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PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 513 insertions, 0 deletions

diff --git a/pkg/p9/client_file.go b/pkg/p9/client_file.go
new file mode 100644
index 000000000..0f02980a0
--- /dev/null
+++ b/pkg/p9/client_file.go
@@ -0,0 +1,513 @@
+// 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 (
+	"fmt"
+	"io"
+	"runtime"
+	"sync/atomic"
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/fd"
+	"gvisor.googlesource.com/gvisor/pkg/log"
+)
+
+// Attach attaches to a server.
+//
+// Note that authentication is not currently supported.
+func (c *Client) Attach(name string) (File, error) {
+	fid, ok := c.fidPool.Get()
+	if !ok {
+		return nil, ErrOutOfFIDs
+	}
+
+	rattach := Rattach{}
+	if err := c.sendRecv(&Tattach{FID: FID(fid), Auth: Tauth{AttachName: name, AuthenticationFID: NoFID, UID: NoUID}}, &rattach); err != nil {
+		c.fidPool.Put(fid)
+		return nil, err
+	}
+
+	return c.newFile(FID(fid)), nil
+}
+
+// newFile returns a new client file.
+func (c *Client) newFile(fid FID) *clientFile {
+	cf := &clientFile{
+		client: c,
+		fid:    fid,
+	}
+
+	// Make sure the file is closed.
+	runtime.SetFinalizer(cf, (*clientFile).Close)
+
+	return cf
+}
+
+// clientFile is provided to clients.
+//
+// This proxies all of the interfaces found in file.go.
+type clientFile struct {
+	// client is the originating client.
+	client *Client
+
+	// fid is the FID for this file.
+	fid FID
+
+	// closed indicates whether this file has been closed.
+	closed uint32
+}
+
+// Walk implements File.Walk.
+func (c *clientFile) Walk(names []string) ([]QID, File, error) {
+	fid, ok := c.client.fidPool.Get()
+	if !ok {
+		return nil, nil, ErrOutOfFIDs
+	}
+
+	rwalk := Rwalk{}
+	if err := c.client.sendRecv(&Twalk{FID: c.fid, NewFID: FID(fid), Names: names}, &rwalk); err != nil {
+		c.client.fidPool.Put(fid)
+		return nil, nil, err
+	}
+
+	// Return a new client file.
+	return rwalk.QIDs, c.client.newFile(FID(fid)), nil
+}
+
+// WalkGetAttr implements File.WalkGetAttr.
+func (c *clientFile) WalkGetAttr(components []string) ([]QID, File, AttrMask, Attr, error) {
+	if !versionSupportsTwalkgetattr(c.client.version) {
+		qids, file, err := c.Walk(components)
+		if err != nil {
+			return nil, nil, AttrMask{}, Attr{}, err
+		}
+		_, valid, attr, err := file.GetAttr(AttrMaskAll())
+		if err != nil {
+			file.Close()
+			return nil, nil, AttrMask{}, Attr{}, err
+		}
+		return qids, file, valid, attr, nil
+	}
+
+	fid, ok := c.client.fidPool.Get()
+	if !ok {
+		return nil, nil, AttrMask{}, Attr{}, ErrOutOfFIDs
+	}
+
+	rwalkgetattr := Rwalkgetattr{}
+	if err := c.client.sendRecv(&Twalkgetattr{FID: c.fid, NewFID: FID(fid), Names: components}, &rwalkgetattr); err != nil {
+		c.client.fidPool.Put(fid)
+		return nil, nil, AttrMask{}, Attr{}, err
+	}
+
+	// Return a new client file.
+	return rwalkgetattr.QIDs, c.client.newFile(FID(fid)), rwalkgetattr.Valid, rwalkgetattr.Attr, nil
+}
+
+// StatFS implements File.StatFS.
+func (c *clientFile) StatFS() (FSStat, error) {
+	rstatfs := Rstatfs{}
+	if err := c.client.sendRecv(&Tstatfs{FID: c.fid}, &rstatfs); err != nil {
+		return FSStat{}, err
+	}
+
+	return rstatfs.FSStat, nil
+}
+
+// FSync implements File.FSync.
+func (c *clientFile) FSync() error {
+	return c.client.sendRecv(&Tfsync{FID: c.fid}, &Rfsync{})
+}
+
+// GetAttr implements File.GetAttr.
+func (c *clientFile) GetAttr(req AttrMask) (QID, AttrMask, Attr, error) {
+	rgetattr := Rgetattr{}
+	if err := c.client.sendRecv(&Tgetattr{FID: c.fid, AttrMask: req}, &rgetattr); err != nil {
+		return QID{}, AttrMask{}, Attr{}, err
+	}
+
+	return rgetattr.QID, rgetattr.Valid, rgetattr.Attr, nil
+}
+
+// SetAttr implements File.SetAttr.
+func (c *clientFile) SetAttr(valid SetAttrMask, attr SetAttr) error {
+	return c.client.sendRecv(&Tsetattr{FID: c.fid, Valid: valid, SetAttr: attr}, &Rsetattr{})
+}
+
+// Remove implements File.Remove.
+func (c *clientFile) Remove() error {
+	if err := c.client.sendRecv(&Tremove{FID: c.fid}, &Rremove{}); err != nil {
+		log.Warningf("Tremove failed, losing FID %v: %v", c.fid, err)
+		return err
+	}
+
+	// "It is correct to consider remove to be a clunk with the side effect
+	// of removing the file if permissions allow."
+	// https://swtch.com/plan9port/man/man9/remove.html
+	// Return the FID to the pool.
+	c.client.fidPool.Put(uint64(c.fid))
+	return nil
+}
+
+// Close implements File.Close.
+func (c *clientFile) Close() error {
+	// Avoid double close.
+	if !atomic.CompareAndSwapUint32(&c.closed, 0, 1) {
+		return nil
+	}
+
+	// Send the close message.
+	if err := c.client.sendRecv(&Tclunk{FID: c.fid}, &Rclunk{}); err != nil {
+		// If an error occurred, we toss away the FID. This isn't ideal,
+		// but I'm not sure what else makes sense in this context.
+		log.Warningf("Tclunk failed, losing FID %v: %v", c.fid, err)
+		return err
+	}
+
+	// Return the FID to the pool.
+	c.client.fidPool.Put(uint64(c.fid))
+	return nil
+}
+
+// Open implements File.Open.
+func (c *clientFile) Open(flags OpenFlags) (*fd.FD, QID, uint32, error) {
+	rlopen := Rlopen{}
+	if err := c.client.sendRecv(&Tlopen{FID: c.fid, Flags: flags}, &rlopen); err != nil {
+		return nil, QID{}, 0, err
+	}
+
+	return rlopen.File, rlopen.QID, rlopen.IoUnit, nil
+}
+
+// Connect implements File.Connect.
+func (c *clientFile) Connect(flags ConnectFlags) (*fd.FD, error) {
+	if !VersionSupportsConnect(c.client.version) {
+		return nil, syscall.ECONNREFUSED
+	}
+	rlconnect := Rlconnect{}
+	if err := c.client.sendRecv(&Tlconnect{FID: c.fid, Flags: flags}, &rlconnect); err != nil {
+		return nil, err
+	}
+
+	return rlconnect.File, nil
+}
+
+// chunk applies fn to p in chunkSize-sized chunks until fn returns a partial result, p is
+// exhausted, or an error is encountered (which may be io.EOF).
+func chunk(chunkSize uint32, fn func([]byte, uint64) (int, error), p []byte, offset uint64) (int, error) {
+	// Some p9.Clients depend on executing fn on zero-byte buffers. Handle this
+	// as a special case (normally it is fine to short-circuit and return (0, nil)).
+	if len(p) == 0 {
+		return fn(p, offset)
+	}
+
+	// total is the cumulative bytes processed.
+	var total int
+	for {
+		var n int
+		var err error
+
+		// We're done, don't bother trying to do anything more.
+		if total == len(p) {
+			return total, nil
+		}
+
+		// Apply fn to a chunkSize-sized (or less) chunk of p.
+		if len(p) < total+int(chunkSize) {
+			n, err = fn(p[total:], offset)
+		} else {
+			n, err = fn(p[total:total+int(chunkSize)], offset)
+		}
+		total += n
+		offset += uint64(n)
+
+		// Return whatever we have processed if we encounter an error. This error
+		// could be io.EOF.
+		if err != nil {
+			return total, err
+		}
+
+		// Did we get a partial result? If so, return it immediately.
+		if n < int(chunkSize) {
+			return total, nil
+		}
+
+		// If we received more bytes than we ever requested, this is a problem.
+		if total > len(p) {
+			panic(fmt.Sprintf("bytes completed (%d)) > requested (%d)", total, len(p)))
+		}
+	}
+}
+
+// ReadAt proxies File.ReadAt.
+func (c *clientFile) ReadAt(p []byte, offset uint64) (int, error) {
+	return chunk(c.client.payloadSize, c.readAt, p, offset)
+}
+
+func (c *clientFile) readAt(p []byte, offset uint64) (int, error) {
+	rread := Rread{Data: p}
+	if err := c.client.sendRecv(&Tread{FID: c.fid, Offset: offset, Count: uint32(len(p))}, &rread); err != nil {
+		return 0, err
+	}
+
+	// The message may have been truncated, or for some reason a new buffer
+	// allocated. This isn't the common path, but we make sure that if the
+	// payload has changed we copy it. See transport.go for more information.
+	if len(p) > 0 && len(rread.Data) > 0 && &rread.Data[0] != &p[0] {
+		copy(p, rread.Data)
+	}
+
+	// io.EOF is not an error that a p9 server can return. Use POSIX semantics to
+	// return io.EOF manually: zero bytes were returned and a non-zero buffer was used.
+	if len(rread.Data) == 0 && len(p) > 0 {
+		return 0, io.EOF
+	}
+
+	return len(rread.Data), nil
+}
+
+// WriteAt proxies File.WriteAt.
+func (c *clientFile) WriteAt(p []byte, offset uint64) (int, error) {
+	return chunk(c.client.payloadSize, c.writeAt, p, offset)
+}
+
+func (c *clientFile) writeAt(p []byte, offset uint64) (int, error) {
+	rwrite := Rwrite{}
+	if err := c.client.sendRecv(&Twrite{FID: c.fid, Offset: offset, Data: p}, &rwrite); err != nil {
+		return 0, err
+	}
+
+	return int(rwrite.Count), nil
+}
+
+// ReadWriterFile wraps a File and implements io.ReadWriter, io.ReaderAt, and io.WriterAt.
+type ReadWriterFile struct {
+	File   File
+	Offset uint64
+}
+
+// Read implements part of the io.ReadWriter interface.
+func (r *ReadWriterFile) Read(p []byte) (int, error) {
+	n, err := r.File.ReadAt(p, r.Offset)
+	r.Offset += uint64(n)
+	if err != nil {
+		return n, err
+	}
+	if n == 0 && len(p) > 0 {
+		return n, io.EOF
+	}
+	return n, nil
+}
+
+// ReadAt implements the io.ReaderAt interface.
+func (r *ReadWriterFile) ReadAt(p []byte, offset int64) (int, error) {
+	n, err := r.File.ReadAt(p, uint64(offset))
+	if err != nil {
+		return 0, err
+	}
+	if n == 0 && len(p) > 0 {
+		return n, io.EOF
+	}
+	return n, nil
+}
+
+// Write implements part of the io.ReadWriter interface.
+func (r *ReadWriterFile) Write(p []byte) (int, error) {
+	n, err := r.File.WriteAt(p, r.Offset)
+	r.Offset += uint64(n)
+	if err != nil {
+		return n, err
+	}
+	if n < len(p) {
+		return n, io.ErrShortWrite
+	}
+	return n, nil
+}
+
+// WriteAt implements the io.WriteAt interface.
+func (r *ReadWriterFile) WriteAt(p []byte, offset int64) (int, error) {
+	n, err := r.File.WriteAt(p, uint64(offset))
+	if err != nil {
+		return n, err
+	}
+	if n < len(p) {
+		return n, io.ErrShortWrite
+	}
+	return n, nil
+}
+
+// Rename implements File.Rename.
+func (c *clientFile) Rename(dir File, name string) error {
+	clientDir, ok := dir.(*clientFile)
+	if !ok {
+		return syscall.EBADF
+	}
+	return c.client.sendRecv(&Trename{FID: c.fid, Directory: clientDir.fid, Name: name}, &Rrename{})
+}
+
+// Create implements File.Create.
+func (c *clientFile) Create(name string, openFlags OpenFlags, permissions FileMode, uid UID, gid GID) (*fd.FD, File, QID, uint32, error) {
+	msg := Tlcreate{
+		FID:         c.fid,
+		Name:        name,
+		OpenFlags:   openFlags,
+		Permissions: permissions,
+		GID:         NoGID,
+	}
+
+	if versionSupportsTucreation(c.client.version) {
+		msg.GID = gid
+		rucreate := Rucreate{}
+		if err := c.client.sendRecv(&Tucreate{Tlcreate: msg, UID: uid}, &rucreate); err != nil {
+			return nil, nil, QID{}, 0, err
+		}
+		return rucreate.File, c, rucreate.QID, rucreate.IoUnit, nil
+	}
+
+	rlcreate := Rlcreate{}
+	if err := c.client.sendRecv(&msg, &rlcreate); err != nil {
+		return nil, nil, QID{}, 0, err
+	}
+	return rlcreate.File, c, rlcreate.QID, rlcreate.IoUnit, nil
+}
+
+// Mkdir implements File.Mkdir.
+func (c *clientFile) Mkdir(name string, permissions FileMode, uid UID, gid GID) (QID, error) {
+	msg := Tmkdir{
+		Directory:   c.fid,
+		Name:        name,
+		Permissions: permissions,
+		GID:         NoGID,
+	}
+
+	if versionSupportsTucreation(c.client.version) {
+		msg.GID = gid
+		rumkdir := Rumkdir{}
+		if err := c.client.sendRecv(&Tumkdir{Tmkdir: msg, UID: uid}, &rumkdir); err != nil {
+			return QID{}, err
+		}
+		return rumkdir.QID, nil
+	}
+
+	rmkdir := Rmkdir{}
+	if err := c.client.sendRecv(&msg, &rmkdir); err != nil {
+		return QID{}, err
+	}
+	return rmkdir.QID, nil
+}
+
+// Symlink implements File.Symlink.
+func (c *clientFile) Symlink(oldname string, newname string, uid UID, gid GID) (QID, error) {
+	msg := Tsymlink{
+		Directory: c.fid,
+		Name:      newname,
+		Target:    oldname,
+		GID:       NoGID,
+	}
+
+	if versionSupportsTucreation(c.client.version) {
+		msg.GID = gid
+		rusymlink := Rusymlink{}
+		if err := c.client.sendRecv(&Tusymlink{Tsymlink: msg, UID: uid}, &rusymlink); err != nil {
+			return QID{}, err
+		}
+		return rusymlink.QID, nil
+	}
+
+	rsymlink := Rsymlink{}
+	if err := c.client.sendRecv(&msg, &rsymlink); err != nil {
+		return QID{}, err
+	}
+	return rsymlink.QID, nil
+}
+
+// Link implements File.Link.
+func (c *clientFile) Link(target File, newname string) error {
+	targetFile, ok := target.(*clientFile)
+	if !ok {
+		return syscall.EBADF
+	}
+	return c.client.sendRecv(&Tlink{Directory: c.fid, Name: newname, Target: targetFile.fid}, &Rlink{})
+}
+
+// Mknod implements File.Mknod.
+func (c *clientFile) Mknod(name string, permissions FileMode, major uint32, minor uint32, uid UID, gid GID) (QID, error) {
+	msg := Tmknod{
+		Directory:   c.fid,
+		Name:        name,
+		Permissions: permissions,
+		Major:       major,
+		Minor:       minor,
+		GID:         NoGID,
+	}
+
+	if versionSupportsTucreation(c.client.version) {
+		msg.GID = gid
+		rumknod := Rumknod{}
+		if err := c.client.sendRecv(&Tumknod{Tmknod: msg, UID: uid}, &rumknod); err != nil {
+			return QID{}, err
+		}
+		return rumknod.QID, nil
+	}
+
+	rmknod := Rmknod{}
+	if err := c.client.sendRecv(&msg, &rmknod); err != nil {
+		return QID{}, err
+	}
+	return rmknod.QID, nil
+}
+
+// RenameAt implements File.RenameAt.
+func (c *clientFile) RenameAt(oldname string, newdir File, newname string) error {
+	clientNewDir, ok := newdir.(*clientFile)
+	if !ok {
+		return syscall.EBADF
+	}
+	return c.client.sendRecv(&Trenameat{OldDirectory: c.fid, OldName: oldname, NewDirectory: clientNewDir.fid, NewName: newname}, &Rrenameat{})
+}
+
+// UnlinkAt implements File.UnlinkAt.
+func (c *clientFile) UnlinkAt(name string, flags uint32) error {
+	return c.client.sendRecv(&Tunlinkat{Directory: c.fid, Name: name, Flags: flags}, &Runlinkat{})
+}
+
+// Readdir implements File.Readdir.
+func (c *clientFile) Readdir(offset uint64, count uint32) ([]Dirent, error) {
+	rreaddir := Rreaddir{}
+	if err := c.client.sendRecv(&Treaddir{Directory: c.fid, Offset: offset, Count: count}, &rreaddir); err != nil {
+		return nil, err
+	}
+
+	return rreaddir.Entries, nil
+}
+
+// Readlink implements File.Readlink.
+func (c *clientFile) Readlink() (string, error) {
+	rreadlink := Rreadlink{}
+	if err := c.client.sendRecv(&Treadlink{FID: c.fid}, &rreadlink); err != nil {
+		return "", err
+	}
+
+	return rreadlink.Target, nil
+}
+
+// Flush implements File.Flush.
+func (c *clientFile) Flush() error {
+	if !VersionSupportsTflushf(c.client.version) {
+		return nil
+	}
+	return c.client.sendRecv(&Tflushf{FID: c.fid}, &Rflushf{})
+}