//*****************************************************************************
// CheckFileFormat
// This function will determine if the in-memory image is a readonly, readwrite,
// or ICR format.
//*****************************************************************************
HRESULT
CheckFileFormat(
LPVOID pData,
ULONG cbData,
MDFileFormat *pFormat) // [OUT] the file format
{
HRESULT hr = NOERROR;
STORAGEHEADER sHdr; // Header for the storage.
PSTORAGESTREAM pStream; // Pointer to each stream.
int i;
ULONG cbStreamBuffer;
_ASSERTE(pFormat != NULL);
*pFormat = MDFormat_Invalid;
// Validate the signature of the format, or it isn't ours.
if (FAILED(hr = MDFormat::VerifySignature((PSTORAGESIGNATURE) pData, cbData)))
goto ErrExit;
// Remaining buffer size behind the stream header (pStream).
cbStreamBuffer = cbData;
// Get back the first stream.
pStream = MDFormat::GetFirstStream_Verify(&sHdr, pData, &cbStreamBuffer);
if (pStream == NULL)
{
Debug_ReportError("Invalid MetaData storage signature - cannot get the first stream header.");
IfFailGo(CLDB_E_FILE_CORRUPT);
}
// Loop through each stream and pick off the ones we need.
for (i = 0; i < sHdr.GetiStreams(); i++)
{
// Do we have enough buffer to read stream header?
if (cbStreamBuffer < sizeof(*pStream))
{
Debug_ReportError("Stream header is not within MetaData block.");
IfFailGo(CLDB_E_FILE_CORRUPT);
}
// Get next stream.
PSTORAGESTREAM pNext = pStream->NextStream_Verify();
// Check that stream header is within the buffer.
if (((LPBYTE)pStream >= ((LPBYTE)pData + cbData)) ||
((LPBYTE)pNext > ((LPBYTE)pData + cbData)))
{
Debug_ReportError("Stream header is not within MetaData block.");
hr = CLDB_E_FILE_CORRUPT;
goto ErrExit;
}
// Check that the stream data starts and fits within the buffer.
// need two checks on size because of wraparound.
if ((pStream->GetOffset() > cbData) ||
(pStream->GetSize() > cbData) ||
((pStream->GetSize() + pStream->GetOffset()) < pStream->GetOffset()) ||
((pStream->GetSize() + pStream->GetOffset()) > cbData))
{
Debug_ReportError("Stream data are not within MetaData block.");
hr = CLDB_E_FILE_CORRUPT;
goto ErrExit;
}
// Pick off the location and size of the data.
if (strcmp(pStream->GetName(), COMPRESSED_MODEL_STREAM_A) == 0)
{
// Validate that only one of compressed/uncompressed is present.
if (*pFormat != MDFormat_Invalid)
{ // Already found a good stream.
Debug_ReportError("Compressed model stream #~ is second important stream.");
hr = CLDB_E_FILE_CORRUPT;
goto ErrExit;
}
// Found the compressed meta data stream.
*pFormat = MDFormat_ReadOnly;
}
else if (strcmp(pStream->GetName(), ENC_MODEL_STREAM_A) == 0)
{
// Validate that only one of compressed/uncompressed is present.
if (*pFormat != MDFormat_Invalid)
{ // Already found a good stream.
Debug_ReportError("ENC model stream #- is second important stream.");
hr = CLDB_E_FILE_CORRUPT;
goto ErrExit;
}
// Found the ENC meta data stream.
*pFormat = MDFormat_ReadWrite;
}
else if (strcmp(pStream->GetName(), SCHEMA_STREAM_A) == 0)
{
// Found the uncompressed format
*pFormat = MDFormat_ICR;
// keep going. We may find the compressed format later.
// If so, we want to use the compressed format.
}
// Pick off the next stream if there is one.
pStream = pNext;
cbStreamBuffer = (ULONG)((LPBYTE)pData + cbData - (LPBYTE)pNext);
}
if (*pFormat == MDFormat_Invalid)
{ // Didn't find a good stream.
Debug_ReportError("Cannot find MetaData stream.");
hr = CLDB_E_FILE_CORRUPT;
}
ErrExit:
return hr;
} // CheckFileFormat
