Between v5.4 and v5.5-rc5, big changes are made around pipe and my test
program behaves differently.
{
err = mknod(fname, S_IFIFO | 0644, /*dev*/0);
fd = open(fname, O_RDWR, /*mode*/0);
err = sigaction(SIGIO, &sa, NULL);
pid = getpid();
err = fcntl(fd, F_SETOWN, pid);
err = fcntl(fd, F_SETSIG, SIGIO);
flags = fcntl(fd, F_GETFL);
err = fcntl(fd, F_SETFL, O_NONBLOCK | O_ASYNC | flags);
ssz = write(fd, &i, 1);
ssz = read(fd, &i, 1);
}
In v5.4, the final write(2) and read(2) generate/send SIGIO for each,
POLLIN and POLLOUT respectively.
But in v5.5-rc5, read(2) doesn't generate/send SIGIO POLLOUT while it
reads 1 byte successfully.
Reading new pipe.c, pipe_read() fires the signal only when the pipe
buffer was full (16 as PIPE_DEF_BUFFERS defines), so my test program
which writes only 1 byte doesn't receive the signal. Am I right? If
so, is this an intentional behaviour and the previous behaviour was
wrong and violated some standards?
J. R. Okajima
