1 /* Get abbreviation at given offset.
2 Copyright (C) 2003, 2004, 2005, 2006, 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 <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 count them while doing so. */
125 abb->attrcnt = 0;
126 unsigned int attrname;
127 unsigned int attrform;
128 do
129 {
130 if (abbrevp >= end)
131 goto invalid;
132 get_uleb128 (attrname, abbrevp, end);
133 if (abbrevp >= end)
134 goto invalid;
135 get_uleb128 (attrform, abbrevp, end);
136 }
137 while (attrname != 0 && attrform != 0 && ++abb->attrcnt);
138
139 /* Return the length to the caller if she asked for it. */
140 if (lengthp != NULL)
141 *lengthp = abbrevp - start_abbrevp;
142
143 /* Add the entry to the hash table. */
144 if (cu != NULL && ! foundit)
145 (void) Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb);
146
147 out:
148 return abb;
149 }
150
151
152 Dwarf_Abbrev *
dwarf_getabbrev(Dwarf_Die * die,Dwarf_Off offset,size_t * lengthp)153 dwarf_getabbrev (Dwarf_Die *die, Dwarf_Off offset, size_t *lengthp)
154 {
155 return __libdw_getabbrev (die->cu->dbg, die->cu,
156 die->cu->orig_abbrev_offset + offset, lengthp,
157 NULL);
158 }
159