static int set_guard_page(port_tls_data_t* tlsdata, Boolean set)
{
int res;
if (!tlsdata)
tlsdata = get_private_tls_data();
if (!tlsdata)
return -1;
if (!tlsdata->guard_page_addr)
return 0;
if ((set && tlsdata->guard_page_set) ||
(!set && !tlsdata->guard_page_set))
return 0; // Already in needed state
res = mprotect(tlsdata->guard_page_addr, tlsdata->guard_page_size,
set ? PROT_NONE : (PROT_READ | PROT_WRITE | PROT_EXEC));
if (res != 0)
return errno;
if (set)
{
res = set_alt_stack(tlsdata, TRUE);
if (res != 0)
return res;
}
tlsdata->guard_page_set = set;
return 0;
}
static void c_handler(Registers* pregs, size_t signum, void* fault_addr)
{ // this exception handler is executed *after* OS signal handler returned
int result;
port_tls_data_t* tlsdata = get_private_tls_data();
switch ((int)signum)
{
case SIGSEGV:
if (tlsdata->restore_guard_page)
{
// Now it's safe to disable alternative stack
set_alt_stack(tlsdata, FALSE);
result = port_process_signal(PORT_SIGNAL_STACK_OVERFLOW, pregs, fault_addr, FALSE);
}
else
result = port_process_signal(PORT_SIGNAL_GPF, pregs, fault_addr, FALSE);
break;
case SIGFPE:
result = port_process_signal(PORT_SIGNAL_ARITHMETIC, pregs, fault_addr, FALSE);
break;
case SIGTRAP:
// Correct return address
pregs->set_ip((void*)((POINTER_SIZE_INT)pregs->get_ip() - 1));
result = port_process_signal(PORT_SIGNAL_BREAKPOINT, pregs, fault_addr, FALSE);
break;
case SIGINT:
result = port_process_signal(PORT_SIGNAL_CTRL_C, pregs, fault_addr, FALSE);
break;
case SIGQUIT:
result = port_process_signal(PORT_SIGNAL_QUIT, pregs, fault_addr, FALSE);
break;
case SIGABRT:
result = port_process_signal(PORT_SIGNAL_ABORT, NULL, fault_addr, FALSE);
break;
default:
result = port_process_signal(PORT_SIGNAL_UNKNOWN, pregs, fault_addr, TRUE);
}
if (result == 0)
{
// Restore guard page if needed
if (tlsdata->restore_guard_page)
{
port_thread_restore_guard_page();
tlsdata->restore_guard_page = FALSE;
if (port_thread_detach_temporary() == 0)
STD_FREE(tlsdata);
}
return;
}
// We've got a crash
if (signum == SIGSEGV)
{
port_thread_restore_guard_page(); // To catch SO again
tlsdata->restore_guard_page = FALSE;
}
if (result > 0) // invoke debugger
{ // Prepare second catch of signal to attach GDB from signal handler
//assert(tlsdata); // Should be attached - provided by general_signal_handler
tlsdata->debugger = TRUE;
return; // To produce signal again
}
// result < 0 - exit process
if (FLAG_CORE)
{ // Return to the same place to produce the same crash and generate core
signal(signum, SIG_DFL); // setup default handler
return;
}
// No core needed - simply terminate
_exit(-1);
}