Wollongong/recvfrom summary


Fitch@DOCKMASTER.ARPA
Sun, 17 Jul 88 20:01 EDT


We can put the Wollongong/recvfrom question to rest. I have what I need
to know concerning QIOs plus an understanding of the Crusades (see
comment 4).

1) The QIO interface DOES require the extra two bytes in the recvfrom
from
   parameter. "The returned "sockaddr" structure is preceeded by
   a 16-bit length. Here is the reasoning -- the networking code under VMS
   uses "DIRECT-IO" which involves locking down pages. The QIO support for
   this allows you lock down a primary buffer (the read/write buffer) and
   one secondary buffer. The real UNIX way is to have 3 areas -- the
   read/write buffer, the returned sockaddr and the returned length. But
   this is exceedingly difficult to do with VAX/VMS QIOs." [David Kashtan].

2) The extra two bytes are not necessary if you go through the C library
   and not the QIOs. As the Wollongong folks picked up, I was obviously
   using the QIOs. The C library smooths out some rough edges and also gives
   you a few more functions. [Jerry Scott].
   The Ada interface I was using imported the QIOs directly instead of getting
   to them via the C library; thus anything you would get for free via the
   library (such as the two byte work around) was lost and was killing my code.

3) The real problem was that the documentation makes the QIOs look like
they
   implement the socket interface (the spare two bytes are used in an example
   MACRO program, but the normal sockaddr is used in the documentation.)
   I have messages from Wollongong asking for more detail, so I can pursue
   this off of tcp-ip.

4) Finally, it is no wonder there were Crusades if people then took
religion
   as seriously as we take programming languages today. My comment on being
   able to read MACRO brought as much mail as the socket/QIO issue. MACRO, C,
   and Ada all got praise and flames. The funny part is that my intention was
   to emphasize that I had to read the code ITSELF and ignore the comments.

--Jack Fitch@Dockmaster.Arpa



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