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.
 156 */
 157
 158 bfd_boolean
 159 bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
 160 {
 161   bfd_size_type sz;
 162   bfd_byte *p = *ptr;
 163 #ifdef HAVE_ZLIB_H
 164   bfd_boolean ret;
 165   bfd_size_type save_size;
 166   bfd_size_type save_rawsize;
 167   bfd_byte *compressed_buffer;
 168 #endif
 169
 170   if (abfd->direction != write_direction && sec->rawsize != 0)
 171     sz = sec->rawsize;
 172   else
 173     sz = sec->size;
 174   if (sz == 0)
 175     return TRUE;
 176
 177   switch (sec->compress_status)
 178     {
 179     case COMPRESS_SECTION_NONE:
 180       if (p == NULL)
 181         {
 182           p = (bfd_byte *) bfd_malloc (sz);
 183           if (p == NULL)
 184             return FALSE;
 185         }
 186       if (!bfd_get_section_contents (abfd, sec, p, 0, sz))
 187         {
 188           if (*ptr != p)
 189             free (p);
 190           return FALSE;
 191         }
 192       *ptr = p;
 193       return TRUE;
 194
 195     case DECOMPRESS_SECTION_SIZED:
 196 #ifndef HAVE_ZLIB_H
 197       bfd_set_error (bfd_error_invalid_operation);
 198       return FALSE;
 199 #else
 200       /* Read in the full compressed section contents.  */
 201       compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
 202       if (compressed_buffer == NULL)
 203         return FALSE;
 204       save_rawsize = sec->rawsize;
 205       save_size = sec->size;
 206       /* Clear rawsize, set size to compressed size and set compress_status
 207          to COMPRESS_SECTION_NONE.  If the compressed size is bigger than
 208          the uncompressed size, bfd_get_section_contents will fail.  */
 209       sec->rawsize = 0;
 210       sec->size = sec->compressed_size;
 211       sec->compress_status = COMPRESS_SECTION_NONE;
 212       ret = bfd_get_section_contents (abfd, sec, compressed_buffer,
 213                                       0, sec->compressed_size);
 214       /* Restore rawsize and size.  */
 215       sec->rawsize = save_rawsize;
 216       sec->size = save_size;
 217       sec->compress_status = DECOMPRESS_SECTION_SIZED;
 218       if (!ret)
 219         goto fail_compressed;
 220
 221       if (p == NULL)
 222         p = (bfd_byte *) bfd_malloc (sz);
 223       if (p == NULL)
 224         goto fail_compressed;
 225
 226       if (!decompress_contents (compressed_buffer, sec->compressed_size, p, sz))
 227         {
 228           bfd_set_error (bfd_error_bad_value);
 229           if (p != *ptr)
 230             free (p);
 231         fail_compressed:
 232           free (compressed_buffer);
 233           return FALSE;
 234         }
 235
 236       free (compressed_buffer);
 237       *ptr = p;
 238       return TRUE;
 239 #endif
 240
 241     case COMPRESS_SECTION_DONE:
 242       if (p == NULL)
 243         {
 244           p = (bfd_byte *) bfd_malloc (sz);
 245           if (p == NULL)
 246             return FALSE;
 247           *ptr = p;
 248         }
 249       memcpy (p, sec->contents, sz);
 250       return TRUE;
 251
 252     default:
 253       abort ();
 254     }
 255 }
 256
 257 /*
 258 FUNCTION
 259         bfd_cache_section_contents
 260
 261 SYNOPSIS
 262         void bfd_cache_section_contents
 263           (asection *sec, void *contents);
 264
 265 DESCRIPTION
 266         Stash @var(contents) so any following reads of @var(sec) do
 267         not need to decompress again.
 268 */
 269
 270 void
 271 bfd_cache_section_contents (asection *sec, void *contents)
 272 {
 273   if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
 274     sec->compress_status = COMPRESS_SECTION_DONE;
 275   sec->contents = contents;
 276   sec->flags |= SEC_IN_MEMORY;
 277 }
 278
 279
 280 /*
 281 FUNCTION
 282         bfd_is_section_compressed
 283
 284 SYNOPSIS
 285         bfd_boolean bfd_is_section_compressed
 286           (bfd *abfd, asection *section);
 287
 288 DESCRIPTION
 289         Return @code{TRUE} if @var{section} is compressed.
 290 */
 291
 292 bfd_boolean
 293 bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
 294 {
 295   bfd_byte compressed_buffer [12];
 296   unsigned int saved = sec->compress_status;
 297   bfd_boolean compressed;
 298
 299   /* Don't decompress the section.  */
 300   sec->compress_status = COMPRESS_SECTION_NONE;
 301
 302   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 303      by the uncompressed section size, 8 bytes in big-endian order.  */
 304   compressed = (bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12)
 305                 && CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"));
 306
 307   /* Check for the pathalogical case of a debug string section that
 308      contains the string ZLIB.... as the first entry.  We assume that
 309      no uncompressed .debug_str section would ever be big enough to
 310      have the first byte of its (big-endian) size be non-zero.  */
 311   if (compressed
 312       && strcmp (sec->name, ".debug_str") == 0
 313       && ISPRINT (compressed_buffer[4]))
 314     compressed = FALSE;
 315
 316   /* Restore compress_status.  */
 317   sec->compress_status = saved;
 318   return compressed;
 319 }
 320
 321 /*
 322 FUNCTION
 323         bfd_init_section_decompress_status
 324
 325 SYNOPSIS
 326         bfd_boolean bfd_init_section_decompress_status
 327           (bfd *abfd, asection *section);
 328
 329 DESCRIPTION
 330         Record compressed section size, update section size with
 331         decompressed size and set compress_status to
 332         DECOMPRESS_SECTION_SIZED.
 333
 334         Return @code{FALSE} if the section is not a valid compressed
 335         section or zlib is not installed on this machine.  Otherwise,
 336         return @code{TRUE}.
 337 */
 338
 339 bfd_boolean
 340 bfd_init_section_decompress_status (bfd *abfd ATTRIBUTE_UNUSED,
 341                                     sec_ptr sec ATTRIBUTE_UNUSED)
 342 {
 343 #ifndef HAVE_ZLIB_H
 344   bfd_set_error (bfd_error_invalid_operation);
 345   return FALSE;
 346 #else
 347   bfd_byte compressed_buffer [12];
 348   bfd_size_type uncompressed_size;
 349
 350   if (sec->rawsize != 0
 351       || sec->contents != NULL
 352       || sec->compress_status != COMPRESS_SECTION_NONE
 353       || !bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12))
 354     {
 355       bfd_set_error (bfd_error_invalid_operation);
 356       return FALSE;
 357     }
 358
 359   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 360      by the uncompressed section size, 8 bytes in big-endian order.  */
 361   if (! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
 362     {
 363       bfd_set_error (bfd_error_wrong_format);
 364       return FALSE;
 365     }
 366
 367   uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
 368   uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
 369   uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
 370   uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
 371   uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
 372   uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
 373   uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
 374   uncompressed_size += compressed_buffer[11];
 375
 376   sec->compressed_size = sec->size;
 377   sec->size = uncompressed_size;
 378   sec->compress_status = DECOMPRESS_SECTION_SIZED;
 379
 380   return TRUE;
 381 #endif
 382 }
 383
 384 /*
 385 FUNCTION
 386         bfd_init_section_compress_status
 387
 388 SYNOPSIS
 389         bfd_boolean bfd_init_section_compress_status
 390           (bfd *abfd, asection *section);
 391
 392 DESCRIPTION
 393         If open for read, compress section, update section size with
 394         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 395
 396         Return @code{FALSE} if the section is not a valid compressed
 397         section or zlib is not installed on this machine.  Otherwise,
 398         return @code{TRUE}.
 399 */
 400
 401 bfd_boolean
 402 bfd_init_section_compress_status (bfd *abfd ATTRIBUTE_UNUSED,
 403                                   sec_ptr sec ATTRIBUTE_UNUSED)
 404 {
 405 #ifndef HAVE_ZLIB_H
 406   bfd_set_error (bfd_error_invalid_operation);
 407   return FALSE;
 408 #else
 409   bfd_size_type uncompressed_size;
 410   bfd_byte *uncompressed_buffer;
 411   bfd_boolean ret;
 412
 413   /* Error if not opened for read.  */
 414   if (abfd->direction != read_direction
 415       || sec->size == 0
 416       || sec->rawsize != 0
 417       || sec->contents != NULL
 418       || sec->compress_status != COMPRESS_SECTION_NONE)
 419     {
 420       bfd_set_error (bfd_error_invalid_operation);
 421       return FALSE;
 422     }
 423
 424   /* Read in the full section contents and compress it.  */
 425   uncompressed_size = sec->size;
 426   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
 427   if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
 428                                  0, uncompressed_size))
 429     ret = FALSE;
 430   else
 431     ret = bfd_compress_section_contents (abfd, sec,
 432                                          uncompressed_buffer,
 433                                          uncompressed_size);
 434
 435   free (uncompressed_buffer);
 436   return ret;
 437 #endif
 438 }