isc/unix/app.c

/*
 * Copyright (C) 1999-2005, 2007-2009, 2013-2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/*! \file */

#include <config.h>

#include <sys/param.h>  /* Openserver 5.0.6A and FD_SETSIZE */
#include <sys/types.h>

#include <stddef.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sys/time.h>
#ifdef HAVE_EPOLL
#include <sys/epoll.h>
#endif

#include <isc/app.h>
#include <isc/boolean.h>
#include <isc/condition.h>
#include <isc/mem.h>
#include <isc/msgs.h>
#include <isc/mutex.h>
#include <isc/event.h>
#include <isc/platform.h>
#include <isc/strerror.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/time.h>
#include <isc/util.h>

#ifdef ISC_PLATFORM_USETHREADS
#include <pthread.h>
#endif

/*%
 * For BIND9 internal applications built with threads, we use a single app
 * context and let multiple worker, I/O, timer threads do actual jobs.
 * For other cases (including BIND9 built without threads) an app context acts
 * as an event loop dispatching various events.
 */
#ifndef ISC_PLATFORM_USETHREADS
#include "../timer_p.h"
#include "../task_p.h"
#include "socket_p.h"
#endif /* ISC_PLATFORM_USETHREADS */

#ifdef ISC_PLATFORM_USETHREADS
static pthread_t        blockedthread;
#endif /* ISC_PLATFORM_USETHREADS */

/*%
 * The following are intended for internal use (indicated by "isc__"
 * prefix) but are not declared as static, allowing direct access from
 * unit tests etc.
 */
isc_result_t isc__app_start(void);
isc_result_t isc__app_ctxstart(isc_appctx_t *ctx);
isc_result_t isc__app_onrun(isc_mem_t *mctx, isc_task_t *task,
                isc_taskaction_t action, void *arg);
isc_result_t isc__app_ctxrun(isc_appctx_t *ctx);
isc_result_t isc__app_run(void);
isc_result_t isc__app_ctxshutdown(isc_appctx_t *ctx);
isc_result_t isc__app_shutdown(void);
isc_result_t isc__app_reload(void);
isc_result_t isc__app_ctxsuspend(isc_appctx_t *ctx);
void isc__app_ctxfinish(isc_appctx_t *ctx);
void isc__app_finish(void);
void isc__app_block(void);
void isc__app_unblock(void);
isc_result_t isc__appctx_create(isc_mem_t *mctx, isc_appctx_t **ctxp);
void isc__appctx_destroy(isc_appctx_t **ctxp);
void isc__appctx_settaskmgr(isc_appctx_t *ctx, isc_taskmgr_t *taskmgr);
void isc__appctx_setsocketmgr(isc_appctx_t *ctx, isc_socketmgr_t *socketmgr);
void isc__appctx_settimermgr(isc_appctx_t *ctx, isc_timermgr_t *timermgr);
isc_result_t isc__app_ctxonrun(isc_appctx_t *ctx, isc_mem_t *mctx,
                   isc_task_t *task, isc_taskaction_t action,
                   void *arg);

/*
 * The application context of this module.  This implementation actually
 * doesn't use it. (This may change in the future).
 */
#define APPCTX_MAGIC        ISC_MAGIC('A', 'p', 'c', 'x')
#define VALID_APPCTX(c)     ISC_MAGIC_VALID(c, APPCTX_MAGIC)

typedef struct isc__appctx {
    isc_appctx_t        common;
    isc_mem_t       *mctx;
    isc_mutex_t     lock;
    isc_eventlist_t     on_run;
    isc_boolean_t       shutdown_requested;
    isc_boolean_t       running;

    /*!
     * We assume that 'want_shutdown' can be read and written atomically.
     */
    isc_boolean_t       want_shutdown;
    /*
     * We assume that 'want_reload' can be read and written atomically.
     */
    isc_boolean_t       want_reload;

    isc_boolean_t       blocked;

    isc_taskmgr_t       *taskmgr;
    isc_socketmgr_t     *socketmgr;
    isc_timermgr_t      *timermgr;
#ifdef ISC_PLATFORM_USETHREADS
    isc_mutex_t     readylock;
    isc_condition_t     ready;
#endif /* ISC_PLATFORM_USETHREADS */
} isc__appctx_t;

static isc__appctx_t isc_g_appctx;

static struct {
    isc_appmethods_t methods;

    /*%
     * The following are defined just for avoiding unused static functions.
     */
    void *run, *shutdown, *start, *reload, *finish, *block, *unblock;
} appmethods = {
    {
        isc__appctx_destroy,
        isc__app_ctxstart,
        isc__app_ctxrun,
        isc__app_ctxsuspend,
        isc__app_ctxshutdown,
        isc__app_ctxfinish,
        isc__appctx_settaskmgr,
        isc__appctx_setsocketmgr,
        isc__appctx_settimermgr,
        isc__app_ctxonrun
    },
    (void *)isc__app_run,
    (void *)isc__app_shutdown,
    (void *)isc__app_start,
    (void *)isc__app_reload,
    (void *)isc__app_finish,
    (void *)isc__app_block,
    (void *)isc__app_unblock
};

#ifdef HAVE_LINUXTHREADS
/*!
 * Linux has sigwait(), but it appears to prevent signal handlers from
 * running, even if they're not in the set being waited for.  This makes
 * it impossible to get the default actions for SIGILL, SIGSEGV, etc.
 * Instead of messing with it, we just use sigsuspend() instead.
 */
#undef HAVE_SIGWAIT
/*!
 * We need to remember which thread is the main thread...
 */
static pthread_t        main_thread;
#endif

#ifndef HAVE_SIGWAIT
static void
exit_action(int arg) {
    UNUSED(arg);
    isc_g_appctx.want_shutdown = ISC_TRUE;
}

static void
reload_action(int arg) {
    UNUSED(arg);
    isc_g_appctx.want_reload = ISC_TRUE;
}
#endif

static isc_result_t
handle_signal(int sig, void (*handler)(int)) {
    struct sigaction sa;
    char strbuf[ISC_STRERRORSIZE];

    memset(&sa, 0, sizeof(sa));
    sa.sa_handler = handler;

    if (sigfillset(&sa.sa_mask) != 0 ||
        sigaction(sig, &sa, NULL) < 0) {
        isc__strerror(errno, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 isc_msgcat_get(isc_msgcat, ISC_MSGSET_APP,
                           ISC_MSG_SIGNALSETUP,
                           "handle_signal() %d setup: %s"),
                 sig, strbuf);
        return (ISC_R_UNEXPECTED);
    }

    return (ISC_R_SUCCESS);
}

isc_result_t
isc__app_ctxstart(isc_appctx_t *ctx0) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;
    isc_result_t result;
    int presult;
    sigset_t sset;
    char strbuf[ISC_STRERRORSIZE];

    REQUIRE(VALID_APPCTX(ctx));

    /*
     * Start an ISC library application.
     */

#ifdef NEED_PTHREAD_INIT
    /*
     * BSDI 3.1 seg faults in pthread_sigmask() if we don't do this.
     */
    presult = pthread_init();
    if (presult != 0) {
        isc__strerror(presult, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_app_start() pthread_init: %s", strbuf);
        return (ISC_R_UNEXPECTED);
    }
#endif

#ifdef ISC_PLATFORM_USETHREADS
#ifdef HAVE_LINUXTHREADS
    main_thread = pthread_self();
#endif /* HAVE_LINUXTHREADS */

    result = isc_mutex_init(&ctx->readylock);
    if (result != ISC_R_SUCCESS)
        return (result);

    result = isc_condition_init(&ctx->ready);
    if (result != ISC_R_SUCCESS)
        goto cleanup_rlock;

    result = isc_mutex_init(&ctx->lock);
    if (result != ISC_R_SUCCESS)
        goto cleanup_rcond;
#else /* ISC_PLATFORM_USETHREADS */
    result = isc_mutex_init(&ctx->lock);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
#endif /* ISC_PLATFORM_USETHREADS */

    ISC_LIST_INIT(ctx->on_run);

    ctx->shutdown_requested = ISC_FALSE;
    ctx->running = ISC_FALSE;
    ctx->want_shutdown = ISC_FALSE;
    ctx->want_reload = ISC_FALSE;
    ctx->blocked = ISC_FALSE;

#ifndef HAVE_SIGWAIT
    /*
     * Install do-nothing handlers for SIGINT and SIGTERM.
     *
     * We install them now because BSDI 3.1 won't block
     * the default actions, regardless of what we do with
     * pthread_sigmask().
     */
    result = handle_signal(SIGINT, exit_action);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    result = handle_signal(SIGTERM, exit_action);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
#endif

    /*
     * Always ignore SIGPIPE.
     */
    result = handle_signal(SIGPIPE, SIG_IGN);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    /*
     * On Solaris 2, delivery of a signal whose action is SIG_IGN
     * will not cause sigwait() to return. We may have inherited
     * unexpected actions for SIGHUP, SIGINT, and SIGTERM from our parent
     * process (e.g, Solaris cron).  Set an action of SIG_DFL to make
     * sure sigwait() works as expected.  Only do this for SIGTERM and
     * SIGINT if we don't have sigwait(), since a different handler is
     * installed above.
     */
    result = handle_signal(SIGHUP, SIG_DFL);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

#ifdef HAVE_SIGWAIT
    result = handle_signal(SIGTERM, SIG_DFL);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    result = handle_signal(SIGINT, SIG_DFL);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
#endif

#ifdef ISC_PLATFORM_USETHREADS
    /*
     * Block SIGHUP, SIGINT, SIGTERM.
     *
     * If isc_app_start() is called from the main thread before any other
     * threads have been created, then the pthread_sigmask() call below
     * will result in all threads having SIGHUP, SIGINT and SIGTERM
     * blocked by default, ensuring that only the thread that calls
     * sigwait() for them will get those signals.
     */
    if (sigemptyset(&sset) != 0 ||
        sigaddset(&sset, SIGHUP) != 0 ||
        sigaddset(&sset, SIGINT) != 0 ||
        sigaddset(&sset, SIGTERM) != 0) {
        isc__strerror(errno, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_app_start() sigsetops: %s", strbuf);
        result = ISC_R_UNEXPECTED;
        goto cleanup;
    }
    presult = pthread_sigmask(SIG_BLOCK, &sset, NULL);
    if (presult != 0) {
        isc__strerror(presult, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_app_start() pthread_sigmask: %s",
                 strbuf);
        result = ISC_R_UNEXPECTED;
        goto cleanup;
    }
#else /* ISC_PLATFORM_USETHREADS */
    /*
     * Unblock SIGHUP, SIGINT, SIGTERM.
     *
     * If we're not using threads, we need to make sure that SIGHUP,
     * SIGINT and SIGTERM are not inherited as blocked from the parent
     * process.
     */
    if (sigemptyset(&sset) != 0 ||
        sigaddset(&sset, SIGHUP) != 0 ||
        sigaddset(&sset, SIGINT) != 0 ||
        sigaddset(&sset, SIGTERM) != 0) {
        isc__strerror(errno, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_app_start() sigsetops: %s", strbuf);
        result = ISC_R_UNEXPECTED;
        goto cleanup;
    }
    presult = sigprocmask(SIG_UNBLOCK, &sset, NULL);
    if (presult != 0) {
        isc__strerror(errno, strbuf, sizeof(strbuf));
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_app_start() sigprocmask: %s", strbuf);
        result = ISC_R_UNEXPECTED;
        goto cleanup;
    }
#endif /* ISC_PLATFORM_USETHREADS */

    return (ISC_R_SUCCESS);

 cleanup:
#ifdef ISC_PLATFORM_USETHREADS
 cleanup_rcond:
    (void)isc_condition_destroy(&ctx->ready);

 cleanup_rlock:
    (void)isc_mutex_destroy(&ctx->readylock);
#endif /* ISC_PLATFORM_USETHREADS */
    return (result);
}

isc_result_t
isc__app_start(void) {
    isc_g_appctx.common.impmagic = APPCTX_MAGIC;
    isc_g_appctx.common.magic = ISCAPI_APPCTX_MAGIC;
    isc_g_appctx.common.methods = &appmethods.methods;
    isc_g_appctx.mctx = NULL;
    /* The remaining members will be initialized in ctxstart() */

    return (isc__app_ctxstart((isc_appctx_t *)&isc_g_appctx));
}

isc_result_t
isc__app_onrun(isc_mem_t *mctx, isc_task_t *task, isc_taskaction_t action,
          void *arg)
{
    return (isc__app_ctxonrun((isc_appctx_t *)&isc_g_appctx, mctx,
                  task, action, arg));
}

isc_result_t
isc__app_ctxonrun(isc_appctx_t *ctx0, isc_mem_t *mctx, isc_task_t *task,
          isc_taskaction_t action, void *arg)
{
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;
    isc_event_t *event;
    isc_task_t *cloned_task = NULL;
    isc_result_t result;

    LOCK(&ctx->lock);

    if (ctx->running) {
        result = ISC_R_ALREADYRUNNING;
        goto unlock;
    }

    /*
     * Note that we store the task to which we're going to send the event
     * in the event's "sender" field.
     */
    isc_task_attach(task, &cloned_task);
    event = isc_event_allocate(mctx, cloned_task, ISC_APPEVENT_SHUTDOWN,
                   action, arg, sizeof(*event));
    if (event == NULL) {
        isc_task_detach(&cloned_task);
        result = ISC_R_NOMEMORY;
        goto unlock;
    }

    ISC_LIST_APPEND(ctx->on_run, event, ev_link);

    result = ISC_R_SUCCESS;

 unlock:
    UNLOCK(&ctx->lock);

    return (result);
}

#ifndef ISC_PLATFORM_USETHREADS
/*!
 * Event loop for nonthreaded programs.
 */
static isc_result_t
evloop(isc__appctx_t *ctx) {
    isc_result_t result;

    while (!ctx->want_shutdown) {
        int n;
        isc_time_t when, now;
        struct timeval tv, *tvp;
        isc_socketwait_t *swait;
        isc_boolean_t readytasks;
        isc_boolean_t call_timer_dispatch = ISC_FALSE;

        /*
         * Check the reload (or suspend) case first for exiting the
         * loop as fast as possible in case:
         *   - the direct call to isc__taskmgr_dispatch() in
         *     isc__app_ctxrun() completes all the tasks so far,
         *   - there is thus currently no active task, and
         *   - there is a timer event
         */
        if (ctx->want_reload) {
            ctx->want_reload = ISC_FALSE;
            return (ISC_R_RELOAD);
        }

        readytasks = isc__taskmgr_ready(ctx->taskmgr);
        if (readytasks) {
            tv.tv_sec = 0;
            tv.tv_usec = 0;
            tvp = &tv;
            call_timer_dispatch = ISC_TRUE;
        } else {
            result = isc__timermgr_nextevent(ctx->timermgr, &when);
            if (result != ISC_R_SUCCESS)
                tvp = NULL;
            else {
                isc_uint64_t us;

                TIME_NOW(&now);
                us = isc_time_microdiff(&when, &now);
                if (us == 0)
                    call_timer_dispatch = ISC_TRUE;
                tv.tv_sec = us / 1000000;
                tv.tv_usec = us % 1000000;
                tvp = &tv;
            }
        }

        swait = NULL;
        n = isc__socketmgr_waitevents(ctx->socketmgr, tvp, &swait);

        if (n == 0 || call_timer_dispatch) {
            /*
             * We call isc__timermgr_dispatch() only when
             * necessary, in order to reduce overhead.  If the
             * select() call indicates a timeout, we need the
             * dispatch.  Even if not, if we set the 0-timeout
             * for the select() call, we need to check the timer
             * events.  In the 'readytasks' case, there may be no
             * timeout event actually, but there is no other way
             * to reduce the overhead.
             * Note that we do not have to worry about the case
             * where a new timer is inserted during the select()
             * call, since this loop only runs in the non-thread
             * mode.
             */
            isc__timermgr_dispatch(ctx->timermgr);
        }
        if (n > 0)
            (void)isc__socketmgr_dispatch(ctx->socketmgr, swait);
        (void)isc__taskmgr_dispatch(ctx->taskmgr);
    }
    return (ISC_R_SUCCESS);
}

/*
 * This is a gross hack to support waiting for condition
 * variables in nonthreaded programs in a limited way;
 * see lib/isc/nothreads/include/isc/condition.h.
 * We implement isc_condition_wait() by entering the
 * event loop recursively until the want_shutdown flag
 * is set by isc_condition_signal().
 */

/*!
 * \brief True if we are currently executing in the recursive
 * event loop.
 */
static isc_boolean_t in_recursive_evloop = ISC_FALSE;

/*!
 * \brief True if we are exiting the event loop as the result of
 * a call to isc_condition_signal() rather than a shutdown
 * or reload.
 */
static isc_boolean_t signalled = ISC_FALSE;

isc_result_t
isc__nothread_wait_hack(isc_condition_t *cp, isc_mutex_t *mp) {
    isc_result_t result;

    UNUSED(cp);
    UNUSED(mp);

    INSIST(!in_recursive_evloop);
    in_recursive_evloop = ISC_TRUE;

    INSIST(*mp == 1); /* Mutex must be locked on entry. */
    --*mp;

    result = evloop(&isc_g_appctx);
    if (result == ISC_R_RELOAD)
        isc_g_appctx.want_reload = ISC_TRUE;
    if (signalled) {
        isc_g_appctx.want_shutdown = ISC_FALSE;
        signalled = ISC_FALSE;
    }

    ++*mp;
    in_recursive_evloop = ISC_FALSE;
    return (ISC_R_SUCCESS);
}

isc_result_t
isc__nothread_signal_hack(isc_condition_t *cp) {

    UNUSED(cp);

    INSIST(in_recursive_evloop);

    isc_g_appctx.want_shutdown = ISC_TRUE;
    signalled = ISC_TRUE;
    return (ISC_R_SUCCESS);
}
#endif /* ISC_PLATFORM_USETHREADS */

isc_result_t
isc__app_ctxrun(isc_appctx_t *ctx0) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;
    int result;
    isc_event_t *event, *next_event;
    isc_task_t *task;
#ifdef ISC_PLATFORM_USETHREADS
    sigset_t sset;
    char strbuf[ISC_STRERRORSIZE];
#ifdef HAVE_SIGWAIT
    int sig;
#endif /* HAVE_SIGWAIT */
#endif /* ISC_PLATFORM_USETHREADS */

    REQUIRE(VALID_APPCTX(ctx));

#ifdef HAVE_LINUXTHREADS
    REQUIRE(main_thread == pthread_self());
#endif

    LOCK(&ctx->lock);

    if (!ctx->running) {
        ctx->running = ISC_TRUE;

        /*
         * Post any on-run events (in FIFO order).
         */
        for (event = ISC_LIST_HEAD(ctx->on_run);
             event != NULL;
             event = next_event) {
            next_event = ISC_LIST_NEXT(event, ev_link);
            ISC_LIST_UNLINK(ctx->on_run, event, ev_link);
            task = event->ev_sender;
            event->ev_sender = NULL;
            isc_task_sendanddetach(&task, &event);
        }

    }

    UNLOCK(&ctx->lock);

#ifndef ISC_PLATFORM_USETHREADS
    if (isc_bind9 && ctx == &isc_g_appctx) {
        result = handle_signal(SIGHUP, reload_action);
        if (result != ISC_R_SUCCESS)
            return (ISC_R_SUCCESS);
    }

    (void) isc__taskmgr_dispatch(ctx->taskmgr);
    result = evloop(ctx);
    return (result);
#else /* ISC_PLATFORM_USETHREADS */
    /*
     * BIND9 internal tools using multiple contexts do not
     * rely on signal.
     */
    if (isc_bind9 && ctx != &isc_g_appctx)
        return (ISC_R_SUCCESS);

    /*
     * There is no danger if isc_app_shutdown() is called before we
     * wait for signals.  Signals are blocked, so any such signal will
     * simply be made pending and we will get it when we call
     * sigwait().
     */
    while (!ctx->want_shutdown) {
#ifdef HAVE_SIGWAIT
        if (isc_bind9) {
            /*
             * BIND9 internal; single context:
             * Wait for SIGHUP, SIGINT, or SIGTERM.
             */
            if (sigemptyset(&sset) != 0 ||
                sigaddset(&sset, SIGHUP) != 0 ||
                sigaddset(&sset, SIGINT) != 0 ||
                sigaddset(&sset, SIGTERM) != 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                         "isc_app_run() sigsetops: %s",
                         strbuf);
                return (ISC_R_UNEXPECTED);
            }

#ifndef HAVE_UNIXWARE_SIGWAIT
            result = sigwait(&sset, &sig);
            if (result == 0) {
                if (sig == SIGINT || sig == SIGTERM)
                    ctx->want_shutdown = ISC_TRUE;
                else if (sig == SIGHUP)
                    ctx->want_reload = ISC_TRUE;
            }

#else /* Using UnixWare sigwait semantics. */
            sig = sigwait(&sset);
            if (sig >= 0) {
                if (sig == SIGINT || sig == SIGTERM)
                    ctx->want_shutdown = ISC_TRUE;
                else if (sig == SIGHUP)
                    ctx->want_reload = ISC_TRUE;
            }
#endif /* HAVE_UNIXWARE_SIGWAIT */
        } else {
            /*
             * External, or BIND9 using multiple contexts:
             * wait until woken up.
             */
            LOCK(&ctx->readylock);
            if (ctx->want_shutdown) {
                /* shutdown() won the race. */
                UNLOCK(&ctx->readylock);
                break;
            }
            if (!ctx->want_reload)
                WAIT(&ctx->ready, &ctx->readylock);
            UNLOCK(&ctx->readylock);
        }
#else  /* Don't have sigwait(). */
        if (isc_bind9) {
            /*
             * BIND9 internal; single context:
             * Install a signal handler for SIGHUP, then wait for
             * all signals.
             */
            result = handle_signal(SIGHUP, reload_action);
            if (result != ISC_R_SUCCESS)
                return (ISC_R_SUCCESS);

            if (sigemptyset(&sset) != 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                         "isc_app_run() sigsetops: %s",
                         strbuf);
                return (ISC_R_UNEXPECTED);
            }
#ifdef HAVE_GPERFTOOLS_PROFILER
            if (sigaddset(&sset, SIGALRM) != 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                         "isc_app_run() sigsetops: %s",
                         strbuf);
                return (ISC_R_UNEXPECTED);
            }
#endif
            (void)sigsuspend(&sset);
        } else {
            /*
             * External, or BIND9 using multiple contexts:
             * wait until woken up.
             */
            LOCK(&ctx->readylock);
            if (ctx->want_shutdown) {
                /* shutdown() won the race. */
                UNLOCK(&ctx->readylock);
                break;
            }
            if (!ctx->want_reload)
                WAIT(&ctx->ready, &ctx->readylock);
            UNLOCK(&ctx->readylock);
        }
#endif /* HAVE_SIGWAIT */

        if (ctx->want_reload) {
            ctx->want_reload = ISC_FALSE;
            return (ISC_R_RELOAD);
        }

        if (ctx->want_shutdown && ctx->blocked)
            exit(1);
    }

    return (ISC_R_SUCCESS);
#endif /* ISC_PLATFORM_USETHREADS */
}

isc_result_t
isc__app_run(void) {
    return (isc__app_ctxrun((isc_appctx_t *)&isc_g_appctx));
}

isc_result_t
isc__app_ctxshutdown(isc_appctx_t *ctx0) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;
    isc_boolean_t want_kill = ISC_TRUE;
#ifdef ISC_PLATFORM_USETHREADS
    char strbuf[ISC_STRERRORSIZE];
#endif /* ISC_PLATFORM_USETHREADS */

    REQUIRE(VALID_APPCTX(ctx));

    LOCK(&ctx->lock);

    REQUIRE(ctx->running);

    if (ctx->shutdown_requested)
        want_kill = ISC_FALSE;
    else
        ctx->shutdown_requested = ISC_TRUE;

    UNLOCK(&ctx->lock);

    if (want_kill) {
        if (isc_bind9 && ctx != &isc_g_appctx)
            /* BIND9 internal, but using multiple contexts */
            ctx->want_shutdown = ISC_TRUE;
        else {
#ifndef ISC_PLATFORM_USETHREADS
            ctx->want_shutdown = ISC_TRUE;
#else /* ISC_PLATFORM_USETHREADS */
#ifdef HAVE_LINUXTHREADS
            if (isc_bind9) {
                /* BIND9 internal, single context */
                int result;

                result = pthread_kill(main_thread, SIGTERM);
                if (result != 0) {
                    isc__strerror(result,
                              strbuf, sizeof(strbuf));
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                             "isc_app_shutdown() "
                             "pthread_kill: %s",
                             strbuf);
                    return (ISC_R_UNEXPECTED);
                }
            }
#else
            if (isc_bind9) {
                /* BIND9 internal, single context */
                if (kill(getpid(), SIGTERM) < 0) {
                    isc__strerror(errno,
                              strbuf, sizeof(strbuf));
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                             "isc_app_shutdown() "
                             "kill: %s", strbuf);
                    return (ISC_R_UNEXPECTED);
                }
            }
#endif /* HAVE_LINUXTHREADS */
            else {
                /* External, multiple contexts */
                LOCK(&ctx->readylock);
                ctx->want_shutdown = ISC_TRUE;
                UNLOCK(&ctx->readylock);
                SIGNAL(&ctx->ready);
            }
#endif /* ISC_PLATFORM_USETHREADS */
        }
    }

    return (ISC_R_SUCCESS);
}

isc_result_t
isc__app_shutdown(void) {
    return (isc__app_ctxshutdown((isc_appctx_t *)&isc_g_appctx));
}

isc_result_t
isc__app_ctxsuspend(isc_appctx_t *ctx0) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;
    isc_boolean_t want_kill = ISC_TRUE;
#ifdef ISC_PLATFORM_USETHREADS
    char strbuf[ISC_STRERRORSIZE];
#endif

    REQUIRE(VALID_APPCTX(ctx));

    LOCK(&ctx->lock);

    REQUIRE(ctx->running);

    /*
     * Don't send the reload signal if we're shutting down.
     */
    if (ctx->shutdown_requested)
        want_kill = ISC_FALSE;

    UNLOCK(&ctx->lock);

    if (want_kill) {
        if (isc_bind9 && ctx != &isc_g_appctx)
            /* BIND9 internal, but using multiple contexts */
            ctx->want_reload = ISC_TRUE;
        else {
#ifndef ISC_PLATFORM_USETHREADS
            ctx->want_reload = ISC_TRUE;
#else /* ISC_PLATFORM_USETHREADS */
#ifdef HAVE_LINUXTHREADS
            if (isc_bind9) {
                /* BIND9 internal, single context */
                int result;

                result = pthread_kill(main_thread, SIGHUP);
                if (result != 0) {
                    isc__strerror(result,
                              strbuf, sizeof(strbuf));
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                             "isc_app_reload() "
                             "pthread_kill: %s",
                             strbuf);
                    return (ISC_R_UNEXPECTED);
                }
            }
#else
            if (isc_bind9) {
                /* BIND9 internal, single context */
                if (kill(getpid(), SIGHUP) < 0) {
                    isc__strerror(errno,
                              strbuf, sizeof(strbuf));
                    UNEXPECTED_ERROR(__FILE__, __LINE__,
                             "isc_app_reload() "
                             "kill: %s", strbuf);
                    return (ISC_R_UNEXPECTED);
                }
            }
#endif /* HAVE_LINUXTHREADS */
            else {
                /* External, multiple contexts */
                LOCK(&ctx->readylock);
                ctx->want_reload = ISC_TRUE;
                UNLOCK(&ctx->readylock);
                SIGNAL(&ctx->ready);
            }
#endif /* ISC_PLATFORM_USETHREADS */
        }
    }

    return (ISC_R_SUCCESS);
}

isc_result_t
isc__app_reload(void) {
    return (isc__app_ctxsuspend((isc_appctx_t *)&isc_g_appctx));
}

void
isc__app_ctxfinish(isc_appctx_t *ctx0) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;

    REQUIRE(VALID_APPCTX(ctx));

    DESTROYLOCK(&ctx->lock);
}

void
isc__app_finish(void) {
    isc__app_ctxfinish((isc_appctx_t *)&isc_g_appctx);
}

void
isc__app_block(void) {
#ifdef ISC_PLATFORM_USETHREADS
    sigset_t sset;
#endif /* ISC_PLATFORM_USETHREADS */
    REQUIRE(isc_g_appctx.running);
    REQUIRE(!isc_g_appctx.blocked);

    isc_g_appctx.blocked = ISC_TRUE;
#ifdef ISC_PLATFORM_USETHREADS
    blockedthread = pthread_self();
    RUNTIME_CHECK(sigemptyset(&sset) == 0 &&
              sigaddset(&sset, SIGINT) == 0 &&
              sigaddset(&sset, SIGTERM) == 0);
    RUNTIME_CHECK(pthread_sigmask(SIG_UNBLOCK, &sset, NULL) == 0);
#endif /* ISC_PLATFORM_USETHREADS */
}

void
isc__app_unblock(void) {
#ifdef ISC_PLATFORM_USETHREADS
    sigset_t sset;
#endif /* ISC_PLATFORM_USETHREADS */

    REQUIRE(isc_g_appctx.running);
    REQUIRE(isc_g_appctx.blocked);

    isc_g_appctx.blocked = ISC_FALSE;

#ifdef ISC_PLATFORM_USETHREADS
    REQUIRE(blockedthread == pthread_self());

    RUNTIME_CHECK(sigemptyset(&sset) == 0 &&
              sigaddset(&sset, SIGINT) == 0 &&
              sigaddset(&sset, SIGTERM) == 0);
    RUNTIME_CHECK(pthread_sigmask(SIG_BLOCK, &sset, NULL) == 0);
#endif /* ISC_PLATFORM_USETHREADS */
}

isc_result_t
isc__appctx_create(isc_mem_t *mctx, isc_appctx_t **ctxp) {
    isc__appctx_t *ctx;

    REQUIRE(mctx != NULL);
    REQUIRE(ctxp != NULL && *ctxp == NULL);

    ctx = isc_mem_get(mctx, sizeof(*ctx));
    if (ctx == NULL)
        return (ISC_R_NOMEMORY);

    ctx->common.impmagic = APPCTX_MAGIC;
    ctx->common.magic = ISCAPI_APPCTX_MAGIC;
    ctx->common.methods = &appmethods.methods;

    ctx->mctx = NULL;
    isc_mem_attach(mctx, &ctx->mctx);

    ctx->taskmgr = NULL;
    ctx->socketmgr = NULL;
    ctx->timermgr = NULL;

    *ctxp = (isc_appctx_t *)ctx;

    return (ISC_R_SUCCESS);
}

void
isc__appctx_destroy(isc_appctx_t **ctxp) {
    isc__appctx_t *ctx;

    REQUIRE(ctxp != NULL);
    ctx = (isc__appctx_t *)*ctxp;
    REQUIRE(VALID_APPCTX(ctx));

    isc_mem_putanddetach(&ctx->mctx, ctx, sizeof(*ctx));

    *ctxp = NULL;
}

void
isc__appctx_settaskmgr(isc_appctx_t *ctx0, isc_taskmgr_t *taskmgr) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;

    REQUIRE(VALID_APPCTX(ctx));

    ctx->taskmgr = taskmgr;
}

void
isc__appctx_setsocketmgr(isc_appctx_t *ctx0, isc_socketmgr_t *socketmgr) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;

    REQUIRE(VALID_APPCTX(ctx));

    ctx->socketmgr = socketmgr;
}

void
isc__appctx_settimermgr(isc_appctx_t *ctx0, isc_timermgr_t *timermgr) {
    isc__appctx_t *ctx = (isc__appctx_t *)ctx0;

    REQUIRE(VALID_APPCTX(ctx));

    ctx->timermgr = timermgr;
}

isc_result_t
isc__app_register(void) {
    return (isc_app_register(isc__appctx_create));
}

#include "../app_api.c"