bfd/compress.c

   1 /* Compressed section support (intended for debug sections).
   2    Copyright (C) 2008-2015 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
  65 /* Compress data of the size specified in @var{uncompressed_size}
  66    and pointed to by @var{uncompressed_buffer} using zlib and store
  67    as the contents field.  This function assumes the contents
  68    field was allocated using bfd_malloc() or equivalent.  If zlib
  69    is not installed on this machine, the input is unmodified.
  70
  71    Return @code{TRUE} if the full section contents is compressed
  72    successfully.  */
  73
  74 static bfd_boolean
  75 bfd_compress_section_contents (bfd *abfd ATTRIBUTE_UNUSED,
  76                                sec_ptr sec ATTRIBUTE_UNUSED,
  77                                bfd_byte *uncompressed_buffer ATTRIBUTE_UNUSED,
  78                                bfd_size_type uncompressed_size ATTRIBUTE_UNUSED)
  79 {
  80   uLong compressed_size;
  81   bfd_byte *compressed_buffer;
  82
  83   compressed_size = compressBound (uncompressed_size) + 12;
  84   compressed_buffer = (bfd_byte *) bfd_malloc (compressed_size);
  85
  86   if (compressed_buffer == NULL)
  87     return FALSE;
  88
  89   if (compress ((Bytef*) compressed_buffer + 12,
  90                 &compressed_size,
  91                 (const Bytef*) uncompressed_buffer,
  92                 uncompressed_size) != Z_OK)
  93     {
  94       free (compressed_buffer);
  95       bfd_set_error (bfd_error_bad_value);
  96       return FALSE;
  97     }
  98
  99   /* Write the zlib header.  In this case, it should be "ZLIB" followed
 100      by the uncompressed section size, 8 bytes in big-endian order.  */
 101   memcpy (compressed_buffer, "ZLIB", 4);
 102   compressed_buffer[11] = uncompressed_size; uncompressed_size >>= 8;
 103   compressed_buffer[10] = uncompressed_size; uncompressed_size >>= 8;
 104   compressed_buffer[9] = uncompressed_size; uncompressed_size >>= 8;
 105   compressed_buffer[8] = uncompressed_size; uncompressed_size >>= 8;
 106   compressed_buffer[7] = uncompressed_size; uncompressed_size >>= 8;
 107   compressed_buffer[6] = uncompressed_size; uncompressed_size >>= 8;
 108   compressed_buffer[5] = uncompressed_size; uncompressed_size >>= 8;
 109   compressed_buffer[4] = uncompressed_size;
 110   compressed_size += 12;
 111
 112   /* Free the uncompressed contents if we compress in place.  */
 113   if (uncompressed_buffer == sec->contents)
 114     free (uncompressed_buffer);
 115
 116   sec->contents = compressed_buffer;
 117   sec->size = compressed_size;
 118   sec->compress_status = COMPRESS_SECTION_DONE;
 119
 120   return TRUE;
 121 }
 122 #endif  /* HAVE_ZLIB_H */
 123
 124 /*
 125 FUNCTION
 126         bfd_get_full_section_contents
 127
 128 SYNOPSIS
 129         bfd_boolean bfd_get_full_section_contents
 130           (bfd *abfd, asection *section, bfd_byte **ptr);
 131
 132 DESCRIPTION
 133         Read all data from @var{section} in BFD @var{abfd}, decompress
 134         if needed, and store in @var{*ptr}.  If @var{*ptr} is NULL,
 135         return @var{*ptr} with memory malloc'd by this function.
 136
 137         Return @code{TRUE} if the full section contents is retrieved
 138         successfully.  If the section has no contents then this function
 139         returns @code{TRUE} but @var{*ptr} is set to NULL.
 140 */
 141
 142 bfd_boolean
 143 bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
 144 {
 145   bfd_size_type sz;
 146   bfd_byte *p = *ptr;
 147 #ifdef HAVE_ZLIB_H
 148   bfd_boolean ret;
 149   bfd_size_type save_size;
 150   bfd_size_type save_rawsize;
 151   bfd_byte *compressed_buffer;
 152 #endif
 153
 154   if (abfd->direction != write_direction && sec->rawsize != 0)
 155     sz = sec->rawsize;
 156   else
 157     sz = sec->size;
 158   if (sz == 0)
 159     {
 160       *ptr = NULL;
 161       return TRUE;
 162     }
 163
 164   switch (sec->compress_status)
 165     {
 166     case COMPRESS_SECTION_NONE:
 167       if (p == NULL)
 168         {
 169           p = (bfd_byte *) bfd_malloc (sz);
 170           if (p == NULL)
 171             return FALSE;
 172         }
 173
 174       if (!bfd_get_section_contents (abfd, sec, p, 0, sz))
 175         {
 176           if (*ptr != p)
 177             free (p);
 178           return FALSE;
 179         }
 180       *ptr = p;
 181       return TRUE;
 182
 183     case DECOMPRESS_SECTION_SIZED:
 184 #ifndef HAVE_ZLIB_H
 185       bfd_set_error (bfd_error_invalid_operation);
 186       return FALSE;
 187 #else
 188       /* Read in the full compressed section contents.  */
 189       compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
 190       if (compressed_buffer == NULL)
 191         return FALSE;
 192       save_rawsize = sec->rawsize;
 193       save_size = sec->size;
 194       /* Clear rawsize, set size to compressed size and set compress_status
 195          to COMPRESS_SECTION_NONE.  If the compressed size is bigger than
 196          the uncompressed size, bfd_get_section_contents will fail.  */
 197       sec->rawsize = 0;
 198       sec->size = sec->compressed_size;
 199       sec->compress_status = COMPRESS_SECTION_NONE;
 200       ret = bfd_get_section_contents (abfd, sec, compressed_buffer,
 201                                       0, sec->compressed_size);
 202       /* Restore rawsize and size.  */
 203       sec->rawsize = save_rawsize;
 204       sec->size = save_size;
 205       sec->compress_status = DECOMPRESS_SECTION_SIZED;
 206       if (!ret)
 207         goto fail_compressed;
 208
 209       if (p == NULL)
 210         p = (bfd_byte *) bfd_malloc (sz);
 211       if (p == NULL)
 212         goto fail_compressed;
 213
 214       if (!decompress_contents (compressed_buffer, sec->compressed_size, p, sz))
 215         {
 216           bfd_set_error (bfd_error_bad_value);
 217           if (p != *ptr)
 218             free (p);
 219         fail_compressed:
 220           free (compressed_buffer);
 221           return FALSE;
 222         }
 223
 224       free (compressed_buffer);
 225       *ptr = p;
 226       return TRUE;
 227 #endif
 228
 229     case COMPRESS_SECTION_DONE:
 230       if (sec->contents == NULL)
 231         return FALSE;
 232       if (p == NULL)
 233         {
 234           p = (bfd_byte *) bfd_malloc (sz);
 235           if (p == NULL)
 236             return FALSE;
 237           *ptr = p;
 238         }
 239       /* PR 17512; file: 5bc29788.  */
 240       if (p != sec->contents)
 241         memcpy (p, sec->contents, sz);
 242       return TRUE;
 243
 244     default:
 245       abort ();
 246     }
 247 }
 248
 249 /*
 250 FUNCTION
 251         bfd_cache_section_contents
 252
 253 SYNOPSIS
 254         void bfd_cache_section_contents
 255           (asection *sec, void *contents);
 256
 257 DESCRIPTION
 258         Stash @var(contents) so any following reads of @var(sec) do
 259         not need to decompress again.
 260 */
 261
 262 void
 263 bfd_cache_section_contents (asection *sec, void *contents)
 264 {
 265   if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
 266     sec->compress_status = COMPRESS_SECTION_DONE;
 267   sec->contents = contents;
 268   sec->flags |= SEC_IN_MEMORY;
 269 }
 270
 271
 272 /*
 273 FUNCTION
 274         bfd_is_section_compressed
 275
 276 SYNOPSIS
 277         bfd_boolean bfd_is_section_compressed
 278           (bfd *abfd, asection *section);
 279
 280 DESCRIPTION
 281         Return @code{TRUE} if @var{section} is compressed.
 282 */
 283
 284 bfd_boolean
 285 bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
 286 {
 287   bfd_byte compressed_buffer [12];
 288   unsigned int saved = sec->compress_status;
 289   bfd_boolean compressed;
 290
 291   /* Don't decompress the section.  */
 292   sec->compress_status = COMPRESS_SECTION_NONE;
 293
 294   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 295      by the uncompressed section size, 8 bytes in big-endian order.  */
 296   compressed = (bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12)
 297                 && CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"));
 298
 299   /* Check for the pathalogical case of a debug string section that
 300      contains the string ZLIB.... as the first entry.  We assume that
 301      no uncompressed .debug_str section would ever be big enough to
 302      have the first byte of its (big-endian) size be non-zero.  */
 303   if (compressed
 304       && strcmp (sec->name, ".debug_str") == 0
 305       && ISPRINT (compressed_buffer[4]))
 306     compressed = FALSE;
 307
 308   /* Restore compress_status.  */
 309   sec->compress_status = saved;
 310   return compressed;
 311 }
 312
 313 /*
 314 FUNCTION
 315         bfd_init_section_decompress_status
 316
 317 SYNOPSIS
 318         bfd_boolean bfd_init_section_decompress_status
 319           (bfd *abfd, asection *section);
 320
 321 DESCRIPTION
 322         Record compressed section size, update section size with
 323         decompressed size and set compress_status to
 324         DECOMPRESS_SECTION_SIZED.
 325
 326         Return @code{FALSE} if the section is not a valid compressed
 327         section or zlib is not installed on this machine.  Otherwise,
 328         return @code{TRUE}.
 329 */
 330
 331 bfd_boolean
 332 bfd_init_section_decompress_status (bfd *abfd ATTRIBUTE_UNUSED,
 333                                     sec_ptr sec ATTRIBUTE_UNUSED)
 334 {
 335 #ifndef HAVE_ZLIB_H
 336   bfd_set_error (bfd_error_invalid_operation);
 337   return FALSE;
 338 #else
 339   bfd_byte compressed_buffer [12];
 340   bfd_size_type uncompressed_size;
 341
 342   if (sec->rawsize != 0
 343       || sec->contents != NULL
 344       || sec->compress_status != COMPRESS_SECTION_NONE
 345       || !bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12))
 346     {
 347       bfd_set_error (bfd_error_invalid_operation);
 348       return FALSE;
 349     }
 350
 351   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 352      by the uncompressed section size, 8 bytes in big-endian order.  */
 353   if (! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
 354     {
 355       bfd_set_error (bfd_error_wrong_format);
 356       return FALSE;
 357     }
 358
 359   uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
 360   uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
 361   uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
 362   uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
 363   uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
 364   uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
 365   uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
 366   uncompressed_size += compressed_buffer[11];
 367
 368   sec->compressed_size = sec->size;
 369   sec->size = uncompressed_size;
 370   sec->compress_status = DECOMPRESS_SECTION_SIZED;
 371
 372   return TRUE;
 373 #endif
 374 }
 375
 376 /*
 377 FUNCTION
 378         bfd_init_section_compress_status
 379
 380 SYNOPSIS
 381         bfd_boolean bfd_init_section_compress_status
 382           (bfd *abfd, asection *section);
 383
 384 DESCRIPTION
 385         If open for read, compress section, update section size with
 386         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 387
 388         Return @code{FALSE} if the section is not a valid compressed
 389         section or zlib is not installed on this machine.  Otherwise,
 390         return @code{TRUE}.
 391 */
 392
 393 bfd_boolean
 394 bfd_init_section_compress_status (bfd *abfd ATTRIBUTE_UNUSED,
 395                                   sec_ptr sec ATTRIBUTE_UNUSED)
 396 {
 397 #ifndef HAVE_ZLIB_H
 398   bfd_set_error (bfd_error_invalid_operation);
 399   return FALSE;
 400 #else
 401   bfd_size_type uncompressed_size;
 402   bfd_byte *uncompressed_buffer;
 403   bfd_boolean ret;
 404
 405   /* Error if not opened for read.  */
 406   if (abfd->direction != read_direction
 407       || sec->size == 0
 408       || sec->rawsize != 0
 409       || sec->contents != NULL
 410       || sec->compress_status != COMPRESS_SECTION_NONE)
 411     {
 412       bfd_set_error (bfd_error_invalid_operation);
 413       return FALSE;
 414     }
 415
 416   /* Read in the full section contents and compress it.  */
 417   uncompressed_size = sec->size;
 418   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
 419   if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
 420                                  0, uncompressed_size))
 421     ret = FALSE;
 422   else
 423     ret = bfd_compress_section_contents (abfd, sec,
 424                                          uncompressed_buffer,
 425                                          uncompressed_size);
 426
 427   /* PR binutils/18087: If compression didn't make
 428      the section smaller, just keep it uncompressed.  */
 429   if (ret && uncompressed_size < sec->size)
 430     {
 431       free (sec->contents);
 432       sec->contents = uncompressed_buffer;
 433       sec->size = uncompressed_size;
 434       sec->compress_status = COMPRESS_SECTION_NONE;
 435     }
 436   else
 437     free (uncompressed_buffer);
 438
 439   return ret;
 440 #endif
 441 }