base/pickle.cc

   1 // Copyright (c) 2006-2008 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 <limits>
  10 #include <string>
  11
  12 //------------------------------------------------------------------------------
  13
  14 // static
  15 const int Pickle::kPayloadUnit = 64;
  16
  17 // We mark a read only pickle with a special capacity_.
  18 static const size_t kCapacityReadOnly = std::numeric_limits<size_t>::max();
  19
  20 // Payload is uint32 aligned.
  21
  22 Pickle::Pickle()
  23     : header_(NULL),
  24       header_size_(sizeof(Header)),
  25       capacity_(0),
  26       variable_buffer_offset_(0) {
  27   Resize(kPayloadUnit);
  28   header_->payload_size = 0;
  29 }
  30
  31 Pickle::Pickle(int header_size)
  32     : header_(NULL),
  33       header_size_(AlignInt(header_size, sizeof(uint32))),
  34       capacity_(0),
  35       variable_buffer_offset_(0) {
  36   DCHECK(static_cast<size_t>(header_size) >= sizeof(Header));
  37   DCHECK(header_size <= kPayloadUnit);
  38   Resize(kPayloadUnit);
  39   header_->payload_size = 0;
  40 }
  41
  42 Pickle::Pickle(const char* data, int data_len)
  43     : header_(reinterpret_cast<Header*>(const_cast<char*>(data))),
  44       header_size_(data_len - header_->payload_size),
  45       capacity_(kCapacityReadOnly),
  46       variable_buffer_offset_(0) {
  47   DCHECK(header_size_ >= sizeof(Header));
  48   DCHECK(header_size_ == AlignInt(header_size_, sizeof(uint32)));
  49 }
  50
  51 Pickle::Pickle(const Pickle& other)
  52     : header_(NULL),
  53       header_size_(other.header_size_),
  54       capacity_(0),
  55       variable_buffer_offset_(other.variable_buffer_offset_) {
  56   size_t payload_size = header_size_ + other.header_->payload_size;
  57   bool resized = Resize(payload_size);
  58   CHECK(resized);  // Realloc failed.
  59   memcpy(header_, other.header_, payload_size);
  60 }
  61
  62 Pickle::~Pickle() {
  63   if (capacity_ != kCapacityReadOnly)
  64     free(header_);
  65 }
  66
  67 Pickle& Pickle::operator=(const Pickle& other) {
  68   if (header_size_ != other.header_size_ && capacity_ != kCapacityReadOnly) {
  69     free(header_);
  70     header_ = NULL;
  71     header_size_ = other.header_size_;
  72   }
  73   bool resized = Resize(other.header_size_ + other.header_->payload_size);
  74   CHECK(resized);  // Realloc failed.
  75   memcpy(header_, other.header_, header_size_ + other.header_->payload_size);
  76   variable_buffer_offset_ = other.variable_buffer_offset_;
  77   return *this;
  78 }
  79
  80 bool Pickle::ReadBool(void** iter, bool* result) const {
  81   DCHECK(iter);
  82
  83   int tmp;
  84   if (!ReadInt(iter, &tmp))
  85     return false;
  86   DCHECK(0 == tmp || 1 == tmp);
  87   *result = tmp ? true : false;
  88   return true;
  89 }
  90
  91 bool Pickle::ReadInt(void** iter, int* result) const {
  92   DCHECK(iter);
  93   if (!*iter)
  94     *iter = const_cast<char*>(payload());
  95
  96   if (!IteratorHasRoomFor(*iter, sizeof(*result)))
  97     return false;
  98
  99   // TODO(jar) bug 1129285: Pickle should be cleaned up, and not dependent on
 100   // alignment.
 101   // Next line is otherwise the same as: memcpy(result, *iter, sizeof(*result));
 102   *result = *reinterpret_cast<int*>(*iter);
 103
 104   UpdateIter(iter, sizeof(*result));
 105   return true;
 106 }
 107
 108 bool Pickle::ReadLong(void** iter, long* result) const {
 109   DCHECK(iter);
 110   if (!*iter)
 111     *iter = const_cast<char*>(payload());
 112
 113   if (!IteratorHasRoomFor(*iter, sizeof(*result)))
 114     return false;
 115
 116   // TODO(jar) bug 1129285: Pickle should be cleaned up, and not dependent on
 117   // alignment.
 118   memcpy(result, *iter, sizeof(*result));
 119
 120   UpdateIter(iter, sizeof(*result));
 121   return true;
 122 }
 123
 124 bool Pickle::ReadLength(void** iter, int* result) const {
 125   if (!ReadInt(iter, result))
 126     return false;
 127   return ((*result) >= 0);
 128 }
 129
 130 bool Pickle::ReadSize(void** iter, size_t* result) const {
 131   DCHECK(iter);
 132   if (!*iter)
 133     *iter = const_cast<char*>(payload());
 134
 135   if (!IteratorHasRoomFor(*iter, sizeof(*result)))
 136     return false;
 137
 138   // TODO(jar) bug 1129285: Pickle should be cleaned up, and not dependent on
 139   // alignment.
 140   // Next line is otherwise the same as: memcpy(result, *iter, sizeof(*result));
 141   *result = *reinterpret_cast<size_t*>(*iter);
 142
 143   UpdateIter(iter, sizeof(*result));
 144   return true;
 145 }
 146
 147 bool Pickle::ReadInt64(void** iter, int64* result) const {
 148   DCHECK(iter);
 149   if (!*iter)
 150     *iter = const_cast<char*>(payload());
 151
 152   if (!IteratorHasRoomFor(*iter, sizeof(*result)))
 153     return false;
 154
 155   memcpy(result, *iter, sizeof(*result));
 156
 157   UpdateIter(iter, sizeof(*result));
 158   return true;
 159 }
 160
 161 bool Pickle::ReadIntPtr(void** iter, intptr_t* result) const {
 162   DCHECK(iter);
 163   if (!*iter)
 164     *iter = const_cast<char*>(payload());
 165
 166   if (!IteratorHasRoomFor(*iter, sizeof(*result)))
 167     return false;
 168
 169   memcpy(result, *iter, sizeof(*result));
 170
 171   UpdateIter(iter, sizeof(*result));
 172   return true;
 173 }
 174
 175 bool Pickle::ReadString(void** iter, std::string* result) const {
 176   DCHECK(iter);
 177
 178   int len;
 179   if (!ReadLength(iter, &len))
 180     return false;
 181   if (!IteratorHasRoomFor(*iter, len))
 182     return false;
 183
 184   char* chars = reinterpret_cast<char*>(*iter);
 185   result->assign(chars, len);
 186
 187   UpdateIter(iter, len);
 188   return true;
 189 }
 190
 191 bool Pickle::ReadWString(void** iter, std::wstring* result) const {
 192   DCHECK(iter);
 193
 194   int len;
 195   if (!ReadLength(iter, &len))
 196     return false;
 197   if (!IteratorHasRoomFor(*iter, len * sizeof(wchar_t)))
 198     return false;
 199
 200   wchar_t* chars = reinterpret_cast<wchar_t*>(*iter);
 201   result->assign(chars, len);
 202
 203   UpdateIter(iter, len * sizeof(wchar_t));
 204   return true;
 205 }
 206
 207 bool Pickle::ReadBytes(void** iter, const char** data, int length) const {
 208   DCHECK(iter);
 209   DCHECK(data);
 210
 211   if (!IteratorHasRoomFor(*iter, length))
 212     return false;
 213
 214   *data = reinterpret_cast<const char*>(*iter);
 215
 216   UpdateIter(iter, length);
 217   return true;
 218 }
 219
 220 bool Pickle::ReadData(void** iter, const char** data, int* length) const {
 221   DCHECK(iter);
 222   DCHECK(data);
 223   DCHECK(length);
 224
 225   if (!ReadLength(iter, length))
 226     return false;
 227
 228   return ReadBytes(iter, data, *length);
 229 }
 230
 231 char* Pickle::BeginWrite(size_t length) {
 232   // write at a uint32-aligned offset from the beginning of the header
 233   size_t offset = AlignInt(header_->payload_size, sizeof(uint32));
 234
 235   size_t new_size = offset + length;
 236   if (header_size_ + new_size > capacity_ && !Resize(header_size_ + new_size))
 237     return NULL;
 238
 239 #ifdef ARCH_CPU_64_BITS
 240   DCHECK_LE(length, std::numeric_limits<uint32>::max());
 241 #endif
 242
 243   header_->payload_size = static_cast<uint32>(new_size);
 244   return payload() + offset;
 245 }
 246
 247 void Pickle::EndWrite(char* dest, int length) {
 248   // Zero-pad to keep tools like purify from complaining about uninitialized
 249   // memory.
 250   if (length % sizeof(uint32))
 251     memset(dest + length, 0, sizeof(uint32) - (length % sizeof(uint32)));
 252 }
 253
 254 bool Pickle::WriteBytes(const void* data, int data_len) {
 255   DCHECK(capacity_ != kCapacityReadOnly) << "oops: pickle is readonly";
 256
 257   char* dest = BeginWrite(data_len);
 258   if (!dest)
 259     return false;
 260
 261   memcpy(dest, data, data_len);
 262
 263   EndWrite(dest, data_len);
 264   return true;
 265 }
 266
 267 bool Pickle::WriteString(const std::string& value) {
 268   if (!WriteInt(static_cast<int>(value.size())))
 269     return false;
 270
 271   return WriteBytes(value.data(), static_cast<int>(value.size()));
 272 }
 273
 274 bool Pickle::WriteWString(const std::wstring& value) {
 275   if (!WriteInt(static_cast<int>(value.size())))
 276     return false;
 277
 278   return WriteBytes(value.data(),
 279                     static_cast<int>(value.size() * sizeof(value.data()[0])));
 280 }
 281
 282 bool Pickle::WriteData(const char* data, int length) {
 283   return WriteInt(length) && WriteBytes(data, length);
 284 }
 285
 286 char* Pickle::BeginWriteData(int length) {
 287   DCHECK_EQ(variable_buffer_offset_, 0U) <<
 288     "There can only be one variable buffer in a Pickle";
 289
 290   if (!WriteInt(length))
 291     return false;
 292
 293   char *data_ptr = BeginWrite(length);
 294   if (!data_ptr)
 295     return NULL;
 296
 297   variable_buffer_offset_ =
 298       data_ptr - reinterpret_cast<char*>(header_) - sizeof(int);
 299
 300   // EndWrite doesn't necessarily have to be called after the write operation,
 301   // so we call it here to pad out what the caller will eventually write.
 302   EndWrite(data_ptr, length);
 303   return data_ptr;
 304 }
 305
 306 void Pickle::TrimWriteData(int new_length) {
 307   DCHECK(variable_buffer_offset_ != 0);
 308
 309   // Fetch the the variable buffer size
 310   int* cur_length = reinterpret_cast<int*>(
 311       reinterpret_cast<char*>(header_) + variable_buffer_offset_);
 312
 313   if (new_length < 0 || new_length > *cur_length) {
 314     NOTREACHED() << "Invalid length in TrimWriteData.";
 315     return;
 316   }
 317
 318   // Update the payload size and variable buffer size
 319   header_->payload_size -= (*cur_length - new_length);
 320   *cur_length = new_length;
 321 }
 322
 323 bool Pickle::Resize(size_t new_capacity) {
 324   new_capacity = AlignInt(new_capacity, kPayloadUnit);
 325
 326   void* p = realloc(header_, new_capacity);
 327   if (!p)
 328     return false;
 329
 330   header_ = reinterpret_cast<Header*>(p);
 331   capacity_ = new_capacity;
 332   return true;
 333 }
 334
 335 // static
 336 const char* Pickle::FindNext(size_t header_size,
 337                              const char* start,
 338                              const char* end) {
 339   DCHECK(header_size == AlignInt(header_size, sizeof(uint32)));
 340   DCHECK(header_size <= static_cast<size_t>(kPayloadUnit));
 341
 342   const Header* hdr = reinterpret_cast<const Header*>(start);
 343   const char* payload_base = start + header_size;
 344   const char* payload_end = payload_base + hdr->payload_size;
 345   if (payload_end < payload_base)
 346     return NULL;
 347
 348   return (payload_end > end) ? NULL : payload_end;
 349 }
 350