RTfifo questions

["Flavio Cappelli" <flv.cpp@libero.it>]

Hello all, I use rtlinux v2.2

I don't understand if, when I get data from a rt-fifo (rtlinux side) with
'rtf_get' and less bytes are available than requested, these bytes are
removed from the fifo or if they are removed only when ther'are
enough datas in the fifo.

I ask this question because in the example 'frack_module.c' seems that
commands are processed when entire command structure is got, without
consider a loos of data when few bytes are available.

But man page of 'rtf_get' reports that less byte than requested may
be returned. Is this related with returning -EINVAL value from fifo
handler ?

Also can a single write on rt-fifo (user side) interrupted in the middle of
data transfer by fifo handler, if ther'is enough space to put the datas ?

Sorry if these questions are trivial, but I did a search into the mailing
list without finding an adequate answer.

Thanks,
    Flavio