Source code of Windows XP (NT5)
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4.4 KiB

#include "priv.h"
#include "nullstm.h"
#ifndef UNIX
// A static empty stream implementation, for back compat & no memory hit
//
// Macros copied from cfdefs.h
//
#define STDMETHODX(fn) HRESULT STDMETHODCALLTYPE fn
#define STDMETHODX_(ret,fn) ret STDMETHODCALLTYPE fn
class CNullStream {
public:
IStream *vtable;
STDMETHODX (QueryInterface)(REFIID riid, void **ppvObj);
STDMETHODX_(ULONG, AddRef)();
STDMETHODX_(ULONG, Release)();
STDMETHODX (Read)(void *pv, ULONG cb, ULONG *pcbRead) { if (pcbRead) *pcbRead = 0; return E_NOTIMPL; }
STDMETHODX (Write)(void const *pv, ULONG cb, ULONG *pcbWritten) { if (pcbWritten) *pcbWritten = 0; return E_NOTIMPL; }
STDMETHODX (Seek)(LARGE_INTEGER dlibMove, DWORD dwOrigin, ULARGE_INTEGER *plibNewPosition) { plibNewPosition->HighPart = plibNewPosition->LowPart = 0; return E_NOTIMPL; }
STDMETHODX (SetSize)(ULARGE_INTEGER libNewSize) { return E_NOTIMPL; }
STDMETHODX (CopyTo)(IStream *, ULARGE_INTEGER, ULARGE_INTEGER *pcbRead, ULARGE_INTEGER *pcbWritten) { if (pcbRead) pcbRead->LowPart = pcbRead->HighPart = 0; if (pcbWritten) pcbWritten->LowPart = pcbWritten->HighPart = 0; return E_NOTIMPL; }
STDMETHODX (Commit)(DWORD) { return E_NOTIMPL; }
STDMETHODX (Revert)() { return E_NOTIMPL; }
STDMETHODX (LockRegion)(ULARGE_INTEGER, ULARGE_INTEGER, DWORD) { return E_NOTIMPL; }
STDMETHODX (UnlockRegion)(ULARGE_INTEGER, ULARGE_INTEGER, DWORD) { return E_NOTIMPL; }
STDMETHODX (Stat)(STATSTG *, DWORD) { return E_NOTIMPL; }
STDMETHODX (Clone)(IStream **ppstm) { *ppstm = NULL; return E_NOTIMPL; }
};
STDMETHODIMP CNullStream::QueryInterface(REFIID riid, void **ppvObj)
{
if (IsEqualIID(riid, IID_IStream) || IsEqualIID(riid, IID_IUnknown))
{
*ppvObj=this;
// DllAddRef(); // if this dll supported CoCreateInstance
return S_OK;
}
*ppvObj = NULL;
return E_NOINTERFACE;
}
STDMETHODIMP_(ULONG) CNullStream::AddRef()
{
// DllAddRef(); // if this dll supported CoCreateInstance
return 2;
}
STDMETHODIMP_(ULONG) CNullStream::Release()
{
// DllRelease(); // if this dll supported CoCreateInstance
return 1;
}
// We need the C vtable declaration, but this is .CPP.
// Simulate the vtable, swiped from objidl.h and touched up.
//
typedef struct IStreamVtbl
{
HRESULT ( STDMETHODCALLTYPE CNullStream::*QueryInterface )(REFIID riid, void **ppvObject);
ULONG ( STDMETHODCALLTYPE CNullStream::*AddRef )( );
ULONG ( STDMETHODCALLTYPE CNullStream::*Release )( );
HRESULT ( STDMETHODCALLTYPE CNullStream::*Read )(
void *pv,
ULONG cb,
ULONG *pcbRead);
HRESULT ( STDMETHODCALLTYPE CNullStream::*Write )(
const void *pv,
ULONG cb,
ULONG *pcbWritten);
HRESULT ( STDMETHODCALLTYPE CNullStream::*Seek )(
LARGE_INTEGER dlibMove,
DWORD dwOrigin,
ULARGE_INTEGER *plibNewPosition);
HRESULT ( STDMETHODCALLTYPE CNullStream::*SetSize )(
ULARGE_INTEGER libNewSize);
HRESULT ( STDMETHODCALLTYPE CNullStream::*CopyTo )(
IStream *pstm,
ULARGE_INTEGER cb,
ULARGE_INTEGER *pcbRead,
ULARGE_INTEGER *pcbWritten);
HRESULT ( STDMETHODCALLTYPE CNullStream::*Commit )(
DWORD grfCommitFlags);
HRESULT ( STDMETHODCALLTYPE CNullStream::*Revert )( );
HRESULT ( STDMETHODCALLTYPE CNullStream::*LockRegion )(
ULARGE_INTEGER libOffset,
ULARGE_INTEGER cb,
DWORD dwLockType);
HRESULT ( STDMETHODCALLTYPE CNullStream::*UnlockRegion )(
ULARGE_INTEGER libOffset,
ULARGE_INTEGER cb,
DWORD dwLockType);
HRESULT ( STDMETHODCALLTYPE CNullStream::*Stat )(
STATSTG *pstatstg,
DWORD grfStatFlag);
HRESULT ( STDMETHODCALLTYPE CNullStream::*Clone )(
IStream **ppstm);
} IStreamVtbl;
IStream* SHConstNullStream()
{
static const IStreamVtbl c_NullStream = {
CNullStream::QueryInterface,
CNullStream::AddRef,
CNullStream::Release,
CNullStream::Read,
CNullStream::Write,
CNullStream::Seek,
CNullStream::SetSize,
CNullStream::CopyTo,
CNullStream::Commit,
CNullStream::Revert,
CNullStream::LockRegion,
CNullStream::UnlockRegion,
CNullStream::Stat,
CNullStream::Clone,
};
static const void * vtable = (void*)&c_NullStream;
return (IStream*)&vtable;
}
#endif