1 /* Get abbreviation at given offset.
2 Copyright (C) 2003, 2004 Red Hat, Inc.
3 Written by Ulrich Drepper <drepper@redhat.com>, 2003.
4
5 This program is Open Source software; you can redistribute it and/or
6 modify it under the terms of the Open Software License version 1.0 as
7 published by the Open Source Initiative.
8
9 You should have received a copy of the Open Software License along
10 with this program; if not, you may obtain a copy of the Open Software
11 License version 1.0 from http://www.opensource.org/licenses/osl.php or
12 by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
13 3001 King Ranch Road, Ukiah, CA 95482. */
14
15 #ifdef HAVE_CONFIG_H
16 # include <config.h>
17 #endif
18
19 #include <assert.h>
20 #include <dwarf.h>
21 #include "libdwP.h"
22
23
24 Dwarf_Abbrev *
25 internal_function_def
__libdw_getabbrev(dbg,cu,offset,lengthp,result)26 __libdw_getabbrev (dbg, cu, offset, lengthp, result)
27 Dwarf *dbg;
28 struct Dwarf_CU *cu;
29 Dwarf_Off offset;
30 size_t *lengthp;
31 Dwarf_Abbrev *result;
32 {
33 /* Don't fail if there is not .debug_abbrev section. */
34 if (dbg->sectiondata[IDX_debug_abbrev] == NULL)
35 return NULL;
36
37 unsigned char *abbrevp
38 = (unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf + offset;
39 if (*abbrevp == '\0')
40 /* We are past the last entry. */
41 return NULL;
42
43 /* 7.5.3 Abbreviations Tables
44
45 [...] Each declaration begins with an unsigned LEB128 number
46 representing the abbreviation code itself. [...] The
47 abbreviation code is followed by another unsigned LEB128
48 number that encodes the entry's tag. [...]
49
50 [...] Following the tag encoding is a 1-byte value that
51 determines whether a debugging information entry using this
52 abbreviation has child entries or not. [...]
53
54 [...] Finally, the child encoding is followed by a series of
55 attribute specifications. Each attribute specification
56 consists of two parts. The first part is an unsigned LEB128
57 number representing the attribute's name. The second part is
58 an unsigned LEB128 number representing the attribute's form. */
59 unsigned char *start_abbrevp = abbrevp;
60 unsigned int code;
61 get_uleb128 (code, abbrevp);
62
63 /* Check whether this code is already in the hash table. */
64 bool foundit = false;
65 Dwarf_Abbrev *abb = NULL;
66 if (cu == NULL
67 || (abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code, NULL)) == NULL)
68 {
69 if (result == NULL)
70 abb = libdw_typed_alloc (dbg, Dwarf_Abbrev);
71 else
72 abb = result;
73 }
74 else
75 {
76 foundit = true;
77
78 assert (abb->offset == offset);
79
80 /* If the caller doesn't need the length we are done. */
81 if (lengthp == NULL)
82 goto out;
83 }
84
85 /* If there is already a value in the hash table we are going to
86 overwrite its content. This must not be a problem, since the
87 content better be the same. */
88 abb->code = code;
89 get_uleb128 (abb->tag, abbrevp);
90 abb->has_children = *abbrevp++ == DW_CHILDREN_yes;
91 abb->attrp = abbrevp;
92 abb->offset = offset;
93
94 /* Skip over all the attributes and count them while doing so. */
95 abb->attrcnt = 0;
96 unsigned int attrname;
97 unsigned int attrform;
98 do
99 {
100 get_uleb128 (attrname, abbrevp);
101 get_uleb128 (attrform, abbrevp);
102 }
103 while (attrname != 0 && attrform != 0 && ++abb->attrcnt);
104
105 /* Return the length to the caller if she asked for it. */
106 if (lengthp != NULL)
107 *lengthp = abbrevp - start_abbrevp;
108
109 /* Add the entry to the hash table. */
110 if (cu != NULL && ! foundit)
111 (void) Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb);
112
113 out:
114 return abb;
115 }
116
117
118 Dwarf_Abbrev *
dwarf_getabbrev(die,offset,lengthp)119 dwarf_getabbrev (die, offset, lengthp)
120 Dwarf_Die *die;
121 Dwarf_Off offset;
122 size_t *lengthp;
123 {
124 return __libdw_getabbrev (die->cu->dbg, die->cu,
125 die->cu->orig_abbrev_offset + offset, lengthp,
126 NULL);
127 }
128