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
39 int
dwarf_siblingof(Dwarf_Die * die,Dwarf_Die * result)40 dwarf_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
62 /* Search for the beginning of the next die on this level. We
63 must not return the dies for children of the given die. */
64 do
65 {
66 /* Find the end of the DIE or the sibling attribute. */
67 addr = __libdw_find_attr (&this_die, DW_AT_sibling, &sibattr.code,
68 &sibattr.form);
69 if (addr != NULL && sibattr.code == DW_AT_sibling)
70 {
71 Dwarf_Off offset;
72 sibattr.valp = addr;
73 if (unlikely (__libdw_formref (&sibattr, &offset) != 0))
74 /* Something went wrong. */
75 return -1;
76
77 /* The sibling attribute should point after this DIE in the CU.
78 But not after the end of the CU. */
79 size_t size = sibattr.cu->endp - sibattr.cu->startp;
80 size_t die_off = this_die.addr - this_die.cu->startp;
81 if (unlikely (offset >= size || offset <= die_off))
82 {
83 __libdw_seterrno (DWARF_E_INVALID_DWARF);
84 return -1;
85 }
86
87 /* Compute the next address. */
88 addr = sibattr.cu->startp + offset;
89 }
90 else if (unlikely (addr == NULL)
91 || unlikely (this_die.abbrev == DWARF_END_ABBREV))
92 return -1;
93 else if (this_die.abbrev->has_children)
94 /* This abbreviation has children. */
95 ++level;
96
97 /* End of the buffer. */
98 unsigned char *endp = sibattr.cu->endp;
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 unsigned char *endp = sibattr.cu->endp;
129 if (addr >= endp)
130 return 1;
131
132 /* Clear the entire DIE structure. This signals we have not yet
133 determined any of the information. */
134 memset (result, '\0', sizeof (Dwarf_Die));
135
136 /* We have the address. */
137 result->addr = addr;
138
139 /* Same CU as the parent. */
140 result->cu = sibattr.cu;
141
142 return 0;
143 }
144 INTDEF(dwarf_siblingof)
145