libdw/dwarf_getaranges.c

/* Return list address ranges.
   Copyright (C) 2000, 2001, 2002, 2004, 2005 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   This program is Open Source software; you can redistribute it and/or
   modify it under the terms of the Open Software License version 1.0 as
   published by the Open Source Initiative.

   You should have received a copy of the Open Software License along
   with this program; if not, you may obtain a copy of the Open Software
   License version 1.0 from http://www.opensource.org/licenses/osl.php or
   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
   3001 King Ranch Road, Ukiah, CA 95482.   */

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

#include <stdlib.h>
#include <assert.h>
#include "libdwP.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]->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 == 0xffffffff)
	{
	  length = read_8ubyte_unaligned_inc (dbg, readp);
	  length_bytes = 8;
	}

      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);

      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) == 0xffffffff)
	    offset_size = 8;
	  else
	    offset_size = 4;
	  new_arange->arange.offset = offset + 3 * offset_size - 4 + 3;

	  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)