[V9,05/13] virtio-9p: Add support to open a file in chroot environment

diff --git a/hw/9pfs/virtio-9p-chroot.c b/hw/9pfs/virtio-9p-chroot.c
index 4aa3b43..8d41087 100644
--- a/hw/9pfs/virtio-9p-chroot.c
+++ b/hw/9pfs/virtio-9p-chroot.c
@@ -80,13 +80,26 @@  static int v9fs_write_request(int sockfd, V9fsFileObjectRequest *request)
     return 0;
 }
 
-/*
- * This patch adds v9fs_receivefd and v9fs_write_request functions,
- * but there is no callers. To avoid compiler warning message,
- * refer these two functions
- */
-void chroot_dummy(void)
+/* Return opened file descriptor on success or -errno on error */
+int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *request)
 {
-    (void)v9fs_receivefd;
-    (void)v9fs_write_request;
+    int fd, sock_error;
+    qemu_mutex_lock(&fs_ctx->chroot_mutex);
+    if (fs_ctx->chroot_socket == -1) {
+        goto error;
+    }
+    if (v9fs_write_request(fs_ctx->chroot_socket, request) < 0) {
+        goto error;
+    }
+    fd = v9fs_receivefd(fs_ctx->chroot_socket, &sock_error);
+    if (fd < 0 && sock_error) {
+        goto error;
+    }
+    qemu_mutex_unlock(&fs_ctx->chroot_mutex);
+    return fd;
+error:
+    close(fs_ctx->chroot_socket);
+    fs_ctx->chroot_socket = -1;
+    qemu_mutex_unlock(&fs_ctx->chroot_mutex);
+    return -EIO;
 }
diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
index a218f95..ceb858d 100644
--- a/hw/9pfs/virtio-9p-chroot.h
+++ b/hw/9pfs/virtio-9p-chroot.h
@@ -32,6 +32,6 @@  typedef struct V9fsFileObjectRequest
 } V9fsFileObjectRequest;
 
 int v9fs_chroot(FsContext *fs_ctx);
-void chroot_dummy(void);
+int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *or);
 
 #endif /* _QEMU_VIRTIO_9P_CHROOT_H */
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 0a015de..c42970e 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -13,6 +13,9 @@ 
 #include "virtio.h"
 #include "virtio-9p.h"
 #include "virtio-9p-xattr.h"
+#include "qemu_socket.h"
+#include "fsdev/qemu-fsdev.h"
+#include "virtio-9p-chroot.h"
 #include <arpa/inet.h>
 #include <pwd.h>
 #include <grp.h>
@@ -20,6 +23,62 @@ 
 #include <sys/un.h>
 #include <attr/xattr.h>
 
+/* Helper routine to fill V9fsFileObjectRequest structure */
+static int fill_fileobjectrequest(V9fsFileObjectRequest *request,
+                const char *oldpath, const char *path, int flags,
+                FsCred *credp, int type)
+{
+    if (oldpath && strlen(oldpath) >= PATH_MAX) {
+        return -ENAMETOOLONG;
+    }
+    /* path can't be NULL */
+    if (!path) {
+        return -EFAULT;
+    }
+
+    if (strlen(path) >= PATH_MAX) {
+        return -ENAMETOOLONG;
+    }
+    strcpy(request->path.path, path);
+    if (oldpath) {
+        strcpy(request->path.old_path, oldpath);
+    } else {
+        request->path.old_path[0] = '\0';
+    }
+
+    memset(&request->data, 0, sizeof(request->data));
+    if (credp) {
+        request->data.mode = credp->fc_mode;
+        request->data.uid = credp->fc_uid;
+        request->data.gid = credp->fc_gid;
+        request->data.dev = credp->fc_rdev;
+    }
+
+    request->data.flags = flags;
+    request->data.type = type;
+    return 0;
+}
+
+static int passthrough_request(FsContext *fs_ctx, const char *old_path,
+                const char *path, int flags, FsCred *credp, int type)
+{
+    V9fsFileObjectRequest request;
+    int retval;
+
+    retval = fill_fileobjectrequest(&request, old_path, path, flags, credp,
+                    type);
+    if (retval < 0) {
+        errno = -retval;
+        return -1;
+    }
+
+    retval = v9fs_request(fs_ctx, &request);
+    if (retval < 0) {
+        errno = -retval;
+        retval = -1;
+    }
+    return retval;
+}
 
 static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
 {
@@ -138,14 +197,27 @@  static int local_closedir(FsContext *ctx, DIR *dir)
     return closedir(dir);
 }
 
-static int local_open(FsContext *ctx, const char *path, int flags)
+static int local_open(FsContext *fs_ctx, const char *path, int flags)
 {
-    return open(rpath(ctx, path), flags);
+    if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        return passthrough_request(fs_ctx, NULL, path, flags, NULL, T_OPEN);
+    } else {
+        return open(rpath(fs_ctx, path), flags);
+    }
 }
 
-static DIR *local_opendir(FsContext *ctx, const char *path)
+static DIR *local_opendir(FsContext *fs_ctx, const char *path)
 {
-    return opendir(rpath(ctx, path));
+    if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        int fd;
+        fd = passthrough_request(fs_ctx, NULL, path, O_DIRECTORY, NULL, T_OPEN);
+        if (fd < 0) {
+            return NULL;
+        }
+        return fdopendir(fd);
+    } else {
+        return opendir(rpath(fs_ctx, path));
+    }
 }
 
 static void local_rewinddir(FsContext *ctx, DIR *dir)