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/* Return descriptor for sibling of die.
Copyright (C) 2000, 2001, 2002 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 <dwarf.h>
#include <stdlib.h>
#include <libdwarfP.h>
int
dwarf_siblingof (dbg, die, return_sub, error)
Dwarf_Debug dbg;
Dwarf_Die die;
Dwarf_Die *return_sub;
Dwarf_Error *error;
{
Dwarf_Small *die_addr;
Dwarf_CU_Info cu;
Dwarf_Unsigned u128;
Dwarf_Die new_die;
if (dbg == NULL)
return DW_DLV_ERROR;
if (die == NULL)
{
Dwarf_Unsigned die_offset;
/* We are supposed to return the DW_TAG_compile_unit die for the
current compile unit. For this to succeed the user must have
looked for the compile unit before. */
if (dbg->cu_list_current == NULL)
{
__libdwarf_error (dbg, error, DW_E_NO_CU);
return DW_DLV_ERROR;
}
cu = dbg->cu_list_current;
die_offset = (cu->offset + 2 * cu->offset_size - 4 + sizeof (Dwarf_Half)
+ cu->offset_size + 1);
/* Check whether this is withing the debug section. */
if (die_offset >= dbg->sections[IDX_debug_info].size)
return DW_DLV_NO_ENTRY;
/* Compute the pointer. */
die_addr = ((Dwarf_Small *) dbg->sections[IDX_debug_info].addr
+ die_offset);
}
else
{
unsigned int level = 0;
/* We start from the given die. */
cu = die->cu;
/* Address of the given die. */
die_addr = die->addr;
/* Search for the beginning of the next die on this level. We
must not return the dies for children of the given die. */
do
{
Dwarf_Abbrev abbrev;
Dwarf_Small *attrp;
Dwarf_Word attr_name;
Dwarf_Word attr_form;
/* Get abbrev code. */
get_uleb128 (u128, die_addr);
/* And get the abbreviation itself. */
abbrev = __libdwarf_get_abbrev (dbg, cu, u128, error);
if (abbrev == NULL)
return DW_DLV_ERROR;
/* This is where the attributes start. */
attrp = abbrev->attrp;
/* Does this abbreviation have children? */
if (abbrev->has_children)
++level;
while (1)
{
/* Are we still in bounds? */
if (attrp >= ((Dwarf_Small *)dbg->sections[IDX_debug_abbrev].addr
+ dbg->sections[IDX_debug_abbrev].size))
{
__libdwarf_error (dbg, error, DW_E_INVALID_DWARF);
return DW_DLV_ERROR;
}
/* Get attribute name and form.
XXX We don't check whether this reads beyond the end of
the section. */
get_uleb128 (attr_name, attrp);
get_uleb128 (attr_form, attrp);
/* We can stop if we found the attribute with value zero. */
if (attr_name == 0 && attr_form == 0)
break;
/* See whether this is an sibling attribute which would help
us to skip ahead. */
if (attr_name == DW_AT_sibling)
{
/* Cool. We just have to decode the parameter and we know
the offset. */
Dwarf_Unsigned offset;
switch (attr_form)
{
case DW_FORM_ref1:
offset = *die_addr;
break;
case DW_FORM_ref2:
offset = read_2ubyte_unaligned (dbg, die_addr);
break;
case DW_FORM_ref4:
offset = read_4ubyte_unaligned (dbg, die_addr);
break;
case DW_FORM_ref8:
offset = read_8ubyte_unaligned (dbg, die_addr);
break;
case DW_FORM_ref_udata:
get_uleb128 (offset, die_addr);
break;
default:
/* The above are all legal forms. Everything else is
an error. */
__libdwarf_error (dbg, error, DW_E_INVALID_DWARF);
return DW_DLV_ERROR;
}
/* Compute the new address. Some sanity check first,
though. */
if (unlikely (offset > 2 * cu->offset_size - 4 + cu->length))
{
__libdwarf_error (dbg, error, DW_E_INVALID_DWARF);
return DW_DLV_ERROR;
}
die_addr =
((Dwarf_Small *) dbg->sections[IDX_debug_info].addr
+ cu->offset + offset);
/* Even if the abbreviation has children we have stepped
over them now. */
if (abbrev->has_children)
--level;
break;
}
/* Skip over the rest of this attribute (if there is any). */
if (attr_form != 0)
{
size_t len;
if (unlikely (__libdwarf_form_val_len (dbg, cu, attr_form,
die_addr, &len, error)
!= DW_DLV_OK))
return DW_DLV_ERROR;
die_addr += len;
}
}
/* Check that we are not yet at the end. */
if (*die_addr == 0)
{
if (level == 0)
return DW_DLV_NO_ENTRY;
do
++die_addr;
while (--level > 0 && *die_addr == 0);
}
}
while (level > 0);
}
/* Are we at the end. */
if (die != NULL
&& die_addr >= ((Dwarf_Small *) dbg->sections[IDX_debug_info].addr
+ cu->offset + cu->length + 2 * cu->offset_size - 4))
return DW_DLV_NO_ENTRY;
/* See whether there is another sibling available or whether this is
the end. */
if (*die_addr == 0)
return DW_DLV_NO_ENTRY;
/* There is more data. Create the data structure. */
new_die = (Dwarf_Die) malloc (sizeof (struct Dwarf_Die_s));
if (new_die == NULL)
{
__libdwarf_error (dbg, error, DW_E_NOMEM);
return DW_DLV_ERROR;
}
#ifdef DWARF_DEBUG
new_die->memtag = DW_DLA_DIE;
#endif
/* Remember the address. */
new_die->addr = die_addr;
/* And the compile unit. */
new_die->cu = cu;
/* 7.5.2 Debugging Information Entry
Each debugging information entry begins with an unsigned LEB128
number containing the abbreviation code for the entry. */
get_uleb128 (u128, die_addr);
/* Find the abbreviation. */
new_die->abbrev = __libdwarf_get_abbrev (dbg, cu, u128, error);
if (new_die->abbrev == NULL)
{
free (new_die);
return DW_DLV_ERROR;
}
/* If we are looking for the first entry this must be a compile unit. */
if (die == NULL && unlikely (new_die->abbrev->tag != DW_TAG_compile_unit))
{
free (new_die);
__libdwarf_error (dbg, error, DW_E_1ST_NO_CU);
return DW_DLV_ERROR;
}
*return_sub = new_die;
return DW_DLV_OK;
}
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