søn, 02 12 2007 kl. 20:18 +0300, skrev Oleg Nesterov:
> On 12/02, Simon Holm Th?gersen wrote:
> >
> > s??n, 02 12 2007 kl. 18:14 +0300, skrev Oleg Nesterov:
> > >
> > > Please comment, I think at least the idea is promising.
> > >
> > I have an issue that sounds related, but I might be completely off. I
> > would expect the simple attached program to keep receiving the same
> > signal, i.e. respond to
> > killall signal-exec -s SIGHUP
> >
> > I tried your patches, but they didn't help.
> >
> > Any ideas?
> >
> >
> > Simon Holm Th??gersen
>
> > #include <signal.h>
> > #include <stdio.h>
> > #include <unistd.h>
> >
> > static char **argv_;
> >
> > static void handler(int signal)
> > {
> > printf("got signal %d\n", signal);
> > execv(argv_[0], argv_);
> > }
> >
> > int main(int argc, char *argv[])
> > {
> > printf("spawned\n");
> > argv_ = argv;
> > if (signal(SIGTERM, handler) == SIG_ERR)
> > err(1, "could not set signal handler for SIGTERM");
> > if (signal(SIGHUP, handler) == SIG_ERR)
> > err(1, "could not set signal handler for SIGTERM");
> > sleep(60);
> > return 0;
> > }
> >
>
> I think this is another issue which should be solved (?).
>
> exec() from the signal handler doesn't do sys_sigreturn(), so we don't unblock
> the signal, and it remains blocked after exec().
>
> Hmm. Is this linux bug, or application bug?
Good question. I haven't been able to find something in the
documentation for execve(2) and signal(2) saying it shouldn't be
possible, and it works on Solaris 10, so I'd say it is a Linux bug.
Actually, having another look at the documentation, signal(7) mentions
that POSIX.1-2003 requires that execve is safe to call from inside a
signal handler.
Simon Holm Thøgersen
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