nsIXPConnect.idl

/* -*- Mode: IDL; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * 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/. */

/* The core XPConnect public interfaces. */

#include "nsISupports.idl"

%{ C++
#include "jspubtd.h"
#include "js/TypeDecls.h"
#include "mozilla/Attributes.h"
#include "nsCOMPtr.h"

struct JSFreeOp;

class nsWrapperCache;
class nsAXPCNativeCallContext;
%}

/***************************************************************************/

// NB: jsval and jsid are declared in nsrootidl.idl

[ptr] native JSContextPtr(JSContext);
[ptr] native JSClassPtr(JSClass);
[ptr] native JSFreeOpPtr(JSFreeOp);
[ptr] native JSObjectPtr(JSObject);
[ptr] native JSValConstPtr(const JS::Value);
      native JSEqualityOp(JSEqualityOp);
[ptr] native JSScriptPtr(JSScript);
[ptr] native voidPtrPtr(void*);
[ptr] native nsAXPCNativeCallContextPtr(nsAXPCNativeCallContext);
[ptr] native nsWrapperCachePtr(nsWrapperCache);
[ref] native JSCompartmentOptions(JS::CompartmentOptions);
[ref] native JSCallArgsRef(const JS::CallArgs);
      native JSHandleId(JS::Handle<jsid>);

/***************************************************************************/

// forward declarations...
interface nsIXPCScriptable;
interface nsIXPConnect;
interface nsIXPConnectWrappedNative;
interface nsIInterfaceInfo;
interface nsIXPCSecurityManager;
interface nsIPrincipal;
interface nsIClassInfo;
interface nsIVariant;
interface nsIStackFrame;
interface nsIObjectInputStream;
interface nsIObjectOutputStream;

/***************************************************************************/
[uuid(73e6ff4a-ab99-4d99-ac00-ba39ccb8e4d7)]
interface nsIXPConnectJSObjectHolder : nsISupports
{
    [notxpcom, nostdcall] JSObjectPtr GetJSObject();
};

[uuid(e787be29-db5d-4a45-a3d6-1de1d6b85c30)]
interface nsIXPConnectWrappedNative : nsIXPConnectJSObjectHolder
{
    /* attribute 'JSObject' inherited from nsIXPConnectJSObjectHolder */
    readonly attribute nsISupports      Native;
    readonly attribute JSObjectPtr      JSObjectPrototype;

    /**
     * These are here as an aid to nsIXPCScriptable implementors
     */

    nsIInterfaceInfo FindInterfaceWithMember(in JSHandleId nameID);
    nsIInterfaceInfo FindInterfaceWithName(in JSHandleId nameID);
    [notxpcom] bool HasNativeMember(in JSHandleId name);

    void debugDump(in short depth);

    /*
     * NOTE: Add new IDL methods _before_ the C++ block below if you
     * add them.  Otherwise the vtable won't be what xpidl thinks it
     * is, since GetObjectPrincipal() is virtual.
     */

%{C++
    /**
     * Faster access to the native object from C++.  Will never return null.
     */
    nsISupports* Native() const { return mIdentity; }

protected:
    nsCOMPtr<nsISupports> mIdentity;
public:
%}
};

%{C++

inline
const nsQueryInterface
do_QueryWrappedNative(nsIXPConnectWrappedNative *aWrappedNative)
{
    return nsQueryInterface(aWrappedNative->Native());
}

inline
const nsQueryInterfaceWithError
do_QueryWrappedNative(nsIXPConnectWrappedNative *aWrappedNative,
                      nsresult *aError)

{
    return nsQueryInterfaceWithError(aWrappedNative->Native(), aError);
}

%}

[uuid(3a01b0d6-074b-49ed-bac3-08c76366cae4)]
interface nsIXPConnectWrappedJS : nsIXPConnectJSObjectHolder
{
    /* attribute 'JSObject' inherited from nsIXPConnectJSObjectHolder */
    readonly attribute nsIInterfaceInfo InterfaceInfo;
    readonly attribute nsIIDPtr         InterfaceIID;

    void debugDump(in short depth);

    void aggregatedQueryInterface(in nsIIDRef uuid,
                                  [iid_is(uuid),retval] out nsQIResult result);

};

// Special interface to unmark the internal JSObject.
// QIing to nsIXPConnectWrappedJSUnmarkGray does *not* addref, it only unmarks,
// and QIing to nsIXPConnectWrappedJSUnmarkGray is always supposed to fail.
[builtinclass, uuid(c02a0ce6-275f-4ea1-9c23-08494898b070)]
interface nsIXPConnectWrappedJSUnmarkGray : nsIXPConnectWrappedJS
{
};

/***************************************************************************/

/**
 * This is a sort of a placeholder interface. It is not intended to be
 * implemented. It exists to give the nsIXPCSecurityManager an iid on
 * which to gate a specific activity in XPConnect.
 *
 * That activity is...
 *
 * When JavaScript code uses a component that is itself implemented in
 * JavaScript then XPConnect will build a wrapper rather than directly
 * expose the JSObject of the component. This allows components implemented
 * in JavaScript to 'look' just like any other xpcom component (from the
 * perspective of the JavaScript caller). This insulates the component from
 * the caller and hides any properties or methods that are not part of the
 * interface as declared in xpidl. Usually this is a good thing.
 *
 * However, in some cases it is useful to allow the JS caller access to the
 * JS component's underlying implementation. In order to facilitate this
 * XPConnect supports the 'wrappedJSObject' property. The caller code can do:
 *
 * // 'foo' is some xpcom component (that might be implemented in JS).
 * try {
 *   var bar = foo.wrappedJSObject;
 *   if(bar) {
 *      // bar is the underlying JSObject. Do stuff with it here.
 *   }
 * } catch(e) {
 *   // security exception?
 * }
 *
 * Recall that 'foo' above is an XPConnect wrapper, not the underlying JS
 * object. The property get "foo.wrappedJSObject" will only succeed if three
 * conditions are met:
 *
 * 1) 'foo' really is an XPConnect wrapper around a JSObject.
 * 2) The underlying JSObject actually implements a "wrappedJSObject"
 *    property that returns a JSObject. This is called by XPConnect. This
 *    restriction allows wrapped objects to only allow access to the underlying
 *    JSObject if they choose to do so. Ususally this just means that 'foo'
 *    would have a property tht looks like:
 *       this.wrappedJSObject = this.
 * 3) The implemementation of nsIXPCSecurityManager (if installed) allows
 *    a property get on the interface below. Although the JSObject need not
 *    implement 'nsIXPCWrappedJSObjectGetter', XPConnect will ask the
 *    security manager if it is OK for the caller to access the only method
 *    in nsIXPCWrappedJSObjectGetter before allowing the activity. This fits
 *    in with the security manager paradigm and makes control over accessing
 *    the property on this interface the control factor for getting the
 *    underlying wrapped JSObject of a JS component from JS code.
 *
 * Notes:
 *
 * a) If 'foo' above were the underlying JSObject and not a wrapper at all,
 *    then this all just works and XPConnect is not part of the picture at all.
 * b) One might ask why 'foo' should not just implement an interface through
 *    which callers might get at the underlying object. There are three reasons:
 *   i)   XPConnect would still have to do magic since JSObject is not a
 *        scriptable type.
 *   ii)  JS Components might use aggregation (like C++ objects) and have
 *        different JSObjects for different interfaces 'within' an aggregate
 *        object. But, using an additional interface only allows returning one
 *        underlying JSObject. However, this allows for the possibility that
 *        each of the aggregte JSObjects could return something different.
 *        Note that one might do: this.wrappedJSObject = someOtherObject;
 *   iii) Avoiding the explicit interface makes it easier for both the caller
 *        and the component.
 *
 *  Anyway, some future implementation of nsIXPCSecurityManager might want
 *  do special processing on 'nsIXPCSecurityManager::CanGetProperty' when
 *  the interface id is that of nsIXPCWrappedJSObjectGetter.
 */

[scriptable, uuid(254bb2e0-6439-11d4-8fe0-0010a4e73d9a)]
interface nsIXPCWrappedJSObjectGetter : nsISupports
{
    readonly attribute nsISupports neverCalled;
};

/***************************************************************************/

/*
 * This interface is implemented by outside code and registered with xpconnect
 * via nsIXPConnect::setFunctionThisTranslator.
 *
 * The reason this exists is to support calls to JavaScript event callbacks
 * needed by the DOM via xpconnect from C++ code.
 *
 * We've added support for wrapping JS function objects as xpcom interfaces
 * by declaring the given interface as a [function] interface. However, to
 * support the requirements of JS event callbacks we need to call the JS
 * function with the 'this' set as the JSObject for which the event is being
 * fired; e.g. a form node.
 *
 * We've decided that for all cases we care about the appropriate 'this' object
 * can be derived from the first param in the call to the callback. In the
 * event handler case the first param is an event object.
 *
 * Though we can't change all the JS code so that it would setup its own 'this',
 * we can add plugin 'helper' support to xpconnect. And that is what we have
 * here.
 *
 * The idea is that at startup time some code that cares about this issue
 * (e.g. the DOM helper code) can register a nsIXPCFunctionThisTranslator
 * object with xpconnect to handle calls to [function] interfaces of a given
 * iid. When xpconnect goes to invoke a method on a wrapped JSObject for
 * an interface marked as [function], xpconnect will check if the first param
 * of the method is an xpcom object pointer and if so it will check to see if a
 * nsIXPCFunctionThisTranslator has been registered for the given iid of the
 * interface being called. If so it will call the translator and get an
 * interface pointer to use as the 'this' for the call. If the translator
 * returns a non-null interface pointer (which it should then have addref'd
 * since it is being returned as an out param), xpconnect will attempt to build
 * a wrapper around the pointer and get a JSObject from that wrapper to use
 * as the 'this' for the call.
 *
 * If a null interface pointer is returned then xpconnect will use the default
 * 'this' - the same JSObject as the function object it is calling.
 */

[uuid(f5f84b70-92eb-41f1-a1dd-2eaac0ed564c)]
interface nsIXPCFunctionThisTranslator : nsISupports
{
    nsISupports TranslateThis(in nsISupports aInitialThis);
};

/***************************************************************************/


%{ C++
// For use with the service manager
// {CB6593E0-F9B2-11d2-BDD6-000064657374}
#define NS_XPCONNECT_CID \
{ 0xcb6593e0, 0xf9b2, 0x11d2, \
    { 0xbd, 0xd6, 0x0, 0x0, 0x64, 0x65, 0x73, 0x74 } }
%}

[noscript, uuid(768507b5-b981-40c7-8276-f6a1da502a24)]
interface nsIXPConnect : nsISupports
{
%{ C++
  NS_DEFINE_STATIC_CID_ACCESSOR(NS_XPCONNECT_CID)
%}

    /**
     * Creates a new global object using the given aCOMObj as the global
     * object. The object will be set up according to the flags (defined
     * below). If you do not pass INIT_JS_STANDARD_CLASSES, then aCOMObj
     * must implement nsIXPCScriptable so it can resolve the standard
     * classes when asked by the JS engine.
     *
     * @param aJSContext the context to use while creating the global object.
     * @param aCOMObj the native object that represents the global object.
     * @param aPrincipal the principal of the code that will run in this
     *                   compartment. Can be null if not on the main thread.
     * @param aFlags one of the flags below specifying what options this
     *               global object wants.
     * @param aOptions JSAPI-specific options for the new compartment.
     */
    nsIXPConnectJSObjectHolder
    initClassesWithNewWrappedGlobal(
                  in JSContextPtr         aJSContext,
                  in nsISupports          aCOMObj,
                  in nsIPrincipal         aPrincipal,
                  in uint32_t             aFlags,
                  in JSCompartmentOptions aOptions);

    const uint32_t INIT_JS_STANDARD_CLASSES  = 1 << 0;
    const uint32_t DONT_FIRE_ONNEWGLOBALHOOK = 1 << 1;
    const uint32_t OMIT_COMPONENTS_OBJECT    = 1 << 2;

    /**
    * wrapNative will create a new JSObject or return an existing one.
    *
    * This method now correctly deals with cases where the passed in xpcom
    * object already has an associated JSObject for the cases:
    *  1) The xpcom object has already been wrapped for use in the same scope
    *     as an nsIXPConnectWrappedNative.
    *  2) The xpcom object is in fact a nsIXPConnectWrappedJS and thus already
    *     has an underlying JSObject.
    *
    * It *might* be possible to QueryInterface the nsIXPConnectJSObjectHolder
    * returned by the method into a nsIXPConnectWrappedNative or a
    * nsIXPConnectWrappedJS.
    *
    * This method will never wrap the JSObject involved in an
    * XPCNativeWrapper before returning.
    *
    * Returns:
    *    success:
    *       NS_OK
    *    failure:
    *       NS_ERROR_XPC_BAD_CONVERT_NATIVE
    *       NS_ERROR_XPC_CANT_GET_JSOBJECT_OF_DOM_OBJECT
    *       NS_ERROR_FAILURE
    */
    JSObjectPtr
    wrapNative(in JSContextPtr aJSContext,
               in JSObjectPtr  aScope,
               in nsISupports  aCOMObj,
               in nsIIDRef     aIID);

    /**
     * Same as wrapNative, but it returns the JSObject in an nsIXPConnectJSObjectHolder.
     */
    nsIXPConnectJSObjectHolder
    wrapNativeHolder(in JSContextPtr aJSContext,
                     in JSObjectPtr  aScope,
                     in nsISupports  aCOMObj,
                     in nsIIDRef     aIID);

    /**
     * Same as wrapNative, but it returns the JSObject in aVal. C++ callers
     * must ensure that aVal is rooted.
     * aIID may be null, it means the same as passing in
     * &NS_GET_IID(nsISupports) but when passing in null certain shortcuts
     * can be taken because we know without comparing IIDs that the caller is
     * asking for an nsISupports wrapper.
     * If aAllowWrapper, then the returned value will be wrapped in the proper
     * type of security wrapper on top of the XPCWrappedNative (if needed).
     * This method doesn't push aJSContext on the context stack, so the caller
     * is required to push it if the top of the context stack is not equal to
     * aJSContext.
     */
    void
    wrapNativeToJSVal(in JSContextPtr aJSContext,
                      in JSObjectPtr  aScope,
                      in nsISupports  aCOMObj,
                      in nsWrapperCachePtr aCache,
                      in nsIIDPtr     aIID,
                      in boolean      aAllowWrapper,
                      out jsval       aVal);

    /**
    * wrapJS will yield a new or previously existing xpcom interface pointer
    * to represent the JSObject passed in.
    *
    * This method now correctly deals with cases where the passed in JSObject
    * already has an associated xpcom interface for the cases:
    *  1) The JSObject has already been wrapped as a nsIXPConnectWrappedJS.
    *  2) The JSObject is in fact a nsIXPConnectWrappedNative and thus already
    *     has an underlying xpcom object.
    *  3) The JSObject is of a jsclass which supports getting the nsISupports
    *     from the JSObject directly. This is used for idlc style objects
    *     (e.g. DOM objects).
    *
    * It *might* be possible to QueryInterface the resulting interface pointer
    * to nsIXPConnectWrappedJS.
    *
    * Returns:
    *   success:
    *     NS_OK
    *    failure:
    *       NS_ERROR_XPC_BAD_CONVERT_JS
    *       NS_ERROR_FAILURE
    */
    void
    wrapJS(in JSContextPtr aJSContext,
           in JSObjectPtr  aJSObj,
           in nsIIDRef     aIID,
           [iid_is(aIID),retval] out nsQIResult result);

    /**
     * Wraps the given jsval in a nsIVariant and returns the new variant.
     */
    nsIVariant
    jSValToVariant(in JSContextPtr cx, in jsval aJSVal);

    /**
    * This only succeeds if the JSObject is a nsIXPConnectWrappedNative.
    * A new wrapper is *never* constructed.
    */
    nsIXPConnectWrappedNative
    getWrappedNativeOfJSObject(in JSContextPtr aJSContext,
                               in JSObjectPtr  aJSObj);

    // Will return null if there is no JS stack right now.
    readonly attribute nsIStackFrame                CurrentJSStack;
    readonly attribute nsAXPCNativeCallContextPtr   CurrentNativeCallContext;

    void debugDump(in short depth);
    void debugDumpObject(in nsISupports aCOMObj, in short depth);
    void debugDumpJSStack(in boolean showArgs,
                          in boolean showLocals,
                          in boolean showThisProps);

    /**
    * wrapJSAggregatedToNative is just like wrapJS except it is used in cases
    * where the JSObject is also aggregated to some native xpcom Object.
    * At present XBL is the only system that might want to do this.
    *
    * XXX write more!
    *
    * Returns:
    *   success:
    *     NS_OK
    *    failure:
    *       NS_ERROR_XPC_BAD_CONVERT_JS
    *       NS_ERROR_FAILURE
    */
    void
    wrapJSAggregatedToNative(in nsISupports  aOuter,
                             in JSContextPtr aJSContext,
                             in JSObjectPtr  aJSObj,
                             in nsIIDRef     aIID,
                             [iid_is(aIID),retval] out nsQIResult result);

    // Methods added since mozilla 0.6....

    /**
    * This only succeeds if the native object is already wrapped by xpconnect.
    * A new wrapper is *never* constructed.
    */
    nsIXPConnectWrappedNative
    getWrappedNativeOfNativeObject(in JSContextPtr aJSContext,
                                   in JSObjectPtr  aScope,
                                   in nsISupports  aCOMObj,
                                   in nsIIDRef     aIID);

    void
    setFunctionThisTranslator(in nsIIDRef aIID,
                              in nsIXPCFunctionThisTranslator aTranslator);

    JSObjectPtr
    getWrappedNativePrototype(in JSContextPtr aJSContext,
                              in JSObjectPtr  aScope,
                              in nsIClassInfo aClassInfo);

    jsval variantToJS(in JSContextPtr ctx, in JSObjectPtr scope, in nsIVariant value);
    nsIVariant JSToVariant(in JSContextPtr ctx, in jsval value);

    /**
     * Create a sandbox for evaluating code in isolation using
     * evalInSandboxObject().
     *
     * @param cx A context to use when creating the sandbox object.
     * @param principal The principal (or NULL to use the null principal)
     *                  to use when evaluating code in this sandbox.
     */
    [noscript] JSObjectPtr createSandbox(in JSContextPtr cx, in nsIPrincipal principal);

    /**
     * Evaluate script in a sandbox, completely isolated from all
     * other running scripts.
     *
     * @param source The source of the script to evaluate.
     * @param filename The filename of the script. May be null.
     * @param cx The context to use when setting up the evaluation of
     *           the script. The actual evaluation will happen on a new
     *           temporary context.
     * @param sandbox The sandbox object to evaluate the script in.
     * @param version The JavaScript version to use for evaluating the script.
     *                Should be a valid JSVersion from jspubtd.h.
     * @return The result of the evaluation as a jsval. If the caller
     *         intends to use the return value from this call the caller
     *         is responsible for rooting the jsval before making a call
     *         to this method.
     */
    [noscript] jsval evalInSandboxObject(in AString source, in string filename,
                                         in JSContextPtr cx,
                                         in JSObjectPtr sandbox,
                                         in int32_t version);

    /**
     * Trigger a JS garbage collection.
     * Use a js::gcreason::Reason from jsfriendapi.h for the kind.
     */
    void GarbageCollect(in uint32_t reason);

    /**
     * Signals a good place to do an incremental GC slice, because the
     * browser is drawing a frame.
     */
    void NotifyDidPaint();

%{C++
    /**
     * Get the object principal for this wrapper.  Note that this may well end
     * up being null; in that case one should seek principals elsewhere.  Null
     * here does NOT indicate system principal or no principals at all, just
     * that this wrapper doesn't have an intrinsic one.
     */
    virtual nsIPrincipal* GetPrincipal(JSObject* obj,
                                       bool allowShortCircuit) const = 0;
    virtual char* DebugPrintJSStack(bool showArgs,
                                    bool showLocals,
                                    bool showThisProps) = 0;
%}

    [noscript] void writeScript(in nsIObjectOutputStream aStream,
                                in JSContextPtr aJSContext,
                                in JSScriptPtr aJSScript);

    [noscript] JSScriptPtr readScript(in nsIObjectInputStream aStream,
                                      in JSContextPtr aJSContext);

    [noscript] void writeFunction(in nsIObjectOutputStream aStream,
                                  in JSContextPtr aJSContext,
                                  in JSObjectPtr aJSObject);

    [noscript] JSObjectPtr readFunction(in nsIObjectInputStream aStream,
                                        in JSContextPtr aJSContext);
};