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/*++
/* 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);
}
}
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