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)) == 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 __libdw_seterrno (DWARF_E_INVALID_DWARF);
103 return NULL;
104 }
105
106 /* If the caller doesn't need the length we are done. */
107 if (lengthp == NULL)
108 goto out;
109 }
110
111 /* If there is already a value in the hash table we are going to
112 overwrite its content. This must not be a problem, since the
113 content better be the same. */
114 abb->code = code;
115 if (abbrevp >= end)
116 goto invalid;
117 get_uleb128 (abb->tag, abbrevp, end);
118 if (abbrevp + 1 >= end)
119 goto invalid;
120 abb->has_children = *abbrevp++ == DW_CHILDREN_yes;
121 abb->attrp = (unsigned char *) abbrevp;
122 abb->offset = offset;
123
124 /* Skip over all the attributes and check rest of the abbrev is valid. */
125 unsigned int attrname;
126 unsigned int attrform;
127 do
128 {
129 if (abbrevp >= end)
130 goto invalid;
131 get_uleb128 (attrname, abbrevp, end);
132 if (abbrevp >= end)
133 goto invalid;
134 get_uleb128 (attrform, abbrevp, end);
135 if (attrform == DW_FORM_implicit_const)
136 {
137 int64_t formval __attribute__((__unused__));
138 if (abbrevp >= end)
139 goto invalid;
140 get_sleb128 (formval, abbrevp, end);
141 }
142 }
143 while (attrname != 0 || attrform != 0);
144
145 /* Return the length to the caller if she asked for it. */
146 if (lengthp != NULL)
147 *lengthp = abbrevp - start_abbrevp;
148
149 /* Add the entry to the hash table. */
150 if (cu != NULL && ! foundit)
151 (void) Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb);
152
153 out:
154 return abb;
155 }
156
157
158 Dwarf_Abbrev *
dwarf_getabbrev(Dwarf_Die * die,Dwarf_Off offset,size_t * lengthp)159 dwarf_getabbrev (Dwarf_Die *die, Dwarf_Off offset, size_t *lengthp)
160 {
161 if (die == NULL || die->cu == NULL)
162 return NULL;
163
164 Dwarf_CU *cu = die->cu;
165 Dwarf *dbg = cu->dbg;
166 Dwarf_Off abbrev_offset = cu->orig_abbrev_offset;
167 Elf_Data *data = dbg->sectiondata[IDX_debug_abbrev];
168 if (data == NULL)
169 return NULL;
170
171 if (offset >= data->d_size - abbrev_offset)
172 {
173 __libdw_seterrno (DWARF_E_INVALID_OFFSET);
174 return NULL;
175 }
176
177 return __libdw_getabbrev (dbg, cu, abbrev_offset + offset, lengthp, NULL);
178 }
179