Talk & select

[Doug McCallum]

In article <1790 at jhunix.HCF.JHU.EDU> eed_waek at jhunix (Alexander Kaplan) writes:
...
>system is a mix of Unix V 3.1 with BSD 4.3 socket.  After
...
>1) When I initiate talk in a hardwired tty line, I get a message
>   error waiting daemon with errno 22 -- invalid argument.
>2) When I initiate talk in a ttyq line (i.e. ethernet connection),
>   I get the same message: error waiting daemon with errno 2 --
>   no such file or directory.
>3) When I initiate talk in a ttyq line but redirect output to a
>   file, I get the same message except with another errno 25 --
>   not a typewriter.
>
>When I looked into the program, I found this error was generated
>after a call to select.

Unless the V.3 vendor added support for select for tty devices, select
won't work.  V.3 does not have a native select.  It does have the "poll"
system call which is similar in functionality but only for STREAMS descriptors.
Poll returns EINVAL (errno 22) when handed an non-STREAMS file descriptor.
It sounds like your select is implemented with a call to poll.

Another note about select and applications like talk that would use 
curses/termcap under V.3.  There is a very primitive select emulation
that will cause problems.  You need to be sure to load your network
library before -lcurses.

Doug McCallum
Interactive Systems Corp
dougm at ico.isc.com