1 files changed, 106 insertions, 0 deletions
diff --git a/src/master/master_monitor.c b/src/master/master_monitor.c
new file mode 100644
index 0000000..6b2ca65
--- /dev/null
+++ b/src/master/master_monitor.c
@@ -0,0 +1,106 @@
+/*++
+/* NAME
+/*	master_monitor 3
+/* SUMMARY
+/*	Postfix master - start-up monitoring
+/* SYNOPSIS
+/*	#include "master.h"
+/*
+/*	int     master_monitor(time_limit)
+/*	int	time_limit;
+/* DESCRIPTION
+/*	master_monitor() forks off a background child process, and
+/*	returns in the child. The result value is the file descriptor
+/*	on which the child process must write one byte after it
+/*	completes successful initialization as a daemon process.
+/*
+/*	The foreground process waits for the child's completion for
+/*	a limited amount of time. It terminates with exit status 0
+/*	in case of success, non-zero otherwise.
+/* DIAGNOSTICS
+/*	Fatal errors: system call failure.
+/* BUGS
+/* SEE ALSO
+/* 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>
+#include <stdlib.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <iostuff.h>
+
+/* Application-specific. */
+
+#include <master.h>
+
+/* master_monitor - fork off a foreground monitor process */
+
+int     master_monitor(int time_limit)
+{
+    pid_t   pid;
+    int     pipes[2];
+    char    buf[1];
+
+    /*
+     * Sanity check.
+     */
+    if (time_limit <= 0)
+	msg_panic("master_monitor: bad time limit: %d", time_limit);
+
+    /*
+     * Set up the plumbing for child-to-parent communication.
+     */
+    if (pipe(pipes) < 0)
+	msg_fatal("pipe: %m");
+    close_on_exec(pipes[0], CLOSE_ON_EXEC);
+    close_on_exec(pipes[1], CLOSE_ON_EXEC);
+
+    /*
+     * Fork the child, and wait for it to report successful initialization.
+     */
+    switch (pid = fork()) {
+    case -1:
+	/* Error. */
+	msg_fatal("fork: %m");
+    case 0:
+	/* Child. Initialize as daemon in the background. */
+	close(pipes[0]);
+	return (pipes[1]);
+    default:
+	/* Parent. Monitor the child in the foreground. */
+	close(pipes[1]);
+	switch (timed_read(pipes[0], buf, 1, time_limit, (void *) 0)) {
+	default:
+	    msg_warn("%m while waiting for daemon initialization");
+	    /* The child process still runs, but something is wrong. */
+	    (void) kill(pid, SIGKILL);
+	    /* FALLTHROUGH */
+	case 0:
+	    /* The child process exited prematurely. */
+	    msg_fatal("daemon initialization failure -- see logs for details");
+	case 1:
+	    /* The child process initialized successfully. */
+	    exit(0);
+	}
+    }
+}