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 <zlib.h>
  23 #include "bfd.h"
  24 #include "libbfd.h"
  25 #include "safe-ctype.h"
  26
  27 static bfd_boolean
  28 decompress_contents (bfd_byte *compressed_buffer,
  29                      bfd_size_type compressed_size,
  30                      bfd_byte *uncompressed_buffer,
  31                      bfd_size_type uncompressed_size)
  32 {
  33   z_stream strm;
  34   int rc;
  35
  36   /* It is possible the section consists of several compressed
  37      buffers concatenated together, so we uncompress in a loop.  */
  38   strm.zalloc = NULL;
  39   strm.zfree = NULL;
  40   strm.opaque = NULL;
  41   strm.avail_in = compressed_size - 12;
  42   strm.next_in = (Bytef*) compressed_buffer + 12;
  43   strm.avail_out = uncompressed_size;
  44
  45   BFD_ASSERT (Z_OK == 0);
  46   rc = inflateInit (&strm);
  47   while (strm.avail_in > 0 && strm.avail_out > 0)
  48     {
  49       if (rc != Z_OK)
  50         break;
  51       strm.next_out = ((Bytef*) uncompressed_buffer
  52                        + (uncompressed_size - strm.avail_out));
  53       rc = inflate (&strm, Z_FINISH);
  54       if (rc != Z_STREAM_END)
  55         break;
  56       rc = inflateReset (&strm);
  57     }
  58   rc |= inflateEnd (&strm);
  59   return rc == Z_OK && strm.avail_out == 0;
  60 }
  61
  62 static bfd_size_type
  63 get_uncompressed_size (bfd_byte *uncompressed_size_buffer)
  64 {
  65   bfd_size_type uncompressed_size = uncompressed_size_buffer[0];
  66   uncompressed_size <<= 8;
  67   uncompressed_size += uncompressed_size_buffer[1];
  68   uncompressed_size <<= 8;
  69   uncompressed_size += uncompressed_size_buffer[2];
  70   uncompressed_size <<= 8;
  71   uncompressed_size += uncompressed_size_buffer[3];
  72   uncompressed_size <<= 8;
  73   uncompressed_size += uncompressed_size_buffer[4];
  74   uncompressed_size <<= 8;
  75   uncompressed_size += uncompressed_size_buffer[5];
  76   uncompressed_size <<= 8;
  77   uncompressed_size += uncompressed_size_buffer[6];
  78   uncompressed_size <<= 8;
  79   uncompressed_size += uncompressed_size_buffer[7];
  80   return uncompressed_size;;
  81 }
  82
  83 /* Compress data of the size specified in @var{uncompressed_size}
  84    and pointed to by @var{uncompressed_buffer} using zlib and store
  85    as the contents field.  This function assumes the contents
  86    field was allocated using bfd_malloc() or equivalent.  If zlib
  87    is not installed on this machine, the input is unmodified.
  88
  89    Return @code{TRUE} if the full section contents is compressed
  90    successfully.  */
  91
  92 static bfd_boolean
  93 bfd_compress_section_contents (bfd *abfd ATTRIBUTE_UNUSED, sec_ptr sec,
  94                                bfd_byte *uncompressed_buffer,
  95                                bfd_size_type uncompressed_size)
  96 {
  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   compressed_size += 12;
 117
 118   /* PR binutils/18087: If compression didn't make the section smaller,
 119      just keep it uncompressed.  */
 120   if (compressed_size < uncompressed_size)
 121     {
 122       /* Write the zlib header.  In this case, it should be "ZLIB" followed
 123          by the uncompressed section size, 8 bytes in big-endian order.  */
 124       memcpy (compressed_buffer, "ZLIB", 4);
 125       compressed_buffer[11] = uncompressed_size; uncompressed_size >>= 8;
 126       compressed_buffer[10] = uncompressed_size; uncompressed_size >>= 8;
 127       compressed_buffer[9] = uncompressed_size; uncompressed_size >>= 8;
 128       compressed_buffer[8] = uncompressed_size; uncompressed_size >>= 8;
 129       compressed_buffer[7] = uncompressed_size; uncompressed_size >>= 8;
 130       compressed_buffer[6] = uncompressed_size; uncompressed_size >>= 8;
 131       compressed_buffer[5] = uncompressed_size; uncompressed_size >>= 8;
 132       compressed_buffer[4] = uncompressed_size;
 133
 134       free (uncompressed_buffer);
 135       sec->contents = compressed_buffer;
 136       sec->size = compressed_size;
 137       sec->compress_status = COMPRESS_SECTION_DONE;
 138     }
 139   else
 140     {
 141       sec->contents = uncompressed_buffer;
 142       sec->compress_status = COMPRESS_SECTION_NONE;
 143     }
 144
 145   return TRUE;
 146 }
 147
 148 /*
 149 FUNCTION
 150         bfd_get_full_section_contents
 151
 152 SYNOPSIS
 153         bfd_boolean bfd_get_full_section_contents
 154           (bfd *abfd, asection *section, bfd_byte **ptr);
 155
 156 DESCRIPTION
 157         Read all data from @var{section} in BFD @var{abfd}, decompress
 158         if needed, and store in @var{*ptr}.  If @var{*ptr} is NULL,
 159         return @var{*ptr} with memory malloc'd by this function.
 160
 161         Return @code{TRUE} if the full section contents is retrieved
 162         successfully.  If the section has no contents then this function
 163         returns @code{TRUE} but @var{*ptr} is set to NULL.
 164 */
 165
 166 bfd_boolean
 167 bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
 168 {
 169   bfd_size_type sz;
 170   bfd_byte *p = *ptr;
 171   bfd_boolean ret;
 172   bfd_size_type save_size;
 173   bfd_size_type save_rawsize;
 174   bfd_byte *compressed_buffer;
 175
 176   if (abfd->direction != write_direction && sec->rawsize != 0)
 177     sz = sec->rawsize;
 178   else
 179     sz = sec->size;
 180   if (sz == 0)
 181     {
 182       *ptr = NULL;
 183       return TRUE;
 184     }
 185
 186   switch (sec->compress_status)
 187     {
 188     case COMPRESS_SECTION_NONE:
 189       if (p == NULL)
 190         {
 191           p = (bfd_byte *) bfd_malloc (sz);
 192           if (p == NULL)
 193             return FALSE;
 194         }
 195
 196       if (!bfd_get_section_contents (abfd, sec, p, 0, sz))
 197         {
 198           if (*ptr != p)
 199             free (p);
 200           return FALSE;
 201         }
 202       *ptr = p;
 203       return TRUE;
 204
 205     case DECOMPRESS_SECTION_SIZED:
 206       /* Read in the full compressed section contents.  */
 207       compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
 208       if (compressed_buffer == NULL)
 209         return FALSE;
 210       save_rawsize = sec->rawsize;
 211       save_size = sec->size;
 212       /* Clear rawsize, set size to compressed size and set compress_status
 213          to COMPRESS_SECTION_NONE.  If the compressed size is bigger than
 214          the uncompressed size, bfd_get_section_contents will fail.  */
 215       sec->rawsize = 0;
 216       sec->size = sec->compressed_size;
 217       sec->compress_status = COMPRESS_SECTION_NONE;
 218       ret = bfd_get_section_contents (abfd, sec, compressed_buffer,
 219                                       0, sec->compressed_size);
 220       /* Restore rawsize and size.  */
 221       sec->rawsize = save_rawsize;
 222       sec->size = save_size;
 223       sec->compress_status = DECOMPRESS_SECTION_SIZED;
 224       if (!ret)
 225         goto fail_compressed;
 226
 227       if (p == NULL)
 228         p = (bfd_byte *) bfd_malloc (sz);
 229       if (p == NULL)
 230         goto fail_compressed;
 231
 232       if (!decompress_contents (compressed_buffer, sec->compressed_size, p, sz))
 233         {
 234           bfd_set_error (bfd_error_bad_value);
 235           if (p != *ptr)
 236             free (p);
 237         fail_compressed:
 238           free (compressed_buffer);
 239           return FALSE;
 240         }
 241
 242       free (compressed_buffer);
 243       *ptr = p;
 244       return TRUE;
 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, sec_ptr sec)
 350 {
 351   bfd_byte compressed_buffer [12];
 352   bfd_size_type uncompressed_size;
 353
 354   if (sec->rawsize != 0
 355       || sec->contents != NULL
 356       || sec->compress_status != COMPRESS_SECTION_NONE
 357       || !bfd_get_section_contents (abfd, sec, compressed_buffer, 0, 12))
 358     {
 359       bfd_set_error (bfd_error_invalid_operation);
 360       return FALSE;
 361     }
 362
 363   /* Read the zlib header.  In this case, it should be "ZLIB" followed
 364      by the uncompressed section size, 8 bytes in big-endian order.  */
 365   if (! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
 366     {
 367       bfd_set_error (bfd_error_wrong_format);
 368       return FALSE;
 369     }
 370
 371   uncompressed_size = get_uncompressed_size (compressed_buffer + 4);
 372   sec->compressed_size = sec->size;
 373   sec->size = uncompressed_size;
 374   sec->compress_status = DECOMPRESS_SECTION_SIZED;
 375
 376   return TRUE;
 377 }
 378
 379 /*
 380 FUNCTION
 381         bfd_init_section_compress_status
 382
 383 SYNOPSIS
 384         bfd_boolean bfd_init_section_compress_status
 385           (bfd *abfd, asection *section);
 386
 387 DESCRIPTION
 388         If open for read, compress section, update section size with
 389         compressed size and set compress_status to COMPRESS_SECTION_DONE.
 390
 391         Return @code{FALSE} if the section is not a valid compressed
 392         section or zlib is not installed on this machine.  Otherwise,
 393         return @code{TRUE}.
 394 */
 395
 396 bfd_boolean
 397 bfd_init_section_compress_status (bfd *abfd, sec_ptr sec)
 398 {
 399   bfd_size_type uncompressed_size;
 400   bfd_byte *uncompressed_buffer;
 401   bfd_boolean ret;
 402
 403   /* Error if not opened for read.  */
 404   if (abfd->direction != read_direction
 405       || sec->size == 0
 406       || sec->rawsize != 0
 407       || sec->contents != NULL
 408       || sec->compress_status != COMPRESS_SECTION_NONE)
 409     {
 410       bfd_set_error (bfd_error_invalid_operation);
 411       return FALSE;
 412     }
 413
 414   /* Read in the full section contents and compress it.  */
 415   uncompressed_size = sec->size;
 416   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
 417   if (!bfd_get_section_contents (abfd, sec, uncompressed_buffer,
 418                                  0, uncompressed_size))
 419     ret = FALSE;
 420   else
 421     ret = bfd_compress_section_contents (abfd, sec,
 422                                          uncompressed_buffer,
 423                                          uncompressed_size);
 424
 425   return ret;
 426 }