Adding upstream version 1:9.18.19.upstream/1%9.18.19

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 421 insertions, 0 deletions

diff --git a/lib/isc/app.c b/lib/isc/app.c
new file mode 100644
index 0000000..da438d7
--- /dev/null
+++ b/lib/isc/app.c
@@ -0,0 +1,421 @@
+/*
+ * 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 <errno.h>
+#include <inttypes.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <isc/app.h>
+#include <isc/atomic.h>
+#include <isc/condition.h>
+#include <isc/event.h>
+#include <isc/mem.h>
+#include <isc/mutex.h>
+#include <isc/string.h>
+#include <isc/task.h>
+#include <isc/thread.h>
+#include <isc/time.h>
+#include <isc/util.h>
+
+/*%
+ * 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));
+}