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 #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 (sec->contents == NULL)
 248         return FALSE;
 249       if (p == NULL)
 250         {
 251           p = (bfd_byte *) bfd_malloc (sz);
 252           if (p == NULL)
 253             return FALSE;
 254           *ptr = p;
 255         }
 256       /* PR 17512; file: 5bc29788.  */
 257       if (p != sec->contents)
 258         memcpy (p, sec->contents, sz);
 259       return TRUE;
 260
 261     default:
 262       abort ();
 263     }
 264 }
 265
 266 /*
 267 FUNCTION
 268         bfd_cache_section_contents
 269
 270 SYNOPSIS
 271         void bfd_cache_section_contents
 272           (asection *sec, void *contents);
 273
 274 DESCRIPTION
 275         Stash @var(contents) so any following reads of @var(sec) do
 276         not need to decompress again.
 277 */
 278
 279 void
 280 bfd_cache_section_contents (asection *sec, void *contents)
 281 {
 282   if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
 283     sec->compress_status = COMPRESS_SECTION_DONE;
 284   sec->contents = contents;
 285   sec->flags |= SEC_IN_MEMORY;
 286 }
 287
 288
 289 /*
 290 FUNCTION
 291         bfd_is_section_compressed
 292
 293 SYNOPSIS
 294         bfd_boolean bfd_is_section_compressed
 295           (bfd *abfd, asection *section);
 296
 297 DESCRIPTION
 298         Return @code{TRUE} if @var{section} is compressed.
 299 */
 300
 301 bfd_boolean
 302 bfd_is_section_compressed (bfd *abfd, sec_ptr sec)
 303 {
 304   bfd_byte compressed_buffer [12];
 305   unsigned int saved = sec->compress_status;
 306   bfd_boolean compressed;
 307
 308   /* Don't decompress the section.  */
 309   sec->compress_status = COMPRESS_SECTION_NONE;
 310
 311   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 312      by the uncompressed section size, 8 bytes in big-endian order.  */
 313   compressed = (bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12)
 314                 && CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"));
 315
 316   /* Check for the pathalogical case of a debug string section that
 317      contains the string ZLIB.... as the first entry.  We assume that
 318      no uncompressed .debug_str section would ever be big enough to
 319      have the first byte of its (big-endian) size be non-zero.  */
 320   if (compressed
 321       && strcmp (sec->name, ".debug_str") == 0
 322       && ISPRINT (compressed_buffer[4]))
 323     compressed = FALSE;
 324
 325   /* Restore compress_status.  */
 326   sec->compress_status = saved;
 327   return compressed;
 328 }
 329
 330 /*
 331 FUNCTION
 332         bfd_init_section_decompress_status
 333
 334 SYNOPSIS
 335         bfd_boolean bfd_init_section_decompress_status
 336           (bfd *abfd, asection *section);
 337
 338 DESCRIPTION
 339         Record compressed section size, update section size with
 340         decompressed size and set compress_status to
 341         DECOMPRESS_SECTION_SIZED.
 342
 343         Return @code{FALSE} if the section is not a valid compressed
 344         section or zlib is not installed on this machine.  Otherwise,
 345         return @code{TRUE}.
 346 */
 347
 348 bfd_boolean
 349 bfd_init_section_decompress_status (bfd *abfd ATTRIBUTE_UNUSED,
 350                                     sec_ptr sec ATTRIBUTE_UNUSED)
 351 {
 352 #ifndef HAVE_ZLIB_H
 353   bfd_set_error (bfd_error_invalid_operation);
 354   return FALSE;
 355 #else
 356   bfd_byte compressed_buffer [12];
 357   bfd_size_type uncompressed_size;
 358
 359   if (sec->rawsize != 0
 360       || sec->contents != NULL
 361       || sec->compress_status != COMPRESS_SECTION_NONE
 362       || !bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12))
 363     {
 364       bfd_set_error (bfd_error_invalid_operation);
 365       return FALSE;
 366     }
 367
 368   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 369      by the uncompressed section size, 8 bytes in big-endian order.  */
 370   if (! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
 371     {
 372       bfd_set_error (bfd_error_wrong_format);
 373       return FALSE;
 374     }
 375
 376   uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
 377   uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
 378   uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
 379   uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
 380   uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
 381   uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
 382   uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
 383   uncompressed_size += compressed_buffer[11];
 384
 385   sec->compressed_size = sec->size;
 386   sec->size = uncompressed_size;
 387   sec->compress_status = DECOMPRESS_SECTION_SIZED;
 388
 389   return TRUE;
 390 #endif
 391 }
 392
 393 /*
 394 FUNCTION
 395         bfd_init_section_compress_status
 396
 397 SYNOPSIS
 398         bfd_boolean bfd_init_section_compress_status
 399           (bfd *abfd, asection *section);
 400
 401 DESCRIPTION
 402         If open for read, compress section, update section size with
 403         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 404
 405         Return @code{FALSE} if the section is not a valid compressed
 406         section or zlib is not installed on this machine.  Otherwise,
 407         return @code{TRUE}.
 408 */
 409
 410 bfd_boolean
 411 bfd_init_section_compress_status (bfd *abfd ATTRIBUTE_UNUSED,
 412                                   sec_ptr sec ATTRIBUTE_UNUSED)
 413 {
 414 #ifndef HAVE_ZLIB_H
 415   bfd_set_error (bfd_error_invalid_operation);
 416   return FALSE;
 417 #else
 418   bfd_size_type uncompressed_size;
 419   bfd_byte *uncompressed_buffer;
 420   bfd_boolean ret;
 421
 422   /* Error if not opened for read.  */
 423   if (abfd->direction != read_direction
 424       || sec->size == 0
 425       || sec->rawsize != 0
 426       || sec->contents != NULL
 427       || sec->compress_status != COMPRESS_SECTION_NONE)
 428     {
 429       bfd_set_error (bfd_error_invalid_operation);
 430       return FALSE;
 431     }
 432
 433   /* Read in the full section contents and compress it.  */
 434   uncompressed_size = sec->size;
 435   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
 436   if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
 437                                  0, uncompressed_size))
 438     ret = FALSE;
 439   else
 440     ret = bfd_compress_section_contents (abfd, sec,
 441                                          uncompressed_buffer,
 442                                          uncompressed_size);
 443
 444   free (uncompressed_buffer);
 445   return ret;
 446 #endif
 447 }