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122 lines
3 KiB
C++
122 lines
3 KiB
C++
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/*++
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Copyright (c) Microsoft Corporation
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Module Name:
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FxSyncRequest.hpp
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Abstract:
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FxSyncRequest is meant to be a completely stack based structure. This
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allows synchronous functions to not have to allocate an FxRequest for
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something that only lives for the lifetime of the function call.
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Additionally, this object can substitute a WDFREQUEST for itself when making
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synchronous calls. This allows the driver writer to pass a WDFREQUEST to a
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synchronous DDI and be able to cancel it on another thread later.
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To overcome the initial reference count that is associated upon request, the
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destructor releases the initial reference and SelfDestruct does nothing
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because there is no memory to free.
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FxSyncRequest derives from FxRequestBase as protected so that it cannot be
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used as a FxRequestBase directly. Instead, m_TrueRequest should be used.
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m_TrueRequest is either this object itself or the WDFREQUEST, as set by
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SetRequestHandle.
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Author:
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Environment:
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kernel mode only
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Revision History:
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--*/
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#ifndef _FXSYNCREQUEST_H_
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#define _FXSYNCREQUEST_H_
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class DECLSPEC_ALIGN(MEMORY_ALLOCATION_ALIGNMENT) FxSyncRequest : protected FxRequestBase {
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public:
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// Create a sync request that allocates its own PIRP
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FxSyncRequest(
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__in PFX_DRIVER_GLOBALS FxDriverGlobals,
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__in_opt FxRequestContext* Context,
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__in_opt WDFREQUEST Request = NULL
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);
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~FxSyncRequest();
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//
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// FxObject overrides
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//
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VOID
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SelfDestruct(
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VOID
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);
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protected:
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PVOID
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operator new(
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__in size_t Size
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)
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{
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UNREFERENCED_PARAMETER(Size);
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ASSERTMSG("FxSyncRequest::operator new called, should only be"
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" declared on the stack\n", FALSE);
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return NULL;
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}
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public:
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NTSTATUS
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Initialize(
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VOID
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)
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{
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NTSTATUS status;
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#if (FX_CORE_MODE == FX_CORE_USER_MODE)
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//
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// FxCrEvent initialization can fail in UMDF so check for status.
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//
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status = m_DestroyedEvent.Initialize();
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if (!NT_SUCCESS(status)) {
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return status;
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}
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#else
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UNREFERENCED_PARAMETER(status);
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DO_NOTHING();
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#endif
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return STATUS_SUCCESS;
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}
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//
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// Since this object can be sitting on a list which is access by another
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// thread and that thread will expect lifetime semantics from AddRef and
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// Release, we need to hold up destruction of the object until all
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// references are released. This event will be set when the last reference
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// is dropped.
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//
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FxCREvent m_DestroyedEvent;
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//
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// By default, this will point to this object. If AssignRequestHandle is
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// called, it will point to the underlying object for that handle. Since
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// this object derives from FxRequestBase as protected, this field is how
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// the object is used as an FxRequestBase* pointer.
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//
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FxRequestBase* m_TrueRequest;
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BOOLEAN m_ClearContextOnDestroy;
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};
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#endif _FXSYNCREQUEST_H_
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