HowTo: catch a signal and get a CrashLog too (Leopard)
HowTo: catch a signal and get a CrashLog too (Leopard)
- Subject: HowTo: catch a signal and get a CrashLog too (Leopard)
- From: David Hoerl <email@hidden>
- Date: Tue, 18 Dec 2007 16:54:13 -0500
[This for archive searchers. signal() signals CrashLog CrashReporter
OSX Darwin]
It took me a while to get this going, thus the post. I have a C-based
command line tool (CLI) process. It writes logs, and while it could
report its own failures, crashes resulted in no log entry. So, I
started catching signals, and write my log (stderr), which worked
fine (see below).
However, it seems that at least in Leopard, when you catch a signal,
CrashReporter will not process the crash. Hmmm. So I found that if I
raised another uncaught signal in the handler, voila, CrashReporter
creates a crash report, so now I get both.
#include <signal.h>
static void crashCatcher(int sig);
static char exitStr[] = "Exit due to Signal ";
static char finalStr[] = ".\n";
// whatever you want to catch - man 3 signal
(void)signal(SIGILL, crashCatcher);
(void)signal(SIGFPE, crashCatcher);
(void)signal(SIGBUS, crashCatcher);
(void)signal(SIGSEGV, crashCatcher);
(void)signal(SIGSYS, crashCatcher); // probably overkill
(void)signal(SIGILL, crashCatcher);
static void
crashCatcher(int sig)
{
char c;
// should not use buffered IO as it may use malloc and friends
// suggested by Dalrymple and Hillegass, "Advanced Mac OS Prog.",
// been very helpful to me
write(STDERR_FILENO, exitStr, strlen(exitStr));
write(STDERR, exitStr, sizeof(exitStr)-1);
c = '0' + (sig/10);
write(STDERR, &c, 1);
c = '0' + (sig);
write(STDERR, &c, 1);
write(STDERR, finalStr, sizeof(finalStr)-1);
// since we caught the signal, CrashReporter will otherwise not run
// however, this signal is uncaught, so it will crash us and
CrashReporter will run!
raise(SIGQUIT);
}
Could be there is a better way, but my googling found nothing.
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