commit 37b42f3db0685561c7fcc12d6c9feca6df11b2f4
Author: Ryota Ozaki <ozaki-r@iij.ad.jp>
Date:   Mon Aug 19 16:34:30 2019 +0900

    mount_9p: enable to communicate with vio9p via its character device file
    
    With this feature, we can mount an exported filesystem by a VM host via
    virtio-9p.

diff --git a/usr.sbin/puffs/mount_9p/mount_9p.8 b/usr.sbin/puffs/mount_9p/mount_9p.8
index 6a7c15bfaa9..20f63627b43 100644
--- a/usr.sbin/puffs/mount_9p/mount_9p.8
+++ b/usr.sbin/puffs/mount_9p/mount_9p.8
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd June 7, 2019
+.Dd October 24, 2019
 .Dt MOUNT_9P 8
 .Os
 .Sh NAME
@@ -36,6 +36,12 @@
 .Op Fl p Ar port
 .Ar [user@]host[:path]
 .Ar mount_point
+.Nm
+.Fl c
+.Op Fl su
+.Op Fl o Ar mntopts
+.Ar devfile
+.Ar mount_point
 .Sh DESCRIPTION
 The
 .Nm
@@ -52,6 +58,18 @@ is supplied, it is used as the mount rootpath on the remote host.
 .Ar path
 must be an absolute path.
 .Pp
+The
+.Fl c
+opiton enables to mount a filesystem exported by a VM host through
+a character device file
+.Ar devfile
+backed by the
+.Xr vio9p 4
+driver.
+See
+.Xr vio9p 4
+for more information.
+.Pp
 By default
 .Nm
 runs in the background with
@@ -74,7 +92,8 @@ environments.
 .Sh SEE ALSO
 .Xr puffs 3 ,
 .Xr puffs 4 ,
-.Xr mount 8
+.Xr mount 8 ,
+.Xr vio9p 4
 .Rs
 .%T RFC and standards documents relating the 9P protocol
 .%U http://ericvh.github.io/9p-rfc/
@@ -87,6 +106,11 @@ utility first appeared in
 .Pp
 Experimental 9P2000.u support appeared in
 .Nx 9.0 .
+.Pp
+The
+.Fl c
+option appeared in
+.Nx 10.0 .
 .Sh CAVEATS
 Permissions are not handled well.
 .Pp
diff --git a/usr.sbin/puffs/mount_9p/ninebuf.c b/usr.sbin/puffs/mount_9p/ninebuf.c
index a9fe6879cf3..7b0ba3f9084 100644
--- a/usr.sbin/puffs/mount_9p/ninebuf.c
+++ b/usr.sbin/puffs/mount_9p/ninebuf.c
@@ -138,7 +138,7 @@ p9pbuf_write(struct puffs_usermount *pu, struct puffs_framebuf *pb,
 		winlen = howmuch;
 		if (puffs_framebuf_getwindow(pb, CUROFF(pb), &win, &winlen)==-1)
 			return errno;
-		n = send(fd, win, winlen, MSG_NOSIGNAL);
+		n = write(fd, win, winlen);
 		switch (n) {
 		case 0:
 			return ECONNRESET;
diff --git a/usr.sbin/puffs/mount_9p/ninepuffs.c b/usr.sbin/puffs/mount_9p/ninepuffs.c
index e9a0550a5c1..49d2b21e780 100644
--- a/usr.sbin/puffs/mount_9p/ninepuffs.c
+++ b/usr.sbin/puffs/mount_9p/ninepuffs.c
@@ -60,6 +60,8 @@ usage(void)
 
 	fprintf(stderr, "usage: %s [-su] [-o mntopts] [-p port] "
 	    "[user@]server[:path] mountpoint\n", getprogname());
+	fprintf(stderr, "       %s -c [-su] [-o mntopts] devfile mountpoint\n",
+	    getprogname());
 	exit(1);
 }
 
@@ -72,7 +74,7 @@ serverconnect(const char *addr, unsigned short port)
 {
 	struct sockaddr_in mysin;
 	struct hostent *he;
-	int s;
+	int s, ret, opt;
 
 	he = gethostbyname2(addr, AF_INET);
 	if (he == NULL) {
@@ -84,6 +86,11 @@ serverconnect(const char *addr, unsigned short port)
 	if (s == -1)
 		err(1, "socket");
 
+	opt = 1;
+	ret = setsockopt(s, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof(opt));
+	if (ret == -1)
+		err(1, "setsockopt(SO_NOSIGPIPE)");
+
 	memset(&mysin, 0, sizeof(struct sockaddr_in));
 	mysin.sin_family = AF_INET;
 	mysin.sin_port = htons(port);
@@ -95,6 +102,17 @@ serverconnect(const char *addr, unsigned short port)
 	return s;
 }
 
+static int
+open_cdev(const char *path)
+{
+	int s;
+
+	s = open(path, O_RDWR, 0);
+	if (s == -1)
+		err(1, "open(%s)", path);
+	return s;
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -108,7 +126,8 @@ main(int argc, char *argv[])
 	unsigned short port;
 	int mntflags, pflags, ch;
 	int detach;
-	int protover = P9PROTO_VERSION;
+	int protover;
+	int server;
 
 	setprogname(argv[0]);
 
@@ -118,9 +137,14 @@ main(int argc, char *argv[])
 	mntflags = pflags = 0;
 	detach = 1;
 	port = DEFPORT_9P;
+	protover = P9PROTO_VERSION;
+	server = P9P_SERVER_TCP;
 
-	while ((ch = getopt(argc, argv, "o:p:su")) != -1) {
+	while ((ch = getopt(argc, argv, "co:p:su")) != -1) {
 		switch (ch) {
+		case 'c':
+			server = P9P_SERVER_CDEV;
+			break;
 		case 'o':
 			mp = getmntopts(optarg, puffsmopts, &mntflags, &pflags);
 			if (mp == NULL)
@@ -209,8 +233,15 @@ main(int argc, char *argv[])
 		srvpath = "/";
 	}
 
-	p9p.servsock = serverconnect(srvhost, port);
+	if (server == P9P_SERVER_TCP) {
+		p9p.servsock = serverconnect(srvhost, port);
+	} else {
+		/* path to a viop9fs chardev file, e.g., /dev/viop9fs0 */
+		p9p.servsock = open_cdev(argv[0]);
+	}
+
 	if ((pn_root = p9p_handshake(pu, user, srvpath)) == NULL) {
+		close(p9p.servsock);
 		puffs_exit(pu, 1);
 		exit(1);
 	}
@@ -232,6 +263,8 @@ main(int argc, char *argv[])
 
 	if (puffs_mainloop(pu) == -1)
 		err(1, "mainloop");
+	close(p9p.servsock);
+	puffs_exit(pu, 1);
 
 	return 0;
 }
diff --git a/usr.sbin/puffs/mount_9p/ninepuffs.h b/usr.sbin/puffs/mount_9p/ninepuffs.h
index d8974d9a725..13dbd269312 100644
--- a/usr.sbin/puffs/mount_9p/ninepuffs.h
+++ b/usr.sbin/puffs/mount_9p/ninepuffs.h
@@ -105,6 +105,9 @@ struct puffs9p {
 	size_t maxreq;		/* negotiated with server */
 
 	int protover;
+	int server;
+#define P9P_SERVER_TCP		0
+#define P9P_SERVER_CDEV		1
 };
 
 struct dirfid {