bfd/compress.c

   1 /* Compressed section support (intended for debug sections).
   2    Copyright (C) 2008-2014 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 "bfd.h"
  23 #include "libbfd.h"
  24 #ifdef HAVE_ZLIB_H
  25 #include <zlib.h>
  26 #endif
  27 #include "safe-ctype.h"
  28
  29 #ifdef HAVE_ZLIB_H
  30 static bfd_boolean
  31 decompress_contents (bfd_byte *compressed_buffer,
  32                      bfd_size_type compressed_size,
  33                      bfd_byte *uncompressed_buffer,
  34                      bfd_size_type uncompressed_size)
  35 {
  36   z_stream strm;
  37   int rc;
  38
  39   /* It is possible the section consists of several compressed
  40      buffers concatenated together, so we uncompress in a loop.  */
  41   strm.zalloc = NULL;
  42   strm.zfree = NULL;
  43   strm.opaque = NULL;
  44   strm.avail_in = compressed_size - 12;
  45   strm.next_in = (Bytef*) compressed_buffer + 12;
  46   strm.avail_out = uncompressed_size;
  47
  48   BFD_ASSERT (Z_OK == 0);
  49   rc = inflateInit (&strm);
  50   while (strm.avail_in > 0 && strm.avail_out > 0)
  51     {
  52       if (rc != Z_OK)
  53         break;
  54       strm.next_out = ((Bytef*) uncompressed_buffer
  55                        + (uncompressed_size - strm.avail_out));
  56       rc = inflate (&strm, Z_FINISH);
  57       if (rc != Z_STREAM_END)
  58         break;
  59       rc = inflateReset (&strm);
  60     }
  61   rc |= inflateEnd (&strm);
  62   return rc == Z_OK && strm.avail_out == 0;
  63 }
  64 #endif
  65
  66 /*
  67 FUNCTION
  68         bfd_compress_section_contents
  69
  70 SYNOPSIS
  71         bfd_boolean bfd_compress_section_contents
  72           (bfd *abfd, asection *section, bfd_byte *uncompressed_buffer,
  73            bfd_size_type uncompressed_size);
  74
  75 DESCRIPTION
  76
  77         Compress data of the size specified in @var{uncompressed_size}
  78         and pointed to by @var{uncompressed_buffer} using zlib and store
  79         as the contents field.  This function assumes the contents
  80         field was allocated using bfd_malloc() or equivalent.  If zlib
  81         is not installed on this machine, the input is unmodified.
  82
  83         Return @code{TRUE} if the full section contents is compressed
  84         successfully.
  85 */
  86
  87 bfd_boolean
  88 bfd_compress_section_contents (bfd *abfd ATTRIBUTE_UNUSED,
  89                                sec_ptr sec ATTRIBUTE_UNUSED,
  90                                bfd_byte *uncompressed_buffer ATTRIBUTE_UNUSED,
  91                                bfd_size_type uncompressed_size ATTRIBUTE_UNUSED)
  92 {
  93 #ifndef HAVE_ZLIB_H
  94   bfd_set_error (bfd_error_invalid_operation);
  95   return FALSE;
  96 #else
  97   uLong compressed_size;
  98   bfd_byte *compressed_buffer;
  99
 100   compressed_size = compressBound (uncompressed_size) + 12;
 101   compressed_buffer = (bfd_byte *) bfd_malloc (compressed_size);
 102
 103   if (compressed_buffer == NULL)
 104     return FALSE;
 105
 106   if (compress ((Bytef*) compressed_buffer + 12,
 107                 &compressed_size,
 108                 (const Bytef*) uncompressed_buffer,
 109                 uncompressed_size) != Z_OK)
 110     {
 111       free (compressed_buffer);
 112       bfd_set_error (bfd_error_bad_value);
 113       return FALSE;
 114     }
 115
 116   /* Write the zlib header.  In this case, it should be "ZLIB" followed
 117      by the uncompressed section size, 8 bytes in big-endian order.  */
 118   memcpy (compressed_buffer, "ZLIB", 4);
 119   compressed_buffer[11] = uncompressed_size; uncompressed_size >>= 8;
 120   compressed_buffer[10] = uncompressed_size; uncompressed_size >>= 8;
 121   compressed_buffer[9] = uncompressed_size; uncompressed_size >>= 8;
 122   compressed_buffer[8] = uncompressed_size; uncompressed_size >>= 8;
 123   compressed_buffer[7] = uncompressed_size; uncompressed_size >>= 8;
 124   compressed_buffer[6] = uncompressed_size; uncompressed_size >>= 8;
 125   compressed_buffer[5] = uncompressed_size; uncompressed_size >>= 8;
 126   compressed_buffer[4] = uncompressed_size;
 127   compressed_size += 12;
 128
 129   /* Free the uncompressed contents if we compress in place.  */
 130   if (uncompressed_buffer == sec->contents)
 131     free (uncompressed_buffer);
 132
 133   sec->contents = compressed_buffer;
 134   sec->size = compressed_size;
 135   sec->compress_status = COMPRESS_SECTION_DONE;
 136
 137   return TRUE;
 138 #endif  /* HAVE_ZLIB_H */
 139 }
 140
 141 /*
 142 FUNCTION
 143         bfd_get_full_section_contents
 144
 145 SYNOPSIS
 146         bfd_boolean bfd_get_full_section_contents
 147           (bfd *abfd, asection *section, bfd_byte **ptr);
 148
 149 DESCRIPTION
 150         Read all data from @var{section} in BFD @var{abfd}, decompress
 151         if needed, and store in @var{*ptr}.  If @var{*ptr} is NULL,
 152         return @var{*ptr} with memory malloc'd by this function.
 153
 154         Return @code{TRUE} if the full section contents is retrieved
 155         successfully.  If the section has no contents then this function
 156         returns @code{TRUE} but @var{*ptr} is set to NULL.
 157 */
 158
 159 bfd_boolean
 160 bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
 161 {
 162   bfd_size_type sz;
 163   bfd_byte *p = *ptr;
 164 #ifdef HAVE_ZLIB_H
 165   bfd_boolean ret;
 166   bfd_size_type save_size;
 167   bfd_size_type save_rawsize;
 168   bfd_byte *compressed_buffer;
 169 #endif
 170
 171   if (abfd->direction != write_direction && sec->rawsize != 0)
 172     sz = sec->rawsize;
 173   else
 174     sz = sec->size;
 175   if (sz == 0)
 176     {
 177       *ptr = NULL;
 178       return TRUE;
 179     }
 180
 181   switch (sec->compress_status)
 182     {
 183     case COMPRESS_SECTION_NONE:
 184       if (p == NULL)
 185         {
 186           p = (bfd_byte *) bfd_malloc (sz);
 187           if (p == NULL)
 188             return FALSE;
 189         }
 190
 191       if (!bfd_get_section_contents (abfd, sec, p, 0, sz))
 192         {
 193           if (*ptr != p)
 194             free (p);
 195           return FALSE;
 196         }
 197       *ptr = p;
 198       return TRUE;
 199
 200     case DECOMPRESS_SECTION_SIZED:
 201 #ifndef HAVE_ZLIB_H
 202       bfd_set_error (bfd_error_invalid_operation);
 203       return FALSE;
 204 #else
 205       /* Read in the full compressed section contents.  */
 206       compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
 207       if (compressed_buffer == NULL)
 208         return FALSE;
 209       save_rawsize = sec->rawsize;
 210       save_size = sec->size;
 211       /* Clear rawsize, set size to compressed size and set compress_status
 212          to COMPRESS_SECTION_NONE.  If the compressed size is bigger than
 213          the uncompressed size, bfd_get_section_contents will fail.  */
 214       sec->rawsize = 0;
 215       sec->size = sec->compressed_size;
 216       sec->compress_status = COMPRESS_SECTION_NONE;
 217       ret = bfd_get_section_contents (abfd, sec, compressed_buffer,
 218                                       0, sec->compressed_size);
 219       /* Restore rawsize and size.  */
 220       sec->rawsize = save_rawsize;
 221       sec->size = save_size;
 222       sec->compress_status = DECOMPRESS_SECTION_SIZED;
 223       if (!ret)
 224         goto fail_compressed;
 225
 226       if (p == NULL)
 227         p = (bfd_byte *) bfd_malloc (sz);
 228       if (p == NULL)
 229         goto fail_compressed;
 230
 231       if (!decompress_contents (compressed_buffer, sec->compressed_size, p, sz))
 232         {
 233           bfd_set_error (bfd_error_bad_value);
 234           if (p != *ptr)
 235             free (p);
 236         fail_compressed:
 237           free (compressed_buffer);
 238           return FALSE;
 239         }
 240
 241       free (compressed_buffer);
 242       *ptr = p;
 243       return TRUE;
 244 #endif
 245
 246     case COMPRESS_SECTION_DONE:
 247       if (p == NULL)
 248         {
 249           p = (bfd_byte *) bfd_malloc (sz);
 250           if (p == NULL)
 251             return FALSE;
 252           *ptr = p;
 253         }
 254       /* PR 17512; file: 5bc29788.  */
 255       if (p != sec->contents)
 256         memcpy (p, sec->contents, sz);
 257       return TRUE;
 258
 259     default:
 260       abort ();
 261     }
 262 }
 263
 264 /*
 265 FUNCTION
 266         bfd_cache_section_contents
 267
 268 SYNOPSIS
 269         void bfd_cache_section_contents
 270           (asection *sec, void *contents);
 271
 272 DESCRIPTION
 273         Stash @var(contents) so any following reads of @var(sec) do
 274         not need to decompress again.
 275 */
 276
 277 void
 278 bfd_cache_section_contents (asection *sec, void *contents)
 279 {
 280   if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
 281     sec->compress_status = COMPRESS_SECTION_DONE;
 282   sec->contents = contents;
 283   sec->flags |= SEC_IN_MEMORY;
 284 }
 285
 286
 287 /*
 288 FUNCTION
 289         bfd_is_section_compressed
 290
 291 SYNOPSIS
 292         bfd_boolean bfd_is_section_compressed
 293           (bfd *abfd, asection *section);
 294
 295 DESCRIPTION
 296         Return @code{TRUE} if @var{section} is compressed.
 297 */
 298
 299 bfd_boolean
 300 bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
 301 {
 302   bfd_byte compressed_buffer [12];
 303   unsigned int saved = sec->compress_status;
 304   bfd_boolean compressed;
 305
 306   /* Don't decompress the section.  */
 307   sec->compress_status = COMPRESS_SECTION_NONE;
 308
 309   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 310      by the uncompressed section size, 8 bytes in big-endian order.  */
 311   compressed = (bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12)
 312                 && CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"));
 313
 314   /* Check for the pathalogical case of a debug string section that
 315      contains the string ZLIB.... as the first entry.  We assume that
 316      no uncompressed .debug_str section would ever be big enough to
 317      have the first byte of its (big-endian) size be non-zero.  */
 318   if (compressed
 319       && strcmp (sec->name, ".debug_str") == 0
 320       && ISPRINT (compressed_buffer[4]))
 321     compressed = FALSE;
 322
 323   /* Restore compress_status.  */
 324   sec->compress_status = saved;
 325   return compressed;
 326 }
 327
 328 /*
 329 FUNCTION
 330         bfd_init_section_decompress_status
 331
 332 SYNOPSIS
 333         bfd_boolean bfd_init_section_decompress_status
 334           (bfd *abfd, asection *section);
 335
 336 DESCRIPTION
 337         Record compressed section size, update section size with
 338         decompressed size and set compress_status to
 339         DECOMPRESS_SECTION_SIZED.
 340
 341         Return @code{FALSE} if the section is not a valid compressed
 342         section or zlib is not installed on this machine.  Otherwise,
 343         return @code{TRUE}.
 344 */
 345
 346 bfd_boolean
 347 bfd_init_section_decompress_status (bfd *abfd ATTRIBUTE_UNUSED,
 348                                     sec_ptr sec ATTRIBUTE_UNUSED)
 349 {
 350 #ifndef HAVE_ZLIB_H
 351   bfd_set_error (bfd_error_invalid_operation);
 352   return FALSE;
 353 #else
 354   bfd_byte compressed_buffer [12];
 355   bfd_size_type uncompressed_size;
 356
 357   if (sec->rawsize != 0
 358       || sec->contents != NULL
 359       || sec->compress_status != COMPRESS_SECTION_NONE
 360       || !bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12))
 361     {
 362       bfd_set_error (bfd_error_invalid_operation);
 363       return FALSE;
 364     }
 365
 366   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 367      by the uncompressed section size, 8 bytes in big-endian order.  */
 368   if (! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
 369     {
 370       bfd_set_error (bfd_error_wrong_format);
 371       return FALSE;
 372     }
 373
 374   uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
 375   uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
 376   uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
 377   uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
 378   uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
 379   uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
 380   uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
 381   uncompressed_size += compressed_buffer[11];
 382
 383   sec->compressed_size = sec->size;
 384   sec->size = uncompressed_size;
 385   sec->compress_status = DECOMPRESS_SECTION_SIZED;
 386
 387   return TRUE;
 388 #endif
 389 }
 390
 391 /*
 392 FUNCTION
 393         bfd_init_section_compress_status
 394
 395 SYNOPSIS
 396         bfd_boolean bfd_init_section_compress_status
 397           (bfd *abfd, asection *section);
 398
 399 DESCRIPTION
 400         If open for read, compress section, update section size with
 401         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 402
 403         Return @code{FALSE} if the section is not a valid compressed
 404         section or zlib is not installed on this machine.  Otherwise,
 405         return @code{TRUE}.
 406 */
 407
 408 bfd_boolean
 409 bfd_init_section_compress_status (bfd *abfd ATTRIBUTE_UNUSED,
 410                                   sec_ptr sec ATTRIBUTE_UNUSED)
 411 {
 412 #ifndef HAVE_ZLIB_H
 413   bfd_set_error (bfd_error_invalid_operation);
 414   return FALSE;
 415 #else
 416   bfd_size_type uncompressed_size;
 417   bfd_byte *uncompressed_buffer;
 418   bfd_boolean ret;
 419
 420   /* Error if not opened for read.  */
 421   if (abfd->direction != read_direction
 422       || sec->size == 0
 423       || sec->rawsize != 0
 424       || sec->contents != NULL
 425       || sec->compress_status != COMPRESS_SECTION_NONE)
 426     {
 427       bfd_set_error (bfd_error_invalid_operation);
 428       return FALSE;
 429     }
 430
 431   /* Read in the full section contents and compress it.  */
 432   uncompressed_size = sec->size;
 433   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
 434   if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
 435                                  0, uncompressed_size))
 436     ret = FALSE;
 437   else
 438     ret = bfd_compress_section_contents (abfd, sec,
 439                                          uncompressed_buffer,
 440                                          uncompressed_size);
 441
 442   free (uncompressed_buffer);
 443   return ret;
 444 #endif
 445 }