bfd/compress.c

/* ELF attributes support (based on ARM EABI attributes).
   Copyright 2008, 2010
   Free Software Foundation, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

#include "config.h"
#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#ifdef HAVE_ZLIB_H
#include <zlib.h>
#endif

/*
FUNCTION
	bfd_uncompress_section_contents

SYNOPSIS
	bfd_boolean bfd_uncompress_section_contents
	  (bfd_byte **buffer, bfd_size_type *size);

DESCRIPTION

	Uncompresses a section that was compressed using zlib, in place.  At
	the call to this function, *@var{buffer} and *@var{size} should point
	to the section contents to be uncompressed.  At the end of the
	function, *@var{buffer} and *@var{size} will point to the uncompressed
	contents.  This function assumes *BUFFER was allocated using
	bfd_malloc() or equivalent.  If the section is not a valid compressed
	section, or zlib is not installed on this machine, the input is
	unmodified.

        Returns @code{FALSE} if unable to uncompress successfully; in that case
        the input is unmodified.  Otherwise, returns @code{TRUE}.
*/

bfd_boolean
bfd_uncompress_section_contents (bfd_byte **buffer ATTRIBUTE_UNUSED,
				 bfd_size_type *size ATTRIBUTE_UNUSED)
{
#ifndef HAVE_ZLIB_H
  return FALSE;
#else
  bfd_size_type compressed_size = *size;
  bfd_byte *compressed_buffer = *buffer;
  bfd_size_type uncompressed_size;
  bfd_byte *uncompressed_buffer;
  z_stream strm;
  int rc;
  bfd_size_type header_size = 12;

  /* Read the zlib header.  In this case, it should be "ZLIB" followed
     by the uncompressed section size, 8 bytes in big-endian order.  */
  if (compressed_size < header_size
      || ! CONST_STRNEQ ((char*) compressed_buffer, "ZLIB"))
    return FALSE;
  uncompressed_size = compressed_buffer[4]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[5]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[6]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[7]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[8]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[9]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[10]; uncompressed_size <<= 8;
  uncompressed_size += compressed_buffer[11];

  /* It is possible the section consists of several compressed
     buffers concatenated together, so we uncompress in a loop.  */
  strm.zalloc = NULL;
  strm.zfree = NULL;
  strm.opaque = NULL;
  strm.avail_in = compressed_size - header_size;
  strm.next_in = (Bytef*) compressed_buffer + header_size;
  strm.avail_out = uncompressed_size;
  uncompressed_buffer = (bfd_byte *) bfd_malloc (uncompressed_size);
  if (! uncompressed_buffer)
    return FALSE;

  rc = inflateInit (&strm);
  while (strm.avail_in > 0)
    {
      if (rc != Z_OK)
        goto fail;
      strm.next_out = ((Bytef*) uncompressed_buffer
                       + (uncompressed_size - strm.avail_out));
      rc = inflate (&strm, Z_FINISH);
      if (rc != Z_STREAM_END)
        goto fail;
      rc = inflateReset (&strm);
    }
  rc = inflateEnd (&strm);
  if (rc != Z_OK
      || strm.avail_out != 0)
    goto fail;

  free (compressed_buffer);
  *buffer = uncompressed_buffer;
  *size = uncompressed_size;
  return TRUE;

 fail:
  free (uncompressed_buffer);
  return FALSE;
#endif  /* HAVE_ZLIB_H */
}