src/libdw/libdw_findcu.c

/* Find CU for given offset.
   Copyright (C) 2003-2010 Red Hat, Inc.
   This file is part of Red Hat elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2003.

   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.

   Red Hat 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 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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   code used in conjunction with Red Hat elfutils except the Non-GPL Code
   covered by this exception.  If you modify this file, you may extend this
   exception to your version of the file, but you are not obligated to do
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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
   license is granted, either expressly or impliedly, by designation as an
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   <http://www.openinventionnetwork.com>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <search.h>
#include "libdwP.h"


struct Dwarf_CU *
internal_function
__libdw_intern_next_unit (dbg, debug_types)
     Dwarf *dbg;
     bool debug_types;
{
  Dwarf_Off *const offsetp
    = debug_types ? &dbg->next_tu_offset : &dbg->next_cu_offset;

  Dwarf_Off oldoff = *offsetp;
  uint16_t version;
  uint8_t address_size;
  uint8_t offset_size;
  Dwarf_Off abbrev_offset;
  uint64_t type_sig8 = 0;
  Dwarf_Off type_offset = 0;

  if (INTUSE(dwarf_next_unit) (dbg, oldoff, offsetp, NULL,
			       &version, &abbrev_offset,
			       &address_size, &offset_size,
			       debug_types ? &type_sig8 : NULL,
			       debug_types ? &type_offset : NULL) != 0)
    /* No more entries.  */
    return NULL;

  /* We only know how to handle the DWARF version 2 through 4 formats.  */
  if (unlikely (version < 2) || unlikely (version > 4))
    {
      __libdw_seterrno (DWARF_E_INVALID_DWARF);
      return NULL;
    }

  /* Create an entry for this CU.  */
  struct Dwarf_CU *newp = libdw_typed_alloc (dbg, struct Dwarf_CU);

  newp->dbg = dbg;
  newp->start = oldoff;
  newp->end = *offsetp;
  newp->address_size = address_size;
  newp->offset_size = offset_size;
  newp->version = version;
  newp->type_sig8 = type_sig8;
  newp->type_offset = type_offset;
  Dwarf_Abbrev_Hash_init (&newp->abbrev_hash, 41);
  newp->orig_abbrev_offset = newp->last_abbrev_offset = abbrev_offset;
  newp->lines = NULL;
  newp->locs = NULL;

  return newp;
}


static int
findcu_cb (const void *arg1, const void *arg2)
{
  struct Dwarf_CU *cu1 = (struct Dwarf_CU *) arg1;
  struct Dwarf_CU *cu2 = (struct Dwarf_CU *) arg2;

  /* Find out which of the two arguments is the search value.  It has
     end offset 0.  */
  if (cu1->end == 0)
    {
      if (cu1->start < cu2->start)
	return -1;
      if (cu1->start >= cu2->end)
	return 1;
    }
  else
    {
      if (cu2->start < cu1->start)
	return 1;
      if (cu2->start >= cu1->end)
	return -1;
    }

  return 0;
}

struct Dwarf_CU *
__libdw_findcu (dbg, start, debug_types)
     Dwarf *dbg;
     Dwarf_Off start;
     bool debug_types;
{
  void **tree = debug_types ? &dbg->tu_tree : &dbg->cu_tree;
  Dwarf_Off *next_offset
    = debug_types ? &dbg->next_tu_offset : &dbg->next_cu_offset;

  /* Maybe we already know that CU.  */
  struct Dwarf_CU fake = { .start = start, .end = 0 };
  struct Dwarf_CU **found = tfind (&fake, tree, findcu_cb);
  if (found != NULL)
    return *found;

  if (start < *next_offset)
    {
      __libdw_seterrno (DWARF_E_INVALID_DWARF);
      return NULL;
    }

  /* No.  Then read more CUs.  */
  while (1)
    {
      Dwarf_Off oldoff = *next_offset;
      struct Dwarf_CU *newp = __libdw_intern_next_unit (dbg, debug_types);
      if (newp == NULL)
	return NULL;

      /* Add the new entry to the search tree.  */
      if (tsearch (newp, tree, findcu_cb) == NULL)
	{
	  /* Something went wrong.  Undo the operation.  */
	  *next_offset = oldoff;
	  __libdw_seterrno (DWARF_E_NOMEM);
	  return NULL;
	}

      /* Is this the one we are looking for?  */
      if (start < *next_offset)
	// XXX Match exact offset.
	return newp;
    }
  /* NOTREACHED */
}