summaryrefslogtreecommitdiff
path: root/base/pickle.h
blob: e7ececff42cdd0537595439fc4e4e576b64ea5e6 (plain)
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
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_PICKLE_H__
#define BASE_PICKLE_H__
#pragma once

#include <string>
#include <iostream>

#include "base/base_export.h"
#include "base/basictypes.h"
//#include "base/gtest_prod_util.h" // jaehwa
//#include "base/logging.h"         // jaehwa
#include "log.h"                // jaehwa
//#include "base/string16.h"        // jaehwa

// This class provides facilities for basic binary value packing and unpacking.
//
// The Pickle class supports appending primitive values (ints, strings, etc.)
// to a pickle instance.  The Pickle instance grows its internal memory buffer
// dynamically to hold the sequence of primitive values.   The internal memory
// buffer is exposed as the "data" of the Pickle.  This "data" can be passed
// to a Pickle object to initialize it for reading.
//
// When reading from a Pickle object, it is important for the consumer to know
// what value types to read and in what order to read them as the Pickle does
// not keep track of the type of data written to it.
//
// The Pickle's data has a header which contains the size of the Pickle's
// payload.  It can optionally support additional space in the header.  That
// space is controlled by the header_size parameter passed to the Pickle
// constructor.
//
class BASE_EXPORT Pickle {
 public:
  // Initialize a Pickle object using the default header size.
  Pickle();

  // Initialize a Pickle object with the specified header size in bytes, which
  // must be greater-than-or-equal-to sizeof(Pickle::Header).  The header size
  // will be rounded up to ensure that the header size is 32bit-aligned.
  explicit Pickle(int header_size);

  // Initializes a Pickle from a const block of data.  The data is not copied;
  // instead the data is merely referenced by this Pickle.  Only const methods
  // should be used on the Pickle when initialized this way.  The header
  // padding size is deduced from the data length.
  Pickle(const char* data, int data_len);

  // Initializes a Pickle as a deep copy of another Pickle.
  Pickle(const Pickle& other);

  virtual ~Pickle();

  // Performs a deep copy.
  Pickle& operator=(const Pickle& other);

  // Returns the size of the Pickle's data.
  size_t size() const { return header_size_ + header_->payload_size; }

  // Returns the data for this Pickle.
  const void* data() const { return header_; }

  // Methods for reading the payload of the Pickle.  To read from the start of
  // the Pickle, initialize *iter to NULL.  If successful, these methods return
  // true.  Otherwise, false is returned to indicate that the result could not
  // be extracted.
  bool ReadBool(void** iter, bool* result) const;
  bool ReadInt(void** iter, int* result) const;
  bool ReadLong(void** iter, long* result) const;
  bool ReadSize(void** iter, size_t* result) const;
  bool ReadUInt16(void** iter, uint16* result) const;
  bool ReadUInt32(void** iter, uint32* result) const;
  bool ReadInt64(void** iter, int64* result) const;
  bool ReadUInt64(void** iter, uint64* result) const;
  bool ReadString(void** iter, std::string* result) const;
//  bool ReadWString(void** iter, std::wstring* result) const;
//  bool ReadString16(void** iter, string16* result) const;
  bool ReadData(void** iter, const char** data, int* length) const;
  bool ReadBytes(void** iter, const char** data, int length) const;

  // Safer version of ReadInt() checks for the result not being negative.
  // Use it for reading the object sizes.
  bool ReadLength(void** iter, int* result) const;

  // Methods for adding to the payload of the Pickle.  These values are
  // appended to the end of the Pickle's payload.  When reading values from a
  // Pickle, it is important to read them in the order in which they were added
  // to the Pickle.
  bool WriteBool(bool value) {
    return WriteInt(value ? 1 : 0);
  }
  bool WriteInt(int value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteLong(long value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteSize(size_t value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteUInt16(uint16 value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteUInt32(uint32 value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteInt64(int64 value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteUInt64(uint64 value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteString(const std::string& value);
//  bool WriteWString(const std::wstring& value);
//  bool WriteString16(const string16& value);
    bool WriteData(const char* data, int length);
    bool WriteBytes(const void* data, int data_len);

  // Same as WriteData, but allows the caller to write directly into the
  // Pickle. This saves a copy in cases where the data is not already
  // available in a buffer. The caller should take care to not write more
  // than the length it declares it will. Use ReadData to get the data.
  // Returns NULL on failure.
  //
  // The returned pointer will only be valid until the next write operation
  // on this Pickle.
  char* BeginWriteData(int length);

  // For Pickles which contain variable length buffers (e.g. those created
  // with BeginWriteData), the Pickle can
  // be 'trimmed' if the amount of data required is less than originally
  // requested.  For example, you may have created a buffer with 10K of data,
  // but decided to only fill 10 bytes of that data.  Use this function
  // to trim the buffer so that we don't send 9990 bytes of unused data.
  // You cannot increase the size of the variable buffer; only shrink it.
  // This function assumes that the length of the variable buffer has
  // not been changed.
  void TrimWriteData(int length);

  // Payload follows after allocation of Header (header size is customizable).
  struct Header {
    uint32 payload_size;  // Specifies the size of the payload.
  };

  // Returns the header, cast to a user-specified type T.  The type T must be a
  // subclass of Header and its size must correspond to the header_size passed
  // to the Pickle constructor.
  template <class T>
  T* headerT() {
    DCHECK_EQ(header_size_, sizeof(T));
    return static_cast<T*>(header_);
  }
  template <class T>
  const T* headerT() const {
    DCHECK_EQ(header_size_, sizeof(T));
    return static_cast<const T*>(header_);
  }

  // Returns true if the given iterator could point to data with the given
  // length. If there is no room for the given data before the end of the
  // payload, returns false.
  bool IteratorHasRoomFor(const void* iter, int len) const {
    if ((len < 0) || (iter < header_) || iter > end_of_payload())
      return false;
    const char* end_of_region = reinterpret_cast<const char*>(iter) + len;
    // Watch out for overflow in pointer calculation, which wraps.
    return (iter <= end_of_region) && (end_of_region <= end_of_payload());
  }

 protected:
  size_t payload_size() const { return header_->payload_size; }

  char* payload() {
    return reinterpret_cast<char*>(header_) + header_size_;
  }
  const char* payload() const {
    return reinterpret_cast<const char*>(header_) + header_size_;
  }

  // Returns the address of the byte immediately following the currently valid
  // header + payload.
  char* end_of_payload() {
    // We must have a valid header_.
    return payload() + payload_size();
  }
  const char* end_of_payload() const {
    // This object may be invalid.
    return header_ ? payload() + payload_size() : NULL;
  }

  size_t capacity() const {
    return capacity_;
  }

  // Resizes the buffer for use when writing the specified amount of data. The
  // location that the data should be written at is returned, or NULL if there
  // was an error. Call EndWrite with the returned offset and the given length
  // to pad out for the next write.
  char* BeginWrite(size_t length);

  // Completes the write operation by padding the data with NULL bytes until it
  // is padded. Should be paired with BeginWrite, but it does not necessarily
  // have to be called after the data is written.
  void EndWrite(char* dest, int length);

  // Resize the capacity, note that the input value should include the size of
  // the header: new_capacity = sizeof(Header) + desired_payload_capacity.
  // A realloc() failure will cause a Resize failure... and caller should check
  // the return result for true (i.e., successful resizing).
  bool Resize(size_t new_capacity);

  // Aligns 'i' by rounding it up to the next multiple of 'alignment'
  static size_t AlignInt(size_t i, int alignment) {
    return i + (alignment - (i % alignment)) % alignment;
  }

  // Moves the iterator by the given number of bytes, making sure it is aligned.
  // Pointer (iterator) is NOT aligned, but the change in the pointer
  // is guaranteed to be a multiple of sizeof(uint32).
  static void UpdateIter(void** iter, int bytes) {
    *iter = static_cast<char*>(*iter) + AlignInt(bytes, sizeof(uint32));
  }

  // Find the end of the pickled data that starts at range_start.  Returns NULL
  // if the entire Pickle is not found in the given data range.
  static const char* FindNext(size_t header_size,
                              const char* range_start,
                              const char* range_end);

  // The allocation granularity of the payload.
  static const int kPayloadUnit;

 private:
  Header* header_;
  size_t header_size_;  // Supports extra data between header and payload.
  // Allocation size of payload (or -1 if allocation is const).
  size_t capacity_;
  size_t variable_buffer_offset_;  // IF non-zero, then offset to a buffer.

//  FRIEND_TEST_ALL_PREFIXES(PickleTest, Resize);
//  FRIEND_TEST_ALL_PREFIXES(PickleTest, FindNext);
//  FRIEND_TEST_ALL_PREFIXES(PickleTest, FindNextWithIncompleteHeader);
//  FRIEND_TEST_ALL_PREFIXES(PickleTest, IteratorHasRoom);
};

#endif  // BASE_PICKLE_H__