1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
// Copyright (c) 2013 Austin T. Clements. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
#include "internal.hh"
#include <stdexcept>
#include <cstring>
using namespace std;
DWARFPP_BEGIN_NAMESPACE
int64_t
cursor::sleb128()
{
// Appendix C
uint64_t result = 0;
unsigned shift = 0;
while (pos < sec->end) {
uint8_t byte = *(uint8_t*)(pos++);
result |= (uint64_t)(byte & 0x7f) << shift;
shift += 7;
if ((byte & 0x80) == 0) {
if (shift < sizeof(result)*8 && (byte & 0x40))
result |= -((uint64_t)1 << shift);
return result;
}
}
underflow();
return 0;
}
shared_ptr<section>
cursor::subsection()
{
// Section 7.4
const char *begin = pos;
section_length length = fixed<uword>();
format fmt;
if (length < 0xfffffff0) {
fmt = format::dwarf32;
length += sizeof(uword);
} else if (length == 0xffffffff) {
length = fixed<uint64_t>();
fmt = format::dwarf64;
length += sizeof(uword) + sizeof(uint64_t);
} else {
throw format_error("initial length has reserved value");
}
pos = begin + length;
return make_shared<section>(sec->type, begin, length, sec->ord, fmt);
}
void
cursor::skip_initial_length()
{
switch (sec->fmt) {
case format::dwarf32:
pos += sizeof(uword);
break;
case format::dwarf64:
pos += sizeof(uword) + sizeof(uint64_t);
break;
default:
throw logic_error("cannot skip initial length with unknown format");
}
}
section_offset
cursor::offset()
{
switch (sec->fmt) {
case format::dwarf32:
return fixed<uint32_t>();
case format::dwarf64:
return fixed<uint64_t>();
default:
throw logic_error("cannot read offset with unknown format");
}
}
void
cursor::string(std::string &out)
{
size_t size;
const char *p = this->cstr(&size);
out.resize(size);
memmove(&out.front(), p, size);
}
const char *
cursor::cstr(size_t *size_out)
{
// Scan string size
const char *p = pos;
while (pos < sec->end && *pos)
pos++;
if (pos == sec->end)
throw format_error("unterminated string");
if (size_out)
*size_out = pos - p;
pos++;
return p;
}
void
cursor::skip_form(DW_FORM form)
{
section_offset tmp;
// Section 7.5.4
switch (form) {
case DW_FORM::addr:
pos += sec->addr_size;
break;
case DW_FORM::sec_offset:
case DW_FORM::ref_addr:
case DW_FORM::strp:
switch (sec->fmt) {
case format::dwarf32:
pos += 4;
break;
case format::dwarf64:
pos += 8;
break;
case format::unknown:
throw logic_error("cannot read form with unknown format");
}
break;
// size+data forms
case DW_FORM::block1:
tmp = fixed<ubyte>();
pos += tmp;
break;
case DW_FORM::block2:
tmp = fixed<uhalf>();
pos += tmp;
break;
case DW_FORM::block4:
tmp = fixed<uword>();
pos += tmp;
break;
case DW_FORM::block:
case DW_FORM::exprloc:
tmp = uleb128();
pos += tmp;
break;
// fixed-length forms
case DW_FORM::flag_present:
break;
case DW_FORM::flag:
case DW_FORM::data1:
case DW_FORM::ref1:
pos += 1;
break;
case DW_FORM::data2:
case DW_FORM::ref2:
pos += 2;
break;
case DW_FORM::data4:
case DW_FORM::ref4:
pos += 4;
break;
case DW_FORM::data8:
case DW_FORM::ref_sig8:
pos += 8;
break;
// variable-length forms
case DW_FORM::sdata:
case DW_FORM::udata:
case DW_FORM::ref_udata:
while (pos < sec->end && (*(uint8_t*)pos & 0x80))
pos++;
pos++;
break;
case DW_FORM::string:
while (pos < sec->end && *pos)
pos++;
pos++;
break;
case DW_FORM::indirect:
skip_form((DW_FORM)uleb128());
break;
default:
throw format_error("unknown form " + to_string(form));
}
}
void
cursor::underflow()
{
throw underflow_error("cannot read past end of DWARF section");
}
DWARFPP_END_NAMESPACE
|
