RTFストリームからすべてのオブジェクト（「パッケージ」クラスオブジェクト）を抽出できるコードを次に示します。
public static void ExtractPackageObjects(string filePath)
{
using (StreamReader sr = new StreamReader(filePath))
{
RtfReader reader = new RtfReader(sr);
IEnumerator<RtfObject> enumerator = reader.Read().GetEnumerator();
while(enumerator.MoveNext())
{
if (enumerator.Current.Text == "object")
{
if (RtfReader.MoveToNextControlWord(enumerator, "objclass"))
{
string className = RtfReader.GetNextText(enumerator);
if (className == "Package")
{
if (RtfReader.MoveToNextControlWord(enumerator, "objdata"))
{
byte[] data = RtfReader.GetNextTextAsByteArray(enumerator);
using (MemoryStream packageData = new MemoryStream())
{
RtfReader.ExtractObjectData(new MemoryStream(data), packageData);
packageData.Position = 0;
PackagedObject po = PackagedObject.Extract(packageData);
File.WriteAllBytes(po.DisplayName, po.Data);
}
}
}
}
}
}
}
}
そして、これがこのコードが使用するユーティリティクラスです。興味深い制御ワードに到達できるようにする単純なストリームベースのRTFパーサーがあります。
シリアル化されたObjectPackagerインスタンスからデータを抽出するユーティリティもあります。Object Packagerはほぼ20年前のOLE1.0のものであり、シリアル化されたバイナリ形式は（私の知る限り）文書化されていませんが、理解できます。
これは提供されたサンプルでは問題なく機能しますが、状況を調整する必要がある場合があります。
public class RtfReader
{
public RtfReader(TextReader reader)
{
if (reader == null)
throw new ArgumentNullException("reader");
Reader = reader;
}
public TextReader Reader { get; private set; }
public IEnumerable<RtfObject> Read()
{
StringBuilder controlWord = new StringBuilder();
StringBuilder text = new StringBuilder();
Stack<RtfParseState> stack = new Stack<RtfParseState>();
RtfParseState state = RtfParseState.Group;
do
{
int i = Reader.Read();
if (i < 0)
{
if (!string.IsNullOrWhiteSpace(controlWord.ToString()))
yield return new RtfControlWord(controlWord.ToString());
if (!string.IsNullOrWhiteSpace(text.ToString()))
yield return new RtfText(text.ToString());
yield break;
}
char c = (char)i;
// noise chars
if ((c == '\r') ||
(c == '\n'))
continue;
switch (state)
{
case RtfParseState.Group:
if (c == '{')
{
stack.Push(state);
break;
}
if (c == '\\')
{
state = RtfParseState.ControlWord;
break;
}
break;
case RtfParseState.ControlWord:
if (c == '\\')
{
// another controlWord
if (!string.IsNullOrWhiteSpace(controlWord.ToString()))
{
yield return new RtfControlWord(controlWord.ToString());
controlWord.Clear();
}
break;
}
if (c == '{')
{
// a new group
state = RtfParseState.Group;
if (!string.IsNullOrWhiteSpace(controlWord.ToString()))
{
yield return new RtfControlWord(controlWord.ToString());
controlWord.Clear();
}
break;
}
if (c == '}')
{
// close group
state = stack.Count > 0 ? stack.Pop() : RtfParseState.Group;
if (!string.IsNullOrWhiteSpace(controlWord.ToString()))
{
yield return new RtfControlWord(controlWord.ToString());
controlWord.Clear();
}
break;
}
if (!Char.IsLetterOrDigit(c))
{
state = RtfParseState.Text;
text.Append(c);
if (!string.IsNullOrWhiteSpace(controlWord.ToString()))
{
yield return new RtfControlWord(controlWord.ToString());
controlWord.Clear();
}
break;
}
controlWord.Append(c);
break;
case RtfParseState.Text:
if (c == '\\')
{
state = RtfParseState.EscapedText;
break;
}
if (c == '{')
{
if (!string.IsNullOrWhiteSpace(text.ToString()))
{
yield return new RtfText(text.ToString());
text.Clear();
}
// a new group
state = RtfParseState.Group;
break;
}
if (c == '}')
{
if (!string.IsNullOrWhiteSpace(text.ToString()))
{
yield return new RtfText(text.ToString());
text.Clear();
}
// close group
state = stack.Count > 0 ? stack.Pop() : RtfParseState.Group;
break;
}
text.Append(c);
break;
case RtfParseState.EscapedText:
if ((c == '\\') || (c == '}') || (c == '{'))
{
state = RtfParseState.Text;
text.Append(c);
break;
}
// ansi character escape
if (c == '\'')
{
text.Append(FromHexa((char)Reader.Read(), (char)Reader.Read()));
break;
}
if (!string.IsNullOrWhiteSpace(text.ToString()))
{
yield return new RtfText(text.ToString());
text.Clear();
}
// in fact, it's a normal controlWord
controlWord.Append(c);
state = RtfParseState.ControlWord;
break;
}
}
while (true);
}
public static bool MoveToNextControlWord(IEnumerator<RtfObject> enumerator, string word)
{
if (enumerator == null)
throw new ArgumentNullException("enumerator");
while (enumerator.MoveNext())
{
if (enumerator.Current.Text == word)
return true;
}
return false;
}
public static string GetNextText(IEnumerator<RtfObject> enumerator)
{
if (enumerator == null)
throw new ArgumentNullException("enumerator");
while (enumerator.MoveNext())
{
RtfText text = enumerator.Current as RtfText;
if (text != null)
return text.Text;
}
return null;
}
public static byte[] GetNextTextAsByteArray(IEnumerator<RtfObject> enumerator)
{
if (enumerator == null)
throw new ArgumentNullException("enumerator");
while (enumerator.MoveNext())
{
RtfText text = enumerator.Current as RtfText;
if (text != null)
{
List<byte> bytes = new List<byte>();
for (int i = 0; i < text.Text.Length; i += 2)
{
bytes.Add((byte)FromHexa(text.Text[i], text.Text[i + 1]));
}
return bytes.ToArray();
}
}
return null;
}
// Extracts an EmbeddedObject/ObjectHeader from a stream
// see [MS -OLEDS]: Object Linking and Embedding (OLE) Data Structures for more information
// chapter 2.2: OLE1.0 Format Structures
public static void ExtractObjectData(Stream inputStream, Stream outputStream)
{
if (inputStream == null)
throw new ArgumentNullException("inputStream");
if (outputStream == null)
throw new ArgumentNullException("outputStream");
BinaryReader reader = new BinaryReader(inputStream);
reader.ReadInt32(); // OLEVersion
int formatId = reader.ReadInt32(); // FormatID
if (formatId != 2) // see 2.2.4 Object Header. 2 means EmbeddedObject
throw new NotSupportedException();
ReadLengthPrefixedAnsiString(reader); // className
ReadLengthPrefixedAnsiString(reader); // topicName
ReadLengthPrefixedAnsiString(reader); // itemName
int nativeDataSize = reader.ReadInt32();
byte[] bytes = reader.ReadBytes(nativeDataSize);
outputStream.Write(bytes, 0, bytes.Length);
}
// see chapter 2.1.4 LengthPrefixedAnsiString
private static string ReadLengthPrefixedAnsiString(BinaryReader reader)
{
int length = reader.ReadInt32();
if (length == 0)
return string.Empty;
byte[] bytes = reader.ReadBytes(length);
return Encoding.Default.GetString(bytes, 0, length - 1);
}
private enum RtfParseState
{
ControlWord,
Text,
EscapedText,
Group
}
private static char FromHexa(char hi, char lo)
{
return (char)byte.Parse(hi.ToString() + lo, NumberStyles.HexNumber);
}
}
// Utility class to parse an OLE1.0 OLEOBJECT
public class PackagedObject
{
private PackagedObject()
{
}
public string DisplayName { get; private set; }
public string IconFilePath { get; private set; }
public int IconIndex { get; private set; }
public string FilePath { get; private set; }
public byte[] Data { get; private set; }
private static string ReadAnsiString(BinaryReader reader)
{
StringBuilder sb = new StringBuilder();
do
{
byte b = reader.ReadByte();
if (b == 0)
return sb.ToString();
sb.Append((char)b);
}
while (true);
}
public static PackagedObject Extract(Stream inputStream)
{
if (inputStream == null)
throw new ArgumentNullException("inputStream");
BinaryReader reader = new BinaryReader(inputStream);
reader.ReadUInt16(); // sig
PackagedObject po = new PackagedObject();
po.DisplayName = ReadAnsiString(reader);
po.IconFilePath = ReadAnsiString(reader);
po.IconIndex = reader.ReadUInt16();
int type = reader.ReadUInt16();
if (type != 3) // 3 is file, 1 is link
throw new NotSupportedException();
reader.ReadInt32(); // nextsize
po.FilePath = ReadAnsiString(reader);
int dataSize = reader.ReadInt32();
po.Data = reader.ReadBytes(dataSize);
// note after that, there may be unicode + long path info
return po;
}
}
public class RtfObject
{
public RtfObject(string text)
{
if (text == null)
throw new ArgumentNullException("text");
Text = text.Trim();
}
public string Text { get; private set; }
}
public class RtfText : RtfObject
{
public RtfText(string text)
: base(text)
{
}
}
public class RtfControlWord : RtfObject
{
public RtfControlWord(string name)
: base(name)
{
}
}
