OC Systems Probe Library - When Program Dumps Core

By default, Aprobe doesn't interfere with the default signal handling behavior. As such, if your program (or your probe) causes a memory violation and dumps core, the normal program exit actions associated with your probes will not be performed. However, here is a simple probe that you can use with other probes to activate a probe and terminate other probes normally when handling the signal. You can compile it once (and call it whatever you want) and put it in $APROBE/ual_lib to use when you need it.

#include <signal.h>
#include <stdlib.h>
#include <sys/ucontext.h>

static void HandlerFormat(
   int         *Signal,
   ap_AddressT *Address)
{
   printf(
     "*********************************\n");
   printf(
     "Detected signal %d at:\n", *Signal);
   ap_PrintAddress(*Address);
   printf(
     "*********************************\n");
}

// This is our handler:
static void MyHandler
   (int sig, siginfo_t *sip, void *ucp)
{
   ap_AddressT Address =
      (ap_AddressT )
      ((ucontext_t *) ucp)
      ->uc_mcontext.gregs[REG_PC];

   ap_Error(
      ap_WarningSev,
      "Signal %d detected. "
      "Performing thread and program exit "
      "actions.",
      sig);
   log (sig, Address) with HandlerFormat;

   ap_EndProgram();

   exit(1);
} /* MyHandler */


probe program
{
   on_entry
   {
      // Register our handler
      ap_RegisterSignalHandler (
         SIGSEGV,
         ap_CallBeforeUserAction,
         MyHandler);
   }
}

probe thread
{
   typedef probe
   {
      on_entry
      {
         log("Entry to 'sigacthandler()'"
             "with signal ", $1);
         ap_LogTraceback (99);
      }
   } SigActHandlerProbe;

   // Create instances of the above probe type:
   SigActHandlerProbe One
      ("sigaction.c":"sigacthandler()"
       in "libc.so");
   SigActHandlerProbe Two
      ("sigaction.c":"sigacthandler()"
       in "libthread.so");
}