1/* Return sibling of given DIE.
2   Copyright (C) 2003-2010, 2014, 2015 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 (Dwarf_Die *die, Dwarf_Die *result)
41{
42  /* Ignore previous errors.  */
43  if (die == NULL)
44    return -1;
45
46  /* result is declared NN */
47
48  if (result != die)
49    result->addr = NULL;
50
51  unsigned int level = 0;
52
53  /* Copy of the current DIE.  */
54  Dwarf_Die this_die = *die;
55  /* Temporary attributes we create.  */
56  Dwarf_Attribute sibattr;
57  /* Copy of the CU in the request.  */
58  sibattr.cu = this_die.cu;
59  /* That's the address we start looking.  */
60  unsigned char *addr = this_die.addr;
61  /* End of the buffer.  */
62  unsigned char *endp = sibattr.cu->endp;
63
64  /* Search for the beginning of the next die on this level.  We
65     must not return the dies for children of the given die.  */
66  do
67    {
68      /* Find the end of the DIE or the sibling attribute.  */
69      addr = __libdw_find_attr (&this_die, DW_AT_sibling, &sibattr.code,
70				&sibattr.form);
71      if (addr != NULL && sibattr.code == DW_AT_sibling)
72	{
73	  Dwarf_Off offset;
74	  sibattr.valp = addr;
75	  if (unlikely (__libdw_formref (&sibattr, &offset) != 0))
76	    /* Something went wrong.  */
77	    return -1;
78
79	  /* The sibling attribute should point after this DIE in the CU.
80	     But not after the end of the CU.  */
81	  size_t size = sibattr.cu->endp - sibattr.cu->startp;
82	  size_t die_off = this_die.addr - this_die.cu->startp;
83	  if (unlikely (offset >= size || offset <= die_off))
84	    {
85	      __libdw_seterrno (DWARF_E_INVALID_DWARF);
86	      return -1;
87	    }
88
89	  /* Compute the next address.  */
90	  addr = sibattr.cu->startp + offset;
91	}
92      else if (unlikely (addr == NULL)
93	       || unlikely (this_die.abbrev == DWARF_END_ABBREV))
94	return -1;
95      else if (this_die.abbrev->has_children)
96	/* This abbreviation has children.  */
97	++level;
98
99
100      while (1)
101	{
102	  /* Make sure we are still in range.  Some producers might skip
103	     the trailing NUL bytes.  */
104	  if (addr >= endp)
105	    return 1;
106
107	  if (*addr != '\0')
108	    break;
109
110	  if (level-- == 0)
111	    {
112	      if (result != die)
113		result->addr = addr;
114	      /* No more sibling at all.  */
115	      return 1;
116	    }
117
118	  ++addr;
119	}
120
121      /* Initialize the 'current DIE'.  */
122      this_die.addr = addr;
123      this_die.abbrev = NULL;
124    }
125  while (level > 0);
126
127  /* Maybe we reached the end of the CU.  */
128  if (addr >= endp)
129    return 1;
130
131  /* Clear the entire DIE structure.  This signals we have not yet
132     determined any of the information.  */
133  memset (result, '\0', sizeof (Dwarf_Die));
134
135  /* We have the address.  */
136  result->addr = addr;
137
138  /* Same CU as the parent.  */
139  result->cu = sibattr.cu;
140
141  return 0;
142}
143INTDEF(dwarf_siblingof)
144