prefork.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

    struct sigaction sa;
#endif

    if (!one_process) {
        ap_fatal_signal_setup(ap_server_conf, pconf);
    }

#ifndef NO_USE_SIGACTION
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;

    sa.sa_handler = sig_term;
    if (sigaction(SIGTERM, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGTERM)");
#ifdef AP_SIG_GRACEFUL_STOP
    if (sigaction(AP_SIG_GRACEFUL_STOP, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf,
                     "sigaction(" AP_SIG_GRACEFUL_STOP_STRING ")");
#endif
#ifdef SIGINT
    if (sigaction(SIGINT, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGINT)");
#endif
#ifdef SIGXCPU
    sa.sa_handler = SIG_DFL;
    if (sigaction(SIGXCPU, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGXCPU)");
#endif
#ifdef SIGXFSZ
    sa.sa_handler = SIG_DFL;
    if (sigaction(SIGXFSZ, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGXFSZ)");
#endif
#ifdef SIGPIPE
    sa.sa_handler = SIG_IGN;
    if (sigaction(SIGPIPE, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGPIPE)");
#endif

    /* we want to ignore HUPs and AP_SIG_GRACEFUL while we're busy
     * processing one
     */
    sigaddset(&sa.sa_mask, SIGHUP);
    sigaddset(&sa.sa_mask, AP_SIG_GRACEFUL);
    sa.sa_handler = restart;
    if (sigaction(SIGHUP, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGHUP)");
    if (sigaction(AP_SIG_GRACEFUL, &sa, NULL) < 0)
        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(" AP_SIG_GRACEFUL_STRING ")");
#else
    if (!one_process) {
#ifdef SIGXCPU
        apr_signal(SIGXCPU, SIG_DFL);
#endif /* SIGXCPU */
#ifdef SIGXFSZ
        apr_signal(SIGXFSZ, SIG_DFL);
#endif /* SIGXFSZ */
    }

    apr_signal(SIGTERM, sig_term);
#ifdef SIGHUP
    apr_signal(SIGHUP, restart);
#endif /* SIGHUP */
#ifdef AP_SIG_GRACEFUL
    apr_signal(AP_SIG_GRACEFUL, restart);
#endif /* AP_SIG_GRACEFUL */
#ifdef AP_SIG_GRACEFUL_STOP
    apr_signal(AP_SIG_GRACEFUL_STOP, sig_term);
#endif /* AP_SIG_GRACEFUL */
#ifdef SIGPIPE
    apr_signal(SIGPIPE, SIG_IGN);
#endif /* SIGPIPE */

#endif
}

/*****************************************************************
 * Child process main loop.
 * The following vars are static to avoid getting clobbered by longjmp();
 * they are really private to child_main.
 */

static int requests_this_child;
static int num_listensocks = 0;


int ap_graceful_stop_signalled(void)
{
    /* not ever called anymore... */
    return 0;
}


static void child_main(int child_num_arg)
{
    apr_pool_t *ptrans;
    apr_allocator_t *allocator;
    apr_status_t status;
    int i;
    ap_listen_rec *lr;
    apr_pollset_t *pollset;
    ap_sb_handle_t *sbh;
    apr_bucket_alloc_t *bucket_alloc;
    int last_poll_idx = 0;

    mpm_state = AP_MPMQ_STARTING; /* for benefit of any hooks that run as this
                                   * child initializes
                                   */

    my_child_num = child_num_arg;
    ap_my_pid = getpid();
    requests_this_child = 0;

    ap_fatal_signal_child_setup(ap_server_conf);

    /* Get a sub context for global allocations in this child, so that
     * we can have cleanups occur when the child exits.
     */
    apr_allocator_create(&allocator);
    apr_allocator_max_free_set(allocator, ap_max_mem_free);
    apr_pool_create_ex(&pchild, pconf, NULL, allocator);
    apr_allocator_owner_set(allocator, pchild);

    apr_pool_create(&ptrans, pchild);
    apr_pool_tag(ptrans, "transaction");

    /* needs to be done before we switch UIDs so we have permissions */
    ap_reopen_scoreboard(pchild, NULL, 0);
    status = apr_proc_mutex_child_init(&accept_mutex, ap_lock_fname, pchild);
    if (status != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, status, ap_server_conf,
                     "Couldn't initialize cross-process lock in child "
                     "(%s) (%d)", ap_lock_fname, ap_accept_lock_mech);
        clean_child_exit(APEXIT_CHILDFATAL);
    }

    if (unixd_setup_child()) {
        clean_child_exit(APEXIT_CHILDFATAL);
    }

    ap_run_child_init(pchild, ap_server_conf);

    ap_create_sb_handle(&sbh, pchild, my_child_num, 0);

    (void) ap_update_child_status(sbh, SERVER_READY, (request_rec *) NULL);

    /* Set up the pollfd array */
    /* ### check the status */
    (void) apr_pollset_create(&pollset, num_listensocks, pchild, 0);

    for (lr = ap_listeners, i = num_listensocks; i--; lr = lr->next) {
        apr_pollfd_t pfd = { 0 };

        pfd.desc_type = APR_POLL_SOCKET;
        pfd.desc.s = lr->sd;
        pfd.reqevents = APR_POLLIN;
        pfd.client_data = lr;

        /* ### check the status */
        (void) apr_pollset_add(pollset, &pfd);
    }

    mpm_state = AP_MPMQ_RUNNING;

    bucket_alloc = apr_bucket_alloc_create(pchild);

    /* die_now is set when AP_SIG_GRACEFUL is received in the child;
     * shutdown_pending is set when SIGTERM is received when running
     * in single process mode.  */
    while (!die_now && !shutdown_pending) {
        conn_rec *current_conn;
        void *csd;

        /*
         * (Re)initialize this child to a pre-connection state.
         */

        apr_pool_clear(ptrans);

        if ((ap_max_requests_per_child > 0
             && requests_this_child++ >= ap_max_requests_per_child)) {
            clean_child_exit(0);
        }

        (void) ap_update_child_status(sbh, SERVER_READY, (request_rec *) NULL);

        /*
         * Wait for an acceptable connection to arrive.
         */

        /* Lock around "accept", if necessary */
        SAFE_ACCEPT(accept_mutex_on());

        if (num_listensocks == 1) {
            /* There is only one listener record, so refer to that one. */
            lr = ap_listeners;
        }
        else {
            /* multiple listening sockets - need to poll */
            for (;;) {
                apr_int32_t numdesc;
                const apr_pollfd_t *pdesc;

                /* timeout == -1 == wait forever */
                status = apr_pollset_poll(pollset, -1, &numdesc, &pdesc);
                if (status != APR_SUCCESS) {
                    if (APR_STATUS_IS_EINTR(status)) {
                        if (one_process && shutdown_pending) {
                            return;
                        }
                        else if (die_now) {
                            /* In graceful stop/restart; drop the mutex
                             * and terminate the child. */
                            SAFE_ACCEPT(accept_mutex_off());
                            clean_child_exit(0);
                        }
                        continue;
                    }
                    /* Single Unix documents select as returning errnos
                     * EBADF, EINTR, and EINVAL... and in none of those
                     * cases does it make sense to continue.  In fact
                     * on Linux 2.0.x we seem to end up with EFAULT
                     * occasionally, and we'd loop forever due to it.
                     */
                    ap_log_error(APLOG_MARK, APLOG_ERR, status,
                                 ap_server_conf, "apr_pollset_poll: (listen)");
                    SAFE_ACCEPT(accept_mutex_off());
                    clean_child_exit(1);
                }

                /* We can always use pdesc[0], but sockets at position N
                 * could end up completely starved of attention in a very
                 * busy server. Therefore, we round-robin across the
                 * returned set of descriptors. While it is possible that
                 * the returned set of descriptors might flip around and
                 * continue to starve some sockets, we happen to know the
                 * internal pollset implementation retains ordering
                 * stability of the sockets. Thus, the round-robin should
                 * ensure that a socket will eventually be serviced.
                 */
                if (last_poll_idx >= numdesc)
                    last_poll_idx = 0;

                /* Grab a listener record from the client_data of the poll
                 * descriptor, and advance our saved index to round-robin
                 * the next fetch.
                 *
                 * ### hmm... this descriptor might have POLLERR rather
                 * ### than POLLIN
                 */
                lr = pdesc[last_poll_idx++].client_data;
                goto got_fd;
            }
        }
    got_fd:
        /* if we accept() something we don't want to die, so we have to
         * defer the exit
         */
        status = lr->accept_func(&csd, lr, ptrans);

        SAFE_ACCEPT(accept_mutex_off());      /* unlock after "accept" */

        if (status == APR_EGENERAL) {
            /* resource shortage or should-not-occur occured */
            clean_child_exit(1);
        }
        else if (status != APR_SUCCESS) {
            continue;
        }

        /*
         * We now have a connection, so set it up with the appropriate
         * socket options, file descriptors, and read/write buffers.
         */

        current_conn = ap_run_create_connection(ptrans, ap_server_conf, csd, my_child_num, sbh, bucket_alloc);
        if (current_conn) {
            ap_process_connection(current_conn, csd);
            ap_lingering_close(current_conn);
        }

        /* Check the pod and the generation number after processing a
         * connection so that we'll go away if a graceful restart occurred
         * while we were processing the connection or we are the lucky
         * idle server process that gets to die.
         */
        if (ap_mpm_pod_check(pod) == APR_SUCCESS) { /* selected as idle? */
            die_now = 1;
        }
        else if (ap_my_generation !=
                 ap_scoreboard_image->global->running_generation) { /* restart? */
            /* yeah, this could be non-graceful restart, in which case the
             * parent will kill us soon enough, but why bother checking?
             */
            die_now = 1;
        }
    }
    clean_child_exit(0);
}


static int make_child(server_rec *s, int slot)
{
    int pid;

    if (slot + 1 > ap_max_daemons_limit) {
        ap_max_daemons_limit = slot + 1;
    }

    if (one_process) {
        apr_signal(SIGHUP, sig_term);
        /* Don't catch AP_SIG_GRACEFUL in ONE_PROCESS mode :) */
        apr_signal(SIGINT, sig_term);
#ifdef SIGQUIT
        apr_signal(SIGQUIT, SIG_DFL);
#endif
        apr_signal(SIGTERM, sig_term);
        child_main(slot);
        return 0;
    }

    (void) ap_update_child_status_from_indexes(slot, 0, SERVER_STARTING,
                                               (request_rec *) NULL);


#ifdef _OSD_POSIX
    /* BS2000 requires a "special" version of fork() before a setuid() call */
    if ((pid = os_fork(unixd_config.user_name)) == -1) {
#elif defined(TPF)
    if ((pid = os_fork(s, slot)) == -1) {
#else
    if ((pid = fork()) == -1) {
#endif
        ap_log_error(APLOG_MARK, APLOG_ERR, errno, s, "fork: Unable to fork new process");

        /* fork didn't succeed. Fix the scoreboard or else
         * it will say SERVER_STARTING forever and ever
         */
        (void) ap_update_child_status_from_indexes(slot, 0, SERVER_DEAD,
                                                   (request_rec *) NULL);

        /* In case system resources are maxxed out, we don't want
         * Apache running away with the CPU trying to fork over and
         * over and over again.
         */
        sleep(10);

        return -1;
    }

    if (!pid) {
#ifdef HAVE_BINDPROCESSOR
        /* by default AIX binds to a single processor
         * this bit unbinds children which will then bind to another cpu
         */
        int status = bindprocessor(BINDPROCESS, (int)getpid(),
                                   PROCESSOR_CLASS_ANY);
        if (status != OK) {
            ap_log_error(APLOG_MARK, APLOG_WARNING, errno,
                         ap_server_conf, "processor unbind failed %d", status);
        }
#endif
        RAISE_SIGSTOP(MAKE_CHILD);
        AP_MONCONTROL(1);
        /* Disable the parent's signal handlers and set up proper handling in
         * the child.
         */
        apr_signal(SIGHUP, just_die);
        apr_signal(SIGTERM, just_die);
        /* The child process just closes listeners on AP_SIG_GRACEFUL.
         * The pod is used for signalling the graceful restart.
         */