public static FileIdentityInformation GetVolumeIdAndUniqueIdForFile(string fullPathWithFileName)
{
var fileHandleInformation = new FileSystemInteractor.BY_HANDLE_FILE_INFORMATION();
var fileInformation = new FileInfo(fullPathWithFileName);
try
{
var fileStream = fileInformation.Open(FileMode.Open, FileAccess.Read);
// The "Dangerous" aspect here refers to the 'SetHandleAsInvalid'. This allows the handle to be re-used
// and, potentially, to point to another resource. This can pose a security risk should the attempt be
// made by external code to retrieve objects on the file system, itself, using this newly invalid IntPtr
// as it could point to another resource, entirely. This does not appear to be an issue for Sync as we
// do not expose this information.
FileSystemInteractor.GetFileInformationByHandle(fileStream.SafeFileHandle.DangerousGetHandle(), out fileHandleInformation);
fileStream.Close();
// The cast is very important. If you omit the cast, you'll be shifting a 32 bit value 32 bits to
// the left. Shift operators on 32 bit variables will use shift stuff by right-hand-side mod 32.
// Effectively, shifting a uint 32 bits to the left is a no-op. Casting to ulong prevents this.
return
(new FileIdentityInformation
(
fileHandleInformation.VolumeSerialNumber,
fileHandleInformation.FileIndexHigh,
fileHandleInformation.FileIndexLow
));
}
catch (Exception ex)
{
throw ex;
}
}
public static FileIdentityInformation GetVolumeIdAndUniqueIdForFolder(string fullPathWithFolderName)
{
var directoryHandleInformation = new FileSystemInteractor.BY_HANDLE_FILE_INFORMATION();
try
{
// OPEN_EXISTING (FileMode.Open) is specified as we know the folder exists when passed into this method;
// however, if it doesn't, a FileNotFoundException is thrown
var createdFolder =
FileSystemInteractor.CreateFile(
fullPathWithFolderName,
FileAccess.Read,
FileShare.Read,
IntPtr.Zero,
FileMode.Open,
Kernel32.FILE_FLAG_BACKUP_SEMANTICS,
IntPtr.Zero
);
FileSystemInteractor.GetFileInformationByHandle(createdFolder.DangerousGetHandle(), out directoryHandleInformation);
return
(new FileIdentityInformation
(
directoryHandleInformation.VolumeSerialNumber,
directoryHandleInformation.FileIndexHigh,
directoryHandleInformation.FileIndexLow
));
}
catch (Exception ex)
{
throw ex;
}
}
