libdwfl/open.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.

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   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.

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   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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   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 "../libelf/libelfP.h"
#undef	_
#include "libdwflP.h"

#include <unistd.h>

#if !USE_ZLIB
# define __libdw_gunzip(...)	false
#endif

#if !USE_BZLIB
# define __libdw_bunzip2(...)	false
#endif

/* Always consumes *ELF, never consumes FD.
   Replaces *ELF on success.  */
static Dwfl_Error
decompress (int fd, Elf **elf)
{
  Dwfl_Error error = DWFL_E_BADELF;

#if USE_ZLIB || USE_BZLIB
  void *buffer;
  size_t size;

  const off64_t offset = (*elf)->start_offset;
  void *const mapped = ((*elf)->map_address == NULL ? NULL
			: (*elf)->map_address + (*elf)->start_offset);
  const size_t mapped_size = (*elf)->maximum_size;

  error = __libdw_gunzip (fd, offset, mapped, mapped_size, &buffer, &size);
  if (error == DWFL_E_BADELF)
    error = __libdw_bunzip2 (fd, offset, mapped, mapped_size, &buffer, &size);
#endif

  elf_end (*elf);
  *elf = NULL;

  if (error == DWFL_E_NOERROR)
    {
      *elf = elf_memory (buffer, size);
      if (*elf == NULL)
	{
	  error = DWFL_E_LIBELF;
	  free (buffer);
	}
      else
	(*elf)->flags |= ELF_F_MALLOCED;
    }

  return error;
}

Dwfl_Error internal_function
__libdw_open_file (int *fdp, Elf **elfp, bool close_on_fail, bool archive_ok)
{
  bool close_fd = false;
  Dwfl_Error error = DWFL_E_NOERROR;

  Elf *elf = elf_begin (*fdp, ELF_C_READ_MMAP_PRIVATE, NULL);
  Elf_Kind kind = elf_kind (elf);
  if (unlikely (kind == ELF_K_NONE))
    {
      if (unlikely (elf == NULL))
	error = DWFL_E_LIBELF;
      else
	{
	  error = decompress (*fdp, &elf);
	  if (error == DWFL_E_NOERROR)
	    {
	      close_fd = true;
	      kind = elf_kind (elf);
	    }
	}
    }

  if (error == DWFL_E_NOERROR
      && kind != ELF_K_ELF
      && !(archive_ok && kind == ELF_K_AR))
    {
      elf_end (elf);
      elf = NULL;
      error = DWFL_E_BADELF;
    }

  if (error == DWFL_E_NOERROR ? close_fd : close_on_fail)
    {
      close (*fdp);
      *fdp = -1;
    }

  *elfp = elf;
  return error;
}