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nullstm.cpp
Package: shell.rar　[view]
Upload User: xhy777
Upload Date: 2007-02-14
Package Size: 24088k
Code Size: 5k
Category:

Windows Kernel

Development Platform:

Visual C++

nullstm.cpp：Code Content
  1. #include "priv.h"
  2. #include "nullstm.h"
  4. #ifndef UNIX
  6. // A static empty stream implementation, for back compat & no memory hit
  7. //
  8. // Macros copied from cfdefs.h
  9. //
  10. #define STDMETHODX(fn)      HRESULT STDMETHODCALLTYPE fn
  11. #define STDMETHODX_(ret,fn) ret STDMETHODCALLTYPE fn
  12. class CNullStream {
  13. public:
  14.     IStream *vtable;
  15.     
  16.     STDMETHODX (QueryInterface)(REFIID riid, void **ppvObj);
  17.     STDMETHODX_(ULONG, AddRef)();
  18.     STDMETHODX_(ULONG, Release)();
  20.     STDMETHODX (Read)(void *pv, ULONG cb, ULONG *pcbRead) { if (pcbRead) *pcbRead = 0; return E_NOTIMPL; }
  21.     STDMETHODX (Write)(void const *pv, ULONG cb, ULONG *pcbWritten) { if (pcbWritten) *pcbWritten = 0; return E_NOTIMPL; }
  22.     STDMETHODX (Seek)(LARGE_INTEGER dlibMove, DWORD dwOrigin, ULARGE_INTEGER *plibNewPosition) { plibNewPosition->HighPart = plibNewPosition->LowPart = 0; return E_NOTIMPL; }
  23.     STDMETHODX (SetSize)(ULARGE_INTEGER libNewSize) { return E_NOTIMPL; }
  24.     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; }
  25.     STDMETHODX (Commit)(DWORD) { return E_NOTIMPL; }
  26.     STDMETHODX (Revert)() { return E_NOTIMPL; }
  27.     STDMETHODX (LockRegion)(ULARGE_INTEGER, ULARGE_INTEGER, DWORD) { return E_NOTIMPL; }
  28.     STDMETHODX (UnlockRegion)(ULARGE_INTEGER, ULARGE_INTEGER, DWORD) { return E_NOTIMPL; }
  29.     STDMETHODX (Stat)(STATSTG *, DWORD) { return E_NOTIMPL; }
  30.     STDMETHODX (Clone)(IStream **ppstm) { *ppstm = NULL; return E_NOTIMPL; }
  31. };
  33. STDMETHODIMP CNullStream::QueryInterface(REFIID riid, void **ppvObj)
  34. {
  35.     if (IsEqualIID(riid, IID_IStream) || IsEqualIID(riid, IID_IUnknown))
  36.     {
  37.         *ppvObj=this;
  38.         // DllAddRef(); // if this dll supported CoCreateInstance
  39.         return S_OK;
  40.     }
  42.     *ppvObj = NULL;
  43.     return E_NOINTERFACE;
  44. }
  45. STDMETHODIMP_(ULONG) CNullStream::AddRef()
  46. {
  47.     // DllAddRef(); // if this dll supported CoCreateInstance
  48.     return 2;
  49. }
  50. STDMETHODIMP_(ULONG) CNullStream::Release()
  51. {
  52.     // DllRelease(); // if this dll supported CoCreateInstance
  53.     return 1;
  54. }
  56. // We need the C vtable declaration, but this is .CPP.
  57. // Simulate the vtable, swiped from objidl.h and touched up.
  58. //
  59. typedef struct IStreamVtbl
  60. {
  61.     HRESULT ( STDMETHODCALLTYPE CNullStream::*QueryInterface )(REFIID riid, void **ppvObject);
  62.     ULONG ( STDMETHODCALLTYPE CNullStream::*AddRef )( );
  63.     ULONG ( STDMETHODCALLTYPE CNullStream::*Release )( );
  64.     
  65.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Read )( 
  66.         void *pv,
  67.         ULONG cb,
  68.         ULONG *pcbRead);
  69.     
  70.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Write )( 
  71.         const void *pv,
  72.         ULONG cb,
  73.         ULONG *pcbWritten);
  74.     
  75.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Seek )( 
  76.         LARGE_INTEGER dlibMove,
  77.         DWORD dwOrigin,
  78.         ULARGE_INTEGER *plibNewPosition);
  79.     
  80.     HRESULT ( STDMETHODCALLTYPE CNullStream::*SetSize )( 
  81.         ULARGE_INTEGER libNewSize);
  82.     
  83.     HRESULT ( STDMETHODCALLTYPE CNullStream::*CopyTo )( 
  84.         IStream *pstm,
  85.         ULARGE_INTEGER cb,
  86.         ULARGE_INTEGER *pcbRead,
  87.         ULARGE_INTEGER *pcbWritten);
  88.     
  89.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Commit )( 
  90.         DWORD grfCommitFlags);
  91.     
  92.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Revert )( );
  93.     
  94.     HRESULT ( STDMETHODCALLTYPE CNullStream::*LockRegion )( 
  95.         ULARGE_INTEGER libOffset,
  96.         ULARGE_INTEGER cb,
  97.         DWORD dwLockType);
  98.     
  99.     HRESULT ( STDMETHODCALLTYPE CNullStream::*UnlockRegion )( 
  100.         ULARGE_INTEGER libOffset,
  101.         ULARGE_INTEGER cb,
  102.         DWORD dwLockType);
  103.     
  104.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Stat )( 
  105.         STATSTG *pstatstg,
  106.         DWORD grfStatFlag);
  107.     
  108.     HRESULT ( STDMETHODCALLTYPE CNullStream::*Clone )( 
  109.         IStream **ppstm);
  110.     
  111. } IStreamVtbl;
  114. IStream* SHConstNullStream()
  115. {
  116.     static const IStreamVtbl c_NullStream = {
  117.         CNullStream::QueryInterface, 
  118.         CNullStream::AddRef,
  119.         CNullStream::Release,
  120.         CNullStream::Read,
  121.         CNullStream::Write,
  122.         CNullStream::Seek,
  123.         CNullStream::SetSize,
  124.         CNullStream::CopyTo,
  125.         CNullStream::Commit,
  126.         CNullStream::Revert,
  127.         CNullStream::LockRegion,
  128.         CNullStream::UnlockRegion,
  129.         CNullStream::Stat,
  130.         CNullStream::Clone,
  131.     };
  132.     static const void * vtable = (void*)&c_NullStream;
  134.     return (IStream*)&vtable;
  135. }
  137. #endif