public static string Extract(ReadOnlyMemory <byte> bytes)
{
if (bytes.Length < 6)
{
throw new UnsupportedFileException("Unable to indentify content type of file");
}
var hex = HexBuilder.Build(bytes.Slice(0, 6));
// Check if its an openxml file.
if (hex.StartsWith("504B0304") || hex.StartsWith("504B0506") || hex.StartsWith("504B0708"))
{
using (var ms = new MemoryStream(bytes.GetUnderlyingArray().Array))
using (var package = Package.Open(ms))
{
if (package.PartExists(new Uri("/word/document.xml", UriKind.Relative)))
{
return(ContentType.Application.Docx);
}
else if (package.PartExists(new Uri("/xl/workbook.xml", UriKind.Relative)))
{
return(ContentType.Application.Xlsx);
}
else if (package.PartExists(new Uri("/ppt/presentation.xml", UriKind.Relative)))
{
return(ContentType.Application.Pptx);
}
else
{
throw new UnsupportedFileException("Unable to indentify content type of file");
}
}
}
if (!HexMimeMappings.TryGetValue(hex, out var type))
{
throw new UnsupportedFileException("Unable to indentify content type of file");
}
return(type);
}
private TextExtractor(ReadOnlyMemory <byte> bytes)
{
_stream = new MemoryStream(bytes.GetUnderlyingArray().Array);
_contentType = ContentTypeExtractor.Extract(bytes);
_disposeStream = true;
}
