1 files changed, 12 insertions, 5 deletions
diff --git a/src/Format/Tcformat.c b/src/Format/Tcformat.c
index 477306ea..efd95caf 100644
--- a/src/Format/Tcformat.c
+++ b/src/Format/Tcformat.c
@@ -9724,75 +9724,82 @@ int AnalyzeHiddenVolumeHost (HWND hwndDlg, int *driveNo, __int64 hiddenVolHostSi
 	{
 		handleWin32Error (hwndDlg, SRC_POS);
 		goto efs_error;
 	}
 
 	result = ReadFile (hDevice, &readBuffer, TC_MAX_VOLUME_SECTOR_SIZE, &bytesReturned, NULL);
 
 	if (result == 0)
 	{
 		handleWin32Error (hwndDlg, SRC_POS);
 		MessageBoxW (hwndDlg, GetString ("CANT_ACCESS_OUTER_VOL"), lpszTitle, ICON_HAND);
 		goto efs_error;
 	}
 
 	CloseHandle (hDevice);
 	hDevice = INVALID_HANDLE_VALUE;
 
 	// Determine file system type
 
 	GetVolumeInformation(szRootPathName, NULL, 0, NULL, NULL, NULL, szFileSystemNameBuffer, ARRAYSIZE(szFileSystemNameBuffer));
 
 	// The Windows API sometimes fails to indentify the file system correctly so we're using "raw" analysis too.
 	if (!wcsncmp (szFileSystemNameBuffer, L"FAT", 3)
 		|| (readBuffer[0x36] == 'F' && readBuffer[0x37] == 'A' && readBuffer[0x38] == 'T')
 		|| (readBuffer[0x52] == 'F' && readBuffer[0x53] == 'A' && readBuffer[0x54] == 'T'))
 	{
 		// FAT12/FAT16/FAT32
 
 		// Retrieve the cluster size
 		*realClusterSize = ((int) readBuffer[0xb] + ((int) readBuffer[0xc] << 8)) * (int) readBuffer[0xd];
 
 		// Get the map of the clusters that are free and in use on the outer volume.
 		// The map will be scanned to determine the size of the uninterrupted block of free
 		// space (provided there is any) whose end is aligned with the end of the volume.
 		// The value will then be used to determine the maximum possible size of the hidden volume.
-
-		return ScanVolClusterBitmap (hwndDlg,
-			driveNo,
-			hiddenVolHostSize / *realClusterSize,
-			pnbrFreeClusters);
+		if (*realClusterSize > 0)
+		{
+			return ScanVolClusterBitmap (hwndDlg,
+				driveNo,
+				hiddenVolHostSize / *realClusterSize,
+				pnbrFreeClusters);
+		}
+		else
+		{
+			// should never happen
+			return -1;
+		}
 	}
 	else if (!wcsncmp (szFileSystemNameBuffer, L"NTFS", 4) || !_wcsnicmp (szFileSystemNameBuffer, L"exFAT", 5))
 	{
 		// NTFS
 		bool bIsNtfs = (0 == wcsncmp (szFileSystemNameBuffer, L"NTFS", 4));
 
 		if (bIsNtfs && bHiddenVolDirect && GetVolumeDataAreaSize (FALSE, hiddenVolHostSize) <= TC_MAX_FAT_SECTOR_COUNT * GetFormatSectorSize())
 			Info ("HIDDEN_VOL_HOST_NTFS", hwndDlg);
 
 		if (!GetDiskFreeSpace(szRootPathName,
 			&dwSectorsPerCluster,
 			&dwBytesPerSector,
 			&dwNumberOfFreeClusters,
 			&dwTotalNumberOfClusters))
 		{
 			handleWin32Error (hwndDlg, SRC_POS);
 			Error ("CANT_GET_OUTER_VOL_INFO", hwndDlg);
 			return -1;
 		};
 
 		*realClusterSize = dwBytesPerSector * dwSectorsPerCluster;
 
 		// Get the map of the clusters that are free and in use on the outer volume.
 		// The map will be scanned to determine the size of the uninterrupted block of free
 		// space (provided there is any) whose end is aligned with the end of the volume.
 		// The value will then be used to determine the maximum possible size of the hidden volume.
 
 		return ScanVolClusterBitmap (hwndDlg,
 			driveNo,
 			hiddenVolHostSize / *realClusterSize,
 			pnbrFreeClusters);
 	}
 	else
 	{
 		// Unsupported file system