ap_ get_client_block — read a block of data from the client
long ap_ get_client_block(request_rec *r, char *buffer, int bufsiz)
Reads up to bufsiz characters into buffer from the
client. Returns the number of bytes read, 0 if
there is no more data, or -1 if an error occurs.
ap_setup_client_block() and
ap_should_client_block() should be called before
this. Note that the buffer should be at least big enough to hold a
chunk-size header line (because it may be used to store one
temporarily). Since a chunk-size header line is simply a number in
hex, 50 bytes should be plenty.