Hi,

This is probably a bit more C++ oriented question, but:

I have my own custom transformation, which crashes whenever I want to clear
buffer with larger piece of text ("delete (pstrBuffer);"), saying:

"Heap block at xxx modified at xxx past requested size of 130"

I know I am obviously trying to release more memory than I am allowed to,
but since I have declared problematic "pstrBuffer = (LPSTR)new char[500];",
why can't I delete all 500 chars? I don't get it.

This is my piece of code, if anyone could help me:

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STDMETHODIMP CAbxDTSCTString::Execute(
LPBYTE pvTransformServerData, // Transform server state data.
LPCDTSTransformColumnInfo pSrcColumnInfo, // Source columns and rowdata
LPDTSTransformColumnInfo pDestColumnInfo, // Dest columns and rowdata
IDTSDataConvert *pIDTSDataConvert, // Pointer to the data conversion
interface
LPDTSTransformStatus pTransformStatus // Result of transform
)
{

// Declarations
DTSColumnData* pDTSDestColumnData; // Destination column data pointer
const DBBINDING* pDBDestBinding; // Destination binding pointer
DTSColumnData* pDTSSourceColumnData; // Source column data pointer
const DBBINDING* pDBSourceBinding; // Source binding pointer
LPSTR pstrBuffer; // Buffer where the return data is being saved to
ULONG ulStatus; // Status of the source data (NULL, etc...)
ULONG ulSourceLength; // Length of the source data
ULONG ulDestLength; // Length of the destination data
ULONG* status; // Status of execution (success, error)
ULONG* ulLength; // Length of the returned data
LPSTR pSourceString; // Source data string
LPSTR pDestString; // Destination string
BOOL bDestWide; // Is destionation ASCII or UNICODE
(Wide)
BOOL bSourceWide; // Is source ASCII or UNICODE (Wide)


USES_CONVERSION;

for (UINT myCol = 0; myCol < pDestColumnInfo->cColumns; myCol++)
{

// Sets source column
pDTSSourceColumnData = &( pSrcColumnInfo->rgColumnData[myCol] );
pDBSourceBinding = pDTSSourceColumnData->pDBBinding;
bSourceWide = ( pDBSourceBinding->wType == DBTYPE_WSTR );
// Sets destination column
pDTSDestColumnData = &( pDestColumnInfo->rgColumnData[myCol] );
pDBDestBinding = pDTSDestColumnData->pDBBinding;
bDestWide = ( pDBDestBinding->wType == DBTYPE_WSTR );

// Get last name status, data length, data ptr.
ulStatus = *(ULONG *)( pDTSSourceColumnData->pvData +
pDBSourceBinding->obStatus );
ulSourceLength = *(ULONG *)( pDTSSourceColumnData->pvData +
pDBSourceBinding->obLength );
pSourceString = ( pDBSourceBinding->wType & DBTYPE_BYREF ?
*(LPSTR *)(pDTSSourceColumnData->pvData
+ pDBSourceBinding->obValue) :
(LPSTR)(pDTSSourceColumnData->pvData +
pDBSourceBinding->obValue) );

// Initializes pointer buffer
pstrBuffer = (LPSTR)new char[ ( (ULONG)m_Length1 + 1 ) *
( bDestWide ? 2 : 1 ) ];

// Sets status to Okay
status = (ULONG *)( pDTSDestColumnData->pvData + pDBDestBinding->obStatus );
*status = DBSTATUS_S_OK;

// Saves source string into the buffer
if ( ulStatus != DBSTATUS_S_ISNULL )
{
if ( bDestWide ) {
if ( bSourceWide )
wcscpy( (LPWSTR)pstrBuffer, (LPCWSTR)pSourceString );
else
wcscpy( (LPWSTR)pstrBuffer, (LPCWSTR)A2W( (LPCSTR)pSourceString) );
RemoveTrailingSpace( (LPWSTR)pstrBuffer, wcslen( (LPWSTR)pstrBuffer ) );
} else {
if ( bSourceWide )
strcpy( (LPSTR)pstrBuffer, (LPCSTR)W2A( (LPCWSTR)pSourceString) );
else
strcpy( (LPSTR)pstrBuffer, (LPCSTR)pSourceString );
RemoveTrailingSpace( (LPSTR)pstrBuffer, strlen( (LPSTR)pstrBuffer ) );
}
}


// Checks if source string is null, or equals "". In such case, it reads
// the default value, if there is one
if ( ulStatus == DBSTATUS_S_ISNULL || ulSourceLength == 0 || ( bDestWide ?
wcslen( (LPWSTR)pstrBuffer ) : strlen( (LPSTR)pstrBuffer ) == 0) )
{
// Saves default string to the buffer
if ( bDestWide )
wcscpy( (LPWSTR)pstrBuffer, m_DefaultValue.m_str );
else
strcpy( (LPSTR)pstrBuffer, W2A(m_DefaultValue.m_str) );
}

// Saves source data to destination column
ulLength = (ULONG *)( pDTSDestColumnData->pvData +
pDBDestBinding->obLength );
ulDestLength = pDBDestBinding->cbMaxLen;

if ( m_Length1 > 0 )
{
// Calc length of data (in bytes) to be moved
*ulLength = ( bDestWide ?
min( (ULONG)m_Length1 * 2, wcslen(
(LPCWSTR)pstrBuffer ) * 2 ) :
min( (ULONG)m_Length1, strlen(
(LPCSTR)pstrBuffer ) ) );
} else {
*ulLength = ( bDestWide ?
min( ulDestLength - 2, wcslen(
(LPCWSTR)pstrBuffer ) * 2 ) :
min( ulDestLength - 1, strlen(
(LPCSTR)pstrBuffer ) ) );
}
pDestString = (LPSTR)(pDTSDestColumnData->pvData + pDBDestBinding->obValue);
memcpy( pDestString, pstrBuffer, *ulLength );

// Terminates string
if( bDestWide )
*(LPWSTR)( pDestString + *ulLength ) = L'\0';
else
*(LPSTR)( pDestString + *ulLength ) = '\0';

}

if ( pstrBuffer )
delete( pstrBuffer );

return NOERROR;

}
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Regards,
Blaz