/* * close_all_except() * * Close all file descriptors except the given keep_fd. */ void close_all_except( int keep_fd ) { int fd; for (fd = 0; fd < keep_fd; fd++) close(fd); close_all_beyond(keep_fd); }
static void fork_blocking_child( blocking_child * c ) { static int atexit_installed; static int blocking_pipes[4] = { -1, -1, -1, -1 }; int rc; int was_pipe; int is_pipe; int saved_errno = 0; int childpid; int keep_fd; int fd; /* * parent and child communicate via a pair of pipes. * * 0 child read request * 1 parent write request * 2 parent read response * 3 child write response */ if (-1 == c->req_write_pipe) { rc = pipe_socketpair(&blocking_pipes[0], &was_pipe); if (0 != rc) { saved_errno = errno; } else { rc = pipe_socketpair(&blocking_pipes[2], &is_pipe); if (0 != rc) { saved_errno = errno; close(blocking_pipes[0]); close(blocking_pipes[1]); } else { INSIST(was_pipe == is_pipe); } } if (0 != rc) { errno = saved_errno; msyslog(LOG_ERR, "unable to create worker pipes: %m"); exit(1); } /* * Move the descriptors the parent will keep open out of the * low descriptors preferred by C runtime buffered FILE *. */ c->req_write_pipe = move_fd(blocking_pipes[1]); c->resp_read_pipe = move_fd(blocking_pipes[2]); /* * wake any worker child on orderly shutdown of the * daemon so that it can notice the broken pipes and * go away promptly. */ if (!atexit_installed) { atexit(&send_worker_home_atexit); atexit_installed = TRUE; } } #ifdef HAVE_DROPROOT /* defer the fork until after root is dropped */ if (droproot && !root_dropped) return; #endif if (syslog_file != NULL) fflush(syslog_file); fflush(stdout); fflush(stderr); signal_no_reset(SIGCHLD, SIG_IGN); childpid = fork(); if (-1 == childpid) { msyslog(LOG_ERR, "unable to fork worker: %m"); exit(1); } if (childpid) { /* this is the parent */ TRACE(1, ("forked worker child (pid %d)\n", childpid)); c->pid = childpid; c->ispipe = is_pipe; /* close the child's pipe descriptors. */ close(blocking_pipes[0]); close(blocking_pipes[3]); memset(blocking_pipes, -1, sizeof(blocking_pipes)); /* wire into I/O loop */ (*addremove_io_fd)(c->resp_read_pipe, is_pipe, FALSE); return; /* parent returns */ } /* * The parent gets the child pid as the return value of fork(). * The child must work for it. */ c->pid = getpid(); worker_process = TRUE; /* * In the child, close all files except stdin, stdout, stderr, * and the two child ends of the pipes. */ DEBUG_INSIST(-1 == c->req_read_pipe); DEBUG_INSIST(-1 == c->resp_write_pipe); c->req_read_pipe = blocking_pipes[0]; c->resp_write_pipe = blocking_pipes[3]; kill_asyncio(0); closelog(); if (syslog_file != NULL) { fclose(syslog_file); syslog_file = NULL; syslogit = TRUE; } keep_fd = max(c->req_read_pipe, c->resp_write_pipe); for (fd = 3; fd < keep_fd; fd++) if (fd != c->req_read_pipe && fd != c->resp_write_pipe) close(fd); close_all_beyond(keep_fd); /* * We get signals from refclock serial I/O on NetBSD in the * worker if we do not reset SIGIO's handler to the default. * It is not conditionalized for NetBSD alone because on * systems where it is not needed, it is harmless, and that * allows us to handle unknown others with NetBSD behavior. * [Bug 1386] */ #if defined(USE_SIGIO) signal_no_reset(SIGIO, SIG_DFL); #elif defined(USE_SIGPOLL) signal_no_reset(SIGPOLL, SIG_DFL); #endif signal_no_reset(SIGHUP, worker_sighup); init_logging("ntp_intres", 0, FALSE); setup_logfile(NULL); /* * And now back to the portable code */ exit_worker(blocking_child_common(c)); }