1 files changed, 862 insertions, 0 deletions

diff --git a/lib/util/event.c b/lib/util/event.c
new file mode 100644
index 0000000..4192770
--- /dev/null
+++ b/lib/util/event.c
@@ -0,0 +1,862 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2013-2018 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+# include "compat/stdbool.h"
+#endif /* HAVE_STDBOOL_H */
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "sudo_compat.h"
+#include "sudo_fatal.h"
+#include "sudo_debug.h"
+#include "sudo_event.h"
+#include "sudo_util.h"
+
+static void sudo_ev_init(struct sudo_event *ev, int fd, short events,
+    sudo_ev_callback_t callback, void *closure);
+
+/* Default event base when none is specified. */
+static struct sudo_event_base *default_base;
+
+/* We need the event base to be available from the signal handler. */
+static struct sudo_event_base *signal_base;
+
+/*
+ * Add an event to the base's active queue and mark it active.
+ * This is extern so sudo_ev_scan_impl() can call it.
+ */
+void
+sudo_ev_activate(struct sudo_event_base *base, struct sudo_event *ev)
+{
+    TAILQ_INSERT_TAIL(&base->active, ev, active_entries);
+    SET(ev->flags, SUDO_EVQ_ACTIVE);
+}
+
+/*
+ * Remove an event from the base's active queue and mark it inactive.
+ */
+static inline void
+sudo_ev_deactivate(struct sudo_event_base *base, struct sudo_event *ev)
+{
+    CLR(ev->flags, SUDO_EVQ_ACTIVE);
+    TAILQ_REMOVE(&base->active, ev, active_entries);
+}
+
+/*
+ * Clear out the base's active queue and mark all events as inactive.
+ */
+static void
+sudo_ev_deactivate_all(struct sudo_event_base *base)
+{
+    struct sudo_event *ev;
+    debug_decl(sudo_ev_deactivate_all, SUDO_DEBUG_EVENT);
+
+    while ((ev = TAILQ_FIRST(&base->active)) != NULL)
+	sudo_ev_deactivate(base, ev);
+
+    debug_return;
+}
+
+/*
+ * Activate all signal events for which the corresponding signal_pending[]
+ * flag is set.
+ */
+static void
+sudo_ev_activate_sigevents(struct sudo_event_base *base)
+{
+    struct sudo_event *ev;
+    sigset_t set, oset;
+    int i;
+    debug_decl(sudo_ev_activate_sigevents, SUDO_DEBUG_EVENT);
+
+    /*
+     * We treat this as a critical section since the signal handler
+     * could modify the siginfo[] entry.
+     */
+    sigfillset(&set);
+    sigprocmask(SIG_BLOCK, &set, &oset);
+    base->signal_caught = 0;
+    for (i = 0; i < NSIG; i++) {
+	if (!base->signal_pending[i])
+	    continue;
+	base->signal_pending[i] = 0;
+	TAILQ_FOREACH(ev, &base->signals[i], entries) {
+	    if (ISSET(ev->events, SUDO_EV_SIGINFO)) {
+		struct sudo_ev_siginfo_container *sc = ev->closure;
+		if (base->siginfo[i]->si_signo == 0) {
+		    /* No siginfo available. */
+		    sc->siginfo = NULL;
+		} else {
+		    sc->siginfo = (siginfo_t *)sc->si_buf;
+		    memcpy(sc->siginfo, base->siginfo[i], sizeof(siginfo_t));
+		}
+	    }
+	    /* Make event active. */
+	    ev->revents = ev->events & (SUDO_EV_SIGNAL|SUDO_EV_SIGINFO);
+	    TAILQ_INSERT_TAIL(&base->active, ev, active_entries);
+	    SET(ev->flags, SUDO_EVQ_ACTIVE);
+	}
+    }
+    sigprocmask(SIG_SETMASK, &oset, NULL);
+
+    debug_return;
+}
+
+/*
+ * Internal callback for SUDO_EV_SIGNAL and SUDO_EV_SIGINFO.
+ */
+static void
+signal_pipe_cb(int fd, int what, void *v)
+{
+    struct sudo_event_base *base = v;
+    unsigned char ch;
+    ssize_t nread;
+    debug_decl(signal_pipe_cb, SUDO_DEBUG_EVENT);
+
+    /*
+     * Drain signal_pipe, the signal handler updated base->signals_pending.
+     * Actual processing of signal events is done when poll/select is
+     * interrupted by a signal.
+     */
+    while ((nread = read(fd, &ch, 1)) > 0) {
+	sudo_debug_printf(SUDO_DEBUG_INFO,
+	    "%s: received signal %d", __func__, (int)ch);
+    }
+    if (nread == -1 && errno != EAGAIN) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
+	    "%s: error reading from signal pipe fd %d", __func__, fd);
+    }
+
+    /* Activate signal events. */
+    sudo_ev_activate_sigevents(base);
+
+    debug_return;
+}
+
+static int
+sudo_ev_base_init(struct sudo_event_base *base)
+{
+    int i;
+    debug_decl(sudo_ev_base_init, SUDO_DEBUG_EVENT);
+
+    TAILQ_INIT(&base->events);
+    TAILQ_INIT(&base->timeouts);
+    for (i = 0; i < NSIG; i++)
+	TAILQ_INIT(&base->signals[i]);
+    if (sudo_ev_base_alloc_impl(base) != 0) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: unable to allocate impl base", __func__);
+	goto bad;
+    }
+    if (pipe2(base->signal_pipe, O_NONBLOCK|O_CLOEXEC) != 0) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: unable to create signal pipe", __func__);
+	goto bad;
+    }
+    sudo_ev_init(&base->signal_event, base->signal_pipe[0],
+	SUDO_EV_READ|SUDO_EV_PERSIST, signal_pipe_cb, base);
+
+    debug_return_int(0);
+bad:
+    /* Note: signal_pipe[] not filled in. */
+    sudo_ev_base_free_impl(base);
+    debug_return_int(-1);
+}
+
+struct sudo_event_base *
+sudo_ev_base_alloc_v1(void)
+{
+    struct sudo_event_base *base;
+    debug_decl(sudo_ev_base_alloc, SUDO_DEBUG_EVENT);
+
+    base = calloc(1, sizeof(*base));
+    if (base == NULL) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+	    "%s: unable to allocate base", __func__);
+	debug_return_ptr(NULL);
+    }
+    if (sudo_ev_base_init(base) != 0) {
+	free(base);
+	debug_return_ptr(NULL);
+    }
+    debug_return_ptr(base);
+}
+
+void
+sudo_ev_base_free_v1(struct sudo_event_base *base)
+{
+    struct sudo_event *ev, *next;
+    int i;
+    debug_decl(sudo_ev_base_free, SUDO_DEBUG_EVENT);
+
+    if (base == NULL)
+	debug_return;
+
+    /* Reset the default base if necessary. */
+    if (default_base == base)
+	default_base = NULL;
+
+    /* Remove any existing events before freeing the base. */
+    TAILQ_FOREACH_SAFE(ev, &base->events, entries, next) {
+	sudo_ev_del(base, ev);
+	ev->base = NULL;
+    }
+    for (i = 0; i < NSIG; i++) {
+	TAILQ_FOREACH_SAFE(ev, &base->signals[i], entries, next) {
+	    sudo_ev_del(base, ev);
+	    ev->base = NULL;
+	}
+	free(base->siginfo[i]);
+	free(base->orig_handlers[i]);
+    }
+    sudo_ev_base_free_impl(base);
+    close(base->signal_pipe[0]);
+    close(base->signal_pipe[1]);
+    free(base);
+
+    debug_return;
+}
+
+void
+sudo_ev_base_setdef_v1(struct sudo_event_base *base)
+{
+    debug_decl(sudo_ev_base_setdef, SUDO_DEBUG_EVENT);
+
+    default_base = base;
+
+    debug_return;
+}
+
+/*
+ * Clear and fill in a struct sudo_event.
+ */
+static void
+sudo_ev_init(struct sudo_event *ev, int fd, short events,
+    sudo_ev_callback_t callback, void *closure)
+{
+    debug_decl(sudo_ev_init, SUDO_DEBUG_EVENT);
+
+    memset(ev, 0, sizeof(*ev));
+    ev->fd = fd;
+    ev->events = events & SUDO_EV_MASK;
+    ev->pfd_idx = -1;
+    ev->callback = callback;
+    ev->closure = closure;
+
+    debug_return;
+}
+
+/*
+ * Set a pre-allocated struct sudo_event.
+ * Allocates space for siginfo_t for SUDO_EV_SIGINFO as needed.
+ */
+int
+sudo_ev_set_v1(struct sudo_event *ev, int fd, short events,
+    sudo_ev_callback_t callback, void *closure)
+{
+    debug_decl(sudo_ev_set, SUDO_DEBUG_EVENT);
+
+    /* For SUDO_EV_SIGINFO we use a container to store closure + siginfo_t */
+    if (ISSET(events, SUDO_EV_SIGINFO)) {
+	struct sudo_ev_siginfo_container *container =
+	    malloc(sizeof(*container) + sizeof(siginfo_t) - 1);
+	if (container == NULL) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+		"%s: unable to allocate siginfo container", __func__);
+	    debug_return_int(-1);
+	}
+	container->closure = closure;
+	closure = container;
+    }
+    sudo_ev_init(ev, fd, events, callback, closure);
+
+    debug_return_int(0);
+}
+
+struct sudo_event *
+sudo_ev_alloc_v1(int fd, short events, sudo_ev_callback_t callback, void *closure)
+{
+    struct sudo_event *ev;
+    debug_decl(sudo_ev_alloc, SUDO_DEBUG_EVENT);
+
+    ev = malloc(sizeof(*ev));
+    if (ev == NULL) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+	    "%s: unable to allocate event", __func__);
+	debug_return_ptr(NULL);
+    }
+    if (sudo_ev_set(ev, fd, events, callback, closure) == -1) {
+	free(ev);
+	debug_return_ptr(NULL);
+    }
+    debug_return_ptr(ev);
+}
+
+void
+sudo_ev_free_v1(struct sudo_event *ev)
+{
+    debug_decl(sudo_ev_free, SUDO_DEBUG_EVENT);
+
+    if (ev == NULL)
+	debug_return;
+
+    /* Make sure ev is not in use before freeing it. */
+    if (ISSET(ev->flags, SUDO_EVQ_INSERTED))
+	(void)sudo_ev_del(NULL, ev);
+    if (ISSET(ev->events, SUDO_EV_SIGINFO))
+	free(ev->closure);
+    free(ev);
+
+    debug_return;
+}
+
+static void
+sudo_ev_handler(int signo, siginfo_t *info, void *context)
+{
+    unsigned char ch = (unsigned char)signo;
+
+    if (signal_base != NULL) {
+	/*
+	 * Update signals_pending[] and siginfo[].
+	 * All signals must be blocked any time siginfo[] is accessed.
+	 * If no siginfo available, zero out the struct in base.
+	 */
+	if (info == NULL)
+	    memset(signal_base->siginfo[signo], 0, sizeof(*info));
+	else
+	    memcpy(signal_base->siginfo[signo], info, sizeof(*info));
+	signal_base->signal_pending[signo] = 1;
+	signal_base->signal_caught = 1;
+
+	/* Wake up the other end of the pipe. */
+	ignore_result(write(signal_base->signal_pipe[1], &ch, 1));
+    }
+}
+
+static int
+sudo_ev_add_signal(struct sudo_event_base *base, struct sudo_event *ev,
+    bool tohead)
+{
+    const int signo = ev->fd;
+    debug_decl(sudo_ev_add_signal, SUDO_DEBUG_EVENT);
+
+    sudo_debug_printf(SUDO_DEBUG_INFO,
+	"%s: adding event %p to base %p, signal %d, events %d",
+	__func__, ev, base, signo, ev->events);
+    if (signo >= NSIG) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+	    "%s: signo %d larger than max %d", __func__, signo, NSIG - 1);
+	debug_return_int(-1);
+    }
+    if ((ev->events & ~(SUDO_EV_SIGNAL|SUDO_EV_SIGINFO|SUDO_EV_PERSIST)) != 0) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+	    "%s: invalid event set 0x%x", __func__, ev->events);
+	debug_return_int(-1);
+    }
+
+    /*
+     * Allocate base->siginfo[signo] and base->orig_handlers[signo] as needed.
+     */
+    if (base->siginfo[signo] == NULL) {
+	base->siginfo[signo] = malloc(sizeof(*base->siginfo[signo]));
+	if (base->siginfo[signo] == NULL) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+		"%s: unable to allocate siginfo for signo %d",
+		__func__, signo);
+	    debug_return_int(-1);
+	}
+    }
+    if (base->orig_handlers[signo] == NULL) {
+	base->orig_handlers[signo] =
+	    malloc(sizeof(*base->orig_handlers[signo]));
+	if (base->orig_handlers[signo] == NULL) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+		"%s: unable to allocate orig_handlers for signo %d",
+		__func__, signo);
+	    debug_return_int(-1);
+	}
+    }
+
+    /* Install signal handler as needed, saving the original value. */
+    if (TAILQ_EMPTY(&base->signals[signo])) {
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sigfillset(&sa.sa_mask);
+	sa.sa_flags = SA_RESTART|SA_SIGINFO;
+	sa.sa_sigaction = sudo_ev_handler;
+	if (sigaction(signo, &sa, base->orig_handlers[signo]) != 0) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+		"%s: unable to install handler for signo %d", __func__, signo);
+	    debug_return_int(-1);
+	}
+	base->num_handlers++;
+    }
+
+    /*
+     * Insert signal event into the proper tail queue.
+     * Signal events are always persistent.
+     */
+    ev->base = base;
+    if (tohead) {
+	TAILQ_INSERT_HEAD(&base->signals[signo], ev, entries);
+    } else {
+	TAILQ_INSERT_TAIL(&base->signals[signo], ev, entries);
+    }
+    SET(ev->events, SUDO_EV_PERSIST);
+    SET(ev->flags, SUDO_EVQ_INSERTED);
+
+    /* Add the internal signal_pipe event on demand. */
+    if (!ISSET(base->signal_event.flags, SUDO_EVQ_INSERTED))
+	sudo_ev_add(base, &base->signal_event, NULL, true);
+
+    /* Update global signal base so handler to update signals_pending[] */
+    signal_base = base;
+
+    debug_return_int(0);
+}
+
+int
+sudo_ev_add_v1(struct sudo_event_base *base, struct sudo_event *ev,
+    const struct timeval *timo, bool tohead)
+{
+    struct timespec tsbuf, *ts = NULL;
+
+    if (timo != NULL) {
+	TIMEVAL_TO_TIMESPEC(timo, &tsbuf);
+	ts = &tsbuf;
+    }
+
+    return sudo_ev_add_v2(base, ev, ts, tohead);
+}
+
+int
+sudo_ev_add_v2(struct sudo_event_base *base, struct sudo_event *ev,
+    const struct timespec *timo, bool tohead)
+{
+    debug_decl(sudo_ev_add, SUDO_DEBUG_EVENT);
+
+    /* If no base specified, use existing or default base. */
+    if (base == NULL) {
+	if (ev->base != NULL) {
+	    base = ev->base;
+	} else if (default_base != NULL) {
+	    base = default_base;
+	} else {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR, "%s: no base specified",
+		__func__);
+	    debug_return_int(-1);
+	}
+    }
+
+    /* Only add new events to the events list. */
+    if (ISSET(ev->flags, SUDO_EVQ_INSERTED)) {
+	/* If event no longer has a timeout, remove from timeouts queue. */
+	if (timo == NULL && ISSET(ev->flags, SUDO_EVQ_TIMEOUTS)) {
+	    sudo_debug_printf(SUDO_DEBUG_INFO,
+		"%s: removing event %p from timeouts queue", __func__, ev);
+	    CLR(ev->flags, SUDO_EVQ_TIMEOUTS);
+	    TAILQ_REMOVE(&base->timeouts, ev, timeouts_entries);
+	}
+    } else {
+	/* Special handling for signal events. */
+	if (ev->events & (SUDO_EV_SIGNAL|SUDO_EV_SIGINFO))
+	    debug_return_int(sudo_ev_add_signal(base, ev, tohead));
+
+	/* Add event to the base. */
+	sudo_debug_printf(SUDO_DEBUG_INFO,
+	    "%s: adding event %p to base %p, fd %d, events %d",
+	    __func__, ev, base, ev->fd, ev->events);
+	if (ev->events & (SUDO_EV_READ|SUDO_EV_WRITE)) {
+	    if (sudo_ev_add_impl(base, ev) != 0)
+		debug_return_int(-1);
+	}
+	ev->base = base;
+	if (tohead) {
+	    TAILQ_INSERT_HEAD(&base->events, ev, entries);
+	} else {
+	    TAILQ_INSERT_TAIL(&base->events, ev, entries);
+	}
+	SET(ev->flags, SUDO_EVQ_INSERTED);
+    }
+    /* Timeouts can be changed for existing events. */
+    if (timo != NULL) {
+	struct sudo_event *evtmp;
+	if (ISSET(ev->flags, SUDO_EVQ_TIMEOUTS)) {
+	    /* Remove from timeouts list, then add back. */
+	    TAILQ_REMOVE(&base->timeouts, ev, timeouts_entries);
+	}
+	/* Convert to absolute time and insert in sorted order; O(n). */
+	sudo_gettime_mono(&ev->timeout);
+	sudo_timespecadd(&ev->timeout, timo, &ev->timeout);
+	TAILQ_FOREACH(evtmp, &base->timeouts, timeouts_entries) {
+	    if (sudo_timespeccmp(&ev->timeout, &evtmp->timeout, <))
+		break;
+	}
+	if (evtmp != NULL) {
+	    TAILQ_INSERT_BEFORE(evtmp, ev, timeouts_entries);
+	} else {
+	    TAILQ_INSERT_TAIL(&base->timeouts, ev, timeouts_entries);
+	}
+	SET(ev->flags, SUDO_EVQ_TIMEOUTS);
+    }
+    debug_return_int(0);
+}
+
+/*
+ * Remove an event from the base, if specified, or the base embedded
+ * in the event if not.  Note that there are multiple tail queues.
+ */
+int
+sudo_ev_del_v1(struct sudo_event_base *base, struct sudo_event *ev)
+{
+    debug_decl(sudo_ev_del, SUDO_DEBUG_EVENT);
+
+    /* Make sure event is really in the queue. */
+    if (!ISSET(ev->flags, SUDO_EVQ_INSERTED)) {
+	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: event %p not in queue",
+	    __func__, ev);
+	debug_return_int(0);
+    }
+
+    /* Check for event base mismatch, if one is specified. */
+    if (base == NULL) {
+	if (ev->base == NULL) {
+	    sudo_debug_printf(SUDO_DEBUG_ERROR, "%s: no base specified",
+		__func__);
+	    debug_return_int(-1);
+	}
+	base = ev->base;
+    } else if (base != ev->base) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR, "%s: mismatch base %p, ev->base %p",
+	    __func__, base, ev->base);
+	debug_return_int(-1);
+    }
+
+    if (ev->events & (SUDO_EV_SIGNAL|SUDO_EV_SIGINFO)) {
+	const int signo = ev->fd;
+
+	sudo_debug_printf(SUDO_DEBUG_INFO,
+	    "%s: removing event %p from base %p, signo %d, events %d",
+	    __func__, ev, base, signo, ev->events);
+
+	/* Unlink from signal event list. */
+	TAILQ_REMOVE(&base->signals[signo], ev, entries);
+	if (TAILQ_EMPTY(&base->signals[signo])) {
+	    if (sigaction(signo, base->orig_handlers[signo], NULL) != 0) {
+		sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
+		    "%s: unable to restore handler for signo %d",
+		    __func__, signo);
+		debug_return_int(-1);
+	    }
+	    base->num_handlers--;
+	}
+	if (base->num_handlers == 0) {
+	    /* No registered signal events, remove internal event. */
+	    sudo_ev_del(base, &base->signal_event);
+	}
+    } else {
+	sudo_debug_printf(SUDO_DEBUG_INFO,
+	    "%s: removing event %p from base %p, fd %d, events %d",
+	    __func__, ev, base, ev->fd, ev->events);
+
+	/* Call backend. */
+	if (ev->events & (SUDO_EV_READ|SUDO_EV_WRITE)) {
+	    if (sudo_ev_del_impl(base, ev) != 0)
+		debug_return_int(-1);
+	}
+
+	/* Unlink from event list. */
+	TAILQ_REMOVE(&base->events, ev, entries);
+
+	/* Unlink from timeouts list. */
+	if (ISSET(ev->flags, SUDO_EVQ_TIMEOUTS))
+	    TAILQ_REMOVE(&base->timeouts, ev, timeouts_entries);
+    }
+
+    /* Unlink from active list. */
+    if (ISSET(ev->flags, SUDO_EVQ_ACTIVE))
+	TAILQ_REMOVE(&base->active, ev, active_entries);
+
+    /* Mark event unused. */
+    ev->flags = 0;
+    ev->pfd_idx = -1;
+
+    debug_return_int(0);
+}
+
+int
+sudo_ev_dispatch_v1(struct sudo_event_base *base)
+{
+    return sudo_ev_loop_v1(base, 0);
+}
+
+/*
+ * Run main event loop.
+ * Returns 0 on success, 1 if no events registered  and -1 on error 
+ */
+int
+sudo_ev_loop_v1(struct sudo_event_base *base, int flags)
+{
+    struct timespec now;
+    struct sudo_event *ev;
+    int nready, rc = 0;
+    debug_decl(sudo_ev_loop, SUDO_DEBUG_EVENT);
+
+    /*
+     * If sudo_ev_loopexit() was called when events were not running
+     * the next invocation of sudo_ev_loop() only runs once.
+     * All other base flags are ignored unless we are running events.
+     * Note that SUDO_EVLOOP_ONCE and SUDO_EVBASE_LOOPONCE are equivalent.
+     */
+    base->flags |= (flags & SUDO_EVLOOP_ONCE);
+    base->flags &= (SUDO_EVBASE_LOOPEXIT|SUDO_EVBASE_LOOPONCE);
+
+    for (;;) {
+rescan:
+	/* Make sure we have some events. */
+	if (TAILQ_EMPTY(&base->events)) {
+	    rc = 1;
+	    break;
+	}
+
+	/* Call backend to scan for I/O events. */
+	TAILQ_INIT(&base->active);
+	nready = sudo_ev_scan_impl(base, flags);
+	switch (nready) {
+	case -1:
+	    if (errno == ENOMEM || errno == EAGAIN)
+		continue;
+	    if (errno == EINTR) {
+		/* Interrupted by signal, check for sigevents. */
+		if (base->signal_caught) {
+		    signal_pipe_cb(base->signal_pipe[0], SUDO_EV_READ, base);
+		    break;
+		}
+		continue;
+	    }
+	    rc = -1;
+	    goto done;
+	case 0:
+	    /* Timed out, activate timeout events. */
+	    sudo_gettime_mono(&now);
+	    while ((ev = TAILQ_FIRST(&base->timeouts)) != NULL) {
+		if (sudo_timespeccmp(&ev->timeout, &now, >))
+		    break;
+		/* Remove from timeouts list. */
+		CLR(ev->flags, SUDO_EVQ_TIMEOUTS);
+		TAILQ_REMOVE(&base->timeouts, ev, timeouts_entries);
+		/* Make event active. */
+		ev->revents = SUDO_EV_TIMEOUT;
+		TAILQ_INSERT_TAIL(&base->active, ev, active_entries);
+		SET(ev->flags, SUDO_EVQ_ACTIVE);
+	    }
+	    if (ISSET(flags, SUDO_EVLOOP_NONBLOCK)) {
+		/* If nonblocking, return immediately if no active events. */
+		if (TAILQ_EMPTY(&base->active))
+		    goto done;
+	    }
+	    break;
+	default:
+	    /* I/O events active, sudo_ev_scan_impl() already added them. */
+	    break;
+	}
+
+	/*
+	 * Service each event in the active queue.
+	 * We store the current event pointer in the base so that
+	 * it can be cleared by sudo_ev_del().  This prevents a use
+	 * after free if the callback frees its own event.
+	 */
+	while ((ev = TAILQ_FIRST(&base->active)) != NULL) {
+	    /* Pop first event off the active queue. */
+	    sudo_ev_deactivate(base, ev);
+	    /* Remove from base unless persistent. */
+	    if (!ISSET(ev->events, SUDO_EV_PERSIST))
+		sudo_ev_del(base, ev);
+	    ev->callback(ev->fd, ev->revents,
+		ev->closure == sudo_ev_self_cbarg() ? ev : ev->closure);
+	    if (ISSET(base->flags, SUDO_EVBASE_LOOPBREAK)) {
+		/* Stop processing events immediately. */
+		SET(base->flags, SUDO_EVBASE_GOT_BREAK);
+		sudo_ev_deactivate_all(base);
+		goto done;
+	    }
+	    if (ISSET(base->flags, SUDO_EVBASE_LOOPCONT)) {
+		/* Rescan events and start polling again. */
+		CLR(base->flags, SUDO_EVBASE_LOOPCONT);
+		sudo_ev_deactivate_all(base);
+		goto rescan;
+	    }
+	}
+	if (ISSET(base->flags, SUDO_EVBASE_LOOPONCE)) {
+	    /* SUDO_EVBASE_LOOPEXIT is always set w/ SUDO_EVBASE_LOOPONCE */
+	    if (ISSET(base->flags, SUDO_EVBASE_LOOPEXIT))
+		SET(base->flags, SUDO_EVBASE_GOT_EXIT);
+	    sudo_ev_deactivate_all(base);
+	    break;
+	}
+    }
+done:
+    base->flags &= SUDO_EVBASE_GOT_MASK;
+    debug_return_int(rc);
+}
+
+void
+sudo_ev_loopexit_v1(struct sudo_event_base *base)
+{
+    debug_decl(sudo_ev_loopexit, SUDO_DEBUG_EVENT);
+
+    if (base == NULL) {
+	if ((base = default_base) == NULL)
+	    debug_return;
+    }
+
+    /* SUDO_EVBASE_LOOPBREAK trumps SUDO_EVBASE_LOOPEXIT */
+    if (!ISSET(base->flags, SUDO_EVBASE_LOOPBREAK)) {
+	/* SUDO_EVBASE_LOOPEXIT trumps SUDO_EVBASE_LOOPCONT */
+	CLR(base->flags, SUDO_EVBASE_LOOPCONT);
+	SET(base->flags, (SUDO_EVBASE_LOOPEXIT|SUDO_EVBASE_LOOPONCE));
+    }
+    debug_return;
+}
+
+void
+sudo_ev_loopbreak_v1(struct sudo_event_base *base)
+{
+    debug_decl(sudo_ev_loopbreak, SUDO_DEBUG_EVENT);
+
+    if (base == NULL) {
+	if ((base = default_base) == NULL)
+	    debug_return;
+    }
+
+    /* SUDO_EVBASE_LOOPBREAK trumps SUDO_EVBASE_LOOP{CONT,EXIT,ONCE}. */
+    CLR(base->flags, (SUDO_EVBASE_LOOPCONT|SUDO_EVBASE_LOOPEXIT|SUDO_EVBASE_LOOPONCE));
+    SET(base->flags, SUDO_EVBASE_LOOPBREAK);
+    debug_return;
+}
+
+void
+sudo_ev_loopcontinue_v1(struct sudo_event_base *base)
+{
+    debug_decl(sudo_ev_loopcontinue, SUDO_DEBUG_EVENT);
+
+    if (base == NULL) {
+	if ((base = default_base) == NULL)
+	    debug_return;
+    }
+
+    /* SUDO_EVBASE_LOOP{BREAK,EXIT} trumps SUDO_EVBASE_LOOPCONT */
+    if (!ISSET(base->flags, SUDO_EVBASE_LOOPONCE|SUDO_EVBASE_LOOPBREAK)) {
+	SET(base->flags, SUDO_EVBASE_LOOPCONT);
+    }
+    debug_return;
+}
+
+bool
+sudo_ev_got_exit_v1(struct sudo_event_base *base)
+{
+    debug_decl(sudo_ev_got_exit, SUDO_DEBUG_EVENT);
+
+    if (base == NULL) {
+	if ((base = default_base) == NULL)
+	    debug_return_bool(false);
+    }
+    debug_return_bool(ISSET(base->flags, SUDO_EVBASE_GOT_EXIT));
+}
+
+bool
+sudo_ev_got_break_v1(struct sudo_event_base *base)
+{
+    debug_decl(sudo_ev_got_break, SUDO_DEBUG_EVENT);
+
+    if (base == NULL) {
+	if ((base = default_base) == NULL)
+	    debug_return_bool(false);
+    }
+    debug_return_bool(ISSET(base->flags, SUDO_EVBASE_GOT_BREAK));
+}
+
+int
+sudo_ev_get_timeleft_v1(struct sudo_event *ev, struct timeval *tv)
+{
+    struct timespec ts;
+    int ret;
+
+    ret = sudo_ev_get_timeleft_v2(ev, &ts);
+    TIMESPEC_TO_TIMEVAL(tv, &ts);
+
+    return ret;
+}
+
+int
+sudo_ev_get_timeleft_v2(struct sudo_event *ev, struct timespec *ts)
+{
+    debug_decl(sudo_ev_get_timeleft, SUDO_DEBUG_EVENT);
+
+    sudo_timespecclear(ts);
+    if (sudo_ev_pending_v1(ev, SUDO_EV_TIMEOUT, ts) != SUDO_EV_TIMEOUT)
+	debug_return_int(-1);
+    debug_return_int(0);
+}
+
+int
+sudo_ev_pending_v1(struct sudo_event *ev, short events, struct timespec *ts)
+{
+    int ret;
+    debug_decl(sudo_ev_pending, SUDO_DEBUG_EVENT);
+
+    sudo_debug_printf(SUDO_DEBUG_INFO, "%s: event %p, flags 0x%x, events 0x%x",
+	__func__, ev, ev->flags, ev->events);
+
+    if (!ISSET(ev->flags, SUDO_EVQ_INSERTED))
+	debug_return_int(0);
+
+    ret = ev->events & events;
+    CLR(ret, SUDO_EV_TIMEOUT);
+    if (ISSET(ev->flags, SUDO_EVQ_TIMEOUTS) && ISSET(events, SUDO_EV_TIMEOUT)) {
+	ret |= SUDO_EV_TIMEOUT;
+	if (ts != NULL) {
+	    struct timespec now;
+
+	    sudo_gettime_mono(&now);
+	    sudo_timespecsub(&ev->timeout, &now, ts);
+	    if (ts->tv_sec < 0)
+		sudo_timespecclear(ts);
+	}
+    }
+
+    debug_return_int(ret);
+}