Date: Fri, 19 Jun 2009 16:03:27 +0200 From: Jilles Tjoelker <jilles@stack.nl> To: Daniel Eischen <deischen@freebsd.org> Cc: freebsd-hackers@freebsd.org, vasanth raonaik <vasanth.raonaik@gmail.com> Subject: Re: Regarding Signal IPC Message-ID: <20090619140326.GA75222@stack.nl> In-Reply-To: <Pine.GSO.4.64.0906190859550.9039@sea.ntplx.net> References: <d9f479c10906190512x4d1cf271w4107bfee0404e52a@mail.gmail.com> <Pine.GSO.4.64.0906190859550.9039@sea.ntplx.net>
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On Fri, Jun 19, 2009 at 09:03:28AM -0400, Daniel Eischen wrote: > On Fri, 19 Jun 2009, vasanth raonaik wrote: > > I want to print out the process ID of the process which is sending the > > Signal. > > Is it possible. if yes, can you please point me to any related documents. > Though I have not tried this, there is an si_pid field > (and other fields you might be interested in) in > struct siginfo. If you use a POSIX signal handler > (see sigaction(2)), a pointer to a struct siginfo is > the 2nd argument to your signal handler. > See <sys/signal.h> for the definition of struct siginfo. Meaningful siginfo is only given for signals sent by sigqueue(2), traps, child processes (SIGCHLD) and sigevent structures (for example mq_notify(2)). If you want to handle signals synchronously, you can use sigtimedwait(2). It is still necessary to call sigaction(2) with the SA_SIGINFO flag, even though the signal handler will not be called because the signal is blocked (a necessary step before using sigwait-like calls). This alternate mechanism may be particularly useful here because getting the siginfo data out of the signal handler safely is a tricky business. Although I haven't tried this, kqueue's SIGEV_SIGNAL may be helpful in managing this from a single-threaded program. This is, however, not portable. -- Jilles Tjoelker
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