libdw/dwarf_getaranges.c

/* Return list address ranges.
   Copyright (C) 2000, 2001, 2002, 2004, 2005, 2006, 2008 Red Hat, Inc.
   This file is part of Red Hat elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   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
   under any Open Source Initiative certified open source license
   (http://www.opensource.org/licenses/index.php) which requires the
   distribution of source code with any binary distribution and to
   distribute linked combinations of the two.  Non-GPL Code permitted under
   this exception must only link to the code of Red Hat elfutils through
   those well defined interfaces identified in the file named EXCEPTION
   found in the source code files (the "Approved Interfaces").  The files
   of Non-GPL Code may instantiate templates or use macros or inline
   functions from the Approved Interfaces without causing the resulting
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   Inc. may make changes or additions to the list of Approved Interfaces.
   Red Hat's grant of this exception is conditioned upon your not adding
   any new exceptions.  If you wish to add a new Approved Interface or
   exception, please contact Red Hat.  You must obey the GNU General Public
   License in all respects for all of the Red Hat elfutils code and other
   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
   so.  If you do not wish to provide this exception without modification,
   you must delete this exception statement from your version and license
   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 <stdlib.h>
#include <assert.h>
#include "libdwP.h"
#include <dwarf.h>

struct arangelist
{
  Dwarf_Arange arange;
  struct arangelist *next;
};

/* Compare by Dwarf_Arange.addr, given pointers into an array of pointeers.  */
static int
compare_aranges (const void *a, const void *b)
{
  Dwarf_Arange *const *p1 = a, *const *p2 = b;
  Dwarf_Arange *l1 = *p1, *l2 = *p2;
  return l1->addr - l2->addr;
}

int
dwarf_getaranges (dbg, aranges, naranges)
     Dwarf *dbg;
     Dwarf_Aranges **aranges;
     size_t *naranges;
{
  if (dbg == NULL)
    return -1;

  if (dbg->aranges != NULL)
    {
      *aranges = dbg->aranges;
      if (naranges != NULL)
	*naranges = dbg->aranges->naranges;
      return 0;
    }

  if (dbg->sectiondata[IDX_debug_aranges] == NULL)
    {
      /* No such section.  */
      *aranges = NULL;
      if (naranges != NULL)
	*naranges = 0;
      return 0;
    }

  if (dbg->sectiondata[IDX_debug_aranges]->d_buf == NULL)
    return -1;

  struct arangelist *arangelist = NULL;
  unsigned int narangelist = 0;

  const char *readp
    = (const char *) dbg->sectiondata[IDX_debug_aranges]->d_buf;
  const char *readendp = readp + dbg->sectiondata[IDX_debug_aranges]->d_size;

  while (readp < readendp)
    {
      const char *hdrstart = readp;

      /* Each entry starts with a header:

	 1. A 4-byte or 12-byte length containing the length of the
	 set of entries for this compilation unit, not including the
	 length field itself. [...]

	 2. A 2-byte version identifier containing the value 2 for
	 DWARF Version 2.1.

	 3. A 4-byte or 8-byte offset into the .debug_info section. [...]

	 4. A 1-byte unsigned integer containing the size in bytes of
	 an address (or the offset portion of an address for segmented
	 addressing) on the target system.

	 5. A 1-byte unsigned integer containing the size in bytes of
	 a segment descriptor on the target system.  */
      Dwarf_Word length = read_4ubyte_unaligned_inc (dbg, readp);
      unsigned int length_bytes = 4;
      if (length == DWARF3_LENGTH_64_BIT)
	{
	  length = read_8ubyte_unaligned_inc (dbg, readp);
	  length_bytes = 8;
	}
      else if (unlikely (length >= DWARF3_LENGTH_MIN_ESCAPE_CODE
			 && length <= DWARF3_LENGTH_MAX_ESCAPE_CODE))
	goto invalid;

      unsigned int version = read_2ubyte_unaligned_inc (dbg, readp);
      if (version != 2)
	{
	invalid:
	  __libdw_seterrno (DWARF_E_INVALID_DWARF);
	  return -1;
	}

      Dwarf_Word offset;
      if (length_bytes == 4)
	offset = read_4ubyte_unaligned_inc (dbg, readp);
      else
	offset = read_8ubyte_unaligned_inc (dbg, readp);

      /* Sanity-check the offset.  */
      if (offset + 4 > dbg->sectiondata[IDX_debug_info]->d_size)
	goto invalid;

      unsigned int address_size = *readp++;
      if (address_size != 4 && address_size != 8)
	goto invalid;

      /* Ignore the segment size value.  */
      // XXX Really?
      (void) *readp++;

      /* Round the address to the next multiple of 2*address_size.  */
      readp += ((2 * address_size - ((readp - hdrstart) % (2 * address_size)))
		% (2 * address_size));

      while (1)
	{
	  Dwarf_Word range_address;
	  Dwarf_Word range_length;

	  if (address_size == 4)
	    {
	      range_address = read_4ubyte_unaligned_inc (dbg, readp);
	      range_length = read_4ubyte_unaligned_inc (dbg, readp);
	    }
	  else
	    {
	      range_address = read_8ubyte_unaligned_inc (dbg, readp);
	      range_length = read_8ubyte_unaligned_inc (dbg, readp);
	    }

	  /* Two zero values mark the end.  */
	  if (range_address == 0 && range_length == 0)
	    break;

	  struct arangelist *new_arange =
	    (struct arangelist *) alloca (sizeof (struct arangelist));

	  new_arange->arange.addr = range_address;
	  new_arange->arange.length = range_length;

	  /* We store the actual CU DIE offset, not the CU header offset.  */
	  const char *cu_header = (dbg->sectiondata[IDX_debug_info]->d_buf
				   + offset);
	  unsigned int offset_size;
	  if (read_4ubyte_unaligned_noncvt (cu_header) == DWARF3_LENGTH_64_BIT)
	    offset_size = 8;
	  else
	    offset_size = 4;
	  new_arange->arange.offset = DIE_OFFSET_FROM_CU_OFFSET (offset,
								 offset_size);

	  /* Sanity-check the data.  */
	  if (new_arange->arange.offset
	      >= dbg->sectiondata[IDX_debug_info]->d_size)
	    goto invalid;

	  new_arange->next = arangelist;
	  arangelist = new_arange;
	  ++narangelist;
	}
    }

  if (narangelist == 0)
    {
      if (naranges != NULL)
	*naranges = 0;
      *aranges = NULL;
      return 0;
    }

  /* Allocate the array for the result.  */
  void *buf = libdw_alloc (dbg, Dwarf_Aranges,
			   sizeof (Dwarf_Aranges)
			   + narangelist * sizeof (Dwarf_Arange), 1);

  /* First use the buffer for the pointers, and sort the entries.
     We'll write the pointers in the end of the buffer, and then
     copy into the buffer from the beginning so the overlap works.  */
  assert (sizeof (Dwarf_Arange) >= sizeof (Dwarf_Arange *));
  Dwarf_Arange **sortaranges = (buf + sizeof (Dwarf_Aranges)
				+ ((sizeof (Dwarf_Arange)
				    - sizeof (Dwarf_Arange *)) * narangelist));

  /* The list is in LIFO order and usually they come in clumps with
     ascending addresses.  So fill from the back to probably start with
     runs already in order before we sort.  */
  unsigned int i = narangelist;
  while (i-- > 0)
    {
      sortaranges[i] = &arangelist->arange;
      arangelist = arangelist->next;
    }
  assert (arangelist == NULL);

  /* Sort by ascending address.  */
  qsort (sortaranges, narangelist, sizeof sortaranges[0], &compare_aranges);

  /* Now that they are sorted, put them in the final array.
     The buffers overlap, so we've clobbered the early elements
     of SORTARANGES by the time we're reading the later ones.  */
  *aranges = buf;
  (*aranges)->dbg = dbg;
  (*aranges)->naranges = narangelist;
  dbg->aranges = *aranges;
  if (naranges != NULL)
    *naranges = narangelist;
  for (i = 0; i < narangelist; ++i)
    (*aranges)->info[i] = *sortaranges[i];

  return 0;
}
INTDEF(dwarf_getaranges)