Problem with FileIOCompletionRoutine ???

HumanOsc

Hello... I like to implement WriteFileEx / ReadFileEx in one of my classes... Is there any safe way to implement LPOVERLAPPED_COMPLETION_ROUTINE as a (non static) member function ? :doh: Thx... :-D -- modified at 5:09 Wednesday 14th September, 2005

cmk

Off the top of my head (i.e. untested) do something like this:

#define IOOP_READ 1
#define IOOP_WRITE 2

#define CK_CONTAINING_RECORD( PTR, TYP, FLD ) \
( (TYP*)( (byte*)(PTR) - (byte*)(&((TYP*)0)->FLD) ) )

class MyFile; // forward reference

class MyOL : public OVERLAPPED {
public:
virtual ~MyOL( void ) {
if( Buff ) delete [] Buff;
}

MyFile  \*File;
DWORD    Op;
DWORD    Cnt;
char    \*Buff;

// go around vtable
OVERLAPPED  Ptr( void )  { return(&Internal); }

};

class MyFile {
protected:
HANDLE hnd;

static  void CALLBACK  iocr( DWORD ERR, DWORD CNT, OVERLAPPED \*OL ) {
    if( !OL )  return;
    MyOL  \*ol = CK\_CONTAINING\_RECORD(OL, MyOL, Internal);
    ol->Cnt = CNT;
    ol->File->OnIOC(ol);
    delete ol;
}

void  onIOC( MyOL \*OL ) {
    switch( OL->Op ) {
        case IOOP\_READ  : ...
        case IOOP\_WRITE : ...
    }
}

public:
bool ReadEx( DWORD SZ ) {
if( !SZ ) return(false);
MyOL *ol = new MyOL();
ol->Op = IOOP_READ;
ol->File = this;
ol->Buff = new char[SZ];
return( ReadFileEx(hnd, ol->Buff, SZ, ol->Ptr(), iocr) );
}
bool WriteEx( DWORD SZ, void *BUFF ) {
if( !SZ || !BUFF ) return(false);
MyOL *ol = new MyOL();
ol->Op = IOOP_WRITE;
ol->File = this;
ol->Buff = new char[SZ];
memcpy(ol->Buff, BUFF, SZ);
return( WriteFileEx(hnd, ol->Buff, SZ, ol->Ptr(), iocr) );
}
};

...cmk Save the whales - collect the whole set

HumanOsc

Hello... This is very guru like solution... :) Big Thx, greets from germany...