1 /* Return child of current DIE.
2 Copyright (C) 2003-2011, 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 <string.h>
36
37 /* Some arbitrary value not conflicting with any existing code. */
38 #define INVALID 0xffffe444
39
40
41 unsigned char *
42 internal_function
__libdw_find_attr(Dwarf_Die * die,unsigned int search_name,unsigned int * codep,unsigned int * formp)43 __libdw_find_attr (Dwarf_Die *die, unsigned int search_name,
44 unsigned int *codep, unsigned int *formp)
45 {
46 Dwarf *dbg = die->cu->dbg;
47 const unsigned char *readp;
48
49 /* Find the abbreviation entry. */
50 Dwarf_Abbrev *abbrevp = __libdw_dieabbrev (die, &readp);
51 if (unlikely (abbrevp == DWARF_END_ABBREV))
52 {
53 invalid_dwarf:
54 __libdw_seterrno (DWARF_E_INVALID_DWARF);
55 return NULL;
56 }
57
58 /* Search the name attribute. */
59 unsigned char *const endp
60 = ((unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf
61 + dbg->sectiondata[IDX_debug_abbrev]->d_size);
62
63 const unsigned char *attrp = abbrevp->attrp;
64 while (1)
65 {
66 /* Get attribute name and form. */
67 if (unlikely (attrp >= endp))
68 goto invalid_dwarf;
69 unsigned int attr_name;
70 get_uleb128 (attr_name, attrp, endp);
71
72 if (unlikely (attrp >= endp))
73 goto invalid_dwarf;
74 unsigned int attr_form;
75 get_uleb128 (attr_form, attrp, endp);
76
77 /* We can stop if we found the attribute with value zero. */
78 if (attr_name == 0 && attr_form == 0)
79 break;
80
81 /* Is this the name attribute? */
82 if (attr_name == search_name && search_name != INVALID)
83 {
84 if (codep != NULL)
85 *codep = attr_name;
86 if (formp != NULL)
87 *formp = attr_form;
88
89 return (unsigned char *) readp;
90 }
91
92 /* Skip over the rest of this attribute (if there is any). */
93 if (attr_form != 0)
94 {
95 size_t len = __libdw_form_val_len (die->cu, attr_form, readp);
96 if (unlikely (len == (size_t) -1l))
97 {
98 readp = NULL;
99 break;
100 }
101
102 // __libdw_form_val_len will have done a bounds check.
103 readp += len;
104 }
105 }
106
107 // XXX Do we need other values?
108 if (codep != NULL)
109 *codep = INVALID;
110 if (formp != NULL)
111 *formp = INVALID;
112
113 return (unsigned char *) readp;
114 }
115
116
117 int
dwarf_child(Dwarf_Die * die,Dwarf_Die * result)118 dwarf_child (Dwarf_Die *die, Dwarf_Die *result)
119 {
120 /* Ignore previous errors. */
121 if (die == NULL)
122 return -1;
123
124 /* Find the abbreviation entry. */
125 Dwarf_Abbrev *abbrevp = __libdw_dieabbrev (die, NULL);
126 if (unlikely (abbrevp == DWARF_END_ABBREV))
127 {
128 __libdw_seterrno (DWARF_E_INVALID_DWARF);
129 return -1;
130 }
131
132 /* If there are no children, do not search. */
133 if (! abbrevp->has_children)
134 return 1;
135
136 /* Skip past the last attribute. */
137 void *addr = __libdw_find_attr (die, INVALID, NULL, NULL);
138
139 if (addr == NULL)
140 return -1;
141
142 /* RESULT can be the same as DIE. So preserve what we need. */
143 struct Dwarf_CU *cu = die->cu;
144
145 /* It's kosher (just suboptimal) to have a null entry first thing (7.5.3).
146 So if this starts with ULEB128 of 0 (even with silly encoding of 0),
147 it is a kosher null entry and we do not really have any children. */
148 const unsigned char *code = addr;
149 const unsigned char *endp = cu->endp;
150 while (1)
151 {
152 if (unlikely (code >= endp)) /* Truncated section. */
153 return 1;
154 if (unlikely (*code == 0x80))
155 ++code;
156 else
157 break;
158 }
159 if (unlikely (*code == '\0'))
160 return 1;
161
162 /* Clear the entire DIE structure. This signals we have not yet
163 determined any of the information. */
164 memset (result, '\0', sizeof (Dwarf_Die));
165
166 /* We have the address. */
167 result->addr = addr;
168
169 /* Same CU as the parent. */
170 result->cu = cu;
171
172 return 0;
173 }
174 INTDEF(dwarf_child)
175