Re: just-in-time debugging?

[Dan Kegel]

 Tony Hoyle ([e-mail]) wrote:
> Is there a way that gdb/ddd could be invoked when a program is about 
> to dump core...?

Yes, I use that to get a symbolic stack dump after a crash,
although I find that the gdb so invoked doesn't accept interactive
commands, and I have to use 'kill -9' afterwards.
Here's the code I use:

void dump_stack(int signum)
{
    (void) signum;
    char s[160];
    // The right command to execute depends on the program.  Adjust to taste.
    system("echo 'info threads\nbt\nthread 3\nbt\nthread 4\nbt\nthread 5\nbt\n' > gdbcmd");
 
    sprintf(s, "gdb -batch -x gdbcmd %s %d", argv0, (int) getpid());
    printf("Crashed!  Starting debugger to get stack dump.  You may need to kill -9 this process afterwards.\n");
    system(s);
    exit(1);
 
} 

main() {
   signal(SIGSEGV, dump_stack);
   signal(SIGBUS, dump_stack);   
...