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

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      master_proto 3h
   6 /* SUMMARY
   7 /*      master process protocol
   8 /* SYNOPSIS
   9 /*      #include <master_proto.h>
  10 /* DESCRIPTION
  11 /* .nf
  12
  13  /*
  14   * Transport names. The master passes the transport name on the command
  15   * line, and thus the name is part of the master to child protocol.
  16   */
  17 #define MASTER_XPORT_NAME_UNIX  "unix"  /* local IPC */
  18 #define MASTER_XPORT_NAME_FIFO  "fifo"  /* local IPC */
  19 #define MASTER_XPORT_NAME_INET  "inet"  /* non-local IPC */
  20 #define MASTER_XPORT_NAME_PASS  "pass"  /* local IPC */
  21
  22  /*
  23   * Format of a status message sent by a child process to the process
  24   * manager. Since this is between processes on the same machine we need not
  25   * worry about byte order and word length.
  26   */
  27 typedef struct MASTER_STATUS {
  28     int     pid;                        /* process ID */
  29     unsigned gen;                       /* child generation number */
  30     int     avail;                      /* availability */
  31 } MASTER_STATUS;
  32
  33 #define MASTER_GEN_NAME "GENERATION"    /* passed via environment */
  34
  35 #define MASTER_STAT_TAKEN       0       /* this one is occupied */
  36 #define MASTER_STAT_AVAIL       1       /* this process is idle */
  37
  38 extern int master_notify(int, unsigned, int);   /* encapsulate status msg */
  39
  40  /*
  41   * File descriptors inherited from the master process. The flow control pipe
  42   * is read by receive processes and is written to by send processes. If
  43   * receive processes get too far ahead they will pause for a brief moment.
  44   */
  45 #define MASTER_FLOW_READ        3
  46 #define MASTER_FLOW_WRITE       4
  47
  48  /*
  49   * File descriptors inherited from the master process. All processes that
  50   * provide a given service share the same status file descriptor, and listen
  51   * on the same service socket(s). The kernel decides what process gets the
  52   * next connection. Usually the number of listening processes is small, so
  53   * one connection will not cause a "thundering herd" effect. When no process
  54   * listens on a given socket, the master process will. MASTER_LISTEN_FD is
  55   * actually the lowest-numbered descriptor of a sequence of descriptors to
  56   * listen on.
  57   */
  58 #define MASTER_STATUS_FD        5       /* shared channel to parent */
  59 #define MASTER_LISTEN_FD        6       /* accept connections here */
  60
  61 /* LICENSE
  62 /* .ad
  63 /* .fi
  64 /*      The Secure Mailer license must be distributed with this software.
  65 /* AUTHOR(S)
  66 /*      Wietse Venema
  67 /*      IBM T.J. Watson Research
  68 /*      P.O. Box 704
  69 /*      Yorktown Heights, NY 10598, USA
  70 /*--*/
  71