1/* Return sibling of given DIE.
2   Copyright (C) 2003-2010, 2014 Red Hat, Inc.
3   This file is part of elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2003.
5
6   This file is free software; you can redistribute it and/or modify
7   it under the terms of either
8
9     * the GNU Lesser General Public License as published by the Free
10       Software Foundation; either version 3 of the License, or (at
11       your option) any later version
12
13   or
14
15     * the GNU General Public License as published by the Free
16       Software Foundation; either version 2 of the License, or (at
17       your option) any later version
18
19   or both in parallel, as here.
20
21   elfutils is distributed in the hope that it will be useful, but
22   WITHOUT ANY WARRANTY; without even the implied warranty of
23   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
24   General Public License for more details.
25
26   You should have received copies of the GNU General Public License and
27   the GNU Lesser General Public License along with this program.  If
28   not, see <http://www.gnu.org/licenses/>.  */
29
30#ifdef HAVE_CONFIG_H
31# include <config.h>
32#endif
33
34#include "libdwP.h"
35#include <dwarf.h>
36#include <string.h>
37
38
39int
40dwarf_siblingof (die, result)
41     Dwarf_Die *die;
42     Dwarf_Die *result;
43{
44  /* Ignore previous errors.  */
45  if (die == NULL)
46    return -1;
47
48  if (result == NULL)
49    return -1;
50
51  if (result != die)
52    result->addr = NULL;
53
54  unsigned int level = 0;
55
56  /* Copy of the current DIE.  */
57  Dwarf_Die this_die = *die;
58  /* Temporary attributes we create.  */
59  Dwarf_Attribute sibattr;
60  /* Copy of the CU in the request.  */
61  sibattr.cu = this_die.cu;
62  /* That's the address we start looking.  */
63  unsigned char *addr = this_die.addr;
64  /* End of the buffer.  */
65  unsigned char *endp = sibattr.cu->endp;
66
67  /* Search for the beginning of the next die on this level.  We
68     must not return the dies for children of the given die.  */
69  do
70    {
71      /* Find the end of the DIE or the sibling attribute.  */
72      addr = __libdw_find_attr (&this_die, DW_AT_sibling, &sibattr.code,
73				&sibattr.form);
74      if (addr != NULL && sibattr.code == DW_AT_sibling)
75	{
76	  Dwarf_Off offset;
77	  sibattr.valp = addr;
78	  if (unlikely (__libdw_formref (&sibattr, &offset) != 0))
79	    /* Something went wrong.  */
80	    return -1;
81
82	  /* Compute the next address.  */
83	  addr = sibattr.cu->startp + offset;
84	}
85      else if (unlikely (addr == NULL)
86	       || unlikely (this_die.abbrev == DWARF_END_ABBREV))
87	return -1;
88      else if (this_die.abbrev->has_children)
89	/* This abbreviation has children.  */
90	++level;
91
92
93      while (1)
94	{
95	  /* Make sure we are still in range.  Some producers might skip
96	     the trailing NUL bytes.  */
97	  if (addr >= endp)
98	    return 1;
99
100	  if (*addr != '\0')
101	    break;
102
103	  if (level-- == 0)
104	    {
105	      if (result != die)
106		result->addr = addr;
107	      /* No more sibling at all.  */
108	      return 1;
109	    }
110
111	  ++addr;
112	}
113
114      /* Initialize the 'current DIE'.  */
115      this_die.addr = addr;
116      this_die.abbrev = NULL;
117    }
118  while (level > 0);
119
120  /* Maybe we reached the end of the CU.  */
121  if (addr >= endp)
122    return 1;
123
124  /* Clear the entire DIE structure.  This signals we have not yet
125     determined any of the information.  */
126  memset (result, '\0', sizeof (Dwarf_Die));
127
128  /* We have the address.  */
129  result->addr = addr;
130
131  /* Same CU as the parent.  */
132  result->cu = sibattr.cu;
133
134  return 0;
135}
136INTDEF(dwarf_siblingof)
137