--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imsgev.c	Thu Mar 27 09:53:52 2014 +0500
@@ -0,0 +1,170 @@
+/*
+ * Copyright (c) 2009 Eric Faurot <eric@openbsd.org>
+ *
+ * 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.
+ */
+
+#include <sys/param.h>
+#include <sys/queue.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "imsgev.h"
+
+void imsgev_add(struct imsgev *);
+void imsgev_dispatch(int, short, void *);
+void imsgev_disconnect(struct imsgev *, int);
+
+void
+imsgev_init(struct imsgev *iev, int fd, void *data,
+    void (*callback)(struct imsgev *, int, struct imsg *),
+    void (*needfd)(struct imsgev *))
+{
+	imsg_init(&iev->ibuf, fd);
+	iev->terminate = 0;
+
+	iev->data = data;
+	iev->handler = imsgev_dispatch;
+	iev->callback = callback;
+	iev->needfd = needfd;
+
+	iev->events = EV_READ;
+	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev);
+	event_add(&iev->ev, NULL);
+}
+
+int
+imsgev_compose(struct imsgev *iev, u_int16_t type, u_int32_t peerid,
+    uint32_t pid, int fd, void *data, u_int16_t datalen)
+{
+	int	r;
+
+	r = imsg_compose(&iev->ibuf, type, peerid, pid, fd, data, datalen);
+	if (r != -1)
+		imsgev_add(iev);
+
+	return (r);
+}
+
+void
+imsgev_close(struct imsgev *iev)
+{
+	iev->terminate = 1;
+	imsgev_add(iev);
+}
+
+void
+imsgev_clear(struct imsgev *iev)
+{
+	event_del(&iev->ev);
+	msgbuf_clear(&iev->ibuf.w);
+	close(iev->ibuf.fd);
+}
+
+void
+imsgev_add(struct imsgev *iev)
+{
+	short	events = 0;
+
+	if (!iev->terminate)
+		events = EV_READ;
+	if (iev->ibuf.w.queued || iev->terminate)
+		events |= EV_WRITE;
+
+	/* optimization: skip event_{del/set/add} if already set */
+	if (events == iev->events)
+		return;
+
+	iev->events = events;
+	event_del(&iev->ev);
+	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev);
+	event_add(&iev->ev, NULL);
+}
+
+void
+imsgev_dispatch(int fd, short ev, void *humppa)
+{
+	struct imsgev	*iev = humppa;
+	struct imsgbuf	*ibuf = &iev->ibuf;
+	struct imsg	 imsg;
+	ssize_t		 n;
+
+	iev->events = 0;
+
+	if (ev & EV_READ) {
+		if ((n = imsg_read(ibuf)) == -1) {
+			/* if we don't have enough fds, free one up and retry */
+			if (errno == EAGAIN) {
+				iev->needfd(iev);
+				n = imsg_read(ibuf);
+			}
+
+			if (n == -1) {
+				imsgev_disconnect(iev, IMSGEV_EREAD);
+				return;
+			}
+		}
+		if (n == 0) {
+			/*
+			 * Connection is closed for reading, and we assume
+			 * it is also closed for writing, so we error out
+			 * if write data is pending.
+			 */
+			imsgev_disconnect(iev,
+			    (iev->ibuf.w.queued) ? IMSGEV_EWRITE : IMSGEV_DONE);
+			return;
+		}
+	}
+
+	if (ev & EV_WRITE) {
+		/*
+		 * We wanted to write data out but the connection is either
+		 * closed, or some error occured. Both case are not recoverable
+		 * from the imsg perspective, so we treat it as a WRITE error.
+		 */
+		if ((n = msgbuf_write(&ibuf->w)) != 1) {
+			imsgev_disconnect(iev, IMSGEV_EWRITE);
+			return;
+		}
+	}
+
+	while (iev->terminate == 0) {
+		if ((n = imsg_get(ibuf, &imsg)) == -1) {
+			imsgev_disconnect(iev, IMSGEV_EIMSG);
+			return;
+		}
+		if (n == 0)
+			break;
+		iev->callback(iev, IMSGEV_IMSG, &imsg);
+		imsg_free(&imsg);
+	}
+
+	if (iev->terminate && iev->ibuf.w.queued == 0) {
+		imsgev_disconnect(iev, IMSGEV_DONE);
+		return;
+	}
+
+	imsgev_add(iev);
+}
+
+void
+imsgev_disconnect(struct imsgev *iev, int code)
+{
+	iev->callback(iev, code, NULL);
+}