pickle.cc revision 5821806d5e7f356e8fa4b058a389a808ea183019 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/pickle.h"
6
7#include <stdlib.h>
8
9#include <algorithm>  // for max()
10
11//------------------------------------------------------------------------------
12
13// static
14const int Pickle::kPayloadUnit = 64;
15
16static const size_t kCapacityReadOnly = static_cast<size_t>(-1);
17
18PickleIterator::PickleIterator(const Pickle& pickle)
19    : read_ptr_(pickle.payload()),
20      read_end_ptr_(pickle.end_of_payload()) {
21}
22
23template <typename Type>
24inline bool PickleIterator::ReadBuiltinType(Type* result) {
25  const char* read_from = GetReadPointerAndAdvance<Type>();
26  if (!read_from)
27    return false;
28  if (sizeof(Type) > sizeof(uint32))
29    memcpy(result, read_from, sizeof(*result));
30  else
31    *result = *reinterpret_cast<const Type*>(read_from);
32  return true;
33}
34
35template<typename Type>
36inline const char* PickleIterator::GetReadPointerAndAdvance() {
37  const char* current_read_ptr = read_ptr_;
38  if (read_ptr_ + sizeof(Type) > read_end_ptr_)
39    return NULL;
40  if (sizeof(Type) < sizeof(uint32))
41    read_ptr_ += AlignInt(sizeof(Type), sizeof(uint32));
42  else
43    read_ptr_ += sizeof(Type);
44  return current_read_ptr;
45}
46
47const char* PickleIterator::GetReadPointerAndAdvance(int num_bytes) {
48  if (num_bytes < 0 || read_end_ptr_ - read_ptr_ < num_bytes)
49    return NULL;
50  const char* current_read_ptr = read_ptr_;
51  read_ptr_ += AlignInt(num_bytes, sizeof(uint32));
52  return current_read_ptr;
53}
54
55inline const char* PickleIterator::GetReadPointerAndAdvance(int num_elements,
56                                                          size_t size_element) {
57  // Check for int32 overflow.
58  int64 num_bytes = static_cast<int64>(num_elements) * size_element;
59  int num_bytes32 = static_cast<int>(num_bytes);
60  if (num_bytes != static_cast<int64>(num_bytes32))
61    return NULL;
62  return GetReadPointerAndAdvance(num_bytes32);
63}
64
65bool PickleIterator::ReadBool(bool* result) {
66  return ReadBuiltinType(result);
67}
68
69bool PickleIterator::ReadInt(int* result) {
70  return ReadBuiltinType(result);
71}
72
73bool PickleIterator::ReadLong(long* result) {
74  return ReadBuiltinType(result);
75}
76
77bool PickleIterator::ReadUInt16(uint16* result) {
78  return ReadBuiltinType(result);
79}
80
81bool PickleIterator::ReadUInt32(uint32* result) {
82  return ReadBuiltinType(result);
83}
84
85bool PickleIterator::ReadInt64(int64* result) {
86  return ReadBuiltinType(result);
87}
88
89bool PickleIterator::ReadUInt64(uint64* result) {
90  return ReadBuiltinType(result);
91}
92
93bool PickleIterator::ReadString(std::string* result) {
94  int len;
95  if (!ReadInt(&len))
96    return false;
97  const char* read_from = GetReadPointerAndAdvance(len);
98  if (!read_from)
99    return false;
100
101  result->assign(read_from, len);
102  return true;
103}
104
105bool PickleIterator::ReadWString(std::wstring* result) {
106  int len;
107  if (!ReadInt(&len))
108    return false;
109  const char* read_from = GetReadPointerAndAdvance(len, sizeof(wchar_t));
110  if (!read_from)
111    return false;
112
113  result->assign(reinterpret_cast<const wchar_t*>(read_from), len);
114  return true;
115}
116
117bool PickleIterator::ReadString16(string16* result) {
118  int len;
119  if (!ReadInt(&len))
120    return false;
121  const char* read_from = GetReadPointerAndAdvance(len, sizeof(char16));
122  if (!read_from)
123    return false;
124
125  result->assign(reinterpret_cast<const char16*>(read_from), len);
126  return true;
127}
128
129bool PickleIterator::ReadData(const char** data, int* length) {
130  *length = 0;
131  *data = 0;
132
133  if (!ReadInt(length))
134    return false;
135
136  return ReadBytes(data, *length);
137}
138
139bool PickleIterator::ReadBytes(const char** data, int length) {
140  const char* read_from = GetReadPointerAndAdvance(length);
141  if (!read_from)
142    return false;
143  *data = read_from;
144  return true;
145}
146
147// Payload is uint32 aligned.
148
149Pickle::Pickle()
150    : header_(NULL),
151      header_size_(sizeof(Header)),
152      capacity_(0),
153      variable_buffer_offset_(0) {
154  Resize(kPayloadUnit);
155  header_->payload_size = 0;
156}
157
158Pickle::Pickle(int header_size)
159    : header_(NULL),
160      header_size_(AlignInt(header_size, sizeof(uint32))),
161      capacity_(0),
162      variable_buffer_offset_(0) {
163  DCHECK_GE(static_cast<size_t>(header_size), sizeof(Header));
164  DCHECK_LE(header_size, kPayloadUnit);
165  Resize(kPayloadUnit);
166  header_->payload_size = 0;
167}
168
169Pickle::Pickle(const char* data, int data_len)
170    : header_(reinterpret_cast<Header*>(const_cast<char*>(data))),
171      header_size_(0),
172      capacity_(kCapacityReadOnly),
173      variable_buffer_offset_(0) {
174  if (data_len >= static_cast<int>(sizeof(Header)))
175    header_size_ = data_len - header_->payload_size;
176
177  if (header_size_ > static_cast<unsigned int>(data_len))
178    header_size_ = 0;
179
180  if (header_size_ != AlignInt(header_size_, sizeof(uint32)))
181    header_size_ = 0;
182
183  // If there is anything wrong with the data, we're not going to use it.
184  if (!header_size_)
185    header_ = NULL;
186}
187
188Pickle::Pickle(const Pickle& other)
189    : header_(NULL),
190      header_size_(other.header_size_),
191      capacity_(0),
192      variable_buffer_offset_(other.variable_buffer_offset_) {
193  size_t payload_size = header_size_ + other.header_->payload_size;
194  bool resized = Resize(payload_size);
195  CHECK(resized);  // Realloc failed.
196  memcpy(header_, other.header_, payload_size);
197}
198
199Pickle::~Pickle() {
200  if (capacity_ != kCapacityReadOnly)
201    free(header_);
202}
203
204Pickle& Pickle::operator=(const Pickle& other) {
205  if (this == &other) {
206    NOTREACHED();
207    return *this;
208  }
209  if (capacity_ == kCapacityReadOnly) {
210    header_ = NULL;
211    capacity_ = 0;
212  }
213  if (header_size_ != other.header_size_) {
214    free(header_);
215    header_ = NULL;
216    header_size_ = other.header_size_;
217  }
218  bool resized = Resize(other.header_size_ + other.header_->payload_size);
219  CHECK(resized);  // Realloc failed.
220  memcpy(header_, other.header_,
221         other.header_size_ + other.header_->payload_size);
222  variable_buffer_offset_ = other.variable_buffer_offset_;
223  return *this;
224}
225
226bool Pickle::WriteString(const std::string& value) {
227  if (!WriteInt(static_cast<int>(value.size())))
228    return false;
229
230  return WriteBytes(value.data(), static_cast<int>(value.size()));
231}
232
233bool Pickle::WriteWString(const std::wstring& value) {
234  if (!WriteInt(static_cast<int>(value.size())))
235    return false;
236
237  return WriteBytes(value.data(),
238                    static_cast<int>(value.size() * sizeof(wchar_t)));
239}
240
241bool Pickle::WriteString16(const string16& value) {
242  if (!WriteInt(static_cast<int>(value.size())))
243    return false;
244
245  return WriteBytes(value.data(),
246                    static_cast<int>(value.size()) * sizeof(char16));
247}
248
249bool Pickle::WriteData(const char* data, int length) {
250  return length >= 0 && WriteInt(length) && WriteBytes(data, length);
251}
252
253bool Pickle::WriteBytes(const void* data, int data_len) {
254  DCHECK_NE(kCapacityReadOnly, capacity_) << "oops: pickle is readonly";
255
256  char* dest = BeginWrite(data_len);
257  if (!dest)
258    return false;
259
260  memcpy(dest, data, data_len);
261
262  EndWrite(dest, data_len);
263  return true;
264}
265
266char* Pickle::BeginWriteData(int length) {
267  DCHECK_EQ(variable_buffer_offset_, 0U) <<
268    "There can only be one variable buffer in a Pickle";
269
270  if (length < 0 || !WriteInt(length))
271    return NULL;
272
273  char *data_ptr = BeginWrite(length);
274  if (!data_ptr)
275    return NULL;
276
277  variable_buffer_offset_ =
278      data_ptr - reinterpret_cast<char*>(header_) - sizeof(int);
279
280  // EndWrite doesn't necessarily have to be called after the write operation,
281  // so we call it here to pad out what the caller will eventually write.
282  EndWrite(data_ptr, length);
283  return data_ptr;
284}
285
286void Pickle::TrimWriteData(int new_length) {
287  DCHECK_NE(variable_buffer_offset_, 0U);
288
289  // Fetch the the variable buffer size
290  int* cur_length = reinterpret_cast<int*>(
291      reinterpret_cast<char*>(header_) + variable_buffer_offset_);
292
293  if (new_length < 0 || new_length > *cur_length) {
294    NOTREACHED() << "Invalid length in TrimWriteData.";
295    return;
296  }
297
298  // Update the payload size and variable buffer size
299  header_->payload_size -= (*cur_length - new_length);
300  *cur_length = new_length;
301}
302
303char* Pickle::BeginWrite(size_t length) {
304  // write at a uint32-aligned offset from the beginning of the header
305  size_t offset = AlignInt(header_->payload_size, sizeof(uint32));
306
307  size_t new_size = offset + length;
308  size_t needed_size = header_size_ + new_size;
309  if (needed_size > capacity_ && !Resize(std::max(capacity_ * 2, needed_size)))
310    return NULL;
311
312#ifdef ARCH_CPU_64_BITS
313  DCHECK_LE(length, kuint32max);
314#endif
315
316  header_->payload_size = static_cast<uint32>(new_size);
317  return payload() + offset;
318}
319
320void Pickle::EndWrite(char* dest, int length) {
321  // Zero-pad to keep tools like valgrind from complaining about uninitialized
322  // memory.
323  if (length % sizeof(uint32))
324    memset(dest + length, 0, sizeof(uint32) - (length % sizeof(uint32)));
325}
326
327bool Pickle::Resize(size_t new_capacity) {
328  new_capacity = AlignInt(new_capacity, kPayloadUnit);
329
330  CHECK_NE(capacity_, kCapacityReadOnly);
331  void* p = realloc(header_, new_capacity);
332  if (!p)
333    return false;
334
335  header_ = reinterpret_cast<Header*>(p);
336  capacity_ = new_capacity;
337  return true;
338}
339
340// static
341const char* Pickle::FindNext(size_t header_size,
342                             const char* start,
343                             const char* end) {
344  DCHECK_EQ(header_size, AlignInt(header_size, sizeof(uint32)));
345  DCHECK_LE(header_size, static_cast<size_t>(kPayloadUnit));
346
347  if (static_cast<size_t>(end - start) < sizeof(Header))
348    return NULL;
349
350  const Header* hdr = reinterpret_cast<const Header*>(start);
351  const char* payload_base = start + header_size;
352  const char* payload_end = payload_base + hdr->payload_size;
353  if (payload_end < payload_base)
354    return NULL;
355
356  return (payload_end > end) ? NULL : payload_end;
357}
358