
  free (input_buffer);
  return uncompressed_size;
}

/*
FUNCTION
	bfd_get_full_section_contents

SYNOPSIS
	bool 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.
*/

bool
bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
{
  bfd_size_type readsz = bfd_get_section_limit_octets (abfd, sec);
  bfd_size_type allocsz = bfd_get_section_alloc_size (abfd, sec);
  bfd_byte *p = *ptr;
  bool ret;
  bfd_size_type save_size;
  bfd_size_type save_rawsize;
  bfd_byte *compressed_buffer;
  unsigned int compression_header_size;
  const unsigned int compress_status = sec->compress_status;

  if (allocsz == 0)
    {
      *ptr = NULL;
      return true;
    }

  if (p == NULL
      && compress_status != COMPRESS_SECTION_DONE
      && _bfd_section_size_insane (abfd, sec))
    {
      /* PR 24708: Avoid attempts to allocate a ridiculous amount
	 of memory.  */
      _bfd_error_handler
	/* xgettext:c-format */
	(_("error: %pB(%pA) is too large (%#" PRIx64 " bytes)"),
	 abfd, sec, (uint64_t) readsz);
      return false;
    }

  switch (compress_status)
    {
    case COMPRESS_SECTION_NONE:
      if (p == NULL)
	{
	  p = (bfd_byte *) bfd_malloc (allocsz);
	  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: %pB(%pA) is too large (%#" PRIx64 " bytes)"),
		  abfd, sec, (uint64_t) allocsz);
	      return false;
	    }
	}

      if (!bfd_get_section_contents (abfd, sec, p, 0, readsz))
	{
	  if (*ptr != p)
	    free (p);
	  return false;
	}
      *ptr = p;
      return true;

    case DECOMPRESS_SECTION_ZLIB:
    case DECOMPRESS_SECTION_ZSTD:
      /* 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 = compress_status;
      if (!ret)
	goto fail_compressed;

      if (p == NULL)
	p = (bfd_byte *) bfd_malloc (allocsz);
      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;
      bool is_zstd = compress_status == DECOMPRESS_SECTION_ZSTD;
      if (!decompress_contents (
	      is_zstd, compressed_buffer + compression_header_size,
	      sec->compressed_size - compression_header_size, p, readsz))
	{
	  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 (allocsz);
	  if (p == NULL)
	    return false;
	  *ptr = p;
	}
      /* PR 17512; file: 5bc29788.  */
      if (p != sec->contents)
	memcpy (p, sec->contents, readsz);
      return true;

    default:
      abort ();
    }
}

/*
FUNCTION
	bfd_is_section_compressed_info

SYNOPSIS
	bool bfd_is_section_compressed_info
	  (bfd *abfd, asection *section,
	   int *compression_header_size_p,
	   bfd_size_type *uncompressed_size_p,
	   unsigned int *uncompressed_alignment_power_p,
	   enum compression_type *ch_type);

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

bool
bfd_is_section_compressed_info (bfd *abfd, sec_ptr sec,
				int *compression_header_size_p,
				bfd_size_type *uncompressed_size_p,
				unsigned int *uncompressed_align_pow_p,
				enum compression_type *ch_type)
{
  bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];
  int compression_header_size;
  int header_size;
  unsigned int saved = sec->compress_status;
  bool compressed;

  *uncompressed_align_pow_p = 0;

  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 = startswith ((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, ch_type,
					     uncompressed_size_p,
					     uncompressed_align_pow_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
	bool bfd_is_section_compressed
	  (bfd *abfd, asection *section);

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

bool
bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
{
  int compression_header_size;
  bfd_size_type uncompressed_size;
  unsigned int uncompressed_align_power;
  enum compression_type ch_type;
  return (bfd_is_section_compressed_info (abfd, sec,
					  &compression_header_size,
					  &uncompressed_size,
					  &uncompressed_align_power,
					  &ch_type)
	  && compression_header_size >= 0
	  && uncompressed_size > 0);
}

/*
FUNCTION
	bfd_init_section_decompress_status

SYNOPSIS
	bool 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_{ZLIB,ZSTD}.

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

bool
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;
  unsigned int uncompressed_alignment_power = 0;
  enum compression_type ch_type;
  z_stream strm;

  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 (! startswith ((char*) header, "ZLIB"))
	{
	  bfd_set_error (bfd_error_wrong_format);
	  return false;
	}
      uncompressed_size = bfd_getb64 (header + 4);
      ch_type = ch_none;
    }
  else if (!bfd_check_compression_header (abfd, header, sec,
					  &ch_type,
					  &uncompressed_size,
					  &uncompressed_alignment_power))
    {
      bfd_set_error (bfd_error_wrong_format);
      return false;
    }

  /* PR28530, reject sizes unsupported by decompress_contents.  */
  strm.avail_in = sec->size;
  strm.avail_out = uncompressed_size;
  if (strm.avail_in != sec->size || strm.avail_out != uncompressed_size)
    {
      bfd_set_error (bfd_error_nonrepresentable_section);
      return false;
    }

  sec->compressed_size = sec->size;
  sec->size = uncompressed_size;
  bfd_set_section_alignment (sec, uncompressed_alignment_power);
  sec->compress_status = (ch_type == ch_compress_zstd
			  ? DECOMPRESS_SECTION_ZSTD : DECOMPRESS_SECTION_ZLIB);

  return true;
}

/*
FUNCTION
	bfd_init_section_compress_status

SYNOPSIS
	bool 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}.
*/

bool
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_section_size_insane (abfd, sec))
    {
      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))
    {
      free (uncompressed_buffer);
      return false;
    }

  sec->contents = uncompressed_buffer;
  if (bfd_compress_section_contents (abfd, sec) == 0)
    {
      free (sec->contents);
      sec->contents = NULL;
      return false;
    }
  return true;
}

/*
FUNCTION
	bfd_compress_section

SYNOPSIS
	bool 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}.  UNCOMPRESSED_BUFFER is freed in both cases.
*/

bool
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;
    }

  sec->contents = uncompressed_buffer;
  if (bfd_compress_section_contents (abfd, sec) == 0)
    {
      free (sec->contents);
      sec->contents = NULL;
      return false;
    }
  return true;
}