1 /* Get abbreviation at given offset.
2 Copyright (C) 2003, 2004, 2005, 2006, 2014, 2017 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 <dwarf.h>
35 #include "libdwP.h"
36
37
38 Dwarf_Abbrev *
39 internal_function
__libdw_getabbrev(Dwarf * dbg,struct Dwarf_CU * cu,Dwarf_Off offset,size_t * lengthp,Dwarf_Abbrev * result)40 __libdw_getabbrev (Dwarf *dbg, struct Dwarf_CU *cu, Dwarf_Off offset,
41 size_t *lengthp, Dwarf_Abbrev *result)
42 {
43 /* Don't fail if there is not .debug_abbrev section. */
44 if (dbg->sectiondata[IDX_debug_abbrev] == NULL)
45 return NULL;
46
47 if (offset >= dbg->sectiondata[IDX_debug_abbrev]->d_size)
48 {
49 __libdw_seterrno (DWARF_E_INVALID_OFFSET);
50 return NULL;
51 }
52
53 const unsigned char *abbrevp
54 = (unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf + offset;
55
56 if (*abbrevp == '\0')
57 /* We are past the last entry. */
58 return DWARF_END_ABBREV;
59
60 /* 7.5.3 Abbreviations Tables
61
62 [...] Each declaration begins with an unsigned LEB128 number
63 representing the abbreviation code itself. [...] The
64 abbreviation code is followed by another unsigned LEB128
65 number that encodes the entry's tag. [...]
66
67 [...] Following the tag encoding is a 1-byte value that
68 determines whether a debugging information entry using this
69 abbreviation has child entries or not. [...]
70
71 [...] Finally, the child encoding is followed by a series of
72 attribute specifications. Each attribute specification
73 consists of two parts. The first part is an unsigned LEB128
74 number representing the attribute's name. The second part is
75 an unsigned LEB128 number representing the attribute's form. */
76 const unsigned char *end = (dbg->sectiondata[IDX_debug_abbrev]->d_buf
77 + dbg->sectiondata[IDX_debug_abbrev]->d_size);
78 const unsigned char *start_abbrevp = abbrevp;
79 unsigned int code;
80 get_uleb128 (code, abbrevp, end);
81
82 /* Check whether this code is already in the hash table. */
83 bool foundit = false;
84 Dwarf_Abbrev *abb = NULL;
85 if (cu == NULL
86 || (abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code)) == NULL)
87 {
88 if (result == NULL)
89 abb = libdw_typed_alloc (dbg, Dwarf_Abbrev);
90 else
91 abb = result;
92 }
93 else
94 {
95 foundit = true;
96
97 if (unlikely (abb->offset != offset))
98 {
99 /* A duplicate abbrev code at a different offset,
100 that should never happen. */
101 invalid:
102 if (! foundit)
103 libdw_typed_unalloc (dbg, Dwarf_Abbrev);
104 __libdw_seterrno (DWARF_E_INVALID_DWARF);
105 return NULL;
106 }
107
108 /* If the caller doesn't need the length we are done. */
109 if (lengthp == NULL)
110 goto out;
111 }
112
113 /* If there is already a value in the hash table we are going to
114 overwrite its content. This must not be a problem, since the
115 content better be the same. */
116 abb->code = code;
117 if (abbrevp >= end)
118 goto invalid;
119 get_uleb128 (abb->tag, abbrevp, end);
120 if (abbrevp + 1 >= end)
121 goto invalid;
122 abb->has_children = *abbrevp++ == DW_CHILDREN_yes;
123 abb->attrp = (unsigned char *) abbrevp;
124 abb->offset = offset;
125
126 /* Skip over all the attributes and check rest of the abbrev is valid. */
127 unsigned int attrname;
128 unsigned int attrform;
129 do
130 {
131 if (abbrevp >= end)
132 goto invalid;
133 get_uleb128 (attrname, abbrevp, end);
134 if (abbrevp >= end)
135 goto invalid;
136 get_uleb128 (attrform, abbrevp, end);
137 if (attrform == DW_FORM_implicit_const)
138 {
139 int64_t formval __attribute__((__unused__));
140 if (abbrevp >= end)
141 goto invalid;
142 get_sleb128 (formval, abbrevp, end);
143 }
144 }
145 while (attrname != 0 || attrform != 0);
146
147 /* Return the length to the caller if she asked for it. */
148 if (lengthp != NULL)
149 *lengthp = abbrevp - start_abbrevp;
150
151 /* Add the entry to the hash table. */
152 if (cu != NULL && ! foundit)
153 if (Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb) == -1)
154 {
155 /* The entry was already in the table, remove the one we just
156 created and get the one already inserted. */
157 libdw_typed_unalloc (dbg, Dwarf_Abbrev);
158 abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code);
159 }
160
161 out:
162 return abb;
163 }
164
165
166 Dwarf_Abbrev *
dwarf_getabbrev(Dwarf_Die * die,Dwarf_Off offset,size_t * lengthp)167 dwarf_getabbrev (Dwarf_Die *die, Dwarf_Off offset, size_t *lengthp)
168 {
169 if (die == NULL || die->cu == NULL)
170 return NULL;
171
172 Dwarf_CU *cu = die->cu;
173 Dwarf *dbg = cu->dbg;
174 Dwarf_Off abbrev_offset = cu->orig_abbrev_offset;
175 Elf_Data *data = dbg->sectiondata[IDX_debug_abbrev];
176 if (data == NULL)
177 return NULL;
178
179 if (offset >= data->d_size - abbrev_offset)
180 {
181 __libdw_seterrno (DWARF_E_INVALID_OFFSET);
182 return NULL;
183 }
184
185 return __libdw_getabbrev (dbg, cu, abbrev_offset + offset, lengthp, NULL);
186 }
187