select for UNIX sockets?

Krzysztof Halasa
2003-06-03T14:42:30Z

Hi,

Should something like this work correctly?

while(1) {
FD_ZERO(&set);
FD_SET(fd, &set);
select(FD_SETSIZE, NULL, &set, NULL, NULL); <<<<<<< for writing

if (FD_ISSET(fd, &set))
sendto(fd, &datagram, 1, 0, ...);
}

fd is a normal local datagram socket. It looks select() returns with
"fd ready for write" and sendto() then blocks as the queue is full.

I don't know if it's expected behaviour or just a not yet known bug.
Of course, I have a more complete test program if needed.

2.4.21rc6, haven't tried any other version.

strace shows:

select(1024, NULL, [3], NULL, NULL) = 1 (out [3])
sendto(3, "\0", 1, 0, {sa_family=AF_UNIX, path="/tmp/tempUn"}, 13 <<< blocks
--
Krzysztof Halasa
Network Administrator