Date: Tue, 31 Jul 2001 21:24:48 +0200 From: Gabriel Ambuehl <gabriel_ambuehl@buz.ch> To: questions@freebsd.org Subject: select() on a named pipe blocks indefinitely Message-ID: <115350818950.20010731212448@buz.ch>
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Hello,
I've there got a strange problem with select on a named pipe (FIFO):
If I call select() on it without supplying a timeout, the program
won't
ever return from the select until it's killed. But without select(),
I see
all the data I
cat > FIFO_PATH
into the named pipe...
{
char result[512];
int fifo_des;
fd_set rset;
mkfifo(FIFO_PATH, (mode_t) (S_IRUSR | S_IWUSR | S_IWGRP));
fifo_des=open((const char *) FIFO_PATH, O_RDONLY|O_NONBLOCK);
//blocks if there's no writer on the pipe but as soon as one
//opens the pipe, it will return as it should. According to UNPv2
//this is the correct behavior.
if (fifo_des < 0)
{
cout << "fatal error: can't open FIFO" << endl;
exit(1);
}
FD_ZERO(&rset);
while(1)
{
FD_SET(fifo_des, &rset);
select(1, &rset, (fd_set *) NULL, (fd_set *) NULL, (struct
timeval *) NULL);
if(FD_ISSET(fifo_des, &rset))
{
read(fifo_des, (void *) &result, (size_t)
sizeof(result));
cout << "message: " << result <<endl;
}
}
close(fifo_des);
unlink(FIFO_PATH);
}
What am I doing wrong?
TIA & best regards,
Gabriel
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