1 /* Look up the DIE in a reference-form attribute.
2 Copyright (C) 2005-2010, 2018 Red Hat, Inc.
3 This file is part of elfutils.
4
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of either
7
8 * the GNU Lesser General Public License as published by the Free
9 Software Foundation; either version 3 of the License, or (at
10 your option) any later version
11
12 or
13
14 * the GNU General Public License as published by the Free
15 Software Foundation; either version 2 of the License, or (at
16 your option) any later version
17
18 or both in parallel, as here.
19
20 elfutils is distributed in the hope that it will be useful, but
21 WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 General Public License for more details.
24
25 You should have received copies of the GNU General Public License and
26 the GNU Lesser General Public License along with this program. If
27 not, see <http://www.gnu.org/licenses/>. */
28
29 #ifdef HAVE_CONFIG_H
30 # include <config.h>
31 #endif
32
33 #include <string.h>
34 #include "libdwP.h"
35 #include <dwarf.h>
36
37
38 Dwarf_Die *
dwarf_formref_die(Dwarf_Attribute * attr,Dwarf_Die * result)39 dwarf_formref_die (Dwarf_Attribute *attr, Dwarf_Die *result)
40 {
41 if (attr == NULL)
42 return NULL;
43
44 struct Dwarf_CU *cu = attr->cu;
45
46 Dwarf_Off offset;
47 if (attr->form == DW_FORM_ref_addr || attr->form == DW_FORM_GNU_ref_alt
48 || attr->form == DW_FORM_ref_sup4 || attr->form == DW_FORM_ref_sup8)
49 {
50 /* This has an absolute offset. */
51
52 uint8_t ref_size;
53 if (cu->version == 2 && attr->form == DW_FORM_ref_addr)
54 ref_size = cu->address_size;
55 else if (attr->form == DW_FORM_ref_sup4)
56 ref_size = 4;
57 else if (attr->form == DW_FORM_ref_sup8)
58 ref_size = 8;
59 else
60 ref_size = cu->offset_size;
61
62 Dwarf *dbg_ret = (attr->form == DW_FORM_GNU_ref_alt
63 ? INTUSE(dwarf_getalt) (cu->dbg) : cu->dbg);
64
65 if (dbg_ret == NULL)
66 {
67 __libdw_seterrno (DWARF_E_NO_ALT_DEBUGLINK);
68 return NULL;
69 }
70
71 if (__libdw_read_offset (cu->dbg, dbg_ret, IDX_debug_info, attr->valp,
72 ref_size, &offset, IDX_debug_info, 0))
73 return NULL;
74
75 return INTUSE(dwarf_offdie) (dbg_ret, offset, result);
76 }
77
78 const unsigned char *datap;
79 size_t size;
80 if (attr->form == DW_FORM_ref_sig8)
81 {
82 /* This doesn't have an offset, but instead a value we
83 have to match in the type unit headers. */
84
85 uint64_t sig = read_8ubyte_unaligned (cu->dbg, attr->valp);
86 cu = Dwarf_Sig8_Hash_find (&cu->dbg->sig8_hash, sig, NULL);
87 if (cu == NULL)
88 {
89 /* Not seen before. We have to scan through the type units.
90 Since DWARFv5 these can (also) be found in .debug_info,
91 so scan that first. */
92 bool scan_debug_types = false;
93 do
94 {
95 cu = __libdw_intern_next_unit (attr->cu->dbg, scan_debug_types);
96 if (cu == NULL)
97 {
98 if (scan_debug_types == false)
99 scan_debug_types = true;
100 else
101 {
102 __libdw_seterrno (INTUSE(dwarf_errno) ()
103 ?: DWARF_E_INVALID_REFERENCE);
104 return NULL;
105 }
106 }
107 }
108 while (cu == NULL || cu->unit_id8 != sig);
109 }
110
111 int secid = cu_sec_idx (cu);
112 datap = cu->dbg->sectiondata[secid]->d_buf;
113 size = cu->dbg->sectiondata[secid]->d_size;
114 offset = cu->start + cu->subdie_offset;
115 }
116 else
117 {
118 /* Other forms produce an offset from the CU. */
119 if (unlikely (__libdw_formref (attr, &offset) != 0))
120 return NULL;
121
122 datap = cu->startp;
123 size = cu->endp - cu->startp;
124 }
125
126 if (unlikely (offset >= size))
127 {
128 __libdw_seterrno (DWARF_E_INVALID_DWARF);
129 return NULL;
130 }
131
132 memset (result, '\0', sizeof (Dwarf_Die));
133 result->addr = (char *) datap + offset;
134 result->cu = cu;
135 return result;
136 }
137 INTDEF (dwarf_formref_die)
138