libdw/dwarf_ranges.c

/* Enumerate the PC ranges covered by a DIE.
   Copyright (C) 2005, 2007 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.

   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.

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

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


ptrdiff_t
dwarf_ranges (Dwarf_Die *die, ptrdiff_t offset, Dwarf_Addr *basep,
	      Dwarf_Addr *startp, Dwarf_Addr *endp)
{
  if (die == NULL)
    return -1;

  if (offset == 0
      /* Usually there is a single contiguous range.  */
      && INTUSE(dwarf_highpc) (die, endp) == 0
      && INTUSE(dwarf_lowpc) (die, startp) == 0)
    /* A offset into .debug_ranges will never be 1, it must be at least a
       multiple of 4.  So we can return 1 as a special case value to mark
       there are no ranges to look for on the next call.  */
    return 1;

  if (offset == 1)
    return 0;

  /* We have to look for a noncontiguous range.  */

  const Elf_Data *d = die->cu->dbg->sectiondata[IDX_debug_ranges];
  if (d == NULL)
    {
      __libdw_seterrno (DWARF_E_NO_DEBUG_RANGES);
      return -1;
    }

  if (offset == 0)
    {
      Dwarf_Attribute attr_mem;
      Dwarf_Attribute *attr = INTUSE(dwarf_attr) (die, DW_AT_ranges,
						  &attr_mem);
      if (attr == NULL)
	return -1;

      /* Must have the form data4 or data8 which act as an offset.  */
      Dwarf_Word start_offset;
      if (INTUSE(dwarf_formudata) (attr, &start_offset) != 0)
	return -1;

      offset = start_offset;
      assert ((Dwarf_Word) offset == start_offset);

      /* Fetch the CU's base address.  */
      Dwarf_Die cudie = CUDIE (attr->cu);

      /* Find the base address of the compilation unit.  It will
	 normally be specified by DW_AT_low_pc.  In DWARF-3 draft 4,
	 the base address could be overridden by DW_AT_entry_pc.  It's
	 been removed, but GCC emits DW_AT_entry_pc and not DW_AT_lowpc
	 for compilation units with discontinuous ranges.  */
      if (unlikely (INTUSE(dwarf_lowpc) (&cudie, basep) != 0)
	  && INTUSE(dwarf_formaddr) (INTUSE(dwarf_attr) (&cudie,
							 DW_AT_entry_pc,
							 &attr_mem),
				     basep) != 0)
	{
	  if (INTUSE(dwarf_errno) () == 0)
	    {
	    invalid:
	      __libdw_seterrno (DWARF_E_INVALID_DWARF);
	    }
	  return -1;
	}
    }
  else if (offset < 0 || (size_t) offset >= d->d_size)
    {
      __libdw_seterrno (DWARF_E_INVALID_OFFSET);
      return -1l;
    }

  unsigned char *readp = d->d_buf + offset;

 next:
  if ((unsigned char *) d->d_buf + d->d_size - readp
      < die->cu->address_size * 2)
    goto invalid;

  Dwarf_Addr begin;
  Dwarf_Addr end;
  if (die->cu->address_size == 8)
    {
      begin = read_8ubyte_unaligned_inc (die->cu->dbg, readp);
      end = read_8ubyte_unaligned_inc (die->cu->dbg, readp);
      if (begin == (uint64_t) -1l) /* Base address entry.  */
	{
	  *basep = end;
	  goto next;
	}
    }
  else
    {
      begin = read_4ubyte_unaligned_inc (die->cu->dbg, readp);
      end = read_4ubyte_unaligned_inc (die->cu->dbg, readp);
      if (begin == (uint32_t) -1) /* Base address entry.  */
	{
	  *basep = end;
	  goto next;
	}
    }

  if (begin == 0 && end == 0) /* End of list entry.  */
    return 0;

  /* We have an address range entry.  */
  *startp = *basep + begin;
  *endp = *basep + end;
  return readp - (unsigned char *) d->d_buf;
}
INTDEF (dwarf_ranges)