Date: Thu, 8 Oct 2009 13:23:37 +0300 From: Vlad Galu <dudu@dudu.ro> To: Kostik Belousov <kostikbel@gmail.com> Cc: Stephen Hocking <stephen.hocking@gmail.com>, hackers@freebsd.org Subject: Re: sigwait - differences between Linux & FreeBSD Message-ID: <ad79ad6b0910080323n76e2c659tadf59bc5f099a182@mail.gmail.com> In-Reply-To: <20091008100209.GG2259@deviant.kiev.zoral.com.ua> References: <6300771b0910071753s6580c099i8c348824a6fe1a72@mail.gmail.com> <20091008100209.GG2259@deviant.kiev.zoral.com.ua>
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On Thu, Oct 8, 2009 at 1:02 PM, Kostik Belousov <kostikbel@gmail.com> wrote: > On Thu, Oct 08, 2009 at 11:53:21AM +1100, Stephen Hocking wrote: >> Hi all, >> >> In my efforts to make the xrdp port more robust under FreeBSD, I have >> discovered that sigwait (kind of an analogue to select(2), but for >> signals rather than I/O) re-enables ignored signals in its list under >> Linux, but not FreeBSD. The sesman daemon uses SIGCHLD to clean up >> after a session has exited. Under Linux this works OK, under FreeSBD >> it doesn't. I have worked around it in a very hackish manner (define a >> dummy signal handler and enable it using signal, which means that the >> sigwait call can then be unblocked by it), but am wondering if anyone >> else has run across the same problem, and if so, if they fixed it in >> an elegant manner. Also, does anyone know the correct semantics of >> sigwait under this situation? > > ports@ is the wrong list to discuss the issue in the base system. > > Solaris 10 sigwait(2) manpage says the following: > If sigwait() is called on an ignored signal, then the occurrence of the > signal will be ignored, unless sigaction() changes the disposition. > > We have the same behaviour as Solaris, ingored signals are not queued or > recorded regardeless of the presence of sigwaiting thread. > This is a bit confusing. sigwait(2) says: "The signals specified by set should be blocked at the time of the call to sigwait()."...
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