bfd/compress.c

   1 /* Compressed section support (intended for debug sections).
   2    Copyright 2008, 2010
   3    Free Software Foundation, Inc.
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "sysdep.h"
  24 #include "bfd.h"
  25 #include "libbfd.h"
  26 #ifdef HAVE_ZLIB_H
  27 #include <zlib.h>
  28 #endif
  29
  30 /*
  31 FUNCTION
  32         bfd_uncompress_section_contents
  33
  34 SYNOPSIS
  35         bfd_boolean bfd_uncompress_section_contents
  36           (bfd_byte **buffer, bfd_size_type *size);
  37
  38 DESCRIPTION
  39
  40         Uncompresses a section that was compressed using zlib, in place.  At
  41         the call to this function, *@var{buffer} and *@var{size} should point
  42         to the section contents to be uncompressed.  At the end of the
  43         function, *@var{buffer} and *@var{size} will point to the uncompressed
  44         contents.  This function assumes *BUFFER was allocated using
  45         bfd_malloc() or equivalent.  If the section is not a valid compressed
  46         section, or zlib is not installed on this machine, the input is
  47         unmodified.
  48
  49         Returns @code{FALSE} if unable to uncompress successfully; in that case
  50         the input is unmodified.  Otherwise, returns @code{TRUE}.
  51 */
  52
  53 bfd_boolean
  54 bfd_uncompress_section_contents (bfd_byte **buffer ATTRIBUTE_UNUSED,
  55                                  bfd_size_type *size ATTRIBUTE_UNUSED)
  56 {
  57 #ifndef HAVE_ZLIB_H
  58   return FALSE;
  59 #else
  60   bfd_size_type compressed_size = *size;
  61   bfd_byte *compressed_buffer = *buffer;
  62   bfd_size_type uncompressed_size;
  63   bfd_byte *uncompressed_buffer;
  64   z_stream strm;
  65   int rc;
  66   bfd_size_type header_size = 12;
  67
  68   /* Read the zlib header.  In this case, it should be "ZLIB" followed
  69      by the uncompressed section size, 8 bytes in big-endian order.  */
  70   if (compressed_size < header_size
  71       || ! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
  72     return FALSE;
  73   uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
  74   uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
  75   uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
  76   uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
  77   uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
  78   uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
  79   uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
  80   uncompressed_size += compressed_buffer[11];
  81
  82   /* It is possible the section consists of several compressed
  83      buffers concatenated together, so we uncompress in a loop.  */
  84   strm.zalloc = NULL;
  85   strm.zfree = NULL;
  86   strm.opaque = NULL;
  87   strm.avail_in = compressed_size - header_size;
  88   strm.next_in = (Bytef*) compressed_buffer + header_size;
  89   strm.avail_out = uncompressed_size;
  90   uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
  91   if (! uncompressed_buffer)
  92     return FALSE;
  93
  94   rc = inflateInit (&strm);
  95   while (strm.avail_in > 0)
  96     {
  97       if (rc != Z_OK)
  98         goto fail;
  99       strm.next_out = ((Bytef*) uncompressed_buffer
 100                        + (uncompressed_size - strm.avail_out));
 101       rc = inflate (&strm, Z_FINISH);
 102       if (rc != Z_STREAM_END)
 103         goto fail;
 104       rc = inflateReset (&strm);
 105     }
 106   rc = inflateEnd (&strm);
 107   if (rc != Z_OK
 108       || strm.avail_out != 0)
 109     goto fail;
 110
 111   free (compressed_buffer);
 112   *buffer = uncompressed_buffer;
 113   *size = uncompressed_size;
 114   return TRUE;
 115
 116  fail:
 117   free (uncompressed_buffer);
 118   return FALSE;
 119 #endif  /* HAVE_ZLIB_H */
 120 }