/*++ /* NAME /* master_monitor 3 /* SUMMARY /* Postfix master - start-up monitoring /* SYNOPSIS /* #include "master.h" /* /* int master_monitor(time_limit) /* int time_limit; /* DESCRIPTION /* master_monitor() forks off a background child process, and /* returns in the child. The result value is the file descriptor /* on which the child process must write one byte after it /* completes successful initialization as a daemon process. /* /* The foreground process waits for the child's completion for /* a limited amount of time. It terminates with exit status 0 /* in case of success, non-zero otherwise. /* DIAGNOSTICS /* Fatal errors: system call failure. /* BUGS /* SEE ALSO /* 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 <signal.h> #include <unistd.h> #include <stdlib.h> /* Utility library. */ #include <msg.h> #include <iostuff.h> /* Application-specific. */ #include <master.h> /* master_monitor - fork off a foreground monitor process */ int master_monitor(int time_limit) { pid_t pid; int pipes[2]; char buf[1]; /* * Sanity check. */ if (time_limit <= 0) msg_panic("master_monitor: bad time limit: %d", time_limit); /* * Set up the plumbing for child-to-parent communication. */ if (pipe(pipes) < 0) msg_fatal("pipe: %m"); close_on_exec(pipes[0], CLOSE_ON_EXEC); close_on_exec(pipes[1], CLOSE_ON_EXEC); /* * Fork the child, and wait for it to report successful initialization. */ switch (pid = fork()) { case -1: /* Error. */ msg_fatal("fork: %m"); case 0: /* Child. Initialize as daemon in the background. */ close(pipes[0]); return (pipes[1]); default: /* Parent. Monitor the child in the foreground. */ close(pipes[1]); switch (timed_read(pipes[0], buf, 1, time_limit, (void *) 0)) { default: /* The child process still runs, but something is wrong. */ (void) kill(pid, SIGKILL); /* FALLTHROUGH */ case 0: /* The child process exited prematurely. */ msg_fatal("daemon initialization failure"); case 1: /* The child process initialized successfully. */ exit(0); } } }