1/* Get abbreviation at given offset.
2   Copyright (C) 2003, 2004, 2005, 2006 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2003.
5
6   Red Hat elfutils is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by the
8   Free Software Foundation; version 2 of the License.
9
10   Red Hat elfutils is distributed in the hope that it will be useful, but
11   WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   General Public License for more details.
14
15   You should have received a copy of the GNU General Public License along
16   with Red Hat elfutils; if not, write to the Free Software Foundation,
17   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18
19   In addition, as a special exception, Red Hat, Inc. gives You the
20   additional right to link the code of Red Hat elfutils with code licensed
21   under any Open Source Initiative certified open source license
22   (http://www.opensource.org/licenses/index.php) which requires the
23   distribution of source code with any binary distribution and to
24   distribute linked combinations of the two.  Non-GPL Code permitted under
25   this exception must only link to the code of Red Hat elfutils through
26   those well defined interfaces identified in the file named EXCEPTION
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36   code used in conjunction with Red Hat elfutils except the Non-GPL Code
37   covered by this exception.  If you modify this file, you may extend this
38   exception to your version of the file, but you are not obligated to do
39   so.  If you do not wish to provide this exception without modification,
40   you must delete this exception statement from your version and license
41   this file solely under the GPL without exception.
42
43   Red Hat elfutils is an included package of the Open Invention Network.
44   An included package of the Open Invention Network is a package for which
45   Open Invention Network licensees cross-license their patents.  No patent
46   license is granted, either expressly or impliedly, by designation as an
47   included package.  Should you wish to participate in the Open Invention
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49   <http://www.openinventionnetwork.com>.  */
50
51#ifdef HAVE_CONFIG_H
52# include <config.h>
53#endif
54
55#include <assert.h>
56#include <dwarf.h>
57#include "libdwP.h"
58
59
60Dwarf_Abbrev *
61internal_function
62__libdw_getabbrev (dbg, cu, offset, lengthp, result)
63     Dwarf *dbg;
64     struct Dwarf_CU *cu;
65     Dwarf_Off offset;
66     size_t *lengthp;
67     Dwarf_Abbrev *result;
68{
69  /* Don't fail if there is not .debug_abbrev section.  */
70  if (dbg->sectiondata[IDX_debug_abbrev] == NULL)
71    return NULL;
72
73  if (offset >= dbg->sectiondata[IDX_debug_abbrev]->d_size)
74    {
75      __libdw_seterrno (DWARF_E_INVALID_OFFSET);
76      return NULL;
77    }
78
79  const unsigned char *abbrevp
80    = (unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf + offset;
81
82  if (*abbrevp == '\0')
83    /* We are past the last entry.  */
84    return DWARF_END_ABBREV;
85
86  /* 7.5.3 Abbreviations Tables
87
88     [...] Each declaration begins with an unsigned LEB128 number
89     representing the abbreviation code itself.  [...]  The
90     abbreviation code is followed by another unsigned LEB128
91     number that encodes the entry's tag.  [...]
92
93     [...] Following the tag encoding is a 1-byte value that
94     determines whether a debugging information entry using this
95     abbreviation has child entries or not. [...]
96
97     [...] Finally, the child encoding is followed by a series of
98     attribute specifications. Each attribute specification
99     consists of two parts. The first part is an unsigned LEB128
100     number representing the attribute's name. The second part is
101     an unsigned LEB128 number representing the attribute's form.  */
102  const unsigned char *start_abbrevp = abbrevp;
103  unsigned int code;
104  get_uleb128 (code, abbrevp);
105
106  /* Check whether this code is already in the hash table.  */
107  bool foundit = false;
108  Dwarf_Abbrev *abb = NULL;
109  if (cu == NULL
110      || (abb = Dwarf_Abbrev_Hash_find (&cu->abbrev_hash, code, NULL)) == NULL)
111    {
112      if (result == NULL)
113	abb = libdw_typed_alloc (dbg, Dwarf_Abbrev);
114      else
115	abb = result;
116    }
117  else
118    {
119      foundit = true;
120
121      assert (abb->offset == offset);
122
123      /* If the caller doesn't need the length we are done.  */
124      if (lengthp == NULL)
125	goto out;
126    }
127
128  /* If there is already a value in the hash table we are going to
129     overwrite its content.  This must not be a problem, since the
130     content better be the same.  */
131  abb->code = code;
132  get_uleb128 (abb->tag, abbrevp);
133  abb->has_children = *abbrevp++ == DW_CHILDREN_yes;
134  abb->attrp = (unsigned char *) abbrevp;
135  abb->offset = offset;
136
137  /* Skip over all the attributes and count them while doing so.  */
138  abb->attrcnt = 0;
139  unsigned int attrname;
140  unsigned int attrform;
141  do
142    {
143      get_uleb128 (attrname, abbrevp);
144      get_uleb128 (attrform, abbrevp);
145    }
146  while (attrname != 0 && attrform != 0 && ++abb->attrcnt);
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    (void) Dwarf_Abbrev_Hash_insert (&cu->abbrev_hash, abb->code, abb);
155
156 out:
157  return abb;
158}
159
160
161Dwarf_Abbrev *
162dwarf_getabbrev (die, offset, lengthp)
163     Dwarf_Die *die;
164     Dwarf_Off offset;
165     size_t *lengthp;
166{
167  return __libdw_getabbrev (die->cu->dbg, die->cu,
168			    die->cu->orig_abbrev_offset + offset, lengthp,
169			    NULL);
170}
171