libdwfl/gzip.c

/* Decompression support for libdwfl: zlib (gzip) and/or bzlib (bzip2).
   Copyright (C) 2009 Red Hat, Inc.
   This file is part of Red Hat elfutils.

   Red Hat elfutils 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; version 2 of the License.

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   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 Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

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   additional right to link the code of Red Hat elfutils with code licensed
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   this file solely under the GPL without exception.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
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#include "libdwflP.h"

#include <unistd.h>

#ifdef BZLIB
# define inflate_groks_header	true
# include <bzlib.h>
# define unzip		__libdw_bunzip2
# define DWFL_E_ZLIB	DWFL_E_BZLIB
# define MAGIC		"BZh"
# define Z(what)	BZ_##what
# define z_stream	bz_stream
# define inflateInit(z)	BZ2_bzDecompressInit (z, 0, 0)
# define inflate(z, f)	BZ2_bzDecompress (z)
# define inflateEnd(z)	BZ2_bzDecompressEnd (z)
# define gzFile		BZFILE *
# define gzdopen	BZ2_bzdopen
# define gzread		BZ2_bzread
# define gzclose	BZ2_bzclose
#else
# define inflate_groks_header	false
# include <zlib.h>
# define unzip		__libdw_gunzip
# define MAGIC		"\037\213"
# define Z(what)	Z_##what
#endif

/* If this is not a compressed image, return DWFL_E_BADELF.
   If we uncompressed it into *WHOLE, *WHOLE_SIZE, return DWFL_E_NOERROR.
   Otherwise return an error for bad compressed data or I/O failure.  */

Dwfl_Error internal_function
unzip (int fd, off64_t start_offset,
       void *mapped, size_t mapped_size,
       void **whole, size_t *whole_size)
{
  void *buffer = NULL;
  size_t size = 0;
  inline bool bigger_buffer (size_t start)
  {
    size_t more = size ? size * 2 : start;
    char *b = realloc (buffer, more);
    while (unlikely (b == NULL) && more >= size + 1024)
      b = realloc (buffer, more -= 1024);
    if (unlikely (b == NULL))
      return false;
    buffer = b;
    size = more;
    return true;
  }
  inline void smaller_buffer (size_t end)
  {
    buffer = realloc (buffer, end) ?: buffer;
    size = end;
  }

  inline Dwfl_Error zlib_fail (int result)
  {
    Dwfl_Error failure = DWFL_E_ZLIB;
    switch (result)
      {
      case Z (MEM_ERROR):
	failure = DWFL_E_NOMEM;
	break;
      }
    free (buffer);
    *whole = NULL;
    return failure;
  }

  /* If the file is already mapped in, look at the header.  */
  if (mapped != NULL
      && (mapped_size <= sizeof MAGIC
	  || memcmp (mapped, MAGIC, sizeof MAGIC - 1)))
    /* Not a compressed file.  */
    return DWFL_E_BADELF;

  if (mapped != NULL && inflate_groks_header)
    {
      /* This style actually only works with bzlib.
	 The stupid zlib interface has nothing to grok the
	 gzip file headers except the slow gzFile interface.  */

      z_stream z = { .next_in = mapped, .avail_in = mapped_size };
      int result = inflateInit (&z);
      if (result != Z (OK))
	return zlib_fail (result);

      do
	{
	  ptrdiff_t pos = (void *) z.next_out - buffer;
	  if (!bigger_buffer (z.avail_in))
	    {
	      result = Z (MEM_ERROR);
	      break;
	    }
	  z.next_out = buffer + pos;
	  z.avail_out = size - pos;
	}
      while ((result = inflate (&z, Z_SYNC_FLUSH)) == Z (OK));

#ifdef BZLIB
      uint64_t total_out = (((uint64_t) z.total_out_hi32 << 32)
			    | z.total_out_lo32);
      smaller_buffer (total_out);
#else
      smaller_buffer (z.total_out);
#endif

      inflateEnd (&z);

      if (result != Z (STREAM_END))
	return zlib_fail (result);
    }
  else
    {
      /* Let the decompression library read the file directly.  */

      int d = dup (fd);
      if (unlikely (d < 0))
	return DWFL_E_BADELF;
      if (start_offset != 0)
	{
	  off64_t off = lseek (d, start_offset, SEEK_SET);
	  if (off != start_offset)
	    {
	      close (d);
	      return DWFL_E_BADELF;
	    }
	}
      gzFile zf = gzdopen (d, "r");
      if (unlikely (zf == NULL))
	{
	  close (d);
	  return zlib_fail (Z (MEM_ERROR));
	}

      /* From here on, zlib will close D.  */

#ifndef BZLIB
      if (gzdirect (zf))
	{
	  gzclose (zf);
	  return DWFL_E_BADELF;
	}
#endif

      ptrdiff_t pos = 0;
      while (1)
	{
	  if (!bigger_buffer (1024))
	    {
	      gzclose (zf);
	      return zlib_fail (Z (MEM_ERROR));
	    }
	  int n = gzread (zf, buffer + pos, size - pos);
	  if (n < 0)
	    {
#ifdef BZLIB
	      int code;
	      BZ2_bzerror (zf, &code);
	      if (code == BZ_DATA_ERROR_MAGIC)
		{
		  gzclose (zf);
		  free (buffer);
		  return DWFL_E_BADELF;
		}
#endif
	      gzclose (zf);
	      return zlib_fail (Z (DATA_ERROR));
	    }
	  if (n == 0)
	    break;
	  pos += n;
	}

      gzclose (zf);
      smaller_buffer (pos);
    }

  *whole = buffer;
  *whole_size = size;

  return DWFL_E_NOERROR;
}