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content/renderer/pepper/npapi_glue.h

-// Copyright (c) 2011 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_NPAPI_GLUE_H_
-#define CONTENT_RENDERER_PEPPER_NPAPI_GLUE_H_
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "content/common/content_export.h"
-#include "ppapi/c/pp_module.h"
-#include "ppapi/c/pp_var.h"
-
-struct NPObject;
-typedef struct _NPVariant NPVariant;
-typedef void* NPIdentifier;
-
-namespace content {
-
-class PepperPluginInstanceImpl;
-class PluginObject;
-
-// Utilities -------------------------------------------------------------------
-
-// Converts the given PP_Var to an NPVariant, returning true on success.
-// False means that the given variant is invalid. In this case, the result
-// NPVariant will be set to a void one.
-//
-// The contents of the PP_Var will be copied unless the PP_Var corresponds to
-// an object.
-bool PPVarToNPVariant(PP_Var var, NPVariant* result);
-
-// Returns a PP_Var that corresponds to the given NPVariant. The contents of
-// the NPVariant will be copied unless the NPVariant corresponds to an
-// object. This will handle all Variant types including POD, strings, and
-// objects.
-//
-// The returned PP_Var will have a refcount of 1, this passing ownership of
-// the reference to the caller. This is suitable for returning to a plugin.
-PP_Var NPVariantToPPVar(PepperPluginInstanceImpl* instance,
-                        const NPVariant* variant);
-
-// Returns a NPIdentifier that corresponds to the given PP_Var. The contents
-// of the PP_Var will be copied. Returns 0 if the given PP_Var is not a a
-// string or integer type.
-NPIdentifier PPVarToNPIdentifier(PP_Var var);
-
-// Returns a PP_Var corresponding to the given identifier. In the case of
-// a string identifier, the returned string will have a reference count of 1.
-PP_Var NPIdentifierToPPVar(NPIdentifier id);
-
-// Helper function to create a PP_Var of type object that contains the given
-// NPObject for use byt he given module. Calling this function multiple times
-// given the same module + NPObject results in the same PP_Var, assuming that
-// there is still a PP_Var with a reference open to it from the previous
-// call.
-//
-// The instance is necessary because we can have different instances pointing to
-// the same NPObject, and we want to keep their refs separate.
-//
-// If no ObjectVar currently exists corresponding to the NPObject, one is
-// created associated with the given module.
-//
-// Note: this could easily be changed to take a PP_Instance instead if that
-// makes certain calls in the future easier. Currently all callers have a
-// PluginInstance so that's what we use here.
-CONTENT_EXPORT PP_Var
-    NPObjectToPPVar(PepperPluginInstanceImpl* instance, NPObject* object);
-
-// This version creates a default v8::Context rather than using the one from
-// the container of |instance|. It is only for use in unit tests, where we don't
-// have a real container for |instance|.
-CONTENT_EXPORT PP_Var NPObjectToPPVarForTest(PepperPluginInstanceImpl* instance,
-                                             NPObject* object);
-
-// PPResultAndExceptionToNPResult ----------------------------------------------
-
-// Convenience object for converting a PPAPI call that can throw an exception
-// and optionally return a value, back to the NPAPI layer which expects a
-// NPVariant as a result.
-//
-// Normal usage is that you will pass the result of exception() to the
-// PPAPI function as the exception output parameter. Then you will either
-// call SetResult with the result of the PPAPI call, or
-// CheckExceptionForNoResult if the PPAPI call doesn't return a PP_Var.
-//
-// Both SetResult and CheckExceptionForNoResult will throw an exception to
-// the JavaScript library if the plugin reported an exception. SetResult
-// will additionally convert the result to an NPVariant and write it to the
-// output parameter given in the constructor.
-class PPResultAndExceptionToNPResult {
- public:
-  // The object_var parameter is the object to associate any exception with.
-  // It may not be NULL.
-  //
-  // The np_result parameter is the NPAPI result output parameter. This may be
-  // NULL if there is no NPVariant result (like for HasProperty). If this is
-  // specified, you must call SetResult() to set it. If it is not, you must
-  // call CheckExceptionForNoResult to do the exception checking with no result
-  // conversion.
-  PPResultAndExceptionToNPResult(NPObject* object_var, NPVariant* np_result);
-
-  ~PPResultAndExceptionToNPResult();
-
-  // Returns true if an exception has been set.
-  bool has_exception() const { return exception_.type != PP_VARTYPE_UNDEFINED; }
-
-  // Returns a pointer to the exception. You would pass this to the PPAPI
-  // function as the exception parameter. If it is set to non-void, this object
-  // will take ownership of destroying it.
-  PP_Var* exception() { return &exception_; }
-
-  // Returns true if everything succeeded with no exception. This is valid only
-  // after calling SetResult/CheckExceptionForNoResult.
-  bool success() const { return success_; }
-
-  // Call this with the return value of the PPAPI function. It will convert
-  // the result to the NPVariant output parameter and pass any exception on to
-  // the JS engine. It will update the success flag and return it.
-  bool SetResult(PP_Var result);
-
-  // Call this after calling a PPAPI function that could have set the
-  // exception. It will pass the exception on to the JS engine and update
-  // the success flag.
-  //
-  // The success flag will be returned.
-  bool CheckExceptionForNoResult();
-
-  // Call this to ignore any exception. This prevents the DCHECK from failing
-  // in the destructor.
-  void IgnoreException();
-
- private:
-  // Throws the current exception to JS. The exception must be set.
-  void ThrowException();
-
-  NPObject* object_var_;  // Non-owning ref (see constructor).
-  NPVariant* np_result_;  // Output value, possibly NULL (see constructor).
-  PP_Var exception_;  // Exception set by the PPAPI call. We own a ref to it.
-  bool success_;      // See the success() function above.
-  bool checked_exception_;  // SetResult/CheckExceptionForNoResult was called.
-
-  DISALLOW_COPY_AND_ASSIGN(PPResultAndExceptionToNPResult);
-};
-
-// PPVarArrayFromNPVariantArray ------------------------------------------------
-
-// Converts an array of NPVariants to an array of PP_Var, and scopes the
-// ownership of the PP_Var. This is used when converting argument lists from
-// WebKit to the plugin.
-class PPVarArrayFromNPVariantArray {
- public:
-  PPVarArrayFromNPVariantArray(PepperPluginInstanceImpl* instance,
-                               size_t size,
-                               const NPVariant* variants);
-  ~PPVarArrayFromNPVariantArray();
-
-  PP_Var* array() { return array_.get(); }
-
- private:
-  size_t size_;
-  scoped_ptr<PP_Var[]> array_;
-
-  DISALLOW_COPY_AND_ASSIGN(PPVarArrayFromNPVariantArray);
-};
-
-// PPVarFromNPObject -----------------------------------------------------------
-
-// Converts an NPObject tp PP_Var, and scopes the ownership of the PP_Var. This
-// is used when converting 'this' pointer from WebKit to the plugin.
-class PPVarFromNPObject {
- public:
-  PPVarFromNPObject(PepperPluginInstanceImpl* instance, NPObject* object);
-  ~PPVarFromNPObject();
-
-  PP_Var var() const { return var_; }
-
- private:
-  const PP_Var var_;
-
-  DISALLOW_COPY_AND_ASSIGN(PPVarFromNPObject);
-};
-
-// NPObjectAccessorWithIdentifier ----------------------------------------------
-
-// Helper class for our NPObject wrapper. This converts a call from WebKit
-// where it gives us an NPObject and an NPIdentifier to an easily-accessible
-// ObjectVar (corresponding to the NPObject) and PP_Var (corresponding to the
-// NPIdentifier).
-//
-// If the NPObject or identifier is invalid, we'll set is_valid() to false.
-// The caller should check is_valid() before doing anything with the class.
-//
-// JS can't have integer functions, so when dealing with these, we don't want
-// to allow integer identifiers. The calling code can decode if it wants to
-// allow integer identifiers (like for property access) or prohibit them
-// (like for method calling) by setting |allow_integer_identifier|. If this
-// is false and the identifier is an integer, we'll set is_valid() to false.
-//
-// Getting an integer identifier in this case should be impossible. V8
-// shouldn't be allowing this, and the Pepper Var calls from the plugin are
-// supposed to error out before calling into V8 (which will then call us back).
-// Aside from an egregious error, the only time this could happen is an NPAPI
-// plugin calling us.
-class NPObjectAccessorWithIdentifier {
- public:
-  NPObjectAccessorWithIdentifier(NPObject* object,
-                                 NPIdentifier identifier,
-                                 bool allow_integer_identifier);
-  ~NPObjectAccessorWithIdentifier();
-
-  // Returns true if both the object and identifier are valid.
-  bool is_valid() const {
-    return object_ && identifier_.type != PP_VARTYPE_UNDEFINED;
-  }
-
-  PluginObject* object() { return object_; }
-  PP_Var identifier() const { return identifier_; }
-
- private:
-  PluginObject* object_;
-  PP_Var identifier_;
-
-  DISALLOW_COPY_AND_ASSIGN(NPObjectAccessorWithIdentifier);
-};
-
-// TryCatch --------------------------------------------------------------------
-
-// Instantiate this object on the stack to catch V8 exceptions and pass them
-// to an optional out parameter supplied by the plugin.
-class TryCatch {
- public:
-  // The given exception may be NULL if the consumer isn't interested in
-  // catching exceptions. If non-NULL, the given var will be updated if any
-  // exception is thrown (so it must outlive the TryCatch object).
-  TryCatch(PP_Var* exception);
-  ~TryCatch();
-
-  // Returns true is an exception has been thrown. This can be true immediately
-  // after construction if the var passed to the constructor is non-void.
-  bool has_exception() const { return has_exception_; }
-
-  // Sets the given exception. If an exception has been previously set, this
-  // function will do nothing (normally you want only the first exception).
-  void SetException(const char* message);
-
- private:
-  static void Catch(void* self, const char* message);
-
-  // True if an exception has been thrown. Since the exception itself may be
-  // NULL if the plugin isn't interested in getting the exception, this will
-  // always indicate if SetException has been called, regardless of whether
-  // the exception itself has been stored.
-  bool has_exception_;
-
-  // May be null if the consumer isn't interesting in catching exceptions.
-  PP_Var* exception_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_PEPPER_NPAPI_GLUE_H_