[650] in arla-drinkers
Re: Netscape: 'Interrupted system call'
daemon@ATHENA.MIT.EDU (Robert Watson)
Mon Mar 1 11:23:44 1999
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Date: Mon, 1 Mar 1999 11:11:10 -0500 (EST)
From: Robert Watson <robert@cyrus.watson.org>
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To: assar@stacken.kth.se
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Subject: Re: Netscape: 'Interrupted system call'
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On 1 Mar 1999 assar@stacken.kth.se wrote:
> Robert Watson <robert@cyrus.watson.org> writes:
> > Error opening /afs/andrew/usr4/rnw/www/teletubbies.gif
> > Interrupted system call
> >
> > Don't ask about the filename. :-) Apparently Netscape does not anticipate
> > receiving EINTR during open()? Or something like that. I seem to recall
> > that Coda had this problem for a while; however, one FreeBSD 4.0, open(2)
> > clearly lists EINTR as a possible error return, so it seems more like a
> > Netscape problem really. (I could be mistaken)
>
> This was a problem with emacs that was using SIGIO and got interrupted
> by that. So either, that code is not working on FreeBSD 4.0 (but I
> believe it should) or Netscape or doing something else.
>
> Can you run truss/ktrace on Netscape and see what signal it's getting
> while running open?
Sure.. I should have attached that before. Here's an excerpt from around
the open():
syscall gettimeofday(0x50011f10,0x0)
returns 0 (0x0) syscall sigprocmask(0x3,0x0) Robert N Watson
returns 0 (0x0) robert@fledge.watson.org
SIGNAL 14 SIGNAL 14 syscall
stat("/afs/andrew/usr4/rnw/audio3.gif",0xefbfbf40)
errno 4 'Interrupted system call' syscall
gettimeofday(0xefbfba04,0x0)
returns 0 (0x0) syscall sigreturn(0xefbfbaa0)
errno 4 'Interrupted system call' SIGNAL 14 SIGNAL 14 SIGNAL 14
syscall open("/afs/andrew/usr4/rnw/audio3.gif",1537,0666)
errno 4 'Interrupted system call' syscall
gettimeofday(0xefbfb9dc,0x0)
returns 0 (0x0) syscall sigreturn(0xefbfba78)
errno 4 'Interrupted system call'
From this behavior, I'm guessing that their threading package uses SIGALRM
(14) for preemption or timeouts of some kind, and that they do not expect
to receive it during their open(). However, I believe this is a Netscape
issue technically, as FreeBSD open(2) does state:
[EINTR] The open() operation was interrupted by a signal.
in the ERRORS section of the man page. I have filled out Netscape's bug
report form, although I don't know whether I should expect them to even
notice, these days. :-) Having an interruptable open() is really a good
idea given that it can potentially block for a long time.
Robert N Watson
robert@fledge.watson.org http://www.watson.org/~robert/
PGP key fingerprint: 03 01 DD 8E 15 67 48 73 25 6D 10 FC EC 68 C1 1C
Carnegie Mellon University http://www.cmu.edu/
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