dwarf_siblingof.c revision de2ed97f33139af5c7a0811e4ec66fc896a13cf2 
1/* Return sibling of given DIE.
2   Copyright (C) 2003-2010 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
66    = ((unsigned char *) cu_data (sibattr.cu)->d_buf + sibattr.cu->end);
67
68  /* Search for the beginning of the next die on this level.  We
69     must not return the dies for children of the given die.  */
70  do
71    {
72      /* Find the end of the DIE or the sibling attribute.  */
73      addr = __libdw_find_attr (&this_die, DW_AT_sibling, &sibattr.code,
74				&sibattr.form);
75      if (sibattr.code == DW_AT_sibling)
76	{
77	  Dwarf_Off offset;
78	  sibattr.valp = addr;
79	  if (unlikely (__libdw_formref (&sibattr, &offset) != 0))
80	    /* Something went wrong.  */
81	    return -1;
82
83	  /* Compute the next address.  */
84	  addr = ((unsigned char *) cu_data (sibattr.cu)->d_buf
85		  + sibattr.cu->start + offset);
86	}
87      else if (unlikely (addr == NULL)
88	       || unlikely (this_die.abbrev == DWARF_END_ABBREV))
89	return -1;
90      else if (this_die.abbrev->has_children)
91	/* This abbreviation has children.  */
92	++level;
93
94
95      while (1)
96	{
97	  /* Make sure we are still in range.  Some producers might skip
98	     the trailing NUL bytes.  */
99	  if (addr >= endp)
100	    return 1;
101
102	  if (*addr != '\0')
103	    break;
104
105	  if (level-- == 0)
106	    {
107	      if (result != die)
108		result->addr = addr;
109	      /* No more sibling at all.  */
110	      return 1;
111	    }
112
113	  ++addr;
114	}
115
116      /* Initialize the 'current DIE'.  */
117      this_die.addr = addr;
118      this_die.abbrev = NULL;
119    }
120  while (level > 0);
121
122  /* Maybe we reached the end of the CU.  */
123  if (addr >= endp)
124    return 1;
125
126  /* Clear the entire DIE structure.  This signals we have not yet
127     determined any of the information.  */
128  memset (result, '\0', sizeof (Dwarf_Die));
129
130  /* We have the address.  */
131  result->addr = addr;
132
133  /* Same CU as the parent.  */
134  result->cu = sibattr.cu;
135
136  return 0;
137}
138INTDEF(dwarf_siblingof)
139