On Sep 22, 2009, at 2:27 PM, Alastair Houghton wrote:
If you was *your* process that crashed, on "normal" UNIX-like
systems you can use signal handlers to catch the crash and do
something about it. Likewise, on a normal UNIX-like platform you'd
get a SIGCHLD from the system and you could check the process exit
status. Or you could act as a debugger using the ptrace() API.
On OS X though, you can't (or couldn't, last I checked which was
some time ago) intercept the system crash reporter using signal-
related APIs because it's triggered by the lower-level Mach
exception port. Even if you somehow handle the signal (in the
parent or the child process), the crash reporter is still triggered
via the Mach exception port.
On Tiger and earlier, the CrashReporter would generate a crash report
for a Mach exception even if it was later delivered as a signal and
handled by the process. Since Leopard, though, a crash report is only
generated if the signal is not handled. So, handling signals is
sufficient to suppress crash reports these days.
That said, it's actually pretty simple to disconnect the CrashReporter
from your process using Mach routines. I had to do this for Wine on
Tiger because Wine routinely provokes exceptions (and uses signal
handlers to deal with the consequences) and the CrashReporter was
suspending the process while it generated its report, slowing it _way_
down.
kern_return_t kret = task_set_exception_ports(
mach_task_self(),
EXC_MASK_BAD_ACCESS | EXC_MASK_BAD_INSTRUCTION |
EXC_MASK_ARITHMETIC,
MACH_PORT_NULL,
EXCEPTION_STATE_IDENTITY,
MACHINE_THREAD_STATE);
I went into it in more depth here:
http://lists.apple.com/archives/unix-porting/2007/Mar/msg00009.html
Regards,
Ken
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