1 /* $NetBSD: master_proto.c,v 1.2 2017/02/14 01:16:45 christos Exp $ */
2
3 /*++
4 /* NAME
5 /* master_proto 3
6 /* SUMMARY
7 /* Postfix master - status notification protocol
8 /* SYNOPSIS
9 /* #include <master_proto.h>
10 /*
11 /* int master_notify(pid, generation, status)
12 /* int pid;
13 /* unsigned generation;
14 /* int status;
15 /* DESCRIPTION
16 /* The master process provides a standard environment for its
17 /* child processes. Part of this environment is a pair of file
18 /* descriptors that the master process shares with all child
19 /* processes that provide the same service.
20 /* .IP MASTER_LISTEN_FD
21 /* The shared file descriptor for accepting client connection
22 /* requests. The master process listens on this socket or FIFO
23 /* when all child processes are busy.
24 /* .IP MASTER_STATUS_FD
25 /* The shared file descriptor for sending child status updates to
26 /* the master process.
27 /* .PP
28 /* A child process uses master_notify() to send a status notification
29 /* message to the master process.
30 /* .IP MASTER_STAT_AVAIL
31 /* The child process is ready to accept client connections.
32 /* .IP MASTER_STAT_TAKEN
33 /* Until further notice, the child process is unavailable for
34 /* accepting client connections.
35 /* .PP
36 /* When a child process terminates without sending a status update,
37 /* the master process will figure out that the child is no longer
38 /* available.
39 /* DIAGNOSTICS
40 /* The result is -1 in case of problems. This usually means that
41 /* the parent disconnected after a reload request, in order to
42 /* force children to commit suicide.
43 /* LICENSE
44 /* .ad
45 /* .fi
46 /* The Secure Mailer license must be distributed with this software.
47 /* AUTHOR(S)
48 /* Wietse Venema
49 /* IBM T.J. Watson Research
50 /* P.O. Box 704
51 /* Yorktown Heights, NY 10598, USA
52 /*--*/
53
54 /* System library. */
55
56 #include <sys_defs.h>
57 #include <unistd.h>
58
59 /* Utility library. */
60
61 #include <msg.h>
62
63 /* Global library. */
64
65 #include "master_proto.h"
66
master_notify(int pid,unsigned generation,int status)67 int master_notify(int pid, unsigned generation, int status)
68 {
69 const char *myname = "master_notify";
70 MASTER_STATUS stat;
71
72 /*
73 * We use a simple binary protocol to minimize security risks. Since this
74 * is local IPC, there are no byte order or word length issues. The
75 * server treats this information as gossip, so sending a bad PID or a
76 * bad status code will only have amusement value.
77 */
78 stat.pid = pid;
79 stat.gen = generation;
80 stat.avail = status;
81
82 if (write(MASTER_STATUS_FD, (void *) &stat, sizeof(stat)) != sizeof(stat)) {
83 if (msg_verbose)
84 msg_info("%s: status %d: %m", myname, status);
85 return (-1);
86 } else {
87 if (msg_verbose)
88 msg_info("%s: status %d", myname, status);
89 return (0);
90 }
91 }
92