signal: Switch from signal() to sigaction.

Use of signal() should be avoided because the behavior of signal() varies
across Unix versions, and has also varied historically across different
versions of Linux.

This patch rewrites para_install_sighandler so that it calls sigaction()
instead of signal(). The implementation is taken from good old APUE.

There are a couple of other users of signal() in the paraslash code. Most
of which are OK because they use signal() only to ignore/reset a signal which
happens to be the only portable use of signal(). All other users of signal()
have to be converted in subsequent patches.

diff --git a/signal.c b/signal.c
index acc87802b33a841f8f5d7f90b971ae97a3edc3b0..9a1dcfb0ac5f4ef240e627e80a26ee0379c94519 100644 (file)
--- a/signal.c
+++ b/signal.c
@@ -117,20 +117,34 @@ void para_reap_children(void)
 }
 
 /**
- * Wrapper around signal(2).
+ * Install the generic signal handler for the given signal number.
  *
  * \param sig The number of the signal to catch.
  *
- * This installs the generic signal handler for the given signal.
- *
  * \return This function returns 1 on success and \p -E_SIGNAL_SIG_ERR on errors.
  *
- * \sa signal(2).
+ * \sa signal(2), sigaction(2).
  */
 int para_install_sighandler(int sig)
 {
+       struct sigaction act;
+
        PARA_DEBUG_LOG("catching signal %d\n", sig);
-       return signal(sig, &generic_signal_handler) == SIG_ERR?  -E_SIGNAL_SIG_ERR : 1;
+       act.sa_handler = &generic_signal_handler;
+       sigemptyset(&act.sa_mask);
+       act.sa_flags = 0;
+       if (sig == SIGALRM) {
+               #ifdef SA_INTERRUPT /* SunOS */
+                       act.sa_flags |= SA_INTERRUPT;
+               #endif
+       } else {
+               #ifdef SA_RESTART /* BSD */
+                       act.sa_flags |= SA_RESTART;
+               #endif
+       }
+       if (sigaction(sig, &act, NULL) < 0)
+               return -E_SIGNAL_SIG_ERR;
+       return 1;
 }
 
 /**