Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 180 insertions, 0 deletions

diff --git a/pkg/p9/file.go b/pkg/p9/file.go
new file mode 100644
index 000000000..ae726f0b9
--- /dev/null
+++ b/pkg/p9/file.go
@@ -0,0 +1,180 @@
+// Copyright 2018 Google Inc.
+//
+// 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 p9
+
+import (
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/fd"
+)
+
+// Attacher is provided by the user.
+type Attacher interface {
+	// Attach returns a new File.
+	Attach(attachName string) (File, error)
+}
+
+// File is a set of operations corresponding to a single node.
+//
+// Functions below MUST return syscall.Errno values.
+// TODO: Enforce that with the type.
+//
+// These must be implemented in all circumstances.
+type File interface {
+	// Walk walks to the path components given in names.
+	//
+	// Walk returns QIDs in the same order that the names were passed in.
+	//
+	// An empty list of arguments should return a copy of the current file.
+	Walk(names []string) ([]QID, File, error)
+
+	// StatFS returns information about the file system associated with
+	// this file.
+	StatFS() (FSStat, error)
+
+	// GetAttr returns attributes of this node.
+	GetAttr(req AttrMask) (QID, AttrMask, Attr, error)
+
+	// SetAttr sets attributes on this node.
+	SetAttr(valid SetAttrMask, attr SetAttr) error
+
+	// Remove removes the file.
+	//
+	// This is deprecated in favor of UnlinkAt below.
+	Remove() error
+
+	// Rename renames the file.
+	Rename(directory File, name string) error
+
+	// Close is called when all references are dropped on the server side,
+	// and Close should be called by the client to drop all references.
+	//
+	// For server-side implementations of Close, the error is ignored.
+	//
+	// Close must be called even when Open has not been called.
+	Close() error
+
+	// Open is called prior to using read/write.
+	//
+	// The *fd.FD may be nil. If an *fd.FD is provided, ownership now
+	// belongs to the caller and the FD must be non-blocking.
+	//
+	// If Open returns a non-nil *fd.FD, it should do so for all possible
+	// OpenFlags. If Open returns a nil *fd.FD, it should similarly return
+	// a nil *fd.FD for all possible OpenFlags.
+	//
+	// This can be assumed to be one-shot only.
+	Open(mode OpenFlags) (*fd.FD, QID, uint32, error)
+
+	// Read reads from this file.
+	//
+	// This may return io.EOF in addition to syscall.Errno values.
+	//
+	// Preconditions: Open has been called and returned success.
+	ReadAt(p []byte, offset uint64) (int, error)
+
+	// Write writes to this file.
+	//
+	// This may return io.EOF in addition to syscall.Errno values.
+	//
+	// Preconditions: Open has been called and returned success.
+	WriteAt(p []byte, offset uint64) (int, error)
+
+	// FSync syncs this node.
+	//
+	// Preconditions: Open has been called and returned success.
+	FSync() error
+
+	// Create creates a new regular file and opens it according to the
+	// flags given.
+	//
+	// See p9.File.Open for a description of *fd.FD.
+	Create(name string, flags OpenFlags, permissions FileMode, uid UID, gid GID) (*fd.FD, File, QID, uint32, error)
+
+	// Mkdir creates a subdirectory.
+	Mkdir(name string, permissions FileMode, uid UID, gid GID) (QID, error)
+
+	// Symlink makes a new symbolic link.
+	Symlink(oldname string, newname string, uid UID, gid GID) (QID, error)
+
+	// Link makes a new hard link.
+	Link(target File, newname string) error
+
+	// Mknod makes a new device node.
+	Mknod(name string, permissions FileMode, major uint32, minor uint32, uid UID, gid GID) (QID, error)
+
+	// RenameAt renames a given file to a new name in a potentially new
+	// directory.
+	//
+	// oldname must be a name relative to this file, which must be a
+	// directory. newname is a name relative to newdir.
+	//
+	// This is deprecated in favor of Rename.
+	RenameAt(oldname string, newdir File, newname string) error
+
+	// UnlinkAt the given named file.
+	//
+	// name must be a file relative to this directory.
+	//
+	// Flags are implementation-specific (e.g. O_DIRECTORY), but are
+	// generally Linux unlinkat(2) flags.
+	UnlinkAt(name string, flags uint32) error
+
+	// Readdir reads directory entries.
+	//
+	// This may return io.EOF in addition to syscall.Errno values.
+	//
+	// Preconditions: Open has been called and returned success.
+	Readdir(offset uint64, count uint32) ([]Dirent, error)
+
+	// Readlink reads the link target.
+	Readlink() (string, error)
+
+	// Flush is called prior to Close.
+	//
+	// Whereas Close drops all references to the file, Flush cleans up the
+	// file state. Behavior is implementation-specific.
+	//
+	// Flush is not related to flush(9p).  Flush is an extension to 9P2000.L,
+	// see version.go.
+	Flush() error
+
+	// WalkGetAttr walks to the next file and returns its maximal set of
+	// attributes.
+	//
+	// Server-side p9.Files may return syscall.ENOSYS to indicate that Walk
+	// and GetAttr should be used separately to satisfy this request.
+	WalkGetAttr([]string) ([]QID, File, AttrMask, Attr, error)
+
+	// Connect establishes a new host-socket backed connection with a
+	// socket. A File does not need to be opened before it can be connected
+	// and it can be connected to multiple times resulting in a unique
+	// *fd.FD each time. In addition, the lifetime of the *fd.FD is
+	// independent from the lifetime of the p9.File and must be managed by
+	// the caller.
+	//
+	// The returned FD must be non-blocking.
+	//
+	// flags indicates the requested type of socket.
+	Connect(flags ConnectFlags) (*fd.FD, error)
+}
+
+// DefaultWalkGetAttr implements File.WalkGetAttr to return ENOSYS for server-side Files.
+type DefaultWalkGetAttr struct{}
+
+// WalkGetAttr implements File.WalkGetAttr.
+func (DefaultWalkGetAttr) WalkGetAttr([]string) ([]QID, File, AttrMask, Attr, error) {
+	return nil, nil, AttrMask{}, Attr{}, syscall.ENOSYS
+}