1 files changed, 110 insertions, 0 deletions
diff --git a/pkg/sentry/fs/ext/file_description.go b/pkg/sentry/fs/ext/file_description.go
new file mode 100644
index 000000000..d244cf1e7
--- /dev/null
+++ b/pkg/sentry/fs/ext/file_description.go
@@ -0,0 +1,110 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ext
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+// fileDescription is embedded by ext implementations of
+// vfs.FileDescriptionImpl.
+type fileDescription struct {
+	vfsfd vfs.FileDescription
+
+	// flags is the same as vfs.OpenOptions.Flags which are passed to
+	// vfs.FilesystemImpl.OpenAt.
+	// TODO(b/134676337): syscalls like read(2), write(2), fchmod(2), fchown(2),
+	// fgetxattr(2), ioctl(2), mmap(2) should fail with EBADF if O_PATH is set.
+	// Only close(2), fstat(2), fstatfs(2) should work.
+	flags uint32
+}
+
+func (fd *fileDescription) filesystem() *filesystem {
+	return fd.vfsfd.VirtualDentry().Mount().Filesystem().Impl().(*filesystem)
+}
+
+func (fd *fileDescription) inode() *inode {
+	return fd.vfsfd.VirtualDentry().Dentry().Impl().(*dentry).inode
+}
+
+// OnClose implements vfs.FileDescriptionImpl.OnClose.
+func (fd *fileDescription) OnClose() error { return nil }
+
+// StatusFlags implements vfs.FileDescriptionImpl.StatusFlags.
+func (fd *fileDescription) StatusFlags(ctx context.Context) (uint32, error) {
+	return fd.flags, nil
+}
+
+// SetStatusFlags implements vfs.FileDescriptionImpl.SetStatusFlags.
+func (fd *fileDescription) SetStatusFlags(ctx context.Context, flags uint32) error {
+	// None of the flags settable by fcntl(F_SETFL) are supported, so this is a
+	// no-op.
+	return nil
+}
+
+// Stat implements vfs.FileDescriptionImpl.Stat.
+func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
+	var stat linux.Statx
+	fd.inode().statTo(&stat)
+	return stat, nil
+}
+
+// SetStat implements vfs.FileDescriptionImpl.SetStat.
+func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
+	if opts.Stat.Mask == 0 {
+		return nil
+	}
+	return syserror.EPERM
+}
+
+// SetStat implements vfs.FileDescriptionImpl.StatFS.
+func (fd *fileDescription) StatFS(ctx context.Context) (linux.Statfs, error) {
+	var stat linux.Statfs
+	fd.filesystem().statTo(&stat)
+	return stat, nil
+}
+
+// Readiness implements waiter.Waitable.Readiness analogously to
+// file_operations::poll == NULL in Linux.
+func (fd *fileDescription) Readiness(mask waiter.EventMask) waiter.EventMask {
+	// include/linux/poll.h:vfs_poll() => DEFAULT_POLLMASK
+	return waiter.EventIn | waiter.EventOut
+}
+
+// EventRegister implements waiter.Waitable.EventRegister analogously to
+// file_operations::poll == NULL in Linux.
+func (fd *fileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) {}
+
+// EventUnregister implements waiter.Waitable.EventUnregister analogously to
+// file_operations::poll == NULL in Linux.
+func (fd *fileDescription) EventUnregister(e *waiter.Entry) {}
+
+// Sync implements vfs.FileDescriptionImpl.Sync.
+func (fd *fileDescription) Sync(ctx context.Context) error {
+	return nil
+}
+
+// Ioctl implements vfs.FileDescriptionImpl.Ioctl.
+func (fd *fileDescription) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	// ioctl(2) specifies that ENOTTY must be returned if the file descriptor is
+	// not associated with a character special device (which is unimplemented).
+	return 0, syserror.ENOTTY
+}