1 files changed, 89 insertions, 0 deletions
diff --git a/src/master/master_proto.c b/src/master/master_proto.c
new file mode 100644
index 0000000..e38d2e1
--- /dev/null
+++ b/src/master/master_proto.c
@@ -0,0 +1,89 @@
+/*++
+/* NAME
+/*	master_proto 3
+/* SUMMARY
+/*	Postfix master - status notification protocol
+/* SYNOPSIS
+/*	#include <master_proto.h>
+/*
+/*	int	master_notify(pid, generation, status)
+/*	int	pid;
+/*	unsigned generation;
+/*	int	status;
+/* DESCRIPTION
+/*	The master process provides a standard environment for its
+/*	child processes. Part of this environment is a pair of file
+/*	descriptors that the master process shares with all child
+/*	processes that provide the same service.
+/* .IP MASTER_LISTEN_FD
+/*	The shared file descriptor for accepting client connection
+/*	requests. The master process listens on this socket or FIFO
+/*	when all child processes are busy.
+/* .IP MASTER_STATUS_FD
+/*	The shared file descriptor for sending child status updates to
+/*	the master process.
+/* .PP
+/*	A child process uses master_notify() to send a status notification
+/*	message to the master process.
+/* .IP MASTER_STAT_AVAIL
+/*	The child process is ready to accept client connections.
+/* .IP MASTER_STAT_TAKEN
+/*	Until further notice, the child process is unavailable for
+/*	accepting client connections.
+/* .PP
+/*	When a child process terminates without sending a status update,
+/*	the master process will figure out that the child is no longer
+/*	available.
+/* DIAGNOSTICS
+/*	The result is -1 in case of problems. This usually means that
+/*	the parent disconnected after a reload request, in order to
+/*	force children to commit suicide.
+/* 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 <unistd.h>
+
+/* Utility library. */
+
+#include <msg.h>
+
+/* Global library. */
+
+#include "master_proto.h"
+
+int     master_notify(int pid, unsigned generation, int status)
+{
+    const char *myname = "master_notify";
+    MASTER_STATUS stat;
+
+    /*
+     * We use a simple binary protocol to minimize security risks. Since this
+     * is local IPC, there are no byte order or word length issues. The
+     * server treats this information as gossip, so sending a bad PID or a
+     * bad status code will only have amusement value.
+     */
+    stat.pid = pid;
+    stat.gen = generation;
+    stat.avail = status;
+
+    if (write(MASTER_STATUS_FD, (void *) &stat, sizeof(stat)) != sizeof(stat)) {
+	if (msg_verbose)
+	    msg_info("%s: status %d: %m", myname, status);
+	return (-1);
+    } else {
+	if (msg_verbose)
+	    msg_info("%s: status %d", myname, status);
+	return (0);
+    }
+}