Var serialization-related proxy stuff. This allows vars to be sent over IPC...

ppapi/proxy/serialized_var.cc

+// Copyright (c) 2010 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.
+
+#include "ppapi/proxy/serialized_var.h"
+
+#include "base/logging.h"
+#include "ipc/ipc_message_utils.h"
+#include "ppapi/proxy/dispatcher.h"
+#include "ppapi/proxy/ppapi_param_traits.h"
+#include "ppapi/proxy/var_serialization_rules.h"
+
+namespace pp {
+namespace proxy {
+
+// SerializedVar::Inner --------------------------------------------------------
+
+SerializedVar::Inner::Inner()
+    : serialization_rules_(NULL),
+      var_(PP_MakeUndefined()),
+      cleanup_mode_(CLEANUP_NONE) {
+#ifndef NDEBUG
+  has_been_serialized_ = false;
+  has_been_deserialized_ = false;
+#endif
+}
+
+SerializedVar::Inner::Inner(VarSerializationRules* serialization_rules)
+    : serialization_rules_(serialization_rules),
+      var_(PP_MakeUndefined()),
+      cleanup_mode_(CLEANUP_NONE) {
+#ifndef NDEBUG
+  has_been_serialized_ = false;
+  has_been_deserialized_ = false;
+#endif
+}
+
+SerializedVar::Inner::Inner(VarSerializationRules* serialization_rules,
+                            const PP_Var& var)
+    : serialization_rules_(serialization_rules),
+      var_(var),
+      cleanup_mode_(CLEANUP_NONE) {
+#ifndef NDEBUG
+  has_been_serialized_ = false;
+  has_been_deserialized_ = false;
+#endif
+}
+
+SerializedVar::Inner::~Inner() {
+  switch (cleanup_mode_) {
+    case END_SEND_PASS_REF:
+      serialization_rules_->EndSendPassRef(var_);
+      break;
+    case END_RECEIVE_CALLER_OWNED:
+      serialization_rules_->EndReceiveCallerOwned(var_);
+      break;
+    default:
+      break;
+  }
+}
+
+PP_Var SerializedVar::Inner::GetVar() const {
+  DCHECK(serialization_rules_);
+
+  // If we're a string var, we should have already converted the string value
+  // to a var ID.
+  DCHECK(var_.type != PP_VARTYPE_STRING || var_.value.as_id != 0);
+  return var_;
+}
+
+PP_Var SerializedVar::Inner::GetIncompleteVar() const {
+  DCHECK(serialization_rules_);
+  return var_;
+}
+
+void SerializedVar::Inner::SetVar(PP_Var var) {
+  // Sanity check, when updating the var we should have received a
+  // serialization rules pointer already.
+  DCHECK(serialization_rules_);
+  var_ = var;
+}
+
+const std::string& SerializedVar::Inner::GetString() const {
+  DCHECK(serialization_rules_);
+  return string_value_;
+}
+
+std::string* SerializedVar::Inner::GetStringPtr() {
+  DCHECK(serialization_rules_);
+  return &string_value_;
+}
+
+void SerializedVar::Inner::WriteToMessage(IPC::Message* m) const {
+  // When writing to the IPC messages, a serization rules handler should
+  // always have been set.
+  //
+  // When sending a message, it should be difficult to trigger this if you're
+  // using the SerializedVarSendInput class and giving a non-NULL dispatcher.
+  // Make sure you're using the proper "Send" helper class.
+  //
+  // It should be more common to see this when handling an incoming message
+  // that returns a var. This means the message handler didn't write to the
+  // output parameter, or possibly you used the wrong helper class
+  // (normally SerializedVarReturnValue).
+  DCHECK(serialization_rules_);
+
+#ifndef NDEBUG
+  // We should only be serializing something once.
+  DCHECK(!has_been_serialized_);
+  has_been_serialized_ = true;
+#endif
+
+  // If the var is not a string type, we should not have ended up with any
+  // string data.
+  DCHECK(var_.type == PP_VARTYPE_STRING || string_value_.empty());
+
+  m->WriteInt(static_cast<int>(var_.type));
+  switch (var_.type) {
+    case PP_VARTYPE_UNDEFINED:
+    case PP_VARTYPE_NULL:
+      // These don't need any data associated with them other than the type we
+      // just serialized.
+      break;
+    case PP_VARTYPE_BOOL:
+      m->WriteBool(var_.value.as_bool);
+      break;
+    case PP_VARTYPE_INT32:
+      m->WriteInt(var_.value.as_int);
+      break;
+    case PP_VARTYPE_DOUBLE:
+      IPC::ParamTraits<double>::Write(m, var_.value.as_double);
+      break;
+    case PP_VARTYPE_STRING:
+      // TODO(brettw) in the case of an invalid string ID, it would be nice
+      // to send something to the other side such that a 0 ID would be
+      // generated there. Then the function implementing the interface can
+      // handle the invalid string as if it was in process rather than seeing
+      // what looks like a valid empty string.
+      m->WriteString(string_value_);
+      break;
+    case PP_VARTYPE_OBJECT:
+      m->WriteInt64(var_.value.as_id);
+      break;
+  }
+}
+
+bool SerializedVar::Inner::ReadFromMessage(const IPC::Message* m, void** iter) {
+#ifndef NDEBUG
+  // We should only deserialize something once or will end up with leaked
+  // references.
+  //
+  // One place this has happened in the past is using
+  // std::vector<SerializedVar>.resize(). If you're doing this manually instead
+  // of using the helper classes for handling in/out vectors of vars, be
+  // sure you use the same pattern as the SerializedVarVector classes.
+  DCHECK(!has_been_deserialized_);
+  has_been_deserialized_ = true;
+#endif
+
+  // When reading, the dispatcher should be set when we get a Deserialize
+  // call (which will supply a dispatcher).
+  int type;
+  if (!m->ReadInt(iter, &type))
+    return false;
+
+  bool success = false;
+  switch (type) {
+    case PP_VARTYPE_UNDEFINED:
+    case PP_VARTYPE_NULL:
+      // These don't have any data associated with them other than the type we
+      // just serialized.
+      success = true;
+      break;
+    case PP_VARTYPE_BOOL:
+      success = m->ReadBool(iter, &var_.value.as_bool);
+      break;
+    case PP_VARTYPE_INT32:
+      success = m->ReadInt(iter, &var_.value.as_int);
+      break;
+    case PP_VARTYPE_DOUBLE:
+      success = IPC::ParamTraits<double>::Read(m, iter, &var_.value.as_double);
+      break;
+    case PP_VARTYPE_STRING:
+      success = m->ReadString(iter, &string_value_);
+      var_.value.as_id = 0;
+      break;
+    case PP_VARTYPE_OBJECT:
+      success = m->ReadInt64(iter, &var_.value.as_id);
+      break;
+    default:
+      // Leave success as false.
+      break;
+  }
+
+  // All success cases get here. We avoid writing the type above so that the
+  // output param is untouched (defaults to VARTYPE_UNDEFINED) even in the
+  // failure case.
+  if (success)
+    var_.type = static_cast<PP_VarType>(type);
+  return success;
+}
+
+// SerializedVar ---------------------------------------------------------------
+
+SerializedVar::SerializedVar() : inner_(new Inner) {
+}
+
+SerializedVar::SerializedVar(VarSerializationRules* serialization_rules)
+    : inner_(new Inner(serialization_rules)) {
+}
+
+SerializedVar::SerializedVar(VarSerializationRules* serialization_rules,
+                             const PP_Var& var)
+    : inner_(new Inner(serialization_rules, var)) {
+}
+
+SerializedVar::~SerializedVar() {
+}
+
+// SerializedVarSendInput ------------------------------------------------------
+
+SerializedVarSendInput::SerializedVarSendInput(Dispatcher* dispatcher,
+                                               const PP_Var& var)
+    : SerializedVar(dispatcher->serialization_rules(), var) {
+  dispatcher->serialization_rules()->SendCallerOwned(var,
+                                                     inner_->GetStringPtr());
+}
+
+// static
+void SerializedVarSendInput::ConvertVector(Dispatcher* dispatcher,
+                                           const PP_Var* input,
+                                           size_t input_count,
+                                           std::vector<SerializedVar>* output) {
+  output->resize(input_count);
+  for (size_t i = 0; i < input_count; i++) {
+    (*output)[i] = SerializedVar(dispatcher->serialization_rules(), input[i]);
+    dispatcher->serialization_rules()->SendCallerOwned(
+        input[i], (*output)[i].inner_->GetStringPtr());
+  }
+}
+
+// ReceiveSerializedVarReturnValue ---------------------------------------------
+
+ReceiveSerializedVarReturnValue::ReceiveSerializedVarReturnValue() {
+}
+
+PP_Var ReceiveSerializedVarReturnValue::Return(Dispatcher* dispatcher) {
+  inner_->set_serialization_rules(dispatcher->serialization_rules());
+  inner_->SetVar(inner_->serialization_rules()->ReceivePassRef(
+      inner_->GetIncompleteVar(), inner_->GetString()));
+  return inner_->GetVar();
+}
+
+// ReceiveSerializedException --------------------------------------------------
+
+ReceiveSerializedException::ReceiveSerializedException(Dispatcher* dispatcher,
+                                                       PP_Var* exception)
+    : SerializedVar(dispatcher->serialization_rules()),
+      exception_(exception) {
+}
+
+ReceiveSerializedException::~ReceiveSerializedException() {
+  if (exception_) {
+    // When an output exception is specified, it will take ownership of the
+    // reference.
+    inner_->SetVar(inner_->serialization_rules()->ReceivePassRef(
+        inner_->GetIncompleteVar(), inner_->GetString()));
+    *exception_ = inner_->GetVar();
+  } else {
+    // When no output exception is specified, the browser thinks we have a ref
+    // to an object that we don't want (this will happen only in the plugin
+    // since the browser will always specify an out exception for the plugin to
+    // write into).
+    //
+    // Strings don't need this handling since we can just avoid creating a
+    // Var from the std::string in the first place.
+    if (inner_->GetVar().type == PP_VARTYPE_OBJECT)
+      inner_->serialization_rules()->ReleaseObjectRef(inner_->GetVar());
+  }
+}
+
+bool ReceiveSerializedException::IsThrown() const {
+  return exception_ && exception_->type != PP_VARTYPE_UNDEFINED;
+}
+
+// ReceiveSerializedVarVectorOutParam ------------------------------------------
+
+ReceiveSerializedVarVectorOutParam::ReceiveSerializedVarVectorOutParam(
+    Dispatcher* dispatcher,
+    uint32_t* output_count,
+    PP_Var** output)
+    : dispatcher_(dispatcher),
+      output_count_(output_count),
+      output_(output) {
+}
+
+ReceiveSerializedVarVectorOutParam::~ReceiveSerializedVarVectorOutParam() {
+  *output_count_ = static_cast<uint32_t>(vector_.size());
+  if (!vector_.size()) {
+    *output_ = NULL;
+    return;
+  }
+
+  *output_ = static_cast<PP_Var*>(malloc(vector_.size() * sizeof(PP_Var)));
+  for (size_t i = 0; i < vector_.size(); i++) {
+    // Here we just mimic what happens when returning a value.
+    ReceiveSerializedVarReturnValue converted;
+    SerializedVar* serialized = &converted;
+    *serialized = vector_[i];
+    (*output_)[i] = converted.Return(dispatcher_);
+  }
+}
+
+std::vector<SerializedVar>* ReceiveSerializedVarVectorOutParam::OutParam() {
+  return &vector_;
+}
+
+// SerializedVarReceiveInput ---------------------------------------------------
+
+SerializedVarReceiveInput::SerializedVarReceiveInput(
+    const SerializedVar& serialized)
+    : serialized_(serialized),
+      dispatcher_(NULL),
+      var_(PP_MakeUndefined()) {
+}
+
+SerializedVarReceiveInput::~SerializedVarReceiveInput() {
+}
+
+PP_Var SerializedVarReceiveInput::Get(Dispatcher* dispatcher) {
+  serialized_.inner_->set_serialization_rules(
+      dispatcher->serialization_rules());
+
+  // Ensure that when the serialized var goes out of scope it cleans up the
+  // stuff we're making in BeginReceiveCallerOwned.
+  serialized_.inner_->set_cleanup_mode(SerializedVar::END_RECEIVE_CALLER_OWNED);
+
+  serialized_.inner_->SetVar(
+      serialized_.inner_->serialization_rules()->BeginReceiveCallerOwned(
+          serialized_.inner_->GetIncompleteVar(),
+          serialized_.inner_->GetStringPtr()));
+  return serialized_.inner_->GetVar();
+}
+
+// SerializedVarVectorReceiveInput ---------------------------------------------
+
+SerializedVarVectorReceiveInput::SerializedVarVectorReceiveInput(
+    const std::vector<SerializedVar>& serialized)
+    : serialized_(serialized) {
+}
+
+SerializedVarVectorReceiveInput::~SerializedVarVectorReceiveInput() {
+  for (size_t i = 0; i < deserialized_.size(); i++) {
+    serialized_[i].inner_->serialization_rules()->EndReceiveCallerOwned(
+        deserialized_[i]);
+  }
+}
+
+PP_Var* SerializedVarVectorReceiveInput::Get(Dispatcher* dispatcher,
+                                             uint32_t* array_size) {
+  deserialized_.resize(serialized_.size());
+  for (size_t i = 0; i < serialized_.size(); i++) {
+    // The vector must be able to clean themselves up after this call is
+    // torn down.
+    serialized_[i].inner_->set_serialization_rules(
+        dispatcher->serialization_rules());
+
+    serialized_[i].inner_->SetVar(
+        serialized_[i].inner_->serialization_rules()->BeginReceiveCallerOwned(
+            serialized_[i].inner_->GetIncompleteVar(),
+            serialized_[i].inner_->GetStringPtr()));
+    deserialized_[i] = serialized_[i].inner_->GetVar();
+  }
+
+  *array_size = static_cast<uint32_t>(serialized_.size());
+  return deserialized_.size() > 0 ? &deserialized_[0] : NULL;
+}
+
+// SerializedVarReturnValue ----------------------------------------------------
+
+SerializedVarReturnValue::SerializedVarReturnValue(SerializedVar* serialized)
+    : serialized_(serialized) {
+}
+
+void SerializedVarReturnValue::Return(Dispatcher* dispatcher,
+                                      const PP_Var& var) {
+  serialized_->inner_->set_serialization_rules(
+      dispatcher->serialization_rules());
+  serialized_->inner_->SetVar(var);
+
+  // Var must clean up after our BeginSendPassRef call.
+  serialized_->inner_->set_cleanup_mode(SerializedVar::END_SEND_PASS_REF);
+
+  dispatcher->serialization_rules()->BeginSendPassRef(
+      serialized_->inner_->GetIncompleteVar(),
+      serialized_->inner_->GetStringPtr());
+}
+
+// SerializedVarOutParam -------------------------------------------------------
+
+SerializedVarOutParam::SerializedVarOutParam(SerializedVar* serialized)
+    : serialized_(serialized),
+      writable_var_(PP_MakeUndefined()) {
+}
+
+SerializedVarOutParam::~SerializedVarOutParam() {
+  if (serialized_->inner_->serialization_rules()) {
+    // When unset, OutParam wasn't called. We'll just leave the var untouched
+    // in that case.
+    serialized_->inner_->SetVar(writable_var_);
+    serialized_->inner_->serialization_rules()->BeginSendPassRef(
+        writable_var_, serialized_->inner_->GetStringPtr());
+
+    // Normally the current object will be created on the stack to wrap a
+    // SerializedVar and won't have a scope around the actual IPC send. So we
+    // need to tell the SerializedVar to do the begin/end send pass ref calls.
+    serialized_->inner_->set_cleanup_mode(SerializedVar::END_SEND_PASS_REF);
+  }
+}
+
+PP_Var* SerializedVarOutParam::OutParam(Dispatcher* dispatcher) {
+  serialized_->inner_->set_serialization_rules(
+      dispatcher->serialization_rules());
+  return &writable_var_;
+}
+
+// SerializedVarVectorOutParam -------------------------------------------------
+
+SerializedVarVectorOutParam::SerializedVarVectorOutParam(
+    std::vector<SerializedVar>* serialized)
+    : dispatcher_(NULL),
+      serialized_(serialized),
+      count_(0),
+      array_(NULL) {
+}
+
+SerializedVarVectorOutParam::~SerializedVarVectorOutParam() {
+  DCHECK(dispatcher_);
+
+  // Convert the array written by the pepper code to the serialized structure.
+  // Note we can't use resize here, we have to allocate a new SerializedVar
+  // for each serialized item. See ParamTraits<vector<SerializedVar>>::Read.
+  serialized_->reserve(count_);
+  for (uint32_t i = 0; i < count_; i++) {
+    // Just mimic what we do for regular OutParams.
+    SerializedVar var;
+    SerializedVarOutParam out(&var);
+    *out.OutParam(dispatcher_) = array_[i];
+    serialized_->push_back(var);
+  }
+
+  // When returning arrays, the pepper code expects the caller to take
+  // ownership of the array.
+  free(array_);
+}
+
+PP_Var** SerializedVarVectorOutParam::ArrayOutParam(Dispatcher* dispatcher) {
+  DCHECK(!dispatcher_);  // Should only be called once.
+  dispatcher_ = dispatcher;
+  return &array_;
+}
+
+}  // namespace proxy
+}  // namespace pp
+