Sync OpenBSD patchset 243:

Switch tmux to use imsg. This is the last major change to make the
client-server protocol more resilient and make the protocol versioning work
properly. In future, the only things requiring a protocol version bump will be
changes in the message structs, and (when both client and server have this
change) mixing different versions should nicely report an error message.

As a side effect this also makes the code tidier, fixes a problem with the way
errors reported during server startup were handled, and supports fd passing
(which will be used in future).

Looked over by eric@, thanks.

Please note that mixing a client with this change with an older server or vice
versa may cause tmux to crash or hang - tmux should be completely exited before
upgrading.

1 files changed, 305 insertions, 0 deletions

diff --git a/compat/imsg-buffer.c b/compat/imsg-buffer.c
new file mode 100644
index 00000000..ef380ab6
--- /dev/null
+++ b/compat/imsg-buffer.c
@@ -0,0 +1,305 @@
+/*	$OpenBSD: imsg-buffer.c,v 1.1 2009/08/11 17:18:35 nicm Exp $	*/
+
+/*
+ * Copyright (c) 2003, 2004 Henning Brauer <henning@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 <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "imsg.h"
+
+int	buf_realloc(struct buf *, size_t);
+void	buf_enqueue(struct msgbuf *, struct buf *);
+void	buf_dequeue(struct msgbuf *, struct buf *);
+
+struct buf *
+buf_open(size_t len)
+{
+	struct buf	*buf;
+
+	if ((buf = calloc(1, sizeof(struct buf))) == NULL)
+		return (NULL);
+	if ((buf->buf = malloc(len)) == NULL) {
+		free(buf);
+		return (NULL);
+	}
+	buf->size = buf->max = len;
+	buf->fd = -1;
+
+	return (buf);
+}
+
+struct buf *
+buf_dynamic(size_t len, size_t max)
+{
+	struct buf	*buf;
+
+	if (max < len)
+		return (NULL);
+
+	if ((buf = buf_open(len)) == NULL)
+		return (NULL);
+
+	if (max > 0)
+		buf->max = max;
+
+	return (buf);
+}
+
+int
+buf_realloc(struct buf *buf, size_t len)
+{
+	u_char	*b;
+
+	/* on static buffers max is eq size and so the following fails */
+	if (buf->wpos + len > buf->max) {
+		errno = ENOMEM;
+		return (-1);
+	}
+
+	b = realloc(buf->buf, buf->wpos + len);
+	if (b == NULL)
+		return (-1);
+	buf->buf = b;
+	buf->size = buf->wpos + len;
+
+	return (0);
+}
+
+int
+buf_add(struct buf *buf, const void *data, size_t len)
+{
+	if (buf->wpos + len > buf->size)
+		if (buf_realloc(buf, len) == -1)
+			return (-1);
+
+	memcpy(buf->buf + buf->wpos, data, len);
+	buf->wpos += len;
+	return (0);
+}
+
+void *
+buf_reserve(struct buf *buf, size_t len)
+{
+	void	*b;
+
+	if (buf->wpos + len > buf->size)
+		if (buf_realloc(buf, len) == -1)
+			return (NULL);
+
+	b = buf->buf + buf->wpos;
+	buf->wpos += len;
+	return (b);
+}
+
+void *
+buf_seek(struct buf *buf, size_t pos, size_t len)
+{
+	/* only allowed to seek in already written parts */
+	if (pos + len > buf->wpos)
+		return (NULL);
+
+	return (buf->buf + pos);
+}
+
+size_t
+buf_size(struct buf *buf)
+{
+	return (buf->wpos);
+}
+
+size_t
+buf_left(struct buf *buf)
+{
+	return (buf->max - buf->wpos);
+}
+
+void
+buf_close(struct msgbuf *msgbuf, struct buf *buf)
+{
+	buf_enqueue(msgbuf, buf);
+}
+
+int
+buf_write(struct msgbuf *msgbuf)
+{
+	struct iovec	 iov[IOV_MAX];
+	struct buf	*buf, *next;
+	unsigned int	 i = 0;
+	ssize_t	n;
+
+	bzero(&iov, sizeof(iov));
+	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
+		if (i >= IOV_MAX)
+			break;
+		iov[i].iov_base = buf->buf + buf->rpos;
+		iov[i].iov_len = buf->wpos - buf->rpos;
+		i++;
+	}
+
+	if ((n = writev(msgbuf->fd, iov, i)) == -1) {
+		if (errno == EAGAIN || errno == ENOBUFS ||
+		    errno == EINTR)	/* try later */
+			return (0);
+		else
+			return (-1);
+	}
+
+	if (n == 0) {			/* connection closed */
+		errno = 0;
+		return (-2);
+	}
+
+	for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
+	    buf = next) {
+		next = TAILQ_NEXT(buf, entry);
+		if (buf->rpos + n >= buf->wpos) {
+			n -= buf->wpos - buf->rpos;
+			buf_dequeue(msgbuf, buf);
+		} else {
+			buf->rpos += n;
+			n = 0;
+		}
+	}
+
+	return (0);
+}
+
+void
+buf_free(struct buf *buf)
+{
+	free(buf->buf);
+	free(buf);
+}
+
+void
+msgbuf_init(struct msgbuf *msgbuf)
+{
+	msgbuf->queued = 0;
+	msgbuf->fd = -1;
+	TAILQ_INIT(&msgbuf->bufs);
+}
+
+void
+msgbuf_clear(struct msgbuf *msgbuf)
+{
+	struct buf	*buf;
+
+	while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
+		buf_dequeue(msgbuf, buf);
+}
+
+int
+msgbuf_write(struct msgbuf *msgbuf)
+{
+	struct iovec	 iov[IOV_MAX];
+	struct buf	*buf, *next;
+	unsigned int	 i = 0;
+	ssize_t		 n;
+	struct msghdr	 msg;
+	struct cmsghdr	*cmsg;
+	union {
+		struct cmsghdr	hdr;
+		char		buf[CMSG_SPACE(sizeof(int))];
+	} cmsgbuf;
+
+	bzero(&iov, sizeof(iov));
+	bzero(&msg, sizeof(msg));
+	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
+		if (i >= IOV_MAX)
+			break;
+		iov[i].iov_base = buf->buf + buf->rpos;
+		iov[i].iov_len = buf->wpos - buf->rpos;
+		i++;
+		if (buf->fd != -1)
+			break;
+	}
+
+	msg.msg_iov = iov;
+	msg.msg_iovlen = i;
+
+	if (buf != NULL && buf->fd != -1) {
+		msg.msg_control = (caddr_t)&cmsgbuf.buf;
+		msg.msg_controllen = sizeof(cmsgbuf.buf);
+		cmsg = CMSG_FIRSTHDR(&msg);
+		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+		cmsg->cmsg_level = SOL_SOCKET;
+		cmsg->cmsg_type = SCM_RIGHTS;
+		*(int *)CMSG_DATA(cmsg) = buf->fd;
+	}
+
+	if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
+		if (errno == EAGAIN || errno == ENOBUFS ||
+		    errno == EINTR)	/* try later */
+			return (0);
+		else
+			return (-1);
+	}
+
+	if (n == 0) {			/* connection closed */
+		errno = 0;
+		return (-2);
+	}
+
+	/*
+	 * assumption: fd got sent if sendmsg sent anything
+	 * this works because fds are passed one at a time
+	 */
+	if (buf != NULL && buf->fd != -1) {
+		close(buf->fd);
+		buf->fd = -1;
+	}
+
+	for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
+	    buf = next) {
+		next = TAILQ_NEXT(buf, entry);
+		if (buf->rpos + n >= buf->wpos) {
+			n -= buf->wpos - buf->rpos;
+			buf_dequeue(msgbuf, buf);
+		} else {
+			buf->rpos += n;
+			n = 0;
+		}
+	}
+
+	return (0);
+}
+
+void
+buf_enqueue(struct msgbuf *msgbuf, struct buf *buf)
+{
+	TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
+	msgbuf->queued++;
+}
+
+void
+buf_dequeue(struct msgbuf *msgbuf, struct buf *buf)
+{
+	TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
+
+	if (buf->fd != -1)
+		close(buf->fd);
+
+	msgbuf->queued--;
+	buf_free(buf);
+}