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
|
/* Copyright 2015 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
#include <cstring>
#include <tuple>
#include <type_traits>
#include "mongo/base/data_type.h"
#include "mongo/base/error_codes.h"
#include "mongo/base/status_with.h"
#include "mongo/platform/endian.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
class ConstDataRange {
public:
// begin and end should point to the first and one past last bytes in
// the range you wish to view.
//
// debug_offset provides a way to indicate that the ConstDataRange is
// located at an offset into some larger logical buffer. By setting it
// to a non-zero value, you'll change the Status messages that are
// returned on failure to be offset by the amount passed to this
// constructor.
ConstDataRange(const char* begin, const char* end, std::ptrdiff_t debug_offset = 0)
: _begin(begin), _end(end), _debug_offset(debug_offset) {
invariant(end >= begin);
}
ConstDataRange(const char* begin, std::size_t length, std::ptrdiff_t debug_offset = 0)
: ConstDataRange(begin, begin + length, debug_offset) {}
const char* data() const {
return _begin;
}
size_t length() const {
return _end - _begin;
}
bool empty() const {
return length() == 0;
}
template <typename T>
Status read(T* t, size_t offset = 0) const {
if (offset > length()) {
return makeOffsetStatus(offset);
}
return DataType::load(
t, _begin + offset, length() - offset, nullptr, offset + _debug_offset);
}
template <typename T>
StatusWith<T> read(std::size_t offset = 0) const {
T t(DataType::defaultConstruct<T>());
Status s = read(&t, offset);
if (s.isOK()) {
return StatusWith<T>(std::move(t));
} else {
return StatusWith<T>(std::move(s));
}
}
friend bool operator==(const ConstDataRange& lhs, const ConstDataRange& rhs) {
return std::tie(lhs._begin, lhs._end) == std::tie(rhs._begin, rhs._end);
}
friend bool operator!=(const ConstDataRange& lhs, const ConstDataRange& rhs) {
return !(lhs == rhs);
}
protected:
const char* _begin;
const char* _end;
std::ptrdiff_t _debug_offset;
Status makeOffsetStatus(size_t offset) const;
};
class DataRange : public ConstDataRange {
public:
typedef char* bytes_type;
DataRange(bytes_type begin, bytes_type end, std::ptrdiff_t debug_offset = 0)
: ConstDataRange(begin, end, debug_offset) {}
DataRange(bytes_type begin, std::size_t length, std::ptrdiff_t debug_offset = 0)
: ConstDataRange(begin, length, debug_offset) {}
template <typename T>
Status write(const T& value, std::size_t offset = 0) {
if (offset > length()) {
return makeOffsetStatus(offset);
}
return DataType::store(value,
const_cast<char*>(_begin + offset),
length() - offset,
nullptr,
offset + _debug_offset);
}
};
struct DataRangeTypeHelper {
static Status makeStoreStatus(size_t t_length, size_t length, std::ptrdiff_t debug_offset);
};
// Enable for classes derived from ConstDataRange
template <typename T>
struct DataType::Handler<T,
typename std::enable_if<std::is_base_of<ConstDataRange, T>::value>::type> {
static Status load(
T* t, const char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
if (t) {
// Assuming you know what you're doing at the read above this
// is fine. Either you're reading into a readable buffer, so
// ptr started off non-const, or the const_cast will feed back
// to const char* taking Const variants. So it'll get tossed
// out again.
*t = T(const_cast<char*>(ptr), const_cast<char*>(ptr) + length);
}
if (advanced) {
*advanced = length;
}
return Status::OK();
}
static Status store(
const T& t, char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
if (t.length() > length) {
return DataRangeTypeHelper::makeStoreStatus(t.length(), length, debug_offset);
}
if (ptr) {
std::memcpy(ptr, t.data(), t.length());
}
if (advanced) {
*advanced = t.length();
}
return Status::OK();
}
static T defaultConstruct() {
return T(nullptr, nullptr);
}
};
} // namespace mongo
|
