/* $NetBSD: app.c,v 1.7.2.2 2024/02/25 15:47:15 martin Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * 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 https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /*! \file */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /*% * For BIND9 applications built with threads, we use a single app * context and let multiple taskmgr and netmgr threads do actual jobs. */ static isc_thread_t blockedthread; static atomic_bool is_running = 0; /* * The application context of this module. */ #define APPCTX_MAGIC ISC_MAGIC('A', 'p', 'c', 'x') #define VALID_APPCTX(c) ISC_MAGIC_VALID(c, APPCTX_MAGIC) struct isc_appctx { unsigned int magic; isc_mem_t *mctx; isc_mutex_t lock; isc_eventlist_t on_run; atomic_bool shutdown_requested; atomic_bool running; atomic_bool want_shutdown; atomic_bool want_reload; atomic_bool blocked; isc_mutex_t readylock; isc_condition_t ready; }; static isc_appctx_t isc_g_appctx; static void handle_signal(int sig, void (*handler)(int)) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = handler; if (sigfillset(&sa.sa_mask) != 0 || sigaction(sig, &sa, NULL) < 0) { FATAL_SYSERROR(errno, "signal %d", sig); } } isc_result_t isc_app_ctxstart(isc_appctx_t *ctx) { int presult; sigset_t sset; REQUIRE(VALID_APPCTX(ctx)); /* * Start an ISC library application. */ isc_mutex_init(&ctx->lock); isc_mutex_init(&ctx->readylock); isc_condition_init(&ctx->ready); ISC_LIST_INIT(ctx->on_run); atomic_init(&ctx->shutdown_requested, false); atomic_init(&ctx->running, false); atomic_init(&ctx->want_shutdown, false); atomic_init(&ctx->want_reload, false); atomic_init(&ctx->blocked, false); /* * Always ignore SIGPIPE. */ handle_signal(SIGPIPE, SIG_IGN); handle_signal(SIGHUP, SIG_DFL); handle_signal(SIGTERM, SIG_DFL); handle_signal(SIGINT, SIG_DFL); /* * 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) { FATAL_SYSERROR(errno, "sigsetops"); } presult = pthread_sigmask(SIG_BLOCK, &sset, NULL); if (presult != 0) { FATAL_SYSERROR(presult, "pthread_sigmask()"); } return (ISC_R_SUCCESS); } isc_result_t isc_app_start(void) { isc_g_appctx.magic = APPCTX_MAGIC; isc_g_appctx.mctx = NULL; /* The remaining members will be initialized in ctxstart() */ return (isc_app_ctxstart(&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_g_appctx, mctx, task, action, arg)); } isc_result_t isc_app_ctxonrun(isc_appctx_t *ctx, isc_mem_t *mctx, isc_task_t *task, isc_taskaction_t action, void *arg) { isc_event_t *event; isc_task_t *cloned_task = NULL; if (atomic_load_acquire(&ctx->running)) { return (ISC_R_ALREADYRUNNING); } /* * 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)); LOCK(&ctx->lock); ISC_LINK_INIT(event, ev_link); ISC_LIST_APPEND(ctx->on_run, event, ev_link); UNLOCK(&ctx->lock); return (ISC_R_SUCCESS); } isc_result_t isc_app_ctxrun(isc_appctx_t *ctx) { isc_event_t *event, *next_event; isc_task_t *task; REQUIRE(VALID_APPCTX(ctx)); if (atomic_compare_exchange_strong_acq_rel(&ctx->running, &(bool){ false }, true)) { /* * Post any on-run events (in FIFO order). */ LOCK(&ctx->lock); 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); } /* * 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 (!atomic_load_acquire(&ctx->want_shutdown)) { if (ctx == &isc_g_appctx) { sigset_t sset; int sig; /* * Wait for SIGHUP, SIGINT, or SIGTERM. */ if (sigemptyset(&sset) != 0 || sigaddset(&sset, SIGHUP) != 0 || sigaddset(&sset, SIGINT) != 0 || sigaddset(&sset, SIGTERM) != 0) { FATAL_SYSERROR(errno, "sigsetops"); } if (sigwait(&sset, &sig) == 0) { switch (sig) { case SIGINT: case SIGTERM: atomic_store_release( &ctx->want_shutdown, true); break; case SIGHUP: atomic_store_release(&ctx->want_reload, true); break; default: UNREACHABLE(); } } } else { /* * Tools using multiple contexts don't * rely on a signal, just wait until woken * up. */ if (atomic_load_acquire(&ctx->want_shutdown)) { break; } if (!atomic_load_acquire(&ctx->want_reload)) { LOCK(&ctx->readylock); WAIT(&ctx->ready, &ctx->readylock); UNLOCK(&ctx->readylock); } } if (atomic_compare_exchange_strong_acq_rel( &ctx->want_reload, &(bool){ true }, false)) { return (ISC_R_RELOAD); } if (atomic_load_acquire(&ctx->want_shutdown) && atomic_load_acquire(&ctx->blocked)) { exit(1); } } return (ISC_R_SUCCESS); } isc_result_t isc_app_run(void) { isc_result_t result; atomic_compare_exchange_enforced(&is_running, &(bool){ false }, true); result = isc_app_ctxrun(&isc_g_appctx); atomic_store_release(&is_running, false); return (result); } bool isc_app_isrunning(void) { return (atomic_load_acquire(&is_running)); } void isc_app_ctxshutdown(isc_appctx_t *ctx) { REQUIRE(VALID_APPCTX(ctx)); REQUIRE(atomic_load_acquire(&ctx->running)); /* If ctx->shutdown_requested == true, we are already shutting * down and we want to just bail out. */ if (atomic_compare_exchange_strong_acq_rel(&ctx->shutdown_requested, &(bool){ false }, true)) { if (ctx != &isc_g_appctx) { /* Tool using multiple contexts */ atomic_store_release(&ctx->want_shutdown, true); SIGNAL(&ctx->ready); } else { /* Normal single BIND9 context */ if (kill(getpid(), SIGTERM) < 0) { FATAL_SYSERROR(errno, "kill"); } } } } void isc_app_shutdown(void) { isc_app_ctxshutdown(&isc_g_appctx); } void isc_app_ctxsuspend(isc_appctx_t *ctx) { REQUIRE(VALID_APPCTX(ctx)); REQUIRE(atomic_load(&ctx->running)); /* * Don't send the reload signal if we're shutting down. */ if (!atomic_load_acquire(&ctx->shutdown_requested)) { if (ctx != &isc_g_appctx) { /* Tool using multiple contexts */ atomic_store_release(&ctx->want_reload, true); SIGNAL(&ctx->ready); } else { /* Normal single BIND9 context */ if (kill(getpid(), SIGHUP) < 0) { FATAL_SYSERROR(errno, "kill"); } } } } void isc_app_reload(void) { isc_app_ctxsuspend(&isc_g_appctx); } void isc_app_ctxfinish(isc_appctx_t *ctx) { REQUIRE(VALID_APPCTX(ctx)); isc_mutex_destroy(&ctx->lock); isc_mutex_destroy(&ctx->readylock); isc_condition_destroy(&ctx->ready); } void isc_app_finish(void) { isc_app_ctxfinish(&isc_g_appctx); } void isc_app_block(void) { sigset_t sset; REQUIRE(atomic_load_acquire(&isc_g_appctx.running)); atomic_compare_exchange_enforced(&isc_g_appctx.blocked, &(bool){ false }, true); 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); } void isc_app_unblock(void) { sigset_t sset; REQUIRE(atomic_load_acquire(&isc_g_appctx.running)); REQUIRE(blockedthread == pthread_self()); atomic_compare_exchange_enforced(&isc_g_appctx.blocked, &(bool){ true }, false); RUNTIME_CHECK(sigemptyset(&sset) == 0 && sigaddset(&sset, SIGINT) == 0 && sigaddset(&sset, SIGTERM) == 0); RUNTIME_CHECK(pthread_sigmask(SIG_BLOCK, &sset, NULL) == 0); } 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)); *ctx = (isc_appctx_t){ .magic = 0 }; isc_mem_attach(mctx, &ctx->mctx); ctx->magic = APPCTX_MAGIC; *ctxp = ctx; return (ISC_R_SUCCESS); } void isc_appctx_destroy(isc_appctx_t **ctxp) { isc_appctx_t *ctx; REQUIRE(ctxp != NULL); ctx = *ctxp; *ctxp = NULL; REQUIRE(VALID_APPCTX(ctx)); ctx->magic = 0; isc_mem_putanddetach(&ctx->mctx, ctx, sizeof(*ctx)); }