bfd/compress.c

   1 /* Compressed section support (intended for debug sections).
   2    Copyright (C) 2008-2018 Free Software Foundation, Inc.
   3
   4    This file is part of BFD, the Binary File Descriptor library.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 #include "sysdep.h"
  22 #include <zlib.h>
  23 #include "bfd.h"
  24 #include "libbfd.h"
  25 #include "safe-ctype.h"
  26
  27 #define MAX_COMPRESSION_HEADER_SIZE 24
  28
  29 static bfd_boolean
  30 decompress_contents (bfd_byte *compressed_buffer,
  31                      bfd_size_type compressed_size,
  32                      bfd_byte *uncompressed_buffer,
  33                      bfd_size_type uncompressed_size)
  34 {
  35   z_stream strm;
  36   int rc;
  37
  38   /* It is possible the section consists of several compressed
  39      buffers concatenated together, so we uncompress in a loop.  */
  40   /* PR 18313: The state field in the z_stream structure is supposed
  41      to be invisible to the user (ie us), but some compilers will
  42      still complain about it being used without initialisation.  So
  43      we first zero the entire z_stream structure and then set the fields
  44      that we need.  */
  45   memset (& strm, 0, sizeof strm);
  46   strm.avail_in = compressed_size;
  47   strm.next_in = (Bytef*) compressed_buffer;
  48   strm.avail_out = uncompressed_size;
  49
  50   BFD_ASSERT (Z_OK == 0);
  51   rc = inflateInit (&strm);
  52   while (strm.avail_in > 0 && strm.avail_out > 0)
  53     {
  54       if (rc != Z_OK)
  55         break;
  56       strm.next_out = ((Bytef*) uncompressed_buffer
  57                        + (uncompressed_size - strm.avail_out));
  58       rc = inflate (&strm, Z_FINISH);
  59       if (rc != Z_STREAM_END)
  60         break;
  61       rc = inflateReset (&strm);
  62     }
  63   rc |= inflateEnd (&strm);
  64   return rc == Z_OK && strm.avail_out == 0;
  65 }
  66
  67 /* Compress data of the size specified in @var{uncompressed_size}
  68    and pointed to by @var{uncompressed_buffer} using zlib and store
  69    as the contents field.  This function assumes the contents
  70    field was allocated using bfd_malloc() or equivalent.
  71
  72    Return the uncompressed size if the full section contents is
  73    compressed successfully.  Otherwise return 0.  */
  74
  75 static bfd_size_type
  76 bfd_compress_section_contents (bfd *abfd, sec_ptr sec,
  77                                bfd_byte *uncompressed_buffer,
  78                                bfd_size_type uncompressed_size)
  79 {
  80   uLong compressed_size;
  81   bfd_byte *buffer;
  82   bfd_size_type buffer_size;
  83   bfd_boolean decompress;
  84   int zlib_size = 0;
  85   int orig_compression_header_size;
  86   bfd_size_type orig_uncompressed_size;
  87   unsigned int orig_uncompressed_alignment_pow;
  88   int header_size = bfd_get_compression_header_size (abfd, NULL);
  89   bfd_boolean compressed
  90     = bfd_is_section_compressed_with_header (abfd, sec,
  91                                              &orig_compression_header_size,
  92                                              &orig_uncompressed_size,
  93                                              &orig_uncompressed_alignment_pow);
  94
  95   /* Either ELF compression header or the 12-byte, "ZLIB" + 8-byte size,
  96      overhead in .zdebug* section.  */
  97   if (!header_size)
  98      header_size = 12;
  99
 100   if (compressed)
 101     {
 102       /* We shouldn't decompress unsupported compressed section.  */
 103       if (orig_compression_header_size < 0)
 104         abort ();
 105
 106       /* Different compression schemes.  Just move the compressed section
 107          contents to the right position. */
 108       if (orig_compression_header_size == 0)
 109         {
 110           /* Convert it from .zdebug* section.  Get the uncompressed
 111              size first.  We need to subtract the 12-byte overhead in
 112              .zdebug* section.  Set orig_compression_header_size to
 113              the 12-bye overhead.  */
 114           orig_compression_header_size = 12;
 115           zlib_size = uncompressed_size - 12;
 116         }
 117       else
 118         {
 119           /* Convert it to .zdebug* section.  */
 120           zlib_size = uncompressed_size - orig_compression_header_size;
 121         }
 122
 123       /* Add the header size.  */
 124       compressed_size = zlib_size + header_size;
 125     }
 126   else
 127     compressed_size = compressBound (uncompressed_size) + header_size;
 128
 129   /* Uncompress if it leads to smaller size.  */
 130   if (compressed && compressed_size > orig_uncompressed_size)
 131     {
 132       decompress = TRUE;
 133       buffer_size = orig_uncompressed_size;
 134     }
 135   else
 136     {
 137       decompress = FALSE;
 138       buffer_size = compressed_size;
 139     }
 140   buffer = (bfd_byte *) bfd_alloc (abfd, buffer_size);
 141   if (buffer == NULL)
 142     return 0;
 143
 144   if (compressed)
 145     {
 146       sec->size = orig_uncompressed_size;
 147       if (decompress)
 148         {
 149           if (!decompress_contents (uncompressed_buffer
 150                                     + orig_compression_header_size,
 151                                     zlib_size, buffer, buffer_size))
 152             {
 153               bfd_set_error (bfd_error_bad_value);
 154               bfd_release (abfd, buffer);
 155               return 0;
 156             }
 157           free (uncompressed_buffer);
 158           bfd_set_section_alignment (abfd, sec,
 159                                      orig_uncompressed_alignment_pow);
 160
 161           sec->contents = buffer;
 162           sec->compress_status = COMPRESS_SECTION_DONE;
 163           return orig_uncompressed_size;
 164         }
 165       else
 166         {
 167           bfd_update_compression_header (abfd, buffer, sec);
 168           memmove (buffer + header_size,
 169                    uncompressed_buffer + orig_compression_header_size,
 170                    zlib_size);
 171         }
 172     }
 173   else
 174     {
 175       if (compress ((Bytef*) buffer + header_size,
 176                     &compressed_size,
 177                     (const Bytef*) uncompressed_buffer,
 178                     uncompressed_size) != Z_OK)
 179         {
 180           bfd_release (abfd, buffer);
 181           bfd_set_error (bfd_error_bad_value);
 182           return 0;
 183         }
 184
 185       compressed_size += header_size;
 186       /* PR binutils/18087: If compression didn't make the section smaller,
 187          just keep it uncompressed.  */
 188       if (compressed_size < uncompressed_size)
 189         bfd_update_compression_header (abfd, buffer, sec);
 190       else
 191         {
 192           /* NOTE: There is a small memory leak here since
 193              uncompressed_buffer is malloced and won't be freed.  */
 194           bfd_release (abfd, buffer);
 195           sec->contents = uncompressed_buffer;
 196           sec->compress_status = COMPRESS_SECTION_NONE;
 197           return uncompressed_size;
 198         }
 199     }
 200
 201   free (uncompressed_buffer);
 202   sec->contents = buffer;
 203   sec->size = compressed_size;
 204   sec->compress_status = COMPRESS_SECTION_DONE;
 205
 206   return uncompressed_size;
 207 }
 208
 209 /*
 210 FUNCTION
 211         bfd_get_full_section_contents
 212
 213 SYNOPSIS
 214         bfd_boolean bfd_get_full_section_contents
 215           (bfd *abfd, asection *section, bfd_byte **ptr);
 216
 217 DESCRIPTION
 218         Read all data from @var{section} in BFD @var{abfd}, decompress
 219         if needed, and store in @var{*ptr}.  If @var{*ptr} is NULL,
 220         return @var{*ptr} with memory malloc'd by this function.
 221
 222         Return @code{TRUE} if the full section contents is retrieved
 223         successfully.  If the section has no contents then this function
 224         returns @code{TRUE} but @var{*ptr} is set to NULL.
 225 */
 226
 227 bfd_boolean
 228 bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
 229 {
 230   bfd_size_type sz;
 231   bfd_byte *p = *ptr;
 232   bfd_boolean ret;
 233   bfd_size_type save_size;
 234   bfd_size_type save_rawsize;
 235   bfd_byte *compressed_buffer;
 236   unsigned int compression_header_size;
 237
 238   if (abfd->direction != write_direction && sec->rawsize != 0)
 239     sz = sec->rawsize;
 240   else
 241     sz = sec->size;
 242   if (sz == 0)
 243     {
 244       *ptr = NULL;
 245       return TRUE;
 246     }
 247
 248   switch (sec->compress_status)
 249     {
 250     case COMPRESS_SECTION_NONE:
 251       if (p == NULL)
 252         {
 253           p = (bfd_byte *) bfd_malloc (sz);
 254           if (p == NULL)
 255             {
 256               /* PR 20801: Provide a more helpful error message.  */
 257               if (bfd_get_error () == bfd_error_no_memory)
 258                 _bfd_error_handler
 259                   /* xgettext:c-format */
 260                   (_("error: %pB(%pA) is too large (%#" PRIx64 " bytes)"),
 261                   abfd, sec, (uint64_t) sz);
 262               return FALSE;
 263             }
 264         }
 265
 266       if (!bfd_get_section_contents (abfd, sec, p, 0, sz))
 267         {
 268           if (*ptr != p)
 269             free (p);
 270           return FALSE;
 271         }
 272       *ptr = p;
 273       return TRUE;
 274
 275     case DECOMPRESS_SECTION_SIZED:
 276       /* Read in the full compressed section contents.  */
 277       compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
 278       if (compressed_buffer == NULL)
 279         return FALSE;
 280       save_rawsize = sec->rawsize;
 281       save_size = sec->size;
 282       /* Clear rawsize, set size to compressed size and set compress_status
 283          to COMPRESS_SECTION_NONE.  If the compressed size is bigger than
 284          the uncompressed size, bfd_get_section_contents will fail.  */
 285       sec->rawsize = 0;
 286       sec->size = sec->compressed_size;
 287       sec->compress_status = COMPRESS_SECTION_NONE;
 288       ret = bfd_get_section_contents (abfd, sec, compressed_buffer,
 289                                       0, sec->compressed_size);
 290       /* Restore rawsize and size.  */
 291       sec->rawsize = save_rawsize;
 292       sec->size = save_size;
 293       sec->compress_status = DECOMPRESS_SECTION_SIZED;
 294       if (!ret)
 295         goto fail_compressed;
 296
 297       if (p == NULL)
 298         p = (bfd_byte *) bfd_malloc (sz);
 299       if (p == NULL)
 300         goto fail_compressed;
 301
 302       compression_header_size = bfd_get_compression_header_size (abfd, sec);
 303       if (compression_header_size == 0)
 304         /* Set header size to the zlib header size if it is a
 305            SHF_COMPRESSED section.  */
 306         compression_header_size = 12;
 307       if (!decompress_contents (compressed_buffer + compression_header_size,
 308                                 sec->compressed_size - compression_header_size, p, sz))
 309         {
 310           bfd_set_error (bfd_error_bad_value);
 311           if (p != *ptr)
 312             free (p);
 313         fail_compressed:
 314           free (compressed_buffer);
 315           return FALSE;
 316         }
 317
 318       free (compressed_buffer);
 319       *ptr = p;
 320       return TRUE;
 321
 322     case COMPRESS_SECTION_DONE:
 323       if (sec->contents == NULL)
 324         return FALSE;
 325       if (p == NULL)
 326         {
 327           p = (bfd_byte *) bfd_malloc (sz);
 328           if (p == NULL)
 329             return FALSE;
 330           *ptr = p;
 331         }
 332       /* PR 17512; file: 5bc29788.  */
 333       if (p != sec->contents)
 334         memcpy (p, sec->contents, sz);
 335       return TRUE;
 336
 337     default:
 338       abort ();
 339     }
 340 }
 341
 342 /*
 343 FUNCTION
 344         bfd_cache_section_contents
 345
 346 SYNOPSIS
 347         void bfd_cache_section_contents
 348           (asection *sec, void *contents);
 349
 350 DESCRIPTION
 351         Stash @var(contents) so any following reads of @var(sec) do
 352         not need to decompress again.
 353 */
 354
 355 void
 356 bfd_cache_section_contents (asection *sec, void *contents)
 357 {
 358   if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
 359     sec->compress_status = COMPRESS_SECTION_DONE;
 360   sec->contents = contents;
 361   sec->flags |= SEC_IN_MEMORY;
 362 }
 363
 364 /*
 365 FUNCTION
 366         bfd_is_section_compressed_with_header
 367
 368 SYNOPSIS
 369         bfd_boolean bfd_is_section_compressed_with_header
 370           (bfd *abfd, asection *section,
 371           int *compression_header_size_p,
 372           bfd_size_type *uncompressed_size_p,
 373           unsigned int *uncompressed_alignment_power_p);
 374
 375 DESCRIPTION
 376         Return @code{TRUE} if @var{section} is compressed.  Compression
 377         header size is returned in @var{compression_header_size_p},
 378         uncompressed size is returned in @var{uncompressed_size_p}
 379         and the uncompressed data alignement power is returned in
 380         @var{uncompressed_align_pow_p}.  If compression is
 381         unsupported, compression header size is returned with -1
 382         and uncompressed size is returned with 0.
 383 */
 384
 385 bfd_boolean
 386 bfd_is_section_compressed_with_header (bfd *abfd, sec_ptr sec,
 387                                        int *compression_header_size_p,
 388                                        bfd_size_type *uncompressed_size_p,
 389                                        unsigned int *uncompressed_align_pow_p)
 390 {
 391   bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];
 392   int compression_header_size;
 393   int header_size;
 394   unsigned int saved = sec->compress_status;
 395   bfd_boolean compressed;
 396
 397   *uncompressed_align_pow_p = 0;
 398
 399   compression_header_size = bfd_get_compression_header_size (abfd, sec);
 400   if (compression_header_size > MAX_COMPRESSION_HEADER_SIZE)
 401     abort ();
 402   header_size = compression_header_size ? compression_header_size : 12;
 403
 404   /* Don't decompress the section.  */
 405   sec->compress_status = COMPRESS_SECTION_NONE;
 406
 407   /* Read the header.  */
 408   if (bfd_get_section_contents (abfd, sec, header, 0, header_size))
 409     {
 410       if (compression_header_size == 0)
 411         /* In this case, it should be "ZLIB" followed by the uncompressed
 412            section size, 8 bytes in big-endian order.  */
 413         compressed = CONST_STRNEQ ((char*) header , "ZLIB");
 414       else
 415         compressed = TRUE;
 416     }
 417   else
 418     compressed = FALSE;
 419
 420   *uncompressed_size_p = sec->size;
 421   if (compressed)
 422     {
 423       if (compression_header_size != 0)
 424         {
 425           if (!bfd_check_compression_header (abfd, header, sec,
 426                                              uncompressed_size_p,
 427                                              uncompressed_align_pow_p))
 428             compression_header_size = -1;
 429         }
 430       /* Check for the pathalogical case of a debug string section that
 431          contains the string ZLIB.... as the first entry.  We assume that
 432          no uncompressed .debug_str section would ever be big enough to
 433          have the first byte of its (big-endian) size be non-zero.  */
 434       else if (strcmp (sec->name, ".debug_str") == 0
 435                && ISPRINT (header[4]))
 436         compressed = FALSE;
 437       else
 438         *uncompressed_size_p = bfd_getb64 (header + 4);
 439     }
 440
 441   /* Restore compress_status.  */
 442   sec->compress_status = saved;
 443   *compression_header_size_p = compression_header_size;
 444   return compressed;
 445 }
 446
 447 /*
 448 FUNCTION
 449         bfd_is_section_compressed
 450
 451 SYNOPSIS
 452         bfd_boolean bfd_is_section_compressed
 453           (bfd *abfd, asection *section);
 454
 455 DESCRIPTION
 456         Return @code{TRUE} if @var{section} is compressed.
 457 */
 458
 459 bfd_boolean
 460 bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
 461 {
 462   int compression_header_size;
 463   bfd_size_type uncompressed_size;
 464   unsigned int uncompressed_align_power;
 465   return (bfd_is_section_compressed_with_header (abfd, sec,
 466                                                  &compression_header_size,
 467                                                  &uncompressed_size,
 468                                                  &uncompressed_align_power)
 469           && compression_header_size >= 0
 470           && uncompressed_size > 0);
 471 }
 472
 473 /*
 474 FUNCTION
 475         bfd_init_section_decompress_status
 476
 477 SYNOPSIS
 478         bfd_boolean bfd_init_section_decompress_status
 479           (bfd *abfd, asection *section);
 480
 481 DESCRIPTION
 482         Record compressed section size, update section size with
 483         decompressed size and set compress_status to
 484         DECOMPRESS_SECTION_SIZED.
 485
 486         Return @code{FALSE} if the section is not a valid compressed
 487         section.  Otherwise, return @code{TRUE}.
 488 */
 489
 490 bfd_boolean
 491 bfd_init_section_decompress_status (bfd *abfd, sec_ptr sec)
 492 {
 493   bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];
 494   int compression_header_size;
 495   int header_size;
 496   bfd_size_type uncompressed_size;
 497   unsigned int uncompressed_alignment_power = 0;
 498
 499   compression_header_size = bfd_get_compression_header_size (abfd, sec);
 500   if (compression_header_size > MAX_COMPRESSION_HEADER_SIZE)
 501     abort ();
 502   header_size = compression_header_size ? compression_header_size : 12;
 503
 504   /* Read the header.  */
 505   if (sec->rawsize != 0
 506       || sec->contents != NULL
 507       || sec->compress_status != COMPRESS_SECTION_NONE
 508       || !bfd_get_section_contents (abfd, sec, header, 0, header_size))
 509     {
 510       bfd_set_error (bfd_error_invalid_operation);
 511       return FALSE;
 512     }
 513
 514   if (compression_header_size == 0)
 515     {
 516       /* In this case, it should be "ZLIB" followed by the uncompressed
 517          section size, 8 bytes in big-endian order.  */
 518       if (! CONST_STRNEQ ((char*) header, "ZLIB"))
 519         {
 520           bfd_set_error (bfd_error_wrong_format);
 521           return FALSE;
 522         }
 523       uncompressed_size = bfd_getb64 (header + 4);
 524     }
 525   else if (!bfd_check_compression_header (abfd, header, sec,
 526                                           &uncompressed_size,
 527                                           &uncompressed_alignment_power))
 528     {
 529       bfd_set_error (bfd_error_wrong_format);
 530       return FALSE;
 531     }
 532
 533   sec->compressed_size = sec->size;
 534   sec->size = uncompressed_size;
 535   bfd_set_section_alignment (abfd, sec, uncompressed_alignment_power);
 536   sec->compress_status = DECOMPRESS_SECTION_SIZED;
 537
 538   return TRUE;
 539 }
 540
 541 /*
 542 FUNCTION
 543         bfd_init_section_compress_status
 544
 545 SYNOPSIS
 546         bfd_boolean bfd_init_section_compress_status
 547           (bfd *abfd, asection *section);
 548
 549 DESCRIPTION
 550         If open for read, compress section, update section size with
 551         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 552
 553         Return @code{FALSE} if the section is not a valid compressed
 554         section.  Otherwise, return @code{TRUE}.
 555 */
 556
 557 bfd_boolean
 558 bfd_init_section_compress_status (bfd *abfd, sec_ptr sec)
 559 {
 560   bfd_size_type uncompressed_size;
 561   bfd_byte *uncompressed_buffer;
 562
 563   /* Error if not opened for read.  */
 564   if (abfd->direction != read_direction
 565       || sec->size == 0
 566       || sec->rawsize != 0
 567       || sec->contents != NULL
 568       || sec->compress_status != COMPRESS_SECTION_NONE)
 569     {
 570       bfd_set_error (bfd_error_invalid_operation);
 571       return FALSE;
 572     }
 573
 574   /* Read in the full section contents and compress it.  */
 575   uncompressed_size = sec->size;
 576   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
 577   /* PR 21431 */
 578   if (uncompressed_buffer == NULL)
 579     return FALSE;
 580
 581   if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
 582                                  0, uncompressed_size))
 583     return FALSE;
 584
 585   uncompressed_size = bfd_compress_section_contents (abfd, sec,
 586                                                      uncompressed_buffer,
 587                                                      uncompressed_size);
 588   return uncompressed_size != 0;
 589 }
 590
 591 /*
 592 FUNCTION
 593         bfd_compress_section
 594
 595 SYNOPSIS
 596         bfd_boolean bfd_compress_section
 597           (bfd *abfd, asection *section, bfd_byte *uncompressed_buffer);
 598
 599 DESCRIPTION
 600         If open for write, compress section, update section size with
 601         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 602
 603         Return @code{FALSE} if compression fail.  Otherwise, return
 604         @code{TRUE}.
 605 */
 606
 607 bfd_boolean
 608 bfd_compress_section (bfd *abfd, sec_ptr sec, bfd_byte *uncompressed_buffer)
 609 {
 610   bfd_size_type uncompressed_size = sec->size;
 611
 612   /* Error if not opened for write.  */
 613   if (abfd->direction != write_direction
 614       || uncompressed_size == 0
 615       || uncompressed_buffer == NULL
 616       || sec->contents != NULL
 617       || sec->compressed_size != 0
 618       || sec->compress_status != COMPRESS_SECTION_NONE)
 619     {
 620       bfd_set_error (bfd_error_invalid_operation);
 621       return FALSE;
 622     }
 623
 624   /* Compress it.  */
 625   return bfd_compress_section_contents (abfd, sec, uncompressed_buffer,
 626                                         uncompressed_size) != 0;
 627 }