Hi list! The Base64 decoding stream in the Base64 unit in the FCL appears to be broken. In particular - it does not handle whitespace (or other characters not from the bas64 alphabet), and - Read does not return the correct number of bytes read when at the end of the stream, and - the meaning of the EOF is a little bit unclear
These bugs can be circumvented by filtering out whitespace first and calling Size [which works!] to determine the actual stream size, but this is of course ugly, slower and not working on non-seekable streams. I saw there already was a small fix after 2.0.4, but there is going on quite some more. Note that the source code mentions RFC2045, which is actually about MIME, but also mentions a Base64 Content Transfer Encoding, but that RFC3548 is a preferred source, as it deals with base64 encoding in general. (URLs for RFCs: http://www.ietf.org/rfc/rfc3548.txt, http://www.ietf.org/rfc/rfc2045.txt.) I'd be happy to send a patch for the TBase64Decoding class: - instead of supporting certain 'magical' Seek operations used in the implementation of TSream.GetSize, override GetSize - ignore characters not in base64 alphabet and not being '=' - try to fix EOF: it should true iff all bytes have been Read Any comments or suggestions are welcome! I also recommend some tests are added to test the base64 decode class. It seems to be rather untested or unreviewed at the moment (no offense!), as I saw e.g. (at line 215) for j := i to 3 do ReadBuf[i] := ReadBuf[i + 1]; which obviously must be not what the author meant. I haven't looked at the base64 encoding class in depth; it might have problems too. Regards, Bram _______________________________________________ fpc-devel maillist - [email protected] http://lists.freepascal.org/mailman/listinfo/fpc-devel
