Re: Missing in sigaction
Re: Missing in sigaction
- Subject: Re: Missing in sigaction
- From: Tilghman Lesher <email@hidden>
- Date: Tue, 27 Mar 2012 15:22:09 -0500
On Tue, Mar 27, 2012 at 1:57 PM, Nat! <email@hidden> wrote:
> instead of many words, here's the output of two program runs once with a sleep( 2) - as in seconds, not as in man - commented in and out. What I believe this demonstrates, is that on Darwin (Kernel Version 10.8.0), blocked signal information is lost, which is incovenient. gdb has a similiar problem.
>
> Or it shows that I am misunderstanding something ;)
>
> The problem is not that the signal is occurring less often, that's expected, but that the struct __siginfo has trouble remembering things.
You really should read the manpage for sigaction, in particular, the
section that reads:
"In general though, signal handlers should do little more than set a
flag; most other actions are not safe."
Note, also, that printf() is not in the list of "safe" functions to
call. Thus your call to p_log is defined as not safe. While sleep()
is safe to call, it also violates one of the cardinal rules of signal
handlers -- do only what is necessary to flag that a signal occurred,
and do not take more time than is necessary. The actual handling of
what the signal represents should be done in a main thread.
-Tilghman
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