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/* Compressed section support (intended for debug sections).

   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 */

}