virtiofsd: Open vhost connection instead of mounting

When run with vhost-user options we conect to the QEMU instead
via a socket.  Start this off by creating the socket.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 79 insertions, 0 deletions

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
new file mode 100644
index 0000000000..cbef6ffdda
--- /dev/null
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -0,0 +1,79 @@
+/*
+ * virtio-fs glue for FUSE
+ * Copyright (C) 2018 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ *   Dave Gilbert  <dgilbert@redhat.com>
+ *
+ * Implements the glue between libfuse and libvhost-user
+ *
+ * This program can be distributed under the terms of the GNU LGPLv2.
+ * See the file COPYING.LIB
+ */
+
+#include "fuse_i.h"
+#include "standard-headers/linux/fuse.h"
+#include "fuse_misc.h"
+#include "fuse_opt.h"
+#include "fuse_virtio.h"
+
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+/* From spec */
+struct virtio_fs_config {
+    char tag[36];
+    uint32_t num_queues;
+};
+
+int virtio_session_mount(struct fuse_session *se)
+{
+    struct sockaddr_un un;
+    mode_t old_umask;
+
+    if (strlen(se->vu_socket_path) >= sizeof(un.sun_path)) {
+        fuse_log(FUSE_LOG_ERR, "Socket path too long\n");
+        return -1;
+    }
+
+    se->fd = -1;
+
+    /*
+     * Create the Unix socket to communicate with qemu
+     * based on QEMU's vhost-user-bridge
+     */
+    unlink(se->vu_socket_path);
+    strcpy(un.sun_path, se->vu_socket_path);
+    size_t addr_len = sizeof(un);
+
+    int listen_sock = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (listen_sock == -1) {
+        fuse_log(FUSE_LOG_ERR, "vhost socket creation: %m\n");
+        return -1;
+    }
+    un.sun_family = AF_UNIX;
+
+    /*
+     * Unfortunately bind doesn't let you set the mask on the socket,
+     * so set umask to 077 and restore it later.
+     */
+    old_umask = umask(0077);
+    if (bind(listen_sock, (struct sockaddr *)&un, addr_len) == -1) {
+        fuse_log(FUSE_LOG_ERR, "vhost socket bind: %m\n");
+        umask(old_umask);
+        return -1;
+    }
+    umask(old_umask);
+
+    if (listen(listen_sock, 1) == -1) {
+        fuse_log(FUSE_LOG_ERR, "vhost socket listen: %m\n");
+        return -1;
+    }
+
+    return -1;
+}