/* Find the split (or skeleton) unit for a given unit.

   Copyright (C) 2018 Red Hat, Inc.

   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify

   it under the terms of either

     * the GNU Lesser General Public License as published by the Free

       Software Foundation; either version 3 of the License, or (at

       your option) any later version

   or

     * the GNU General Public License as published by the Free

       Software Foundation; either version 2 of the License, or (at

       your option) any later version

   or both in parallel, as here.

   elfutils 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 copies of the GNU General Public License and

   the GNU Lesser General Public License along with this program.  If

   not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#include "libdwP.h"

#include "libelfP.h"

#include <limits.h>

#include <search.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

void

try_split_file (Dwarf_CU *cu, const char *dwo_path)

{

  int split_fd = open (dwo_path, O_RDONLY);

  if (split_fd != -1)

    {

      Dwarf *split_dwarf = dwarf_begin (split_fd, DWARF_C_READ);

      if (split_dwarf != NULL)

	{

	  Dwarf_CU *split = NULL;

	  while (dwarf_get_units (split_dwarf, split, &split,

				  NULL, NULL, NULL, NULL) == 0)

	    {

	      if (split->unit_type == DW_UT_split_compile

		  && cu->unit_id8 == split->unit_id8)

		{

		  if (tsearch (split->dbg, &cu->dbg->split_tree,

			       __libdw_finddbg_cb) == NULL)

		    {

		      /* Something went wrong.  Don't link.  */

		      __libdw_seterrno (DWARF_E_NOMEM);

		      break;

		    }

		  /* Link skeleton and split compile units.  */

		  __libdw_link_skel_split (cu, split);

		  /* We have everything we need from this ELF

		     file.  And we are going to close the fd to

		     not run out of file descriptors.  */

		  elf_cntl (split_dwarf->elf, ELF_C_FDDONE);

		  break;

		}

	    }

	  if (cu->split == (Dwarf_CU *) -1)

	    dwarf_end (split_dwarf);

	}

      /* Always close, because we don't want to run out of file

	 descriptors.  See also the elf_fcntl ELF_C_FDDONE call

	 above.  */

      close (split_fd);

    }

}

Dwarf_CU *

internal_function

__libdw_find_split_unit (Dwarf_CU *cu)

{

  /* Only try once.  */

  if (cu->split != (Dwarf_CU *) -1)

    return cu->split;

  /* We need a skeleton unit with a comp_dir and [GNU_]dwo_name attributes.

     The split unit will be the first in the dwo file and should have the

     same id as the skeleton.  */

  if (cu->unit_type == DW_UT_skeleton)

    {

      Dwarf_Die cudie = CUDIE (cu);

      Dwarf_Attribute dwo_name;

      /* It is fine if dwo_dir doesn't exists, but then dwo_name needs

	 to be an absolute path.  */

      if (dwarf_attr (&cudie, DW_AT_dwo_name, &dwo_name) != NULL

	  || dwarf_attr (&cudie, DW_AT_GNU_dwo_name, &dwo_name) != NULL)

	{

	  /* First try the dwo file name in the same directory

	     as we found the skeleton file.  */

	  const char *dwo_file = dwarf_formstring (&dwo_name);

	  const char *debugdir = cu->dbg->debugdir;

	  char *dwo_path = __libdw_filepath (debugdir, NULL, dwo_file);

	  if (dwo_path != NULL)

	    {

	      try_split_file (cu, dwo_path);

	      free (dwo_path);

	    }

	  if (cu->split == (Dwarf_CU *) -1)

	    {

	      /* Try compdir plus dwo_name.  */

	      Dwarf_Attribute compdir;

	      dwarf_attr (&cudie, DW_AT_comp_dir, &compdir);

	      const char *dwo_dir = dwarf_formstring (&compdir);

	      if (dwo_dir != NULL)

		{

		  dwo_path = __libdw_filepath (debugdir, dwo_dir, dwo_file);

		  if (dwo_path != NULL)

		    {

		      try_split_file (cu, dwo_path);

		      free (dwo_path);

		    }

		}

	    }

	  /* XXX If still not found we could try stripping dirs from the

	     comp_dir and adding them from the comp_dir, assuming

	     someone moved a whole build tree around.  */

	}

    }

  /* If we found nothing, make sure we don't try again.  */

  if (cu->split == (Dwarf_CU *) -1)

    cu->split = NULL;

  return cu->split;

}