extensions/renderer/bindings/exception_handler.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef EXTENSIONS_RENDERER_BINDINGS_EXCEPTION_HANDLER_H_
#define EXTENSIONS_RENDERER_BINDINGS_EXCEPTION_HANDLER_H_

#include <string>

#include "base/memory/weak_ptr.h"
#include "extensions/renderer/bindings/api_binding_types.h"
#include "v8/include/v8.h"

namespace extensions {

// A class to handle uncaught exceptions encountered in the bindings system
// while running untrusted code, such as exceptions thrown during callback
// execution or event handling.
class ExceptionHandler {
 public:
  ExceptionHandler(const binding::AddConsoleError& add_console_error);

  ExceptionHandler(const ExceptionHandler&) = delete;
  ExceptionHandler& operator=(const ExceptionHandler&) = delete;

  ~ExceptionHandler();

  // Returns a v8::Value wrapping a weak reference to this ExceptionHandler.
  v8::Local<v8::Value> GetV8Wrapper(v8::Isolate* isolate);

  // Returns the ExceptionHandler associated with `value`, or null if the value
  // doesn't refer to a valid ExceptionHandler (which could happen with a
  // irrelevant v8::Value or if the ExceptionHandler was destroyed).
  static ExceptionHandler* FromV8Wrapper(v8::Isolate* isolate,
                                         v8::Local<v8::Value> value);

  // Handles an exception in the given `context`. `message` is a message to
  // prefix the error message with, e.g. "Exception in response to foo".
  // The `try_catch` is the TryCatch that caught the exception.
  void HandleException(v8::Local<v8::Context> context,
                       const std::string& message,
                       v8::TryCatch* try_catch);
  // Same as above, but accepts a v8::Value for the exception rather than
  // retrieving it from a TryCatch.
  void HandleException(v8::Local<v8::Context> context,
                       const std::string& full_message,
                       v8::Local<v8::Value> exception_value);

  // Sets a custom handler for the given context, which will be notified of
  // exceptions thrown. This is only allowed to be called while the context is
  // valid.
  void SetHandlerForContext(v8::Local<v8::Context> context,
                            v8::Local<v8::Function> handler);

  // Safely runs an `extension_callback` with the provided `callback_arguments`,
  // handling any exceptions that arise. If an exception is found, prefixes the
  // exception with `message`.
  void RunExtensionCallback(v8::Local<v8::Context> context,
                            v8::Local<v8::Function> extension_callback,
                            v8::LocalVector<v8::Value> callback_arguments,
                            const std::string& message);

 private:
  // Returns the custom handler for the given `context`, or an empty handle if
  // no custom handle exists.
  v8::Local<v8::Function> GetCustomHandler(v8::Local<v8::Context> context);

  binding::AddConsoleError add_console_error_;

  base::WeakPtrFactory<ExceptionHandler> weak_factory_{this};
};

}  // namespace extensions

#endif  // EXTENSIONS_RENDERER_BINDINGS_EXCEPTION_HANDLER_H_