1 /*

     2  * Copyright (C) 2009 Google Inc. All rights reserved.

     3  *

     4  * Redistribution and use in source and binary forms, with or without

     5  * modification, are permitted provided that the following conditions are

     6  * met:

     7  *

     8  *     * Redistributions of source code must retain the above copyright

     9  * notice, this list of conditions and the following disclaimer.

    10  *     * Redistributions in binary form must reproduce the above

    11  * copyright notice, this list of conditions and the following disclaimer

    12  * in the documentation and/or other materials provided with the

    13  * distribution.

    14  *     * Neither the name of Google Inc. nor the names of its

    15  * contributors may be used to endorse or promote products derived from

    16  * this software without specific prior written permission.

    17  *

    18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

    19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

    20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

    21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

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    23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

    24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

    25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

    26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

    27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

    28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    29  */

    30 

    31 #ifndef V8IsolatedContext_h

    32 #define V8IsolatedContext_h

    33 

    34 #include "IsolatedWorld.h"

    35 #include "ScriptSourceCode.h" // for WebCore::ScriptSourceCode

    36 #include "V8DOMWindow.h"

    37 #include "V8Proxy.h"

    38 #include "V8Utilities.h"

    39 #include <v8.h>

    40 

    41 namespace WebCore {

    42 

    43 class V8Proxy;

    44 

    45 // V8IsolatedContext

    46 //

    47 // V8IsolatedContext represents a isolated execution environment for

    48 // JavaScript.  Each isolated world executes in parallel with the main

    49 // JavaScript world.  An isolated world has access to the same DOM data

    50 // structures as the main world but none of the JavaScript pointers.

    51 //

    52 // It is an error to ever share a JavaScript pointer between two isolated

    53 // worlds or between an isolated world and the main world.  Because

    54 // isolated worlds have access to the DOM, they need their own DOM wrappers

    55 // to avoid having pointers to the main world's DOM wrappers (which are

    56 // JavaScript objects).

    57 class V8IsolatedContext {

    58 public:

    59     // Creates an isolated world. To destroy it, call destroy().

    60     // This will delete the isolated world when the context it owns is GC'd.

    61     V8IsolatedContext(V8Proxy* proxy, int extensionGroup);

    62     ~V8IsolatedContext();

    63 

    64     // Call this to destroy the isolated world. It will be deleted sometime

    65     // after this call, once all script references to the world's context

    66     // have been dropped.

    67     void destroy();

    68 

    69     // Returns the isolated world associated with

    70     // v8::Context::GetEntered().  Because worlds are isolated, the entire

    71     // JavaScript call stack should be from the same isolated world.

    72     // Returns 0 if the entered context is from the main world.

    73     //

    74     // FIXME: Consider edge cases with DOM mutation events that might

    75     // violate this invariant.

    76     //

    77     static V8IsolatedContext* getEntered()

    78     {

    79         // This is a temporary performance optimization.   Essentially,

    80         // GetHiddenValue is too slow for this code path.  We need to get the

    81         // V8 team to add a real property to v8::Context for isolated worlds.

    82         // Until then, we optimize the common case of not having any isolated

    83         // worlds at all.

    84         if (!IsolatedWorld::count())

    85             return 0;

    86         if (!v8::Context::InContext())

    87             return 0;

    88         return reinterpret_cast<V8IsolatedContext*>(getGlobalObject(v8::Context::GetEntered())->GetPointerFromInternalField(V8DOMWindow::enteredIsolatedWorldIndex));

    89     }

    90 

    91     v8::Handle<v8::Context> context() { return m_context->get(); }

    92     PassRefPtr<SharedPersistent<v8::Context> > sharedContext() { return m_context; }

    93 

    94     IsolatedWorld* world() const { return m_world.get(); }

    95 

    96 private:

    97     static v8::Handle<v8::Object> getGlobalObject(v8::Handle<v8::Context> context)

    98     {

    99         return v8::Handle<v8::Object>::Cast(context->Global()->GetPrototype());

   100     }

   101 

   102     // Called by the garbage collector when our JavaScript context is about

   103     // to be destroyed.

   104     static void contextWeakReferenceCallback(v8::Persistent<v8::Value> object, void* isolatedContext);

   105 

   106     // The underlying v8::Context. This object is keep on the heap as

   107     // long as |m_context| has not been garbage collected.

   108     RefPtr<SharedPersistent<v8::Context> > m_context;

   109 

   110     RefPtr<IsolatedWorld> m_world;

   111 };

   112 

   113 } // namespace WebCore

   114 

   115 #endif // V8IsolatedContext_h