1 files changed, 118 insertions, 0 deletions
diff --git a/src/util/sigdelay.c b/src/util/sigdelay.c
new file mode 100644
index 0000000..6f07a22
--- /dev/null
+++ b/src/util/sigdelay.c
@@ -0,0 +1,118 @@
+/*++
+/* NAME
+/*	sigdelay 3
+/* SUMMARY
+/*	delay/resume signal delivery
+/* SYNOPSIS
+/*	#include <sigdelay.h>
+/*
+/*	void	sigdelay()
+/*
+/*	void	sigresume()
+/* DESCRIPTION
+/*	sigdelay() delays delivery of signals. Signals that
+/*	arrive in the mean time will be queued.
+/*
+/*	sigresume() resumes delivery of signals. Signals that have
+/*	arrived in the mean time will be delivered.
+/* DIAGNOSTICS
+/*	All errors are fatal.
+/* BUGS
+/*	The signal queue may be really short (as in: one per signal type).
+/*
+/*	Some signals such as SIGKILL cannot be blocked.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <signal.h>
+
+/* Utility library. */
+
+#include "msg.h"
+#include "posix_signals.h"
+#include "sigdelay.h"
+
+/* Application-specific. */
+
+static sigset_t saved_sigmask;
+static sigset_t block_sigmask;
+static int suspending;
+static int siginit_done;
+
+/* siginit - compute signal mask only once */
+
+static void siginit(void)
+{
+    int     sig;
+
+    siginit_done = 1;
+    sigemptyset(&block_sigmask);
+    for (sig = 1; sig < NSIG; sig++)
+	sigaddset(&block_sigmask, sig);
+}
+
+/* sigresume - deliver delayed signals and disable signal delay */
+
+void    sigresume(void)
+{
+    if (suspending != 0) {
+	suspending = 0;
+	if (sigprocmask(SIG_SETMASK, &saved_sigmask, (sigset_t *) 0) < 0)
+	    msg_fatal("sigresume: sigprocmask: %m");
+    }
+}
+
+/* sigdelay - save signal mask and block all signals */
+
+void    sigdelay(void)
+{
+    if (siginit_done == 0)
+	siginit();
+    if (suspending == 0) {
+	suspending = 1;
+	if (sigprocmask(SIG_BLOCK, &block_sigmask, &saved_sigmask) < 0)
+	    msg_fatal("sigdelay: sigprocmask: %m");
+    }
+}
+
+#ifdef TEST
+
+ /*
+  * Test program - press Ctrl-C twice while signal delivery is delayed, and
+  * see how many signals are delivered when signal delivery is resumed.
+  */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+static void gotsig(int sig)
+{
+    printf("Got signal %d\n", sig);
+}
+
+int     main(int unused_argc, char **unused_argv)
+{
+    signal(SIGINT, gotsig);
+    signal(SIGQUIT, gotsig);
+
+    printf("Delaying signal delivery\n");
+    sigdelay();
+    sleep(5);
+    printf("Resuming signal delivery\n");
+    sigresume();
+    exit(0);
+}
+
+#endif