OPNROWST.CPP

//-------------------------------------------------------------------- 
// Microsoft OLE DB Sample Provider 
// (C) Copyright 1994 - 1996 Microsoft Corporation.  All Rights Reserved. 
// 
// @doc 
// 
// @module OPNROWST.CPP | IOpenRowset interface implementation 
// 
 
// Includes ------------------------------------------------------------------ 
 
#include "headers.h" 
 
 
// Code ---------------------------------------------------------------------- 
 
 
 
// CImpIOpenRowset::OpenRowset ------------------------------------------------ 
// 
// @mfunc Opens and returns a rowset that includes all rows from a single base table 
// 
// @rdesc HRESULT 
//      @flag S_OK                  | The method succeeded 
//      @flag E_INVALIDARG          | pTableID was NULL 
//      @flag E_FAIL                | Provider-specific error 
//      @flag DB_E_NOTABLE          | Specified table does not exist in current Data 
//                                  | Data Source object 
//      @flag E_OUTOFMEMORY         | Out of memory 
//      @flag E_NOINTERFACE         | The requested interface was not available 
 
STDMETHODIMP CImpIOpenRowset::OpenRowset 
    ( 
    IUnknown*                   pUnkOuter,          //@parm IN    | Controlling unknown, if any 
    DBID*                       pTableID,           //@parm IN    | table to open 
DBID*pIndexID,//@parm IN  | DBID of the index 
    REFIID                      riid,               //@parm IN    | interface to return 
    ULONG                       cProperties,        //@parm IN    | count of properties 
    DBPROPSETrgProperties[],     //@parm INOUT | array of property values 
    IUnknown**                  ppRowset            //@parm OUT   | where to return interface 
    ) 
{ 
    int  cCharsCopied; 
    char szFileName[MAX_PATH ]; 
    char szFile[_MAX_PATH ] = ""; 
 
    CFileIO*    pFileio = NULL; 
    CRowset*    pRowset = NULL; 
    HRESULT     hr; 
 
    // NULL out-params in case of error 
    if( ppRowset ) 
    *ppRowset = NULL; 
 
    // validate in-params 
    if (pUnkOuter) 
        return ResultFromScode( DB_E_NOAGGREGATION ); 
 
    if (!pTableID && !pIndexID) 
        return ResultFromScode( E_INVALIDARG ); 
 
    if (pTableID->eKind != DBKIND_NAME || !pTableID->uName.pwszName) 
        return ResultFromScode( E_INVALIDARG ); 
 
    if ((cProperties != 0) && (!rgProperties)) 
        return ResultFromScode( E_INVALIDARG ); 
 
    assert( m_pObj ); 
 
    // this DBSession object can only create 1 Rowset object 
    if (m_pObj->m_fRowsetCreated) 
        return ResultFromScode( E_FAIL ); 
 
    // get file name 
    cCharsCopied = WideCharToMultiByte( CP_ACP, 0, pTableID->uName.pwszName, -1, 
                        szFileName, sizeof( szFileName ), NULL, NULL ); 
    if (!cCharsCopied) 
        return ResultFromScode( E_FAIL ); 
 
    // Concatenate the path and filename 
    lstrcat( szFile, m_pObj->m_szPath ); 
    lstrcat( szFile, "\\" ); 
    lstrcat( szFile, szFileName ); 
 
    // open and initialize a file object 
    pFileio = new CFileIO(); 
    if (!pFileio) 
        return ResultFromScode( E_OUTOFMEMORY ); 
 
    hr = pFileio->fInit( szFile ); 
    if (FAILED( hr )) 
        { 
        delete pFileio; 
        return ResultFromScode( E_FAIL ); 
        } 
 
    // open and initialize a rowset\cursor object 
    pRowset = new CRowset( NULL ); 
    if (!pRowset) 
        { 
        delete pFileio; 
        return ResultFromScode( E_OUTOFMEMORY ); 
        } 
    // Initialize the rowset\cursor. 
    // For now, since don't yet support "setable" properties, so no properties to pass. 
    // The rowset will always create all of its interfaces. 
    // This is all-or-nothing. 
    if (!pRowset->FInit( pFileio )) 
        { 
        delete pFileio; 
        delete pRowset; 
        return ResultFromScode( DB_E_NOTABLE ); 
        } 
//At this point we have handed off the pFileio pointer to the sample 
//provider so null it out. 
pFileio = NULL; 
 
    // get requested interface pointer on rowset\cursor 
    hr = pRowset->QueryInterface( riid, (void **) ppRowset ); 
    if (FAILED( hr )) 
    { 
    delete pRowset; 
    delete pFileio; 
 
// After a call to QI we still want to return S_OK, 
// if the ppRowset was NULL because Execution was to happen 
// we just don't want to return a result set. 
if( ppRowset == NULL ) 
return ResultFromScode(S_OK); 
else 
        return ResultFromScode( E_NOINTERFACE ); 
    } 
 
    // all went well 
    m_pObj->m_fRowsetCreated = TRUE; 
//Assign creator pointer. Used for IRosetInfo::GetSpecificetion 
    pRowset->m_pCreator = m_pObj;      
pRowset->m_pCreator->AddRef(); 
    return ResultFromScode( S_OK ); 
}