1 files changed, 69 insertions, 0 deletions
diff --git a/src/util/killme_after.c b/src/util/killme_after.c
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+++ b/src/util/killme_after.c
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+/*++
+/* NAME
+/*	killme_after 3
+/* SUMMARY
+/*	programmed death
+/* SYNOPSIS
+/*	#include <killme_after.h>
+/*
+/*	void	killme_after(seconds)
+/*	unsigned int seconds;
+/* DESCRIPTION
+/*	The killme_after() function does a best effort to terminate
+/*	the process after the specified time, should it still exist.
+/*	It is meant to be used in a signal handler, as an insurance
+/*	against getting stuck somewhere while preparing for exit.
+/* DIAGNOSTICS
+/*	None. This routine does a best effort, damn the torpedoes.
+/* 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
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <signal.h>
+#include <unistd.h>
+
+/* Utility library. */
+
+#include <killme_after.h>
+
+/* killme_after - self-assured death */
+
+void    killme_after(unsigned int seconds)
+{
+    struct sigaction sig_action;
+
+    /*
+     * Schedule an ALARM signal, and make sure the signal will be delivered
+     * even if we are being called from a signal handler and SIGALRM delivery
+     * is blocked.
+     * 
+     * Undocumented: when a process runs with PID 1, Linux won't deliver a
+     * signal unless the process specifies a handler (i.e. SIG_DFL is treated
+     * as SIG_IGN). Conveniently, _exit() can be used directly as a signal
+     * handler. This changes the wait status that a parent would see, but in
+     * the case of "init" mode on Linux, no-one would care.
+     */
+    alarm(0);
+    sigemptyset(&sig_action.sa_mask);
+    sig_action.sa_flags = 0;
+    sig_action.sa_handler = (getpid() == 1 ? _exit : SIG_DFL);
+    sigaction(SIGALRM, &sig_action, (struct sigaction *) 0);
+    alarm(seconds);
+    sigaddset(&sig_action.sa_mask, SIGALRM);
+    sigprocmask(SIG_UNBLOCK, &sig_action.sa_mask, (sigset_t *) 0);
+}