// Make sure there is a part to write to and that it contains
// the expected start markup.
private void EnsureXmlWriter()
{
// It does not make sense to reuse a writer outside of streaming creation.
if (!_package.InStreamingCreation)
Invariant.Assert(_xmlWriter == null);
if (_xmlWriter != null)
return;
EnsurePropertyPart(); // Should succeed or throw an exception.
Stream writerStream;
if(_package.InStreamingCreation)
writerStream = _propertyPart.GetStream(FileMode.Create, FileAccess.Write);
else
writerStream = new IgnoreFlushAndCloseStream(_propertyPart.GetStream(FileMode.Create, FileAccess.Write));
_xmlWriter = new XmlTextWriter(writerStream, System.Text.Encoding.UTF8);
WriteXmlStartTagsForPackageProperties();
}
internal static String GenerateDigestValue(
Stream s,
List<String> transforms,
HashAlgorithm hashAlgorithm)
{
s.Seek(0, SeekOrigin.Begin);
// We need to be able to dispose streams generated by the
// Transform object but we don't want to dispose the stream
// passed to us so we insert this to block any propagated Dispose() calls.
Stream transformStream = new IgnoreFlushAndCloseStream(s);
List<Stream> transformStreams = null;
// canonicalize the part content if asked
if (transforms != null)
{
transformStreams = new List<Stream>(transforms.Count);
transformStreams.Add(transformStream);
foreach (String transformName in transforms)
{
// ignore empty strings at this point (as well as Relationship Transforms) - these are legal
if ((transformName.Length == 0)
|| (String.CompareOrdinal(transformName, XTable.Get(XTable.ID.RelationshipsTransformName)) == 0))
{
continue;
}
// convert the transform names into objects (if defined)
Transform transform = StringToTransform(transformName);
if (transform == null)
{
// throw XmlException so the outer loop knows the signature is invalid
throw new XmlException(SR.Get(SRID.UnsupportedTransformAlgorithm));
}
transformStream = TransformXml(transform, transformStream);
transformStreams.Add(transformStream);
}
}
// hash it and encode to Base64
String hashValueString = System.Convert.ToBase64String(HashStream(hashAlgorithm, transformStream));
// dispose of any generated streams
if (transformStreams != null)
{
foreach (Stream stream in transformStreams)
stream.Close();
}
return hashValueString;
}
