IsEncryptedPackageEnvelope(
string fileName
)
{
bool retval = false;
if (fileName == null)
{
throw new ArgumentNullException("fileName");
}
StorageRoot root = null;
try
{
//
// When StorageRoot.Open is called on a file that is not a compound file,
// it throws an IOException whose inner exception is a COMException whose
// error code is 0x80030050, STG_E_FILEALREADYEXISTS. Check for that case
// and return false because that means that this is not an RM-protected file.
//
// Any other exception is a real error. For example, StorageRoot.Open
// throws FileNotFoundException if path does not exist, and we let that
// flow through.
//
root = StorageRoot.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
//
// It's a compound file. Does it contain an "EncryptedPackage" stream?
//
retval = ContainsEncryptedPackageStream(root);
}
catch (IOException ex)
{
COMException comException = ex.InnerException as COMException;
if (comException != null && comException.ErrorCode == STG_E_FILEALREADYEXISTS)
{
return(false);
}
throw; // Any other kind of IOException is a real error.
}
finally
{
if (root != null)
{
root.Close();
}
}
return(retval);
}
IsEncryptedPackageEnvelope(
Stream stream
)
{
if (stream == null)
{
throw new ArgumentNullException("stream");
}
bool retval = false;
StorageRoot root = null;
try
{
//
// When StorageRoot.CreateOnStream is called on a stream that is not
// a storage object, it throws an IOException whose inner exception is
// a COMException whose error code is 0x80030050, STG_E_FILEALREADYEXISTS.
// Check for that case and return false because that means that this
// stream is not an RM-protected file.
//
// Any other exception is a real error.
//
root = StorageRoot.CreateOnStream(stream, FileMode.Open);
//
// It's a compound file. Does it contain an "EncryptedPackage" stream?
//
retval = ContainsEncryptedPackageStream(root);
}
catch (IOException ex)
{
COMException comException = ex.InnerException as COMException;
if (comException != null && comException.ErrorCode == STG_E_FILEALREADYEXISTS)
{
return(false);
}
throw; // Any other kind of IOException is a real error.
}
finally
{
if (root != null)
{
root.Close();
}
}
return(retval);
}
