public static Stream FromStream(this IFileFormatFactory fileFormatFactory, Stream stream, out IFileFormat fileFormat)
{
// Read the file signature from the stream into a buffer, which is then concatenated with the original stream.
// This allows us to read the file signature from streams that don't support seeking.
int maxSignatureLength = fileFormatFactory.GetKnownFileFormats()
.Where(format => format.Signatures is object && format.Signatures.Any())
.SelectMany(format => format.Signatures.Select(sig => sig.Length))
.OrderByDescending(length => length)
.FirstOrDefault();
MemoryStream fileSignatureBuffer = new MemoryStream(new byte[maxSignatureLength], 0, maxSignatureLength, writable: true, publiclyVisible: true);
try {
int bytesRead = stream.Read(fileSignatureBuffer.GetBuffer(), 0, maxSignatureLength);
fileSignatureBuffer.SetLength(bytesRead);
fileFormat = fileFormatFactory.FromStream(fileSignatureBuffer);
fileSignatureBuffer.Seek(0, SeekOrigin.Begin);
return(new ConcatStream(fileSignatureBuffer, stream));
}
catch (Exception) {
fileSignatureBuffer.Dispose();
throw;
}
}
public static IFileFormat FromFile(this IFileFormatFactory fileFormatFactory, string filePath)
{
using (Stream stream = File.OpenRead(filePath))
return(fileFormatFactory.FromStream(stream) ?? fileFormatFactory.FromFileExtension(filePath));
}