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sad

sad (2f30.org simple audio daemon) with a Cygwin/OSS port on branch cygwin

git clone https://github.com/equwal/sad

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commit c541e89831fc9acdac8115454d2923f0fa820fdb
sin <sin@2f30.org>
2014-12-28 20:11:12 +0000

Add initial implementation of the notifier API

 Makefile |   3 +-
 PROTOCOL |   8 +
 cmd.c    |  16 ++
 notify.c | 107 +++++++++++
 queue.h  | 648 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 sad.c    |   8 +-
 sad.h    |  18 ++
 7 files changed, 805 insertions(+), 3 deletions(-)
diff --git a/Makefile b/Makefile
index bb16556..b778bfd 100644
--- a/Makefile
+++ b/Makefile
@@ -14,6 +14,7 @@ OBJ =\
 	fifo.o\
 	library.o\
 	mp3.o\
+	notify.o\
 	output.o\
 	playlist.o\
 	sad.o\
@@ -35,7 +36,7 @@ all: $(BIN)
 $(BIN): $(OBJ)
 	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(OBJ) $(LDLIBS)
 
-$(OBJ): arg.h compat.h config.h sad.h
+$(OBJ): arg.h compat.h config.h queue.h sad.h
 
 install: all
 	mkdir -p $(DESTDIR)$(PREFIX)/bin
diff --git a/PROTOCOL b/PROTOCOL
index 86cd034..06c5652 100644
--- a/PROTOCOL
+++ b/PROTOCOL
@@ -101,3 +101,11 @@ Possible states:
 	volume: 0-100
 	elapsed: total time elapsed within current song in seconds
 	duration: total song duration in seconds
+
+wait event-name
+Subscribe to the provided event.  When the event triggers, a reply will
+be sent back to the client.  The reply has the form:
+"event: %s\n", eventname
+
+Events are not queued.  It is not an error to wait on the same event
+more than once, however, be prepared to receive a single event reply.
diff --git a/cmd.c b/cmd.c
index 923c661..b108150 100644
--- a/cmd.c
+++ b/cmd.c
@@ -342,6 +342,21 @@ cmddisable(int fd, char *arg)
 	dprintf(fd, "OK\n");
 }
 
+static void
+cmdwait(int fd, char *arg)
+{
+	if (!arg[0]) {
+		dprintf(fd, "ERR expected event name\n");
+		return;
+	}
+
+	if (addsubscribername(fd, arg) < 0) {
+		dprintf(fd, "ERR unknown event type\n");
+		return;
+	}
+	dprintf(fd, "OK\n");
+}
+
 static Cmd cmds[] = {
 	{ "status",     cmdstatus     },
 	{ "volume",     cmdvolume     },
@@ -364,6 +379,7 @@ static Cmd cmds[] = {
 	{ "version",    cmdversion    },
 	{ "enable",     cmdenable     },
 	{ "disable",    cmddisable    },
+	{ "wait",       cmdwait       },
 };
 
 /* shamelessly taken from isakmpd ui.c */
diff --git a/notify.c b/notify.c
new file mode 100644
index 0000000..46f795c
--- /dev/null
+++ b/notify.c
@@ -0,0 +1,107 @@
+#include <sys/select.h>
+
+#include <err.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "queue.h"
+#include "sad.h"
+
+Eventdesc Eventmap[] = {
+	{ EVSONGFINISHED, "songfinished" },
+};
+
+struct subscriber {
+	int clifd;
+	int event;
+	TAILQ_ENTRY(subscriber) entry;
+};
+
+static TAILQ_HEAD(subscribers, subscriber) subscribers;
+
+int
+initnotifier(void)
+{
+	TAILQ_INIT(&subscribers);
+}
+
+int
+addsubscriber(int clifd, int event)
+{
+	struct subscriber *s;
+	int    i;
+
+	for (i = 0; i < LEN(Eventmap); i++)
+		if (Eventmap[i].event == event)
+			break;
+	if (i == LEN(Eventmap))
+		return -1;
+
+	TAILQ_FOREACH(s, &subscribers, entry)
+		if (s->clifd == clifd &&
+		    s->event == event)
+			return 0; /* do not queue events */
+
+	s = malloc(sizeof(*s));
+	if (!s)
+		err(1, "malloc");
+
+	s->clifd = clifd;
+	s->event = event;
+	TAILQ_INSERT_TAIL(&subscribers, s, entry);
+
+	return 0;
+}
+
+int
+addsubscribername(int clifd, const char *name)
+{
+	int i;
+
+	for (i = 0; i < LEN(Eventmap); i++)
+		if (!strcmp(Eventmap[i].name, name))
+			return addsubscriber(clifd, Eventmap[i].event);
+	return -1;
+}
+
+int
+notify(int event)
+{
+	struct subscriber *s, *tmp;
+	int    i;
+
+	for (i = 0; i < LEN(Eventmap); i++)
+		if (Eventmap[i].event == event)
+			break;
+	if (i == LEN(Eventmap))
+		return -1;
+
+	TAILQ_FOREACH_SAFE(s, &subscribers, entry, tmp) {
+		if (s->event != event)
+			continue;
+		for (i = 0; i < LEN(Eventmap); i++) {
+			if (Eventmap[i].event == s->event) {
+				dprintf(s->clifd, "event: %s\n", Eventmap[i].name);
+				dprintf(s->clifd, "OK\n");
+				TAILQ_REMOVE(&subscribers, s, entry);
+				free(s);
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+void
+removesubscriber(int clifd)
+{
+	struct subscriber *s, *tmp;
+
+	TAILQ_FOREACH_SAFE(s, &subscribers, entry, tmp) {
+		if (s->clifd == clifd) {
+			TAILQ_REMOVE(&subscribers, s, entry);
+			free(s);
+		}
+	}
+}
diff --git a/queue.h b/queue.h
new file mode 100644
index 0000000..f8f09bf
--- /dev/null
+++ b/queue.h
@@ -0,0 +1,648 @@
+/*	$OpenBSD: queue.h,v 1.38 2013/07/03 15:05:21 fgsch Exp $	*/
+/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/
+
+/*
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)queue.h	8.5 (Berkeley) 8/20/94
+ */
+
+#ifndef	_SYS_QUEUE_H_
+#define	_SYS_QUEUE_H_
+
+/*
+ * This file defines five types of data structures: singly-linked lists, 
+ * lists, simple queues, tail queues, and circular queues.
+ *
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction.  Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * A circle queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or after
+ * an existing element, at the head of the list, or at the end of the list.
+ * A circle queue may be traversed in either direction, but has a more
+ * complex end of list detection.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
+#define _Q_INVALIDATE(a) (a) = ((void *)-1)
+#else
+#define _Q_INVALIDATE(a)
+#endif
+
+/*
+ * Singly-linked List definitions.
+ */
+#define SLIST_HEAD(name, type)						\
+struct name {								\
+	struct type *slh_first;	/* first element */			\
+}
+ 
+#define	SLIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+ 
+#define SLIST_ENTRY(type)						\
+struct {								\
+	struct type *sle_next;	/* next element */			\
+}
+ 
+/*
+ * Singly-linked List access methods.
+ */
+#define	SLIST_FIRST(head)	((head)->slh_first)
+#define	SLIST_END(head)		NULL
+#define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
+#define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)
+
+#define	SLIST_FOREACH(var, head, field)					\
+	for((var) = SLIST_FIRST(head);					\
+	    (var) != SLIST_END(head);					\
+	    (var) = SLIST_NEXT(var, field))
+
+#define	SLIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SLIST_FIRST(head);				\
+	    (var) && ((tvar) = SLIST_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Singly-linked List functions.
+ */
+#define	SLIST_INIT(head) {						\
+	SLIST_FIRST(head) = SLIST_END(head);				\
+}
+
+#define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
+	(elm)->field.sle_next = (slistelm)->field.sle_next;		\
+	(slistelm)->field.sle_next = (elm);				\
+} while (0)
+
+#define	SLIST_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.sle_next = (head)->slh_first;			\
+	(head)->slh_first = (elm);					\
+} while (0)
+
+#define	SLIST_REMOVE_AFTER(elm, field) do {				\
+	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
+} while (0)
+
+#define	SLIST_REMOVE_HEAD(head, field) do {				\
+	(head)->slh_first = (head)->slh_first->field.sle_next;		\
+} while (0)
+
+#define SLIST_REMOVE(head, elm, type, field) do {			\
+	if ((head)->slh_first == (elm)) {				\
+		SLIST_REMOVE_HEAD((head), field);			\
+	} else {							\
+		struct type *curelm = (head)->slh_first;		\
+									\
+		while (curelm->field.sle_next != (elm))			\
+			curelm = curelm->field.sle_next;		\
+		curelm->field.sle_next =				\
+		    curelm->field.sle_next->field.sle_next;		\
+		_Q_INVALIDATE((elm)->field.sle_next);			\
+	}								\
+} while (0)
+
+/*
+ * List definitions.
+ */
+#define LIST_HEAD(name, type)						\
+struct name {								\
+	struct type *lh_first;	/* first element */			\
+}
+
+#define LIST_HEAD_INITIALIZER(head)					\
+	{ NULL }
+
+#define LIST_ENTRY(type)						\
+struct {								\
+	struct type *le_next;	/* next element */			\
+	struct type **le_prev;	/* address of previous next element */	\
+}
+
+/*
+ * List access methods
+ */
+#define	LIST_FIRST(head)		((head)->lh_first)
+#define	LIST_END(head)			NULL
+#define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
+#define	LIST_NEXT(elm, field)		((elm)->field.le_next)
+
+#define LIST_FOREACH(var, head, field)					\
+	for((var) = LIST_FIRST(head);					\
+	    (var)!= LIST_END(head);					\
+	    (var) = LIST_NEXT(var, field))
+
+#define	LIST_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = LIST_FIRST(head);				\
+	    (var) && ((tvar) = LIST_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * List functions.
+ */
+#define	LIST_INIT(head) do {						\
+	LIST_FIRST(head) = LIST_END(head);				\
+} while (0)
+
+#define LIST_INSERT_AFTER(listelm, elm, field) do {			\
+	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
+		(listelm)->field.le_next->field.le_prev =		\
+		    &(elm)->field.le_next;				\
+	(listelm)->field.le_next = (elm);				\
+	(elm)->field.le_prev = &(listelm)->field.le_next;		\
+} while (0)
+
+#define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.le_prev = (listelm)->field.le_prev;		\
+	(elm)->field.le_next = (listelm);				\
+	*(listelm)->field.le_prev = (elm);				\
+	(listelm)->field.le_prev = &(elm)->field.le_next;		\
+} while (0)
+
+#define LIST_INSERT_HEAD(head, elm, field) do {				\
+	if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
+		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
+	(head)->lh_first = (elm);					\
+	(elm)->field.le_prev = &(head)->lh_first;			\
+} while (0)
+
+#define LIST_REMOVE(elm, field) do {					\
+	if ((elm)->field.le_next != NULL)				\
+		(elm)->field.le_next->field.le_prev =			\
+		    (elm)->field.le_prev;				\
+	*(elm)->field.le_prev = (elm)->field.le_next;			\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+#define LIST_REPLACE(elm, elm2, field) do {				\
+	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
+		(elm2)->field.le_next->field.le_prev =			\
+		    &(elm2)->field.le_next;				\
+	(elm2)->field.le_prev = (elm)->field.le_prev;			\
+	*(elm2)->field.le_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.le_prev);				\
+	_Q_INVALIDATE((elm)->field.le_next);				\
+} while (0)
+
+/*
+ * Simple queue definitions.
+ */
+#define SIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqh_first;	/* first element */			\
+	struct type **sqh_last;	/* addr of last next element */		\
+}
+
+#define SIMPLEQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).sqh_first }
+
+#define SIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqe_next;	/* next element */			\
+}
+
+/*
+ * Simple queue access methods.
+ */
+#define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
+#define	SIMPLEQ_END(head)	    NULL
+#define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
+#define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
+
+#define SIMPLEQ_FOREACH(var, head, field)				\
+	for((var) = SIMPLEQ_FIRST(head);				\
+	    (var) != SIMPLEQ_END(head);					\
+	    (var) = SIMPLEQ_NEXT(var, field))
+
+#define	SIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = SIMPLEQ_FIRST(head);				\
+	    (var) && ((tvar) = SIMPLEQ_NEXT(var, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Simple queue functions.
+ */
+#define	SIMPLEQ_INIT(head) do {						\
+	(head)->sqh_first = NULL;					\
+	(head)->sqh_last = &(head)->sqh_first;				\
+} while (0)
+
+#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(head)->sqh_first = (elm);					\
+} while (0)
+
+#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqe_next = NULL;					\
+	*(head)->sqh_last = (elm);					\
+	(head)->sqh_last = &(elm)->field.sqe_next;			\
+} while (0)
+
+#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+	(listelm)->field.sqe_next = (elm);				\
+} while (0)
+
+#define SIMPLEQ_REMOVE_HEAD(head, field) do {			\
+	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
+		(head)->sqh_last = &(head)->sqh_first;			\
+} while (0)
+
+#define SIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
+	if (((elm)->field.sqe_next = (elm)->field.sqe_next->field.sqe_next) \
+	    == NULL)							\
+		(head)->sqh_last = &(elm)->field.sqe_next;		\
+} while (0)
+
+/*
+ * XOR Simple queue definitions.
+ */
+#define XSIMPLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *sqx_first;	/* first element */			\
+	struct type **sqx_last;	/* addr of last next element */		\
+	unsigned long sqx_cookie;					\
+}
+
+#define XSIMPLEQ_ENTRY(type)						\
+struct {								\
+	struct type *sqx_next;	/* next element */			\
+}
+
+/*
+ * XOR Simple queue access methods.
+ */
+#define XSIMPLEQ_XOR(head, ptr)	    ((__typeof(ptr))((head)->sqx_cookie ^ \
+					(unsigned long)(ptr)))
+#define	XSIMPLEQ_FIRST(head)	    XSIMPLEQ_XOR(head, ((head)->sqx_first))
+#define	XSIMPLEQ_END(head)	    NULL
+#define	XSIMPLEQ_EMPTY(head)	    (XSIMPLEQ_FIRST(head) == XSIMPLEQ_END(head))
+#define	XSIMPLEQ_NEXT(head, elm, field)    XSIMPLEQ_XOR(head, ((elm)->field.sqx_next))
+
+
+#define XSIMPLEQ_FOREACH(var, head, field)				\
+	for ((var) = XSIMPLEQ_FIRST(head);				\
+	    (var) != XSIMPLEQ_END(head);				\
+	    (var) = XSIMPLEQ_NEXT(head, var, field))
+
+#define	XSIMPLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = XSIMPLEQ_FIRST(head);				\
+	    (var) && ((tvar) = XSIMPLEQ_NEXT(head, var, field), 1);	\
+	    (var) = (tvar))
+
+/*
+ * XOR Simple queue functions.
+ */
+#define	XSIMPLEQ_INIT(head) do {					\
+	arc4random_buf(&(head)->sqx_cookie, sizeof((head)->sqx_cookie)); \
+	(head)->sqx_first = XSIMPLEQ_XOR(head, NULL);			\
+	(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first);	\
+} while (0)
+
+#define XSIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.sqx_next = (head)->sqx_first) ==		\
+	    XSIMPLEQ_XOR(head, NULL))					\
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
+	(head)->sqx_first = XSIMPLEQ_XOR(head, (elm));			\
+} while (0)
+
+#define XSIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.sqx_next = XSIMPLEQ_XOR(head, NULL);		\
+	*(XSIMPLEQ_XOR(head, (head)->sqx_last)) = XSIMPLEQ_XOR(head, (elm)); \
+	(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);	\
+} while (0)
+
+#define XSIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.sqx_next = (listelm)->field.sqx_next) ==	\
+	    XSIMPLEQ_XOR(head, NULL))					\
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(elm)->field.sqx_next); \
+	(listelm)->field.sqx_next = XSIMPLEQ_XOR(head, (elm));		\
+} while (0)
+
+#define XSIMPLEQ_REMOVE_HEAD(head, field) do {				\
+	if (((head)->sqx_first = XSIMPLEQ_XOR(head,			\
+	    (head)->sqx_first)->field.sqx_next) == XSIMPLEQ_XOR(head, NULL)) \
+		(head)->sqx_last = XSIMPLEQ_XOR(head, &(head)->sqx_first); \
+} while (0)
+
+#define XSIMPLEQ_REMOVE_AFTER(head, elm, field) do {			\
+	if (((elm)->field.sqx_next = XSIMPLEQ_XOR(head,			\
+	    (elm)->field.sqx_next)->field.sqx_next)			\
+	    == XSIMPLEQ_XOR(head, NULL))				\
+		(head)->sqx_last = 					\
+		    XSIMPLEQ_XOR(head, &(elm)->field.sqx_next);		\
+} while (0)
+
+		    
+/*
+ * Tail queue definitions.
+ */
+#define TAILQ_HEAD(name, type)						\
+struct name {								\
+	struct type *tqh_first;	/* first element */			\
+	struct type **tqh_last;	/* addr of last next element */		\
+}
+
+#define TAILQ_HEAD_INITIALIZER(head)					\
+	{ NULL, &(head).tqh_first }
+
+#define TAILQ_ENTRY(type)						\
+struct {								\
+	struct type *tqe_next;	/* next element */			\
+	struct type **tqe_prev;	/* address of previous next element */	\
+}
+
+/* 
+ * tail queue access methods 
+ */
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#define	TAILQ_END(head)			NULL
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+#define TAILQ_LAST(head, headname)					\
+	(*(((struct headname *)((head)->tqh_last))->tqh_last))
+/* XXX */
+#define TAILQ_PREV(elm, headname, field)				\
+	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+#define	TAILQ_EMPTY(head)						\
+	(TAILQ_FIRST(head) == TAILQ_END(head))
+
+#define TAILQ_FOREACH(var, head, field)					\
+	for((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_NEXT(var, field))
+
+#define	TAILQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = TAILQ_FIRST(head);					\
+	    (var) != TAILQ_END(head) &&					\
+	    ((tvar) = TAILQ_NEXT(var, field), 1);			\
+	    (var) = (tvar))
+
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
+	for((var) = TAILQ_LAST(head, headname);				\
+	    (var) != TAILQ_END(head);					\
+	    (var) = TAILQ_PREV(var, headname, field))
+
+#define	TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
+	for ((var) = TAILQ_LAST(head, headname);			\
+	    (var) != TAILQ_END(head) &&					\
+	    ((tvar) = TAILQ_PREV(var, headname, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Tail queue functions.
+ */
+#define	TAILQ_INIT(head) do {						\
+	(head)->tqh_first = NULL;					\
+	(head)->tqh_last = &(head)->tqh_first;				\
+} while (0)
+
+#define TAILQ_INSERT_HEAD(head, elm, field) do {			\
+	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
+		(head)->tqh_first->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(head)->tqh_first = (elm);					\
+	(elm)->field.tqe_prev = &(head)->tqh_first;			\
+} while (0)
+
+#define TAILQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.tqe_next = NULL;					\
+	(elm)->field.tqe_prev = (head)->tqh_last;			\
+	*(head)->tqh_last = (elm);					\
+	(head)->tqh_last = &(elm)->field.tqe_next;			\
+} while (0)
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    &(elm)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm)->field.tqe_next;		\
+	(listelm)->field.tqe_next = (elm);				\
+	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
+} while (0)
+
+#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
+	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
+	(elm)->field.tqe_next = (listelm);				\
+	*(listelm)->field.tqe_prev = (elm);				\
+	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
+} while (0)
+
+#define TAILQ_REMOVE(head, elm, field) do {				\
+	if (((elm)->field.tqe_next) != NULL)				\
+		(elm)->field.tqe_next->field.tqe_prev =			\
+		    (elm)->field.tqe_prev;				\
+	else								\
+		(head)->tqh_last = (elm)->field.tqe_prev;		\
+	*(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+#define TAILQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
+		(elm2)->field.tqe_next->field.tqe_prev =		\
+		    &(elm2)->field.tqe_next;				\
+	else								\
+		(head)->tqh_last = &(elm2)->field.tqe_next;		\
+	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
+	*(elm2)->field.tqe_prev = (elm2);				\
+	_Q_INVALIDATE((elm)->field.tqe_prev);				\
+	_Q_INVALIDATE((elm)->field.tqe_next);				\
+} while (0)
+
+/*
+ * Circular queue definitions.
+ */
+#define CIRCLEQ_HEAD(name, type)					\
+struct name {								\
+	struct type *cqh_first;		/* first element */		\
+	struct type *cqh_last;		/* last element */		\
+}
+
+#define CIRCLEQ_HEAD_INITIALIZER(head)					\
+	{ CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
+
+#define CIRCLEQ_ENTRY(type)						\
+struct {								\
+	struct type *cqe_next;		/* next element */		\
+	struct type *cqe_prev;		/* previous element */		\
+}
+
+/*
+ * Circular queue access methods 
+ */
+#define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
+#define	CIRCLEQ_LAST(head)		((head)->cqh_last)
+#define	CIRCLEQ_END(head)		((void *)(head))
+#define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
+#define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
+#define	CIRCLEQ_EMPTY(head)						\
+	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
+
+#define CIRCLEQ_FOREACH(var, head, field)				\
+	for((var) = CIRCLEQ_FIRST(head);				\
+	    (var) != CIRCLEQ_END(head);					\
+	    (var) = CIRCLEQ_NEXT(var, field))
+
+#define	CIRCLEQ_FOREACH_SAFE(var, head, field, tvar)			\
+	for ((var) = CIRCLEQ_FIRST(head);				\
+	    (var) != CIRCLEQ_END(head) &&				\
+	    ((tvar) = CIRCLEQ_NEXT(var, field), 1);			\
+	    (var) = (tvar))
+
+#define CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
+	for((var) = CIRCLEQ_LAST(head);					\
+	    (var) != CIRCLEQ_END(head);					\
+	    (var) = CIRCLEQ_PREV(var, field))
+
+#define	CIRCLEQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)	\
+	for ((var) = CIRCLEQ_LAST(head, headname);			\
+	    (var) != CIRCLEQ_END(head) && 				\
+	    ((tvar) = CIRCLEQ_PREV(var, headname, field), 1);		\
+	    (var) = (tvar))
+
+/*
+ * Circular queue functions.
+ */
+#define	CIRCLEQ_INIT(head) do {						\
+	(head)->cqh_first = CIRCLEQ_END(head);				\
+	(head)->cqh_last = CIRCLEQ_END(head);				\
+} while (0)
+
+#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
+	(elm)->field.cqe_next = (listelm)->field.cqe_next;		\
+	(elm)->field.cqe_prev = (listelm);				\
+	if ((listelm)->field.cqe_next == CIRCLEQ_END(head))		\
+		(head)->cqh_last = (elm);				\
+	else								\
+		(listelm)->field.cqe_next->field.cqe_prev = (elm);	\
+	(listelm)->field.cqe_next = (elm);				\
+} while (0)
+
+#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
+	(elm)->field.cqe_next = (listelm);				\
+	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
+	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))		\
+		(head)->cqh_first = (elm);				\
+	else								\
+		(listelm)->field.cqe_prev->field.cqe_next = (elm);	\
+	(listelm)->field.cqe_prev = (elm);				\
+} while (0)
+
+#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
+	(elm)->field.cqe_next = (head)->cqh_first;			\
+	(elm)->field.cqe_prev = CIRCLEQ_END(head);			\
+	if ((head)->cqh_last == CIRCLEQ_END(head))			\
+		(head)->cqh_last = (elm);				\
+	else								\
+		(head)->cqh_first->field.cqe_prev = (elm);		\
+	(head)->cqh_first = (elm);					\
+} while (0)
+
+#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
+	(elm)->field.cqe_next = CIRCLEQ_END(head);			\
+	(elm)->field.cqe_prev = (head)->cqh_last;			\
+	if ((head)->cqh_first == CIRCLEQ_END(head))			\
+		(head)->cqh_first = (elm);				\
+	else								\
+		(head)->cqh_last->field.cqe_next = (elm);		\
+	(head)->cqh_last = (elm);					\
+} while (0)
+
+#define	CIRCLEQ_REMOVE(head, elm, field) do {				\
+	if ((elm)->field.cqe_next == CIRCLEQ_END(head))			\
+		(head)->cqh_last = (elm)->field.cqe_prev;		\
+	else								\
+		(elm)->field.cqe_next->field.cqe_prev =			\
+		    (elm)->field.cqe_prev;				\
+	if ((elm)->field.cqe_prev == CIRCLEQ_END(head))			\
+		(head)->cqh_first = (elm)->field.cqe_next;		\
+	else								\
+		(elm)->field.cqe_prev->field.cqe_next =			\
+		    (elm)->field.cqe_next;				\
+	_Q_INVALIDATE((elm)->field.cqe_prev);				\
+	_Q_INVALIDATE((elm)->field.cqe_next);				\
+} while (0)
+
+#define CIRCLEQ_REPLACE(head, elm, elm2, field) do {			\
+	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==		\
+	    CIRCLEQ_END(head))						\
+		(head)->cqh_last = (elm2);				\
+	else								\
+		(elm2)->field.cqe_next->field.cqe_prev = (elm2);	\
+	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==		\
+	    CIRCLEQ_END(head))						\
+		(head)->cqh_first = (elm2);				\
+	else								\
+		(elm2)->field.cqe_prev->field.cqe_next = (elm2);	\
+	_Q_INVALIDATE((elm)->field.cqe_prev);				\
+	_Q_INVALIDATE((elm)->field.cqe_next);				\
+} while (0)
+
+#endif	/* !_SYS_QUEUE_H_ */
diff --git a/sad.c b/sad.c
index 747be17..b86090e 100644
--- a/sad.c
+++ b/sad.c
@@ -82,10 +82,12 @@ playaudio(void)
 		s->state = PLAYING;
 		break;
 	case PLAYING:
-		if ((nbytes = s->decoder->decode(buf, sizeof(buf))) <= 0)
+		if ((nbytes = s->decoder->decode(buf, sizeof(buf))) <= 0) {
 			playnextsong();
-		else
+			notify(EVSONGFINISHED);
+		} else {
 			playoutput(buf, nbytes);
+		}
 		break;
 	}
 }
@@ -121,6 +123,7 @@ main(int argc, char *argv[])
 
 	initdecoders();
 	openoutputs();
+	initnotifier();
 
 	while (1) {
 		rfds = master;
@@ -144,6 +147,7 @@ main(int argc, char *argv[])
 				if (docmd(i) < 0) {
 					close(i);
 					FD_CLR(i, &master);
+					removesubscriber(i);
 				}
 			}
 		}
diff --git a/sad.h b/sad.h
index 6833a46..8e78363 100644
--- a/sad.h
+++ b/sad.h
@@ -17,6 +17,10 @@ enum {
 	PAUSED
 };
 
+enum {
+	EVSONGFINISHED,
+};
+
 typedef struct {
 	int (*init)(void);
 	int (*open)(const char *);
@@ -52,6 +56,11 @@ typedef struct {
 	size_t maxsongs;
 } Library;
 
+typedef struct eventdesc {
+	int   event;
+	char *name;
+} Eventdesc;
+
 /* sad.c */
 extern fd_set   master;
 extern fd_set   rfds;
@@ -116,3 +125,12 @@ int enableoutput(const char *);
 int disableoutput(const char *);
 int playoutput(void *, size_t);
 int setvol(int);
+
+/* notify.c */
+extern Eventdesc Eventmap[];
+
+int initnotifier(void);
+int addsubscriber(int, int);
+int addsubscribername(int, const char *);
+int notify(int);
+void removesubscriber(int);