about CgiEnvironment and POSTDATA when using multiplexed FastCgi

In the CgiEnvironment constructor, it looks like it attempts to read all
of stdin.
FastCgi, however, chunks the stdin packets.

1) Is the read function, as defined in a subclass bridging a
multiplexing FastCgi with Cgicc, supposed to block until there
everything can be read, as done in the official FastCgi SDK's
FCGX_GetStr(FCGX_Stream*, char*, int)?
Or use EAGAIN / exceptions and wrap input->read in a for(;;)?
I'm using another FastCgi class because the fact that I'm threading
the processing means that multiplexing is the way to go to unleash the
performance of parallelism, and FCGX_* is not multiplexing-safe.
Note: the FastCgi instance class basically calls
std::string::append(input_buffer.end(), stdin_data, stdin_len). 
2) Is there an ability to limit the size of POSTDATA by using a function
hook? The non-virtuality of CgiEnvironment implies that implementing
this would require patch && make && sudo make install.

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