John, > It is unclear from the various documentions in the kernel and glibc what > the proper behaviour should be for the case when a child process > catches a SIGNAL (say for instance, SIGTERM), and then calls exit() > from within its caught SIGNAL handler. > > Since the exit() will cause a SIGCHLD to the parent, and the parent > (let's say) has a SIGCHLD sigaction (SA_SIGINFO sa_flags set), should > the parent's WIFSIGNALED(siginfo->si_status) be true? > > To recap, the WIFSIGNALED section of the waitpid() manpage says: > > WIFSIGNALED(status) > returns true if the child process was terminated by a signal. > > So the dilemna: the child caught the signal, so it wasn't terminated by > a signal, but rather its signal handler (let's say) called exit. > > Furthermore: > > WTERMSIG(status) > returns the number of the signal that caused the child process > to terminate. This macro should only be employed if WIFSIGNALED > returned true. > > Observered behaviour with 2.6.20.6 is that is WIFSIGNALED(status) > returns true (possibly incorrect), and furthermore, WTERMSIG(status) > returns the exit(VALUE) VALUE from the child's exit() call, and not the > SIGNAL (let's say SIGTERM that the child caught). This may be correct, > since the siginfo_t * si_status member is: > > int si_status; /* Exit value or signal */ > > but there's no clarity on which: exit value or signal. Since the child > exited, I'm likely to assume exit status, which is current observed > behaviour, but then, WIFSIGNALED(status) should be FALSE, which its not > (observed with 2.6.20.6). > > So could someone clarify the kernel's intent? > > I can provide a short C program to illustrate above behaviour, if > needed. It also could be that I'm just misinterpreting the intent, > which is why I'm not calling this a bug, despite a possible > inconsistency in behaviour.
If the child terminated by calling exit(), regardless of whether it was done from inside a signal handler, then WIFEXITED() should test true, but WIFSIGNALED() will not. If you are seeing otherwise, then show a *short* program that demonstrates the behavior. (But it seems unlikely that there would be a kernel bug on this point, so do check your program carefully!) Cheers, Michael - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
