content/renderer/pepper/pepper_try_catch.h

// Copyright 2014 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 CONTENT_RENDERER_PEPPER_PEPPER_TRY_CATCH_H_
#define CONTENT_RENDERER_PEPPER_PEPPER_TRY_CATCH_H_

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "content/common/content_export.h"
#include "ppapi/c/pp_var.h"
#include "ppapi/shared_impl/scoped_pp_var.h"
#include "v8/include/v8.h"

namespace content {

class PepperPluginInstanceImpl;
class V8VarConverter;

// Base class for scripting TryCatch helpers.
class CONTENT_EXPORT PepperTryCatch {
 public:
  // PepperTryCatch objects should only be used as stack variables. This object
  // takes a reference on the given PepperPluginInstanceImpl.
  PepperTryCatch(PepperPluginInstanceImpl* instance,
                 V8VarConverter* var_converter);
  virtual ~PepperTryCatch();

  virtual void SetException(const char* message) = 0;
  virtual bool HasException() = 0;
  // Gets the context to execute scripts in.
  virtual v8::Local<v8::Context> GetContext() = 0;

  // Convenience functions for doing conversions to/from V8 values and sets an
  // exception if there is an error in the conversion.
  v8::Local<v8::Value> ToV8(PP_Var var);
  ppapi::ScopedPPVar FromV8(v8::Local<v8::Value> v8_value);
  ppapi::ScopedPPVar FromV8Maybe(v8::MaybeLocal<v8::Value> v8_value);

 protected:
  // Make sure that |instance_| is alive for the lifetime of PepperTryCatch.
  // PepperTryCatch is used mostly in Pepper scripting code, where it can be
  // possible to enter JavaScript synchronously which can cause the plugin to
  // be deleted.
  //
  // Note that PepperTryCatch objects should only ever be on the stack, so this
  // shouldn't keep the instance around for too long.
  scoped_refptr<PepperPluginInstanceImpl> instance_;

  V8VarConverter* var_converter_;
};

// Catches var exceptions and emits a v8 exception.
class PepperTryCatchV8 : public PepperTryCatch {
 public:
  PepperTryCatchV8(PepperPluginInstanceImpl* instance,
                   V8VarConverter* var_converter,
                   v8::Isolate* isolate);
  ~PepperTryCatchV8() override;

  bool ThrowException();
  void ThrowException(const char* message);
  PP_Var* exception() { return &exception_; }

  // PepperTryCatch
  void SetException(const char* message) override;
  bool HasException() override;
  v8::Local<v8::Context> GetContext() override;

 private:
  PP_Var exception_;

  DISALLOW_COPY_AND_ASSIGN(PepperTryCatchV8);
};

// Catches v8 exceptions and emits a var exception.
class PepperTryCatchVar : public PepperTryCatch {
 public:
  // The PP_Var exception will be placed in |exception|. The user of this class
  // is responsible for managing the lifetime of the exception. It is valid to
  //  pass NULL for |exception| in which case no exception will be set.
  PepperTryCatchVar(PepperPluginInstanceImpl* instance,
                    V8VarConverter* var_converter,
                    PP_Var* exception);
  ~PepperTryCatchVar() override;

  // PepperTryCatch
  void SetException(const char* message) override;
  bool HasException() override;
  v8::Local<v8::Context> GetContext() override;

 private:
  // Code which uses PepperTryCatchVar doesn't typically have a HandleScope,
  // make one for them. Note that this class is always allocated on the stack.
  v8::HandleScope handle_scope_;

  v8::Local<v8::Context> context_;

  v8::TryCatch try_catch_;

  PP_Var* exception_;
  bool exception_is_set_;

  DISALLOW_COPY_AND_ASSIGN(PepperTryCatchVar);
};

}  // namespace content

#endif  // CONTENT_RENDERER_PEPPER_PEPPER_TRY_CATCH_H_