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From: kcwong@ssd.kodak.com (K.C. Wong)
Newsgroups: comp.windows.open-look
Subject: wait() call in xview
Message-ID: <1991Jun21.125203.6899@ssd.kodak.com>
Date: 21 Jun 91 12:52:03 GMT
Sender: news@ssd.kodak.com
Organization: Eastman Kodak
Lines: 35
Originator: kcwong@osprey.ssd.kodak.com


The Xview programming manual says not to use wait() and wait3() calls.
Is it safe to use wait4() calls?

I found that some times using the notify_set_wait3_func() call not
practical. It throws my processing off logically.

For example, on a sparc station 2, I would like to find out if the
floppy is in the drive before doing any writing by making the
system call "eject -q" (which takes only a fraction of a second).
Using the callback scheme with notify_set_wait3_func() is inconvenient
at best.

I would like to do,

	pid = fork()

	in child, exec ("eject -q")

	in parent, wait4(pid,...) non-blocking in a loop,
	and check the exit code value.

	if exit code values is 0 (=> floppy is in)
	perform something.

Since the call I exec takes such a short time, could I do the above?
I don't want to handle any events during these processing.

Your input is very welcome.

Regards,
K.C.Wong
kcwong@ssd.kodak.com

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