/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jswrapper_h
#define jswrapper_h

#include "mozilla/Attributes.h"

#include "jsapi.h"
#include "jsproxy.h"

namespace js {

class DummyFrameGuard;

/*
 * A wrapper is a proxy with a target object to which it generally forwards
 * operations, but may restrict access to certain operations or instrument
 * the trap operations in various ways. A wrapper is distinct from a Direct Proxy
 * Handler in the sense that it can be "unwrapped" in C++, exposing the underlying
 * object (Direct Proxy Handlers have an underlying target object, but don't
 * expect to expose this object via any kind of unwrapping operation). Callers
 * should be careful to avoid unwrapping security wrappers in the wrong context.
 */
class JS_FRIEND_API(Wrapper) : public DirectProxyHandler
{
    unsigned mFlags;
    bool mSafeToUnwrap;

  public:
    using BaseProxyHandler::Action;

    enum Flags {
        CROSS_COMPARTMENT = 1 << 0,
        LAST_USED_FLAG = CROSS_COMPARTMENT
    };

    /*
     * Wrappers can explicitly specify that they are unsafe to unwrap from a
     * security perspective (as is the case for SecurityWrappers). If a wrapper
     * is not safe to unwrap, operations requiring full access to the underlying
     * object (via CheckedUnwrap) will throw. Otherwise, they will succeed.
     */
    void setSafeToUnwrap(bool safe) { mSafeToUnwrap = safe; }
    bool isSafeToUnwrap() { return mSafeToUnwrap; }

    static JSObject *New(JSContext *cx, JSObject *obj, JSObject *proto,
                         JSObject *parent, Wrapper *handler);

    static JSObject *Renew(JSContext *cx, JSObject *existing, JSObject *obj, Wrapper *handler);

    static Wrapper *wrapperHandler(JSObject *wrapper);

    static JSObject *wrappedObject(JSObject *wrapper);

    unsigned flags() const {
        return mFlags;
    }

    explicit Wrapper(unsigned flags, bool hasPrototype = false);

    virtual ~Wrapper();

    static Wrapper singleton;
    static Wrapper singletonWithPrototype;

    static void *getWrapperFamily();
};

/* Base class for all cross compartment wrapper handlers. */
class JS_FRIEND_API(CrossCompartmentWrapper) : public Wrapper
{
  public:
    CrossCompartmentWrapper(unsigned flags, bool hasPrototype = false);

    virtual ~CrossCompartmentWrapper();

    virtual bool finalizeInBackground(Value priv) MOZ_OVERRIDE;

    /* ES5 Harmony fundamental wrapper traps. */
    virtual bool preventExtensions(JSContext *cx, HandleObject wrapper) MOZ_OVERRIDE;
    virtual bool getPropertyDescriptor(JSContext *cx, HandleObject wrapper, HandleId id,
                                       PropertyDescriptor *desc, unsigned flags) MOZ_OVERRIDE;
    virtual bool getOwnPropertyDescriptor(JSContext *cx, HandleObject wrapper, HandleId id,
                                          PropertyDescriptor *desc, unsigned flags) MOZ_OVERRIDE;
    virtual bool defineProperty(JSContext *cx, HandleObject wrapper, HandleId id,
                                PropertyDescriptor *desc) MOZ_OVERRIDE;
    virtual bool getOwnPropertyNames(JSContext *cx, HandleObject wrapper,
                                     AutoIdVector &props) MOZ_OVERRIDE;
    virtual bool delete_(JSContext *cx, HandleObject wrapper, HandleId id, bool *bp) MOZ_OVERRIDE;
    virtual bool enumerate(JSContext *cx, HandleObject wrapper, AutoIdVector &props) MOZ_OVERRIDE;

    /* ES5 Harmony derived wrapper traps. */
    virtual bool has(JSContext *cx, HandleObject wrapper, HandleId id, bool *bp) MOZ_OVERRIDE;
    virtual bool hasOwn(JSContext *cx, HandleObject wrapper, HandleId id, bool *bp) MOZ_OVERRIDE;
    virtual bool get(JSContext *cx, HandleObject wrapper, HandleObject receiver,
                     HandleId id, MutableHandleValue vp) MOZ_OVERRIDE;
    virtual bool set(JSContext *cx, HandleObject wrapper, HandleObject receiver,
                     HandleId id, bool strict, MutableHandleValue vp) MOZ_OVERRIDE;
    virtual bool keys(JSContext *cx, HandleObject wrapper, AutoIdVector &props) MOZ_OVERRIDE;
    virtual bool iterate(JSContext *cx, HandleObject wrapper, unsigned flags,
                         MutableHandleValue vp) MOZ_OVERRIDE;

    /* Spidermonkey extensions. */
    virtual bool isExtensible(JSObject *proxy) MOZ_OVERRIDE;
    virtual bool call(JSContext *cx, HandleObject wrapper, const CallArgs &args) MOZ_OVERRIDE;
    virtual bool construct(JSContext *cx, HandleObject wrapper, const CallArgs &args) MOZ_OVERRIDE;
    virtual bool nativeCall(JSContext *cx, IsAcceptableThis test, NativeImpl impl,
                            CallArgs args) MOZ_OVERRIDE;
    virtual bool hasInstance(JSContext *cx, HandleObject wrapper, MutableHandleValue v,
                             bool *bp) MOZ_OVERRIDE;
    virtual const char *className(JSContext *cx, HandleObject proxy) MOZ_OVERRIDE;
    virtual JSString *fun_toString(JSContext *cx, HandleObject wrapper,
                                   unsigned indent) MOZ_OVERRIDE;
    virtual bool regexp_toShared(JSContext *cx, HandleObject proxy, RegExpGuard *g) MOZ_OVERRIDE;
    virtual bool defaultValue(JSContext *cx, HandleObject wrapper, JSType hint,
                              MutableHandleValue vp) MOZ_OVERRIDE;
    virtual bool getPrototypeOf(JSContext *cx, HandleObject proxy, MutableHandleObject protop);

    static CrossCompartmentWrapper singleton;
    static CrossCompartmentWrapper singletonWithPrototype;
};

/*
 * Base class for security wrappers. A security wrapper is potentially hiding
 * all or part of some wrapped object thus SecurityWrapper defaults to denying
 * access to the wrappee. This is the opposite of Wrapper which tries to be
 * completely transparent.
 *
 * NB: Currently, only a few ProxyHandler operations are overridden to deny
 * access, relying on derived SecurityWrapper to block access when necessary.
 */
template <class Base>
class JS_FRIEND_API(SecurityWrapper) : public Base
{
  public:
    SecurityWrapper(unsigned flags);

    virtual bool isExtensible(JSObject *wrapper) MOZ_OVERRIDE;
    virtual bool preventExtensions(JSContext *cx, HandleObject wrapper) MOZ_OVERRIDE;
    virtual bool enter(JSContext *cx, HandleObject wrapper, HandleId id, Wrapper::Action act,
                       bool *bp) MOZ_OVERRIDE;
    virtual bool nativeCall(JSContext *cx, IsAcceptableThis test, NativeImpl impl,
                            CallArgs args) MOZ_OVERRIDE;
    virtual bool defaultValue(JSContext *cx, HandleObject wrapper, JSType hint,
                              MutableHandleValue vp) MOZ_OVERRIDE;
    virtual bool objectClassIs(HandleObject obj, ESClassValue classValue,
                               JSContext *cx) MOZ_OVERRIDE;
    virtual bool regexp_toShared(JSContext *cx, HandleObject proxy, RegExpGuard *g) MOZ_OVERRIDE;
    virtual bool defineProperty(JSContext *cx, HandleObject wrapper, HandleId id,
                                PropertyDescriptor *desc) MOZ_OVERRIDE;

    /*
     * Allow our subclasses to select the superclass behavior they want without
     * needing to specify an exact superclass.
     */
    typedef Base Permissive;
    typedef SecurityWrapper<Base> Restrictive;
};

typedef SecurityWrapper<Wrapper> SameCompartmentSecurityWrapper;
typedef SecurityWrapper<CrossCompartmentWrapper> CrossCompartmentSecurityWrapper;

class JS_FRIEND_API(DeadObjectProxy) : public BaseProxyHandler
{
  public:
    static int sDeadObjectFamily;

    explicit DeadObjectProxy();

    /* ES5 Harmony fundamental wrapper traps. */
    virtual bool preventExtensions(JSContext *cx, HandleObject proxy) MOZ_OVERRIDE;
    virtual bool getPropertyDescriptor(JSContext *cx, HandleObject wrapper, HandleId id,
                                       PropertyDescriptor *desc, unsigned flags) MOZ_OVERRIDE;
    virtual bool getOwnPropertyDescriptor(JSContext *cx, HandleObject wrapper, HandleId id,
                                          PropertyDescriptor *desc, unsigned flags) MOZ_OVERRIDE;
    virtual bool defineProperty(JSContext *cx, HandleObject wrapper, HandleId id,
                                PropertyDescriptor *desc) MOZ_OVERRIDE;
    virtual bool getOwnPropertyNames(JSContext *cx, HandleObject wrapper,
                                     AutoIdVector &props) MOZ_OVERRIDE;
    virtual bool delete_(JSContext *cx, HandleObject wrapper, HandleId id, bool *bp) MOZ_OVERRIDE;
    virtual bool enumerate(JSContext *cx, HandleObject wrapper, AutoIdVector &props) MOZ_OVERRIDE;

    /* Spidermonkey extensions. */
    virtual bool isExtensible(JSObject *proxy) MOZ_OVERRIDE;
    virtual bool call(JSContext *cx, HandleObject proxy, const CallArgs &args) MOZ_OVERRIDE;
    virtual bool construct(JSContext *cx, HandleObject proxy, const CallArgs &args) MOZ_OVERRIDE;
    virtual bool nativeCall(JSContext *cx, IsAcceptableThis test, NativeImpl impl,
                            CallArgs args) MOZ_OVERRIDE;
    virtual bool hasInstance(JSContext *cx, HandleObject proxy, MutableHandleValue v,
                             bool *bp) MOZ_OVERRIDE;
    virtual bool objectClassIs(HandleObject obj, ESClassValue classValue,
                               JSContext *cx) MOZ_OVERRIDE;
    virtual const char *className(JSContext *cx, HandleObject proxy) MOZ_OVERRIDE;
    virtual JSString *fun_toString(JSContext *cx, HandleObject proxy, unsigned indent) MOZ_OVERRIDE;
    virtual bool regexp_toShared(JSContext *cx, HandleObject proxy, RegExpGuard *g) MOZ_OVERRIDE;
    virtual bool defaultValue(JSContext *cx, HandleObject obj, JSType hint,
                              MutableHandleValue vp) MOZ_OVERRIDE;
    virtual bool getElementIfPresent(JSContext *cx, HandleObject obj, HandleObject receiver,
                                     uint32_t index, MutableHandleValue vp,
                                     bool *present) MOZ_OVERRIDE;
    virtual bool getPrototypeOf(JSContext *cx, HandleObject proxy,
                                MutableHandleObject protop) MOZ_OVERRIDE;

    static DeadObjectProxy singleton;
};

extern JSObject *
TransparentObjectWrapper(JSContext *cx, HandleObject existing, HandleObject obj,
                         HandleObject wrappedProto, HandleObject parent,
                         unsigned flags);

// Proxy family for wrappers. Public so that IsWrapper() can be fully inlined by
// jsfriendapi users.
extern JS_FRIEND_DATA(int) sWrapperFamily;

inline bool
IsWrapper(JSObject *obj)
{
    return IsProxy(obj) && GetProxyHandler(obj)->family() == &sWrapperFamily;
}

// Given a JSObject, returns that object stripped of wrappers. If
// stopAtOuter is true, then this returns the outer window if it was
// previously wrapped. Otherwise, this returns the first object for
// which JSObject::isWrapper returns false.
JS_FRIEND_API(JSObject *)
UncheckedUnwrap(JSObject *obj, bool stopAtOuter = true, unsigned *flagsp = NULL);

// Given a JSObject, returns that object stripped of wrappers. At each stage,
// the security wrapper has the opportunity to veto the unwrap. Since checked
// code should never be unwrapping outer window wrappers, we always stop at
// outer windows.
JS_FRIEND_API(JSObject *)
CheckedUnwrap(JSObject *obj, bool stopAtOuter = true);

// Unwrap only the outermost security wrapper, with the same semantics as
// above. This is the checked version of Wrapper::wrappedObject.
JS_FRIEND_API(JSObject *)
UnwrapOneChecked(JSObject *obj, bool stopAtOuter = true);

JS_FRIEND_API(bool)
IsCrossCompartmentWrapper(JSObject *obj);

bool
IsDeadProxyObject(JSObject *obj);

JSObject *
NewDeadProxyObject(JSContext *cx, JSObject *parent);

void
NukeCrossCompartmentWrapper(JSContext *cx, JSObject *wrapper);

bool
RemapWrapper(JSContext *cx, JSObject *wobj, JSObject *newTarget);

JS_FRIEND_API(bool)
RemapAllWrappersForObject(JSContext *cx, JSObject *oldTarget,
                          JSObject *newTarget);

// API to recompute all cross-compartment wrappers whose source and target
// match the given filters.
JS_FRIEND_API(bool)
RecomputeWrappers(JSContext *cx, const CompartmentFilter &sourceFilter,
                  const CompartmentFilter &targetFilter);

/*
 * This auto class should be used around any code, such as brain transplants,
 * that may touch dead zones. Brain transplants can cause problems
 * because they operate on all compartments, whether live or dead. A brain
 * transplant can cause a formerly dead object to be "reanimated" by causing a
 * read or write barrier to be invoked on it during the transplant. In this way,
 * a zone becomes a zombie, kept alive by repeatedly consuming
 * (transplanted) brains.
 *
 * To work around this issue, we observe when mark bits are set on objects in
 * dead zones. If this happens during a brain transplant, we do a full,
 * non-incremental GC at the end of the brain transplant. This will clean up any
 * objects that were improperly marked.
 */
struct JS_FRIEND_API(AutoMaybeTouchDeadZones)
{
    // The version that takes an object just uses it for its runtime.
    AutoMaybeTouchDeadZones(JSContext *cx);
    AutoMaybeTouchDeadZones(JSObject *obj);
    ~AutoMaybeTouchDeadZones();

  private:
    JSRuntime *runtime;
    unsigned markCount;
    bool inIncremental;
    bool manipulatingDeadZones;
};

} /* namespace js */

#endif /* jswrapper_h */