Re: Catching SIGSEGV
--- In nslu2-linux@..., David Given <dg <at> ...> wrote:
> I'm not quite sure what you're trying to do here --- AIUI sigwait()
> blocks until a signal *for the blocked thread* is received, so no code
> that can generate the signal will be run... (unless you send it manually
> from another thread).
Ah! I had thought that all signals would be passed to all threads (which is indeed the case for signals
arising from outside).
>
> If you're trying to catch a signal thrown by code in a different thread,
> then I don't think that will work.
>
> The simplest approach is to just register a SIGSEGV signal handler in
> the thread that's going to be doing the work. Then, when the signal is
> thrown, your handler will run. If you want to do the work in a different
> thread, then you'll need some sort of IPC between threads (but beware
> that you can only run a small subset of functions safely from inside a
> signal handler).
Yes, I have now set up a sigaction-type handler in main(), and it seems to be inherited by processes created
subsequently to that. It sort of works, but I need to know where the SIGSEGV came from, in order to know where
to look for the bug. Here is my current handler:
void errHandler(int signum, siginfo_t *info, void *ptr) {
int count = backtrace( tracePtrs, 100 );
backtrace_symbols_fd(tracePtrs, count, 2);
fatal("Heat failed with %s: si_code=%d",
strsignal(signum), info->si_code);
(Continue reading)
). I can easily get the program to produce a message "Segmentation Violation" on stderr, but noway can I catch it before getting that message. I have written sigemptyset(&set); sigaddset(&set, SIGUSR1); sigaddset(&set, SIGUSR2); sigaddset(&set, SIGTERM); sigaddset(&set, SIGINT); sigaddset(&set, SIGSEGV); sigaddset(&set, SIGBUS); sigaddset(&set, SIGILL); sigaddset(&set, SIGFPE); sigaddset(&set, SIGSYS); and I have created a pthread which contains sigwait(&set, &signal); printf("Display signal %d\n", signal); switch (signal) { case SIGSEGV: case SIGBUS: case SIGILL: case SIGFPE: case SIGSYS: fatal("Heat failed: %s", strerror(errno)); case SIGTERM: case SIGINT: warn("Heat terminated");
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