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 <[email protected]>, 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 // We start off with abbrevp at offset, which is checked above.
81 get_uleb128 (code, abbrevp, end);
82
83 /* Check whether this code is already in the hash table. */
84 bool foundit = false;
85 Dwarf_Abbrev *abb = NULL;
86 if (cu == NULL
87 || (abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code)) == NULL)
88 {
89 if (result == NULL)
90 abb = libdw_typed_alloc (dbg, Dwarf_Abbrev);
91 else
92 abb = result;
93 }
94 else
95 {
96 foundit = true;
97
98 if (unlikely (abb->offset != offset))
99 {
100 /* A duplicate abbrev code at a different offset,
101 that should never happen. */
102 invalid:
103 if (! foundit)
104 libdw_typed_unalloc (dbg, Dwarf_Abbrev);
105 __libdw_seterrno (DWARF_E_INVALID_DWARF);
106 return NULL;
107 }
108
109 /* If the caller doesn't need the length we are done. */
110 if (lengthp == NULL)
111 goto out;
112 }
113
114 /* If there is already a value in the hash table we are going to
115 overwrite its content. This must not be a problem, since the
116 content better be the same. */
117 abb->code = code;
118 if (abbrevp >= end)
119 goto invalid;
120 get_uleb128 (abb->tag, abbrevp, end);
121 if (abbrevp + 1 >= end)
122 goto invalid;
123 abb->has_children = *abbrevp++ == DW_CHILDREN_yes;
124 abb->attrp = (unsigned char *) abbrevp;
125 abb->offset = offset;
126
127 /* Skip over all the attributes and check rest of the abbrev is valid. */
128 unsigned int attrname;
129 unsigned int attrform;
130 do
131 {
132 if (abbrevp >= end)
133 goto invalid;
134 get_uleb128 (attrname, abbrevp, end);
135 if (abbrevp >= end)
136 goto invalid;
137 get_uleb128 (attrform, abbrevp, end);
138 if (attrform == DW_FORM_implicit_const)
139 {
140 int64_t formval __attribute__((__unused__));
141 if (abbrevp >= end)
142 goto invalid;
143 get_sleb128 (formval, abbrevp, end);
144 }
145 }
146 while (attrname != 0 || attrform != 0);
147
148 /* Return the length to the caller if she asked for it. */
149 if (lengthp != NULL)
150 *lengthp = abbrevp - start_abbrevp;
151
152 /* Add the entry to the hash table. */
153 if (cu != NULL && ! foundit)
154 if (Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb) == -1)
155 {
156 /* The entry was already in the table, remove the one we just
157 created and get the one already inserted. */
158 libdw_typed_unalloc (dbg, Dwarf_Abbrev);
159 abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code);
160 }
161
162 out:
163 return abb;
164 }
165
166
167 Dwarf_Abbrev *
dwarf_getabbrev(Dwarf_Die * die,Dwarf_Off offset,size_t * lengthp)168 dwarf_getabbrev (Dwarf_Die *die, Dwarf_Off offset, size_t *lengthp)
169 {
170 if (die == NULL || die->cu == NULL)
171 return NULL;
172
173 Dwarf_CU *cu = die->cu;
174 Dwarf *dbg = cu->dbg;
175 Dwarf_Off abbrev_offset = cu->orig_abbrev_offset;
176 Elf_Data *data = dbg->sectiondata[IDX_debug_abbrev];
177 if (data == NULL)
178 return NULL;
179
180 if (offset >= data->d_size - abbrev_offset)
181 {
182 __libdw_seterrno (DWARF_E_INVALID_OFFSET);
183 return NULL;
184 }
185
186 return __libdw_getabbrev (dbg, cu, abbrev_offset + offset, lengthp, NULL);
187 }
188