external/ibm-public/postfix/dist/src/master/master_proto.c

   1 /*      $NetBSD$        */
   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
  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, (char *) &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 }