src/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.

   In addition, as a special exception, Red Hat, Inc. gives You the
   additional right to link the code of Red Hat elfutils with code licensed
   under any Open Source Initiative certified open source license
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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 "system.h"

#include <unistd.h>

#ifdef LZMA
# define USE_INFLATE	1
# include <lzma.h>
# define unzip		__libdw_unlzma
# define DWFL_E_ZLIB	DWFL_E_LZMA
# define MAGIC		"\xFD" "7zXZ\0" /* XZ file format.  */
# define MAGIC2		"\x5d\0"	/* Raw LZMA format.  */
# define Z(what)	LZMA_##what
# define LZMA_ERRNO	LZMA_PROG_ERROR
# define z_stream	lzma_stream
# define inflateInit(z)	lzma_auto_decoder (z, 1 << 30, 0)
# define do_inflate(z)	lzma_code (z, LZMA_RUN)
# define inflateEnd(z)	lzma_end (z)
#elif defined BZLIB
# define USE_INFLATE	1
# include <bzlib.h>
# define unzip		__libdw_bunzip2
# define DWFL_E_ZLIB	DWFL_E_BZLIB
# define MAGIC		"BZh"
# define Z(what)	BZ_##what
# define BZ_ERRNO	BZ_IO_ERROR
# define z_stream	bz_stream
# define inflateInit(z)	BZ2_bzDecompressInit (z, 0, 0)
# define do_inflate(z)	BZ2_bzDecompress (z)
# define inflateEnd(z)	BZ2_bzDecompressEnd (z)
#else
# define USE_INFLATE	0
# define crc32		loser_crc32
# include <zlib.h>
# define unzip		__libdw_gunzip
# define MAGIC		"\037\213"
# define Z(what)	Z_##what
#endif

#define READ_SIZE		(1 << 20)

/* 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.
   If we return an error after reading the first part of the file,
   leave that portion malloc'd in *WHOLE, *WHOLE_SIZE.  If *WHOLE
   is not null on entry, we'll use it in lieu of repeating a read.  */

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) ?: end == 0 ? NULL : buffer;
    size = end;
  }

  void *input_buffer = NULL;
  off_t input_pos = 0;

  inline Dwfl_Error fail (Dwfl_Error failure)
  {
    if (input_pos == (off_t) mapped_size)
      *whole = input_buffer;
    else
      {
	free (input_buffer);
	*whole = NULL;
      }
    free (buffer);
    return failure;
  }

  inline Dwfl_Error zlib_fail (int result)
  {
    switch (result)
      {
      case Z (MEM_ERROR):
	return fail (DWFL_E_NOMEM);
      case Z (ERRNO):
	return fail (DWFL_E_ERRNO);
      default:
	return fail (DWFL_E_ZLIB);
      }
  }

  if (mapped == NULL)
    {
      if (*whole == NULL)
	{
	  input_buffer = malloc (READ_SIZE);
	  if (unlikely (input_buffer == NULL))
	    return DWFL_E_NOMEM;

	  ssize_t n = pread_retry (fd, input_buffer, READ_SIZE, start_offset);
	  if (unlikely (n < 0))
	    return zlib_fail (Z (ERRNO));

	  input_pos = n;
	  mapped = input_buffer;
	  mapped_size = n;
	}
      else
	{
	  input_buffer = *whole;
	  input_pos = mapped_size = *whole_size;
	}
    }

#define NOMAGIC(magic) \
  (mapped_size <= sizeof magic || memcmp (mapped, magic, sizeof magic - 1))

  /* First, look at the header.  */
  if (NOMAGIC (MAGIC)
#ifdef MAGIC2
      && NOMAGIC (MAGIC2)
#endif
      )
    /* Not a compressed file.  */
    return DWFL_E_BADELF;

#if USE_INFLATE

  /* This style actually only works with bzlib and liblzma.
     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))
    {
      inflateEnd (&z);
      return zlib_fail (result);
    }

  do
    {
      if (z.avail_in == 0 && input_buffer != NULL)
	{
	  ssize_t n = pread_retry (fd, input_buffer, READ_SIZE,
				   start_offset + input_pos);
	  if (unlikely (n < 0))
	    {
	      inflateEnd (&z);
	      return zlib_fail (Z (ERRNO));
	    }
	  z.next_in = input_buffer;
	  z.avail_in = n;
	  input_pos += n;
	}
      if (z.avail_out == 0)
	{
	  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 = do_inflate (&z)) == 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  /* gzip only.  */

  /* Let the decompression library read the file directly.  */

  gzFile zf;
  Dwfl_Error open_stream (void)
  {
    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;
	  }
      }
    zf = gzdopen (d, "r");
    if (unlikely (zf == NULL))
      {
	close (d);
	return zlib_fail (Z (MEM_ERROR));
      }

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

    return DWFL_E_NOERROR;
  }

  Dwfl_Error result = open_stream ();

  if (result == DWFL_E_NOERROR && gzdirect (zf))
    {
      gzclose (zf);
      return fail (DWFL_E_BADELF);
    }

  if (result != DWFL_E_NOERROR)
    return fail (result);

  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)
	{
	  int code;
	  gzerror (zf, &code);
	  gzclose (zf);
	  return zlib_fail (code);
	}
      if (n == 0)
	break;
      pos += n;
    }

  gzclose (zf);
  smaller_buffer (pos);
#endif

  free (input_buffer);

  *whole = buffer;
  *whole_size = size;

  return DWFL_E_NOERROR;
}