Adding upstream version 3.4.23.upstream/3.4.23upstream

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

1 files changed, 1261 insertions, 0 deletions

diff --git a/src/util/events.c b/src/util/events.c
new file mode 100644
index 0000000..c2157bb
--- /dev/null
+++ b/src/util/events.c
@@ -0,0 +1,1261 @@
+/*++
+/* NAME
+/*	events 3
+/* SUMMARY
+/*	event manager
+/* SYNOPSIS
+/*	#include <events.h>
+/*
+/*	time_t	event_time()
+/*
+/*	void	event_loop(delay)
+/*	int	delay;
+/*
+/*	time_t	event_request_timer(callback, context, delay)
+/*	void	(*callback)(int event, void *context);
+/*	void	*context;
+/*	int	delay;
+/*
+/*	int	event_cancel_timer(callback, context)
+/*	void	(*callback)(int event, void *context);
+/*	void	*context;
+/*
+/*	void	event_enable_read(fd, callback, context)
+/*	int	fd;
+/*	void	(*callback)(int event, void *context);
+/*	void	*context;
+/*
+/*	void	event_enable_write(fd, callback, context)
+/*	int	fd;
+/*	void	(*callback)(int event, void *context);
+/*	void	*context;
+/*
+/*	void	event_disable_readwrite(fd)
+/*	int	fd;
+/*
+/*	void	event_drain(time_limit)
+/*	int	time_limit;
+/*
+/*	void	event_fork(void)
+/* DESCRIPTION
+/*	This module delivers I/O and timer events.
+/*	Multiple I/O streams and timers can be monitored simultaneously.
+/*	Events are delivered via callback routines provided by the
+/*	application. When requesting an event, the application can provide
+/*	private context that is passed back when the callback routine is
+/*	executed.
+/*
+/*	event_time() returns a cached value of the current time.
+/*
+/*	event_loop() monitors all I/O channels for which the application has
+/*	expressed interest, and monitors the timer request queue.
+/*	It notifies the application whenever events of interest happen.
+/*	A negative delay value causes the function to pause until something
+/*	happens; a positive delay value causes event_loop() to return when
+/*	the next event happens or when the delay time in seconds is over,
+/*	whatever happens first. A zero delay effectuates a poll.
+/*
+/*	Note: in order to avoid race conditions, event_loop() cannot
+/*	not be called recursively.
+/*
+/*	event_request_timer() causes the specified callback function to
+/*	be called with the specified context argument after \fIdelay\fR
+/*	seconds, or as soon as possible thereafter. The delay should
+/*	not be negative (the manifest EVENT_NULL_DELAY provides for
+/*	convenient zero-delay notification).
+/*	The event argument is equal to EVENT_TIME.
+/*	Only one timer request can be active per (callback, context) pair.
+/*	Calling event_request_timer() with an existing (callback, context)
+/*	pair does not schedule a new event, but updates the time of event
+/*	delivery. The result is the absolute time at which the timer is
+/*	scheduled to go off.
+/*
+/*	event_cancel_timer() cancels the specified (callback, context) request.
+/*	The application is allowed to cancel non-existing requests. The result
+/*	value is the amount of time left before the timer would have gone off,
+/*	or -1 in case of no pending timer.
+/*
+/*	event_enable_read() (event_enable_write()) enables read (write) events
+/*	on the named I/O channel. It is up to the application to assemble
+/*	partial reads or writes.
+/*	An I/O channel cannot handle more than one request at the
+/*	same time. The application is allowed to enable an event that
+/*	is already enabled (same channel, same read or write operation,
+/*	but perhaps a different callback or context). On systems with
+/*	kernel-based event filters this is preferred usage, because
+/*	each disable and enable request would cost a system call.
+/*
+/*	The manifest constants EVENT_NULL_CONTEXT and EVENT_NULL_TYPE
+/*	provide convenient null values.
+/*
+/*	The callback routine has the following arguments:
+/* .IP fd
+/*	The stream on which the event happened.
+/* .IP event
+/*	An indication of the event type:
+/* .RS
+/* .IP EVENT_READ
+/*	read event,
+/* .IP EVENT_WRITE
+/*	write event,
+/* .IP EVENT_XCPT
+/*	exception (actually, any event other than read or write).
+/* .RE
+/* .IP context
+/*	Application context given to event_enable_read() (event_enable_write()).
+/* .PP
+/*	event_disable_readwrite() disables further I/O events on the specified
+/*	I/O channel. The application is allowed to cancel non-existing
+/*	I/O event requests.
+/*
+/*	event_drain() repeatedly calls event_loop() until no more timer
+/*	events or I/O events are pending or until the time limit is reached.
+/*	This routine must not be called from an event_whatever() callback
+/*	routine. Note: this function assumes that no new I/O events
+/*	will be registered.
+/*
+/*	event_fork() must be called by a child process after it is
+/*	created with fork(), to re-initialize event processing.
+/* DIAGNOSTICS
+/*	Panics: interface violations. Fatal errors: out of memory,
+/*	system call failure. Warnings: the number of available
+/*	file descriptors is much less than FD_SETSIZE.
+/* BUGS
+/*	This module is based on event selection. It assumes that the
+/*	event_loop() routine is called frequently. This approach is
+/*	not suitable for applications with compute-bound loops that
+/*	take a significant amount of time.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System libraries. */
+
+#include "sys_defs.h"
+#include <sys/time.h>			/* XXX: 44BSD uses bzero() */
+#include <time.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stddef.h>			/* offsetof() */
+#include <string.h>			/* bzero() prototype for 44BSD */
+#include <limits.h>			/* INT_MAX */
+
+#ifdef USE_SYS_SELECT_H
+#include <sys/select.h>
+#endif
+
+/* Application-specific. */
+
+#include "mymalloc.h"
+#include "msg.h"
+#include "iostuff.h"
+#include "ring.h"
+#include "events.h"
+
+#if !defined(EVENTS_STYLE)
+#error "must define EVENTS_STYLE"
+#endif
+
+ /*
+  * Traditional BSD-style select(2). Works everywhere, but has a built-in
+  * upper bound on the number of file descriptors, and that limit is hard to
+  * change on Linux. Is sometimes emulated with SYSV-style poll(2) which
+  * doesn't have the file descriptor limit, but unfortunately does not help
+  * to improve the performance of servers with lots of connections.
+  */
+#define EVENT_ALLOC_INCR		10
+
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+typedef fd_set EVENT_MASK;
+
+#define EVENT_MASK_BYTE_COUNT(mask)	sizeof(*(mask))
+#define EVENT_MASK_ZERO(mask)		FD_ZERO(mask)
+#define EVENT_MASK_SET(fd, mask)	FD_SET((fd), (mask))
+#define EVENT_MASK_ISSET(fd, mask)	FD_ISSET((fd), (mask))
+#define EVENT_MASK_CLR(fd, mask)	FD_CLR((fd), (mask))
+#define EVENT_MASK_CMP(m1, m2) memcmp((m1), (m2), EVENT_MASK_BYTE_COUNT(m1))
+#else
+
+ /*
+  * Kernel-based event filters (kqueue, /dev/poll, epoll). We use the
+  * following file descriptor mask structure which is expanded on the fly.
+  */
+typedef struct {
+    char   *data;			/* bit mask */
+    size_t  data_len;			/* data byte count */
+} EVENT_MASK;
+
+ /* Bits per byte, byte in vector, bit offset in byte, bytes per set. */
+#define EVENT_MASK_NBBY		(8)
+#define EVENT_MASK_FD_BYTE(fd, mask) \
+	(((unsigned char *) (mask)->data)[(fd) / EVENT_MASK_NBBY])
+#define EVENT_MASK_FD_BIT(fd)	(1 << ((fd) % EVENT_MASK_NBBY))
+#define EVENT_MASK_BYTES_NEEDED(len) \
+	(((len) + (EVENT_MASK_NBBY -1)) / EVENT_MASK_NBBY)
+#define EVENT_MASK_BYTE_COUNT(mask)	((mask)->data_len)
+
+ /* Memory management. */
+#define EVENT_MASK_ALLOC(mask, bit_len) do { \
+	size_t _byte_len = EVENT_MASK_BYTES_NEEDED(bit_len); \
+	(mask)->data = mymalloc(_byte_len); \
+	memset((mask)->data, 0, _byte_len); \
+	(mask)->data_len = _byte_len; \
+    } while (0)
+#define EVENT_MASK_REALLOC(mask, bit_len) do { \
+	size_t _byte_len = EVENT_MASK_BYTES_NEEDED(bit_len); \
+	size_t _old_len = (mask)->data_len; \
+	(mask)->data = myrealloc((mask)->data, _byte_len); \
+	if (_byte_len > _old_len) \
+	    memset((mask)->data + _old_len, 0, _byte_len - _old_len); \
+	(mask)->data_len = _byte_len; \
+    } while (0)
+#define EVENT_MASK_FREE(mask)	myfree((mask)->data)
+
+ /* Set operations, modeled after FD_ZERO/SET/ISSET/CLR. */
+#define EVENT_MASK_ZERO(mask) \
+	memset((mask)->data, 0, (mask)->data_len)
+#define EVENT_MASK_SET(fd, mask) \
+	(EVENT_MASK_FD_BYTE((fd), (mask)) |= EVENT_MASK_FD_BIT(fd))
+#define EVENT_MASK_ISSET(fd, mask) \
+	(EVENT_MASK_FD_BYTE((fd), (mask)) & EVENT_MASK_FD_BIT(fd))
+#define EVENT_MASK_CLR(fd, mask) \
+	(EVENT_MASK_FD_BYTE((fd), (mask)) &= ~EVENT_MASK_FD_BIT(fd))
+#define EVENT_MASK_CMP(m1, m2) \
+	memcmp((m1)->data, (m2)->data, EVENT_MASK_BYTE_COUNT(m1))
+#endif
+
+ /*
+  * I/O events.
+  */
+typedef struct EVENT_FDTABLE EVENT_FDTABLE;
+
+struct EVENT_FDTABLE {
+    EVENT_NOTIFY_RDWR_FN callback;
+    char   *context;
+};
+static EVENT_MASK event_rmask;		/* enabled read events */
+static EVENT_MASK event_wmask;		/* enabled write events */
+static EVENT_MASK event_xmask;		/* for bad news mostly */
+static int event_fdlimit;		/* per-process open file limit */
+static EVENT_FDTABLE *event_fdtable;	/* one slot per file descriptor */
+static int event_fdslots;		/* number of file descriptor slots */
+static int event_max_fd = -1;		/* highest fd number seen */
+
+ /*
+  * FreeBSD kqueue supports no system call to find out what descriptors are
+  * registered in the kernel-based filter. To implement our own sanity checks
+  * we maintain our own descriptor bitmask.
+  * 
+  * FreeBSD kqueue does support application context pointers. Unfortunately,
+  * changing that information would cost a system call, and some of the
+  * competitors don't support application context. To keep the implementation
+  * simple we maintain our own table with call-back information.
+  * 
+  * FreeBSD kqueue silently unregisters a descriptor from its filter when the
+  * descriptor is closed, so our information could get out of sync with the
+  * kernel. But that will never happen, because we have to meticulously
+  * unregister a file descriptor before it is closed, to avoid errors on
+  * systems that are built with EVENTS_STYLE == EVENTS_STYLE_SELECT.
+  */
+#if (EVENTS_STYLE == EVENTS_STYLE_KQUEUE)
+#include <sys/event.h>
+
+ /*
+  * Some early FreeBSD implementations don't have the EV_SET macro.
+  */
+#ifndef EV_SET
+#define EV_SET(kp, id, fi, fl, ffl, da, ud) do { \
+        (kp)->ident = (id); \
+        (kp)->filter = (fi); \
+        (kp)->flags = (fl); \
+        (kp)->fflags = (ffl); \
+        (kp)->data = (da); \
+        (kp)->udata = (ud); \
+    } while(0)
+#endif
+
+ /*
+  * Macros to initialize the kernel-based filter; see event_init().
+  */
+static int event_kq;			/* handle to event filter */
+
+#define EVENT_REG_INIT_HANDLE(er, n) do { \
+	er = event_kq = kqueue(); \
+    } while (0)
+#define EVENT_REG_INIT_TEXT	"kqueue"
+
+#define EVENT_REG_FORK_HANDLE(er, n) do { \
+	(void) close(event_kq); \
+	EVENT_REG_INIT_HANDLE(er, (n)); \
+    } while (0)
+
+ /*
+  * Macros to update the kernel-based filter; see event_enable_read(),
+  * event_enable_write() and event_disable_readwrite().
+  */
+#define EVENT_REG_FD_OP(er, fh, ev, op) do { \
+	struct kevent dummy; \
+	EV_SET(&dummy, (fh), (ev), (op), 0, 0, 0); \
+	(er) = kevent(event_kq, &dummy, 1, 0, 0, 0); \
+    } while (0)
+
+#define EVENT_REG_ADD_OP(e, f, ev) EVENT_REG_FD_OP((e), (f), (ev), EV_ADD)
+#define EVENT_REG_ADD_READ(e, f)   EVENT_REG_ADD_OP((e), (f), EVFILT_READ)
+#define EVENT_REG_ADD_WRITE(e, f)  EVENT_REG_ADD_OP((e), (f), EVFILT_WRITE)
+#define EVENT_REG_ADD_TEXT         "kevent EV_ADD"
+
+#define EVENT_REG_DEL_OP(e, f, ev) EVENT_REG_FD_OP((e), (f), (ev), EV_DELETE)
+#define EVENT_REG_DEL_READ(e, f)   EVENT_REG_DEL_OP((e), (f), EVFILT_READ)
+#define EVENT_REG_DEL_WRITE(e, f)  EVENT_REG_DEL_OP((e), (f), EVFILT_WRITE)
+#define EVENT_REG_DEL_TEXT         "kevent EV_DELETE"
+
+ /*
+  * Macros to retrieve event buffers from the kernel; see event_loop().
+  */
+typedef struct kevent EVENT_BUFFER;
+
+#define EVENT_BUFFER_READ(event_count, event_buf, buflen, delay) do { \
+	struct timespec ts; \
+	struct timespec *tsp; \
+	if ((delay) < 0) { \
+	    tsp = 0; \
+	} else { \
+	    tsp = &ts; \
+	    ts.tv_nsec = 0; \
+	    ts.tv_sec = (delay); \
+	} \
+	(event_count) = kevent(event_kq, (struct kevent *) 0, 0, (event_buf), \
+			  (buflen), (tsp)); \
+    } while (0)
+#define EVENT_BUFFER_READ_TEXT	"kevent"
+
+ /*
+  * Macros to process event buffers from the kernel; see event_loop().
+  */
+#define EVENT_GET_FD(bp)	((bp)->ident)
+#define EVENT_GET_TYPE(bp)	((bp)->filter)
+#define EVENT_TEST_READ(bp)	(EVENT_GET_TYPE(bp) == EVFILT_READ)
+#define EVENT_TEST_WRITE(bp)	(EVENT_GET_TYPE(bp) == EVFILT_WRITE)
+
+#endif
+
+ /*
+  * Solaris /dev/poll does not support application context, so we have to
+  * maintain our own. This has the benefit of avoiding an expensive system
+  * call just to change a call-back function or argument.
+  * 
+  * Solaris /dev/poll does have a way to query if a specific descriptor is
+  * registered. However, we maintain a descriptor mask anyway because a) it
+  * avoids having to make an expensive system call to find out if something
+  * is registered, b) some EVENTS_STYLE_MUMBLE implementations need a
+  * descriptor bitmask anyway and c) we use the bitmask already to implement
+  * sanity checks.
+  */
+#if (EVENTS_STYLE == EVENTS_STYLE_DEVPOLL)
+#include <sys/devpoll.h>
+#include <fcntl.h>
+
+ /*
+  * Macros to initialize the kernel-based filter; see event_init().
+  */
+static int event_pollfd;		/* handle to file descriptor set */
+
+#define EVENT_REG_INIT_HANDLE(er, n) do { \
+	er = event_pollfd = open("/dev/poll", O_RDWR); \
+	if (event_pollfd >= 0) close_on_exec(event_pollfd, CLOSE_ON_EXEC); \
+    } while (0)
+#define EVENT_REG_INIT_TEXT	"open /dev/poll"
+
+#define EVENT_REG_FORK_HANDLE(er, n) do { \
+	(void) close(event_pollfd); \
+	EVENT_REG_INIT_HANDLE(er, (n)); \
+    } while (0)
+
+ /*
+  * Macros to update the kernel-based filter; see event_enable_read(),
+  * event_enable_write() and event_disable_readwrite().
+  */
+#define EVENT_REG_FD_OP(er, fh, ev) do { \
+	struct pollfd dummy; \
+	dummy.fd = (fh); \
+	dummy.events = (ev); \
+	(er) = write(event_pollfd, (void *) &dummy, \
+	    sizeof(dummy)) != sizeof(dummy) ? -1 : 0; \
+    } while (0)
+
+#define EVENT_REG_ADD_READ(e, f)  EVENT_REG_FD_OP((e), (f), POLLIN)
+#define EVENT_REG_ADD_WRITE(e, f) EVENT_REG_FD_OP((e), (f), POLLOUT)
+#define EVENT_REG_ADD_TEXT        "write /dev/poll"
+
+#define EVENT_REG_DEL_BOTH(e, f)  EVENT_REG_FD_OP((e), (f), POLLREMOVE)
+#define EVENT_REG_DEL_TEXT        "write /dev/poll"
+
+ /*
+  * Macros to retrieve event buffers from the kernel; see event_loop().
+  */
+typedef struct pollfd EVENT_BUFFER;
+
+#define EVENT_BUFFER_READ(event_count, event_buf, buflen, delay) do { \
+	struct dvpoll dvpoll; \
+	dvpoll.dp_fds = (event_buf); \
+	dvpoll.dp_nfds = (buflen); \
+	dvpoll.dp_timeout = (delay) < 0 ? -1 : (delay) * 1000; \
+	(event_count) = ioctl(event_pollfd, DP_POLL, &dvpoll); \
+    } while (0)
+#define EVENT_BUFFER_READ_TEXT	"ioctl DP_POLL"
+
+ /*
+  * Macros to process event buffers from the kernel; see event_loop().
+  */
+#define EVENT_GET_FD(bp)	((bp)->fd)
+#define EVENT_GET_TYPE(bp)	((bp)->revents)
+#define EVENT_TEST_READ(bp)	(EVENT_GET_TYPE(bp) & POLLIN)
+#define EVENT_TEST_WRITE(bp)	(EVENT_GET_TYPE(bp) & POLLOUT)
+
+#endif
+
+ /*
+  * Linux epoll supports no system call to find out what descriptors are
+  * registered in the kernel-based filter. To implement our own sanity checks
+  * we maintain our own descriptor bitmask.
+  * 
+  * Linux epoll does support application context pointers. Unfortunately,
+  * changing that information would cost a system call, and some of the
+  * competitors don't support application context. To keep the implementation
+  * simple we maintain our own table with call-back information.
+  * 
+  * Linux epoll silently unregisters a descriptor from its filter when the
+  * descriptor is closed, so our information could get out of sync with the
+  * kernel. But that will never happen, because we have to meticulously
+  * unregister a file descriptor before it is closed, to avoid errors on
+  * systems that are built with EVENTS_STYLE == EVENTS_STYLE_SELECT.
+  */
+#if (EVENTS_STYLE == EVENTS_STYLE_EPOLL)
+#include <sys/epoll.h>
+
+ /*
+  * Macros to initialize the kernel-based filter; see event_init().
+  */
+static int event_epollfd;		/* epoll handle */
+
+#define EVENT_REG_INIT_HANDLE(er, n) do { \
+	er = event_epollfd = epoll_create(n); \
+	if (event_epollfd >= 0) close_on_exec(event_epollfd, CLOSE_ON_EXEC); \
+    } while (0)
+#define EVENT_REG_INIT_TEXT	"epoll_create"
+
+#define EVENT_REG_FORK_HANDLE(er, n) do { \
+	(void) close(event_epollfd); \
+	EVENT_REG_INIT_HANDLE(er, (n)); \
+    } while (0)
+
+ /*
+  * Macros to update the kernel-based filter; see event_enable_read(),
+  * event_enable_write() and event_disable_readwrite().
+  */
+#define EVENT_REG_FD_OP(er, fh, ev, op) do { \
+	struct epoll_event dummy; \
+	dummy.events = (ev); \
+	dummy.data.fd = (fh); \
+	(er) = epoll_ctl(event_epollfd, (op), (fh), &dummy); \
+    } while (0)
+
+#define EVENT_REG_ADD_OP(e, f, ev) EVENT_REG_FD_OP((e), (f), (ev), EPOLL_CTL_ADD)
+#define EVENT_REG_ADD_READ(e, f)   EVENT_REG_ADD_OP((e), (f), EPOLLIN)
+#define EVENT_REG_ADD_WRITE(e, f)  EVENT_REG_ADD_OP((e), (f), EPOLLOUT)
+#define EVENT_REG_ADD_TEXT         "epoll_ctl EPOLL_CTL_ADD"
+
+#define EVENT_REG_DEL_OP(e, f, ev) EVENT_REG_FD_OP((e), (f), (ev), EPOLL_CTL_DEL)
+#define EVENT_REG_DEL_READ(e, f)   EVENT_REG_DEL_OP((e), (f), EPOLLIN)
+#define EVENT_REG_DEL_WRITE(e, f)  EVENT_REG_DEL_OP((e), (f), EPOLLOUT)
+#define EVENT_REG_DEL_TEXT         "epoll_ctl EPOLL_CTL_DEL"
+
+ /*
+  * Macros to retrieve event buffers from the kernel; see event_loop().
+  */
+typedef struct epoll_event EVENT_BUFFER;
+
+#define EVENT_BUFFER_READ(event_count, event_buf, buflen, delay) do { \
+	(event_count) = epoll_wait(event_epollfd, (event_buf), (buflen), \
+				  (delay) < 0 ? -1 : (delay) * 1000); \
+    } while (0)
+#define EVENT_BUFFER_READ_TEXT	"epoll_wait"
+
+ /*
+  * Macros to process event buffers from the kernel; see event_loop().
+  */
+#define EVENT_GET_FD(bp)	((bp)->data.fd)
+#define EVENT_GET_TYPE(bp)	((bp)->events)
+#define EVENT_TEST_READ(bp)	(EVENT_GET_TYPE(bp) & EPOLLIN)
+#define EVENT_TEST_WRITE(bp)	(EVENT_GET_TYPE(bp) & EPOLLOUT)
+
+#endif
+
+ /*
+  * Timer events. Timer requests are kept sorted, in a circular list. We use
+  * the RING abstraction, so we get to use a couple ugly macros.
+  * 
+  * When a call-back function adds a timer request, we label the request with
+  * the event_loop() call instance that invoked the call-back. We use this to
+  * prevent zero-delay timer requests from running in a tight loop and
+  * starving I/O events.
+  */
+typedef struct EVENT_TIMER EVENT_TIMER;
+
+struct EVENT_TIMER {
+    time_t  when;			/* when event is wanted */
+    EVENT_NOTIFY_TIME_FN callback;	/* callback function */
+    char   *context;			/* callback context */
+    long    loop_instance;		/* event_loop() call instance */
+    RING    ring;			/* linkage */
+};
+
+static RING event_timer_head;		/* timer queue head */
+static long event_loop_instance;	/* event_loop() call instance */
+
+#define RING_TO_TIMER(r) \
+	((EVENT_TIMER *) ((void *) (r) - offsetof(EVENT_TIMER, ring)))
+
+#define FOREACH_QUEUE_ENTRY(entry, head) \
+	for (entry = ring_succ(head); entry != (head); entry = ring_succ(entry))
+
+#define FIRST_TIMER(head) \
+	(ring_succ(head) != (head) ? RING_TO_TIMER(ring_succ(head)) : 0)
+
+ /*
+  * Other private data structures.
+  */
+static time_t event_present;		/* cached time of day */
+
+#define EVENT_INIT_NEEDED()	(event_present == 0)
+
+/* event_init - set up tables and such */
+
+static void event_init(void)
+{
+    EVENT_FDTABLE *fdp;
+    int     err;
+
+    if (!EVENT_INIT_NEEDED())
+	msg_panic("event_init: repeated call");
+
+    /*
+     * Initialize the file descriptor masks and the call-back table. Where
+     * possible we extend these data structures on the fly. With select(2)
+     * based implementations we can only handle FD_SETSIZE open files.
+     */
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+    if ((event_fdlimit = open_limit(FD_SETSIZE)) < 0)
+	msg_fatal("unable to determine open file limit");
+#else
+    if ((event_fdlimit = open_limit(INT_MAX)) < 0)
+	msg_fatal("unable to determine open file limit");
+#endif
+    if (event_fdlimit < FD_SETSIZE / 2 && event_fdlimit < 256)
+	msg_warn("could allocate space for only %d open files", event_fdlimit);
+    event_fdslots = EVENT_ALLOC_INCR;
+    event_fdtable = (EVENT_FDTABLE *)
+	mymalloc(sizeof(EVENT_FDTABLE) * event_fdslots);
+    for (fdp = event_fdtable; fdp < event_fdtable + event_fdslots; fdp++) {
+	fdp->callback = 0;
+	fdp->context = 0;
+    }
+
+    /*
+     * Initialize the I/O event request masks.
+     */
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+    EVENT_MASK_ZERO(&event_rmask);
+    EVENT_MASK_ZERO(&event_wmask);
+    EVENT_MASK_ZERO(&event_xmask);
+#else
+    EVENT_MASK_ALLOC(&event_rmask, event_fdslots);
+    EVENT_MASK_ALLOC(&event_wmask, event_fdslots);
+    EVENT_MASK_ALLOC(&event_xmask, event_fdslots);
+
+    /*
+     * Initialize the kernel-based filter.
+     */
+    EVENT_REG_INIT_HANDLE(err, event_fdslots);
+    if (err < 0)
+	msg_fatal("%s: %m", EVENT_REG_INIT_TEXT);
+#endif
+
+    /*
+     * Initialize timer stuff.
+     */
+    ring_init(&event_timer_head);
+    (void) time(&event_present);
+
+    /*
+     * Avoid an infinite initialization loop.
+     */
+    if (EVENT_INIT_NEEDED())
+	msg_panic("event_init: unable to initialize");
+}
+
+/* event_extend - make room for more descriptor slots */
+
+static void event_extend(int fd)
+{
+    const char *myname = "event_extend";
+    int     old_slots = event_fdslots;
+    int     new_slots = (event_fdslots > fd / 2 ?
+			 2 * old_slots : fd + EVENT_ALLOC_INCR);
+    EVENT_FDTABLE *fdp;
+
+#ifdef EVENT_REG_UPD_HANDLE
+    int     err;
+
+#endif
+
+    if (msg_verbose > 2)
+	msg_info("%s: fd %d", myname, fd);
+    event_fdtable = (EVENT_FDTABLE *)
+	myrealloc((void *) event_fdtable, sizeof(EVENT_FDTABLE) * new_slots);
+    event_fdslots = new_slots;
+    for (fdp = event_fdtable + old_slots;
+	 fdp < event_fdtable + new_slots; fdp++) {
+	fdp->callback = 0;
+	fdp->context = 0;
+    }
+
+    /*
+     * Initialize the I/O event request masks.
+     */
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+    EVENT_MASK_REALLOC(&event_rmask, new_slots);
+    EVENT_MASK_REALLOC(&event_wmask, new_slots);
+    EVENT_MASK_REALLOC(&event_xmask, new_slots);
+#endif
+#ifdef EVENT_REG_UPD_HANDLE
+    EVENT_REG_UPD_HANDLE(err, new_slots);
+    if (err < 0)
+	msg_fatal("%s: %s: %m", myname, EVENT_REG_UPD_TEXT);
+#endif
+}
+
+/* event_time - look up cached time of day */
+
+time_t  event_time(void)
+{
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    return (event_present);
+}
+
+/* event_drain - loop until all pending events are done */
+
+void    event_drain(int time_limit)
+{
+    EVENT_MASK zero_mask;
+    time_t  max_time;
+
+    if (EVENT_INIT_NEEDED())
+	return;
+
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+    EVENT_MASK_ZERO(&zero_mask);
+#else
+    EVENT_MASK_ALLOC(&zero_mask, event_fdslots);
+#endif
+    (void) time(&event_present);
+    max_time = event_present + time_limit;
+    while (event_present < max_time
+	   && (event_timer_head.pred != &event_timer_head
+	       || EVENT_MASK_CMP(&zero_mask, &event_xmask) != 0)) {
+	event_loop(1);
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+	if (EVENT_MASK_BYTE_COUNT(&zero_mask)
+	    != EVENT_MASK_BYTES_NEEDED(event_fdslots))
+	    EVENT_MASK_REALLOC(&zero_mask, event_fdslots);
+#endif
+    }
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+    EVENT_MASK_FREE(&zero_mask);
+#endif
+}
+
+/* event_fork - resume event processing after fork() */
+
+void    event_fork(void)
+{
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+    EVENT_FDTABLE *fdp;
+    int     err;
+    int     fd;
+
+    /*
+     * No event was ever registered, so there's nothing to be done.
+     */
+    if (EVENT_INIT_NEEDED())
+	return;
+
+    /*
+     * Close the existing filter handle and open a new kernel-based filter.
+     */
+    EVENT_REG_FORK_HANDLE(err, event_fdslots);
+    if (err < 0)
+	msg_fatal("%s: %m", EVENT_REG_INIT_TEXT);
+
+    /*
+     * Populate the new kernel-based filter with events that were registered
+     * in the parent process.
+     */
+    for (fd = 0; fd <= event_max_fd; fd++) {
+	if (EVENT_MASK_ISSET(fd, &event_wmask)) {
+	    EVENT_MASK_CLR(fd, &event_wmask);
+	    fdp = event_fdtable + fd;
+	    event_enable_write(fd, fdp->callback, fdp->context);
+	} else if (EVENT_MASK_ISSET(fd, &event_rmask)) {
+	    EVENT_MASK_CLR(fd, &event_rmask);
+	    fdp = event_fdtable + fd;
+	    event_enable_read(fd, fdp->callback, fdp->context);
+	}
+    }
+#endif
+}
+
+/* event_enable_read - enable read events */
+
+void    event_enable_read(int fd, EVENT_NOTIFY_RDWR_FN callback, void *context)
+{
+    const char *myname = "event_enable_read";
+    EVENT_FDTABLE *fdp;
+    int     err;
+
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    /*
+     * Sanity checks.
+     */
+    if (fd < 0 || fd >= event_fdlimit)
+	msg_panic("%s: bad file descriptor: %d", myname, fd);
+
+    if (msg_verbose > 2)
+	msg_info("%s: fd %d", myname, fd);
+
+    if (fd >= event_fdslots)
+	event_extend(fd);
+
+    /*
+     * Disallow mixed (i.e. read and write) requests on the same descriptor.
+     */
+    if (EVENT_MASK_ISSET(fd, &event_wmask))
+	msg_panic("%s: fd %d: read/write I/O request", myname, fd);
+
+    /*
+     * Postfix 2.4 allows multiple event_enable_read() calls on the same
+     * descriptor without requiring event_disable_readwrite() calls between
+     * them. With kernel-based filters (kqueue, /dev/poll, epoll) it's
+     * wasteful to make system calls when we change only application
+     * call-back information. It has a noticeable effect on smtp-source
+     * performance.
+     */
+    if (EVENT_MASK_ISSET(fd, &event_rmask) == 0) {
+	EVENT_MASK_SET(fd, &event_xmask);
+	EVENT_MASK_SET(fd, &event_rmask);
+	if (event_max_fd < fd)
+	    event_max_fd = fd;
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+	EVENT_REG_ADD_READ(err, fd);
+	if (err < 0)
+	    msg_fatal("%s: %s: %m", myname, EVENT_REG_ADD_TEXT);
+#endif
+    }
+    fdp = event_fdtable + fd;
+    if (fdp->callback != callback || fdp->context != context) {
+	fdp->callback = callback;
+	fdp->context = context;
+    }
+}
+
+/* event_enable_write - enable write events */
+
+void    event_enable_write(int fd, EVENT_NOTIFY_RDWR_FN callback, void *context)
+{
+    const char *myname = "event_enable_write";
+    EVENT_FDTABLE *fdp;
+    int     err;
+
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    /*
+     * Sanity checks.
+     */
+    if (fd < 0 || fd >= event_fdlimit)
+	msg_panic("%s: bad file descriptor: %d", myname, fd);
+
+    if (msg_verbose > 2)
+	msg_info("%s: fd %d", myname, fd);
+
+    if (fd >= event_fdslots)
+	event_extend(fd);
+
+    /*
+     * Disallow mixed (i.e. read and write) requests on the same descriptor.
+     */
+    if (EVENT_MASK_ISSET(fd, &event_rmask))
+	msg_panic("%s: fd %d: read/write I/O request", myname, fd);
+
+    /*
+     * Postfix 2.4 allows multiple event_enable_write() calls on the same
+     * descriptor without requiring event_disable_readwrite() calls between
+     * them. With kernel-based filters (kqueue, /dev/poll, epoll) it's
+     * incredibly wasteful to make unregister and register system calls when
+     * we change only application call-back information. It has a noticeable
+     * effect on smtp-source performance.
+     */
+    if (EVENT_MASK_ISSET(fd, &event_wmask) == 0) {
+	EVENT_MASK_SET(fd, &event_xmask);
+	EVENT_MASK_SET(fd, &event_wmask);
+	if (event_max_fd < fd)
+	    event_max_fd = fd;
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+	EVENT_REG_ADD_WRITE(err, fd);
+	if (err < 0)
+	    msg_fatal("%s: %s: %m", myname, EVENT_REG_ADD_TEXT);
+#endif
+    }
+    fdp = event_fdtable + fd;
+    if (fdp->callback != callback || fdp->context != context) {
+	fdp->callback = callback;
+	fdp->context = context;
+    }
+}
+
+/* event_disable_readwrite - disable request for read or write events */
+
+void    event_disable_readwrite(int fd)
+{
+    const char *myname = "event_disable_readwrite";
+    EVENT_FDTABLE *fdp;
+    int     err;
+
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    /*
+     * Sanity checks.
+     */
+    if (fd < 0 || fd >= event_fdlimit)
+	msg_panic("%s: bad file descriptor: %d", myname, fd);
+
+    if (msg_verbose > 2)
+	msg_info("%s: fd %d", myname, fd);
+
+    /*
+     * Don't complain when there is nothing to cancel. The request may have
+     * been canceled from another thread.
+     */
+    if (fd >= event_fdslots)
+	return;
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT)
+#ifdef EVENT_REG_DEL_BOTH
+    /* XXX Can't seem to disable READ and WRITE events selectively. */
+    if (EVENT_MASK_ISSET(fd, &event_rmask)
+	|| EVENT_MASK_ISSET(fd, &event_wmask)) {
+	EVENT_REG_DEL_BOTH(err, fd);
+	if (err < 0)
+	    msg_fatal("%s: %s: %m", myname, EVENT_REG_DEL_TEXT);
+    }
+#else
+    if (EVENT_MASK_ISSET(fd, &event_rmask)) {
+	EVENT_REG_DEL_READ(err, fd);
+	if (err < 0)
+	    msg_fatal("%s: %s: %m", myname, EVENT_REG_DEL_TEXT);
+    } else if (EVENT_MASK_ISSET(fd, &event_wmask)) {
+	EVENT_REG_DEL_WRITE(err, fd);
+	if (err < 0)
+	    msg_fatal("%s: %s: %m", myname, EVENT_REG_DEL_TEXT);
+    }
+#endif						/* EVENT_REG_DEL_BOTH */
+#endif						/* != EVENTS_STYLE_SELECT */
+    EVENT_MASK_CLR(fd, &event_xmask);
+    EVENT_MASK_CLR(fd, &event_rmask);
+    EVENT_MASK_CLR(fd, &event_wmask);
+    fdp = event_fdtable + fd;
+    fdp->callback = 0;
+    fdp->context = 0;
+}
+
+/* event_request_timer - (re)set timer */
+
+time_t  event_request_timer(EVENT_NOTIFY_TIME_FN callback, void *context, int delay)
+{
+    const char *myname = "event_request_timer";
+    RING   *ring;
+    EVENT_TIMER *timer;
+
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    /*
+     * Sanity checks.
+     */
+    if (delay < 0)
+	msg_panic("%s: invalid delay: %d", myname, delay);
+
+    /*
+     * Make sure we schedule this event at the right time.
+     */
+    time(&event_present);
+
+    /*
+     * See if they are resetting an existing timer request. If so, take the
+     * request away from the timer queue so that it can be inserted at the
+     * right place.
+     */
+    FOREACH_QUEUE_ENTRY(ring, &event_timer_head) {
+	timer = RING_TO_TIMER(ring);
+	if (timer->callback == callback && timer->context == context) {
+	    timer->when = event_present + delay;
+	    timer->loop_instance = event_loop_instance;
+	    ring_detach(ring);
+	    if (msg_verbose > 2)
+		msg_info("%s: reset 0x%lx 0x%lx %d", myname,
+			 (long) callback, (long) context, delay);
+	    break;
+	}
+    }
+
+    /*
+     * If not found, schedule a new timer request.
+     */
+    if (ring == &event_timer_head) {
+	timer = (EVENT_TIMER *) mymalloc(sizeof(EVENT_TIMER));
+	timer->when = event_present + delay;
+	timer->callback = callback;
+	timer->context = context;
+	timer->loop_instance = event_loop_instance;
+	if (msg_verbose > 2)
+	    msg_info("%s: set 0x%lx 0x%lx %d", myname,
+		     (long) callback, (long) context, delay);
+    }
+
+    /*
+     * Timer requests are kept sorted to reduce lookup overhead in the event
+     * loop.
+     * 
+     * XXX Append the new request after existing requests for the same time
+     * slot. The event_loop() routine depends on this to avoid starving I/O
+     * events when a call-back function schedules a zero-delay timer request.
+     */
+    FOREACH_QUEUE_ENTRY(ring, &event_timer_head) {
+	if (timer->when < RING_TO_TIMER(ring)->when)
+	    break;
+    }
+    ring_prepend(ring, &timer->ring);
+
+    return (timer->when);
+}
+
+/* event_cancel_timer - cancel timer */
+
+int     event_cancel_timer(EVENT_NOTIFY_TIME_FN callback, void *context)
+{
+    const char *myname = "event_cancel_timer";
+    RING   *ring;
+    EVENT_TIMER *timer;
+    int     time_left = -1;
+
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    /*
+     * See if they are canceling an existing timer request. Do not complain
+     * when the request is not found. It might have been canceled from some
+     * other thread.
+     */
+    FOREACH_QUEUE_ENTRY(ring, &event_timer_head) {
+	timer = RING_TO_TIMER(ring);
+	if (timer->callback == callback && timer->context == context) {
+	    if ((time_left = timer->when - event_present) < 0)
+		time_left = 0;
+	    ring_detach(ring);
+	    myfree((void *) timer);
+	    break;
+	}
+    }
+    if (msg_verbose > 2)
+	msg_info("%s: 0x%lx 0x%lx %d", myname,
+		 (long) callback, (long) context, time_left);
+    return (time_left);
+}
+
+/* event_loop - wait for the next event */
+
+void    event_loop(int delay)
+{
+    const char *myname = "event_loop";
+    static int nested;
+
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+    fd_set  rmask;
+    fd_set  wmask;
+    fd_set  xmask;
+    struct timeval tv;
+    struct timeval *tvp;
+    int     new_max_fd;
+
+#else
+    EVENT_BUFFER event_buf[100];
+    EVENT_BUFFER *bp;
+
+#endif
+    int     event_count;
+    EVENT_TIMER *timer;
+    int     fd;
+    EVENT_FDTABLE *fdp;
+    int     select_delay;
+
+    if (EVENT_INIT_NEEDED())
+	event_init();
+
+    /*
+     * XXX Also print the select() masks?
+     */
+    if (msg_verbose > 2) {
+	RING   *ring;
+
+	FOREACH_QUEUE_ENTRY(ring, &event_timer_head) {
+	    timer = RING_TO_TIMER(ring);
+	    msg_info("%s: time left %3d for 0x%lx 0x%lx", myname,
+		     (int) (timer->when - event_present),
+		     (long) timer->callback, (long) timer->context);
+	}
+    }
+
+    /*
+     * Find out when the next timer would go off. Timer requests are sorted.
+     * If any timer is scheduled, adjust the delay appropriately.
+     */
+    if ((timer = FIRST_TIMER(&event_timer_head)) != 0) {
+	event_present = time((time_t *) 0);
+	if ((select_delay = timer->when - event_present) < 0) {
+	    select_delay = 0;
+	} else if (delay >= 0 && select_delay > delay) {
+	    select_delay = delay;
+	}
+    } else {
+	select_delay = delay;
+    }
+    if (msg_verbose > 2)
+	msg_info("event_loop: select_delay %d", select_delay);
+
+    /*
+     * Negative delay means: wait until something happens. Zero delay means:
+     * poll. Positive delay means: wait at most this long.
+     */
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+    if (select_delay < 0) {
+	tvp = 0;
+    } else {
+	tvp = &tv;
+	tv.tv_usec = 0;
+	tv.tv_sec = select_delay;
+    }
+
+    /*
+     * Pause until the next event happens. When select() has a problem, don't
+     * go into a tight loop. Allow select() to be interrupted due to the
+     * arrival of a signal.
+     */
+    rmask = event_rmask;
+    wmask = event_wmask;
+    xmask = event_xmask;
+
+    event_count = select(event_max_fd + 1, &rmask, &wmask, &xmask, tvp);
+    if (event_count < 0) {
+	if (errno != EINTR)
+	    msg_fatal("event_loop: select: %m");
+	return;
+    }
+#else
+    EVENT_BUFFER_READ(event_count, event_buf,
+		      sizeof(event_buf) / sizeof(event_buf[0]),
+		      select_delay);
+    if (event_count < 0) {
+	if (errno != EINTR)
+	    msg_fatal("event_loop: " EVENT_BUFFER_READ_TEXT ": %m");
+	return;
+    }
+#endif
+
+    /*
+     * Before entering the application call-back routines, make sure we
+     * aren't being called from a call-back routine. Doing so would make us
+     * vulnerable to all kinds of race conditions.
+     */
+    if (nested++ > 0)
+	msg_panic("event_loop: recursive call");
+
+    /*
+     * Deliver timer events. Allow the application to add/delete timer queue
+     * requests while it is being called back. Requests are sorted: we keep
+     * running over the timer request queue from the start, and stop when we
+     * reach the future or the list end. We also stop when we reach a timer
+     * request that was added by a call-back that was invoked from this
+     * event_loop() call instance, for reasons that are explained below.
+     * 
+     * To avoid dangling pointer problems 1) we must remove a request from the
+     * timer queue before delivering its event to the application and 2) we
+     * must look up the next timer request *after* calling the application.
+     * The latter complicates the handling of zero-delay timer requests that
+     * are added by event_loop() call-back functions.
+     * 
+     * XXX When a timer event call-back function adds a new timer request,
+     * event_request_timer() labels the request with the event_loop() call
+     * instance that invoked the timer event call-back. We use this instance
+     * label here to prevent zero-delay timer requests from running in a
+     * tight loop and starving I/O events. To make this solution work,
+     * event_request_timer() appends a new request after existing requests
+     * for the same time slot.
+     */
+    event_present = time((time_t *) 0);
+    event_loop_instance += 1;
+
+    while ((timer = FIRST_TIMER(&event_timer_head)) != 0) {
+	if (timer->when > event_present)
+	    break;
+	if (timer->loop_instance == event_loop_instance)
+	    break;
+	ring_detach(&timer->ring);		/* first this */
+	if (msg_verbose > 2)
+	    msg_info("%s: timer 0x%lx 0x%lx", myname,
+		     (long) timer->callback, (long) timer->context);
+	timer->callback(EVENT_TIME, timer->context);	/* then this */
+	myfree((void *) timer);
+    }
+
+    /*
+     * Deliver I/O events. Allow the application to cancel event requests
+     * while it is being called back. To this end, we keep an eye on the
+     * contents of event_xmask, so that we deliver only events that are still
+     * wanted. We do not change the event request masks. It is up to the
+     * application to determine when a read or write is complete.
+     */
+#if (EVENTS_STYLE == EVENTS_STYLE_SELECT)
+    if (event_count > 0) {
+	for (new_max_fd = 0, fd = 0; fd <= event_max_fd; fd++) {
+	    if (FD_ISSET(fd, &event_xmask)) {
+		new_max_fd = fd;
+		/* In case event_fdtable is updated. */
+		fdp = event_fdtable + fd;
+		if (FD_ISSET(fd, &xmask)) {
+		    if (msg_verbose > 2)
+			msg_info("%s: exception fd=%d act=0x%lx 0x%lx", myname,
+			     fd, (long) fdp->callback, (long) fdp->context);
+		    fdp->callback(EVENT_XCPT, fdp->context);
+		} else if (FD_ISSET(fd, &wmask)) {
+		    if (msg_verbose > 2)
+			msg_info("%s: write fd=%d act=0x%lx 0x%lx", myname,
+			     fd, (long) fdp->callback, (long) fdp->context);
+		    fdp->callback(EVENT_WRITE, fdp->context);
+		} else if (FD_ISSET(fd, &rmask)) {
+		    if (msg_verbose > 2)
+			msg_info("%s: read fd=%d act=0x%lx 0x%lx", myname,
+			     fd, (long) fdp->callback, (long) fdp->context);
+		    fdp->callback(EVENT_READ, fdp->context);
+		}
+	    }
+	}
+	event_max_fd = new_max_fd;
+    }
+#else
+    for (bp = event_buf; bp < event_buf + event_count; bp++) {
+	fd = EVENT_GET_FD(bp);
+	if (fd < 0 || fd > event_max_fd)
+	    msg_panic("%s: bad file descriptor: %d", myname, fd);
+	if (EVENT_MASK_ISSET(fd, &event_xmask)) {
+	    fdp = event_fdtable + fd;
+	    if (EVENT_TEST_READ(bp)) {
+		if (msg_verbose > 2)
+		    msg_info("%s: read fd=%d act=0x%lx 0x%lx", myname,
+			     fd, (long) fdp->callback, (long) fdp->context);
+		fdp->callback(EVENT_READ, fdp->context);
+	    } else if (EVENT_TEST_WRITE(bp)) {
+		if (msg_verbose > 2)
+		    msg_info("%s: write fd=%d act=0x%lx 0x%lx", myname,
+			     fd, (long) fdp->callback,
+			     (long) fdp->context);
+		fdp->callback(EVENT_WRITE, fdp->context);
+	    } else {
+		if (msg_verbose > 2)
+		    msg_info("%s: other fd=%d act=0x%lx 0x%lx", myname,
+			     fd, (long) fdp->callback, (long) fdp->context);
+		fdp->callback(EVENT_XCPT, fdp->context);
+	    }
+	}
+    }
+#endif
+    nested--;
+}
+
+#ifdef TEST
+
+ /*
+  * Proof-of-concept test program for the event manager. Schedule a series of
+  * events at one-second intervals and let them happen, while echoing any
+  * lines read from stdin.
+  */
+#include <stdio.h>
+#include <ctype.h>
+#include <stdlib.h>
+
+/* timer_event - display event */
+
+static void timer_event(int unused_event, void *context)
+{
+    printf("%ld: %s\n", (long) event_present, context);
+    fflush(stdout);
+}
+
+/* echo - echo text received on stdin */
+
+static void echo(int unused_event, void *unused_context)
+{
+    char    buf[BUFSIZ];
+
+    if (fgets(buf, sizeof(buf), stdin) == 0)
+	exit(0);
+    printf("Result: %s", buf);
+}
+
+/* request - request a bunch of timer events */
+
+static void request(int unused_event, void *unused_context)
+{
+    event_request_timer(timer_event, "3 first", 3);
+    event_request_timer(timer_event, "3 second", 3);
+    event_request_timer(timer_event, "4 first", 4);
+    event_request_timer(timer_event, "4 second", 4);
+    event_request_timer(timer_event, "2 first", 2);
+    event_request_timer(timer_event, "2 second", 2);
+    event_request_timer(timer_event, "1 first", 1);
+    event_request_timer(timer_event, "1 second", 1);
+    event_request_timer(timer_event, "0 first", 0);
+    event_request_timer(timer_event, "0 second", 0);
+}
+
+int     main(int argc, void **argv)
+{
+    if (argv[1])
+	msg_verbose = atoi(argv[1]);
+    event_request_timer(request, (void *) 0, 0);
+    event_enable_read(fileno(stdin), echo, (void *) 0);
+    event_drain(10);
+    exit(0);
+}
+
+#endif