base/pickle.cc

   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
  14 const int Pickle::kPayloadUnit = 64;
  15
  16 static const size_t kCapacityReadOnly = static_cast<size_t>(-1);
  17
  18 PickleIterator::PickleIterator(const Pickle& pickle)
  19     : read_ptr_(pickle.payload()),
  20       read_end_ptr_(pickle.end_of_payload()) {
  21 }
  22
  23 template <typename Type>
  24 inline 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
  35 template<typename Type>
  36 inline 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
  47 const 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
  55 inline 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
  65 bool PickleIterator::ReadBool(bool* result) {
  66   return ReadBuiltinType(result);
  67 }
  68
  69 bool PickleIterator::ReadInt(int* result) {
  70   return ReadBuiltinType(result);
  71 }
  72
  73 bool PickleIterator::ReadLong(long* result) {
  74   return ReadBuiltinType(result);
  75 }
  76
  77 bool PickleIterator::ReadUInt16(uint16* result) {
  78   return ReadBuiltinType(result);
  79 }
  80
  81 bool PickleIterator::ReadUInt32(uint32* result) {
  82   return ReadBuiltinType(result);
  83 }
  84
  85 bool PickleIterator::ReadInt64(int64* result) {
  86   return ReadBuiltinType(result);
  87 }
  88
  89 bool PickleIterator::ReadUInt64(uint64* result) {
  90   return ReadBuiltinType(result);
  91 }
  92
  93 bool PickleIterator::ReadFloat(float* result) {
  94   return ReadBuiltinType(result);
  95 }
  96
  97 bool PickleIterator::ReadString(std::string* result) {
  98   int len;
  99   if (!ReadInt(&len))
 100     return false;
 101   const char* read_from = GetReadPointerAndAdvance(len);
 102   if (!read_from)
 103     return false;
 104
 105   result->assign(read_from, len);
 106   return true;
 107 }
 108
 109 bool PickleIterator::ReadWString(std::wstring* result) {
 110   int len;
 111   if (!ReadInt(&len))
 112     return false;
 113   const char* read_from = GetReadPointerAndAdvance(len, sizeof(wchar_t));
 114   if (!read_from)
 115     return false;
 116
 117   result->assign(reinterpret_cast<const wchar_t*>(read_from), len);
 118   return true;
 119 }
 120
 121 bool PickleIterator::ReadString16(string16* result) {
 122   int len;
 123   if (!ReadInt(&len))
 124     return false;
 125   const char* read_from = GetReadPointerAndAdvance(len, sizeof(char16));
 126   if (!read_from)
 127     return false;
 128
 129   result->assign(reinterpret_cast<const char16*>(read_from), len);
 130   return true;
 131 }
 132
 133 bool PickleIterator::ReadData(const char** data, int* length) {
 134   *length = 0;
 135   *data = 0;
 136
 137   if (!ReadInt(length))
 138     return false;
 139
 140   return ReadBytes(data, *length);
 141 }
 142
 143 bool PickleIterator::ReadBytes(const char** data, int length) {
 144   const char* read_from = GetReadPointerAndAdvance(length);
 145   if (!read_from)
 146     return false;
 147   *data = read_from;
 148   return true;
 149 }
 150
 151 // Payload is uint32 aligned.
 152
 153 Pickle::Pickle()
 154     : header_(NULL),
 155       header_size_(sizeof(Header)),
 156       capacity_(0),
 157       variable_buffer_offset_(0) {
 158   Resize(kPayloadUnit);
 159   header_->payload_size = 0;
 160 }
 161
 162 Pickle::Pickle(int header_size)
 163     : header_(NULL),
 164       header_size_(AlignInt(header_size, sizeof(uint32))),
 165       capacity_(0),
 166       variable_buffer_offset_(0) {
 167   DCHECK_GE(static_cast<size_t>(header_size), sizeof(Header));
 168   DCHECK_LE(header_size, kPayloadUnit);
 169   Resize(kPayloadUnit);
 170   header_->payload_size = 0;
 171 }
 172
 173 Pickle::Pickle(const char* data, int data_len)
 174     : header_(reinterpret_cast<Header*>(const_cast<char*>(data))),
 175       header_size_(0),
 176       capacity_(kCapacityReadOnly),
 177       variable_buffer_offset_(0) {
 178   if (data_len >= static_cast<int>(sizeof(Header)))
 179     header_size_ = data_len - header_->payload_size;
 180
 181   if (header_size_ > static_cast<unsigned int>(data_len))
 182     header_size_ = 0;
 183
 184   if (header_size_ != AlignInt(header_size_, sizeof(uint32)))
 185     header_size_ = 0;
 186
 187   // If there is anything wrong with the data, we're not going to use it.
 188   if (!header_size_)
 189     header_ = NULL;
 190 }
 191
 192 Pickle::Pickle(const Pickle& other)
 193     : header_(NULL),
 194       header_size_(other.header_size_),
 195       capacity_(0),
 196       variable_buffer_offset_(other.variable_buffer_offset_) {
 197   size_t payload_size = header_size_ + other.header_->payload_size;
 198   bool resized = Resize(payload_size);
 199   CHECK(resized);  // Realloc failed.
 200   memcpy(header_, other.header_, payload_size);
 201 }
 202
 203 Pickle::~Pickle() {
 204   if (capacity_ != kCapacityReadOnly)
 205     free(header_);
 206 }
 207
 208 Pickle& Pickle::operator=(const Pickle& other) {
 209   if (this == &other) {
 210     NOTREACHED();
 211     return *this;
 212   }
 213   if (capacity_ == kCapacityReadOnly) {
 214     header_ = NULL;
 215     capacity_ = 0;
 216   }
 217   if (header_size_ != other.header_size_) {
 218     free(header_);
 219     header_ = NULL;
 220     header_size_ = other.header_size_;
 221   }
 222   bool resized = Resize(other.header_size_ + other.header_->payload_size);
 223   CHECK(resized);  // Realloc failed.
 224   memcpy(header_, other.header_,
 225          other.header_size_ + other.header_->payload_size);
 226   variable_buffer_offset_ = other.variable_buffer_offset_;
 227   return *this;
 228 }
 229
 230 bool Pickle::WriteString(const std::string& value) {
 231   if (!WriteInt(static_cast<int>(value.size())))
 232     return false;
 233
 234   return WriteBytes(value.data(), static_cast<int>(value.size()));
 235 }
 236
 237 bool Pickle::WriteWString(const std::wstring& value) {
 238   if (!WriteInt(static_cast<int>(value.size())))
 239     return false;
 240
 241   return WriteBytes(value.data(),
 242                     static_cast<int>(value.size() * sizeof(wchar_t)));
 243 }
 244
 245 bool Pickle::WriteString16(const string16& value) {
 246   if (!WriteInt(static_cast<int>(value.size())))
 247     return false;
 248
 249   return WriteBytes(value.data(),
 250                     static_cast<int>(value.size()) * sizeof(char16));
 251 }
 252
 253 bool Pickle::WriteData(const char* data, int length) {
 254   return length >= 0 && WriteInt(length) && WriteBytes(data, length);
 255 }
 256
 257 bool Pickle::WriteBytes(const void* data, int data_len) {
 258   DCHECK_NE(kCapacityReadOnly, capacity_) << "oops: pickle is readonly";
 259
 260   char* dest = BeginWrite(data_len);
 261   if (!dest)
 262     return false;
 263
 264   memcpy(dest, data, data_len);
 265
 266   EndWrite(dest, data_len);
 267   return true;
 268 }
 269
 270 char* Pickle::BeginWriteData(int length) {
 271   DCHECK_EQ(variable_buffer_offset_, 0U) <<
 272     "There can only be one variable buffer in a Pickle";
 273
 274   if (length < 0 || !WriteInt(length))
 275     return NULL;
 276
 277   char *data_ptr = BeginWrite(length);
 278   if (!data_ptr)
 279     return NULL;
 280
 281   variable_buffer_offset_ =
 282       data_ptr - reinterpret_cast<char*>(header_) - sizeof(int);
 283
 284   // EndWrite doesn't necessarily have to be called after the write operation,
 285   // so we call it here to pad out what the caller will eventually write.
 286   EndWrite(data_ptr, length);
 287   return data_ptr;
 288 }
 289
 290 void Pickle::TrimWriteData(int new_length) {
 291   DCHECK_NE(variable_buffer_offset_, 0U);
 292
 293   // Fetch the the variable buffer size
 294   int* cur_length = reinterpret_cast<int*>(
 295       reinterpret_cast<char*>(header_) + variable_buffer_offset_);
 296
 297   if (new_length < 0 || new_length > *cur_length) {
 298     NOTREACHED() << "Invalid length in TrimWriteData.";
 299     return;
 300   }
 301
 302   // Update the payload size and variable buffer size
 303   header_->payload_size -= (*cur_length - new_length);
 304   *cur_length = new_length;
 305 }
 306
 307 char* Pickle::BeginWrite(size_t length) {
 308   // write at a uint32-aligned offset from the beginning of the header
 309   size_t offset = AlignInt(header_->payload_size, sizeof(uint32));
 310
 311   size_t new_size = offset + length;
 312   size_t needed_size = header_size_ + new_size;
 313   if (needed_size > capacity_ && !Resize(std::max(capacity_ * 2, needed_size)))
 314     return NULL;
 315
 316 #ifdef ARCH_CPU_64_BITS
 317   DCHECK_LE(length, kuint32max);
 318 #endif
 319
 320   header_->payload_size = static_cast<uint32>(new_size);
 321   return mutable_payload() + offset;
 322 }
 323
 324 void Pickle::EndWrite(char* dest, int length) {
 325   // Zero-pad to keep tools like valgrind from complaining about uninitialized
 326   // memory.
 327   if (length % sizeof(uint32))
 328     memset(dest + length, 0, sizeof(uint32) - (length % sizeof(uint32)));
 329 }
 330
 331 bool Pickle::Resize(size_t new_capacity) {
 332   new_capacity = AlignInt(new_capacity, kPayloadUnit);
 333
 334   CHECK_NE(capacity_, kCapacityReadOnly);
 335   void* p = realloc(header_, new_capacity);
 336   if (!p)
 337     return false;
 338
 339   header_ = reinterpret_cast<Header*>(p);
 340   capacity_ = new_capacity;
 341   return true;
 342 }
 343
 344 // static
 345 const char* Pickle::FindNext(size_t header_size,
 346                              const char* start,
 347                              const char* end) {
 348   DCHECK_EQ(header_size, AlignInt(header_size, sizeof(uint32)));
 349   DCHECK_LE(header_size, static_cast<size_t>(kPayloadUnit));
 350
 351   if (static_cast<size_t>(end - start) < sizeof(Header))
 352     return NULL;
 353
 354   const Header* hdr = reinterpret_cast<const Header*>(start);
 355   const char* payload_base = start + header_size;
 356   const char* payload_end = payload_base + hdr->payload_size;
 357   if (payload_end < payload_base)
 358     return NULL;
 359
 360   return (payload_end > end) ? NULL : payload_end;
 361 }