/*++ /* 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, (char *) &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); } }