How to not write a Signal Handler... by example

Published February 4th, 2005

Read some scary code in Asterisk today:

Quote from Asterisk:

static void hup_handler(int num)       
{                  
        if (option_verbose > 1)
                printf("Received HUP signal -- Reloading configs\n");
        if (restartnow)
                execvp(_argv[0], _argv);
        /* XXX This could deadlock XXX */   
        ast_module_reload(NULL);     
}
  1. printf should not be used in a signal. handler.
  2. Calling execvp here is completely bogus. Signals can come at any time, and Asterisk is a multithreaded program. The signal will be handled by a random thread, and this will not do any cleanup of the resources used by asterisk.

Written by Paul Querna, CTO @ ScaleFT. @pquerna