forwarded message from Henry Cejtin

[Stephen Weeks]

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From: Henry Cejtin <henry@sourcelight.com>
To: sweeks@intertrust.com
Subject: Re: alternate stacks for signal handlers
Date: Wed, 26 Jul 2000 20:09:30 -0500

Ah,  I  see  because  you WANT the system call to fail, right?  Pretty scary.
Some may restart any way.  Also this would mean you have  to  understand  the
concept  of  a  system  call failing because of an interrupt.  Also note that
some system calls won't fail, but will return short counts.  I.e.,  if  I  am
reading  from  a slow device, and I have gotten something, but not everything
yet, and an interrupt arrives, then if the read returns -1 (with errno EINTR)
then  I  would have no idea how much I got.  (POSIX actually allows this, but
no Unix does this since it would be horrible.)  Thus the read will return and
look  like all is ok, but you won't have gotten all you asked for even though
you are not at EOF.

Any way, you are right, the SA_RESTART will have to go.  I  was  hoping  that
the  rest  of  the  code  would  not have to be aware of system calls failing
because of signals, but I guess it does.