1 /* Advance to next CU header.
2 Copyright (C) 2002-2010 Red Hat, Inc.
3 This file is part of elfutils.
4 Written by Ulrich Drepper <drepper@redhat.com>, 2002.
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 <libdwP.h>
35 #include <dwarf.h>
36
37
38 int
dwarf_next_unit(dwarf,off,next_off,header_sizep,versionp,abbrev_offsetp,address_sizep,offset_sizep,type_signaturep,type_offsetp)39 dwarf_next_unit (dwarf, off, next_off, header_sizep, versionp, abbrev_offsetp,
40 address_sizep, offset_sizep, type_signaturep, type_offsetp)
41 Dwarf *dwarf;
42 Dwarf_Off off;
43 Dwarf_Off *next_off;
44 size_t *header_sizep;
45 Dwarf_Half *versionp;
46 Dwarf_Off *abbrev_offsetp;
47 uint8_t *address_sizep;
48 uint8_t *offset_sizep;
49 uint64_t *type_signaturep;
50 Dwarf_Off *type_offsetp;
51 {
52 const bool debug_types = type_signaturep != NULL;
53 const size_t sec_idx = debug_types ? IDX_debug_types : IDX_debug_info;
54
55 /* Maybe there has been an error before. */
56 if (dwarf == NULL)
57 return -1;
58
59 /* If we reached the end before don't do anything. */
60 if (off == (Dwarf_Off) -1l
61 || unlikely (dwarf->sectiondata[sec_idx] == NULL)
62 /* Make sure there is enough space in the .debug_info section
63 for at least the initial word. We cannot test the rest since
64 we don't know yet whether this is a 64-bit object or not. */
65 || unlikely (off + 4 >= dwarf->sectiondata[sec_idx]->d_size))
66 {
67 *next_off = (Dwarf_Off) -1l;
68 return 1;
69 }
70
71 /* This points into the .debug_info section to the beginning of the
72 CU entry. */
73 const unsigned char *data = dwarf->sectiondata[sec_idx]->d_buf;
74 const unsigned char *bytes = data + off;
75
76 /* The format of the CU header is described in dwarf2p1 7.5.1:
77
78 1. A 4-byte or 12-byte unsigned integer representing the length
79 of the .debug_info contribution for that compilation unit, not
80 including the length field itself. In the 32-bit DWARF format,
81 this is a 4-byte unsigned integer (which must be less than
82 0xfffffff0); in the 64-bit DWARF format, this consists of the
83 4-byte value 0xffffffff followed by an 8-byte unsigned integer
84 that gives the actual length (see Section 7.2.2).
85
86 2. A 2-byte unsigned integer representing the version of the
87 DWARF information for that compilation unit. For DWARF Version
88 2.1, the value in this field is 2.
89
90 3. A 4-byte or 8-byte unsigned offset into the .debug_abbrev
91 section. This offset associates the compilation unit with a
92 particular set of debugging information entry abbreviations. In
93 the 32-bit DWARF format, this is a 4-byte unsigned length; in
94 the 64-bit DWARF format, this is an 8-byte unsigned length (see
95 Section 7.4).
96
97 4. A 1-byte unsigned integer representing the size in bytes of
98 an address on the target architecture. If the system uses
99 segmented addressing, this value represents the size of the
100 offset portion of an address. */
101 uint64_t length = read_4ubyte_unaligned_inc (dwarf, bytes);
102 size_t offset_size = 4;
103 /* Lengths of 0xfffffff0 - 0xffffffff are escape codes. Oxffffffff is
104 used to indicate that 64-bit dwarf information is being used, the
105 other values are currently reserved. */
106 if (length == DWARF3_LENGTH_64_BIT)
107 offset_size = 8;
108 else if (unlikely (length >= DWARF3_LENGTH_MIN_ESCAPE_CODE
109 && length <= DWARF3_LENGTH_MAX_ESCAPE_CODE))
110 {
111 invalid:
112 __libdw_seterrno (DWARF_E_INVALID_DWARF);
113 return -1;
114 }
115
116 /* Now we know how large the header is. */
117 if (unlikely (DIE_OFFSET_FROM_CU_OFFSET (off, offset_size, debug_types)
118 >= dwarf->sectiondata[sec_idx]->d_size))
119 {
120 *next_off = -1;
121 return 1;
122 }
123
124 if (length == DWARF3_LENGTH_64_BIT)
125 /* This is a 64-bit DWARF format. */
126 length = read_8ubyte_unaligned_inc (dwarf, bytes);
127
128 /* Read the version stamp. Always a 16-bit value. */
129 uint_fast16_t version = read_2ubyte_unaligned_inc (dwarf, bytes);
130
131 /* Get offset in .debug_abbrev. Note that the size of the entry
132 depends on whether this is a 32-bit or 64-bit DWARF definition. */
133 uint64_t abbrev_offset;
134 if (__libdw_read_offset_inc (dwarf, sec_idx, &bytes, offset_size,
135 &abbrev_offset, IDX_debug_abbrev, 0))
136 return -1;
137
138 /* The address size. Always an 8-bit value. */
139 uint8_t address_size = *bytes++;
140
141 if (debug_types)
142 {
143 uint64_t type_sig8 = read_8ubyte_unaligned_inc (dwarf, bytes);
144
145 Dwarf_Off type_offset;
146 if (__libdw_read_offset_inc (dwarf, sec_idx, &bytes, offset_size,
147 &type_offset, sec_idx, 0))
148 return -1;
149
150 /* Validate that the TYPE_OFFSET points past the header. */
151 if (unlikely (type_offset < (size_t) (bytes - (data + off))))
152 goto invalid;
153
154 *type_signaturep = type_sig8;
155 if (type_offsetp != NULL)
156 *type_offsetp = type_offset;
157 }
158
159 /* Store the header length. */
160 if (header_sizep != NULL)
161 *header_sizep = bytes - (data + off);
162
163 if (versionp != NULL)
164 *versionp = version;
165
166 if (abbrev_offsetp != NULL)
167 *abbrev_offsetp = abbrev_offset;
168
169 if (address_sizep != NULL)
170 *address_sizep = address_size;
171
172 /* Store the offset size. */
173 if (offset_sizep != NULL)
174 *offset_sizep = offset_size;
175
176 /* See definition of DIE_OFFSET_FROM_CU_OFFSET macro
177 for an explanation of the trick in this expression. */
178 *next_off = off + 2 * offset_size - 4 + length;
179
180 return 0;
181 }
182 INTDEF(dwarf_next_unit)
183
184 int
185 dwarf_nextcu (dwarf, off, next_off, header_sizep, abbrev_offsetp,
186 address_sizep, offset_sizep)
187 Dwarf *dwarf;
188 Dwarf_Off off;
189 Dwarf_Off *next_off;
190 size_t *header_sizep;
191 Dwarf_Off *abbrev_offsetp;
192 uint8_t *address_sizep;
193 uint8_t *offset_sizep;
194 {
195 return INTUSE(dwarf_next_unit) (dwarf, off, next_off, header_sizep, NULL,
196 abbrev_offsetp, address_sizep, offset_sizep,
197 NULL, NULL);
198 }
199 INTDEF(dwarf_nextcu)
200