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PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 705 insertions, 0 deletions

diff --git a/pkg/p9/handlers.go b/pkg/p9/handlers.go
new file mode 100644
index 000000000..83a66d3ae
--- /dev/null
+++ b/pkg/p9/handlers.go
@@ -0,0 +1,705 @@
+// 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 (
+	"io"
+	"os"
+	"sync/atomic"
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/log"
+)
+
+// newErr returns a new error message from an error.
+func newErr(err error) *Rlerror {
+	switch e := err.(type) {
+	case syscall.Errno:
+		return &Rlerror{Error: uint32(e)}
+	case *os.PathError:
+		return newErr(e.Err)
+	case *os.SyscallError:
+		return newErr(e.Err)
+	default:
+		log.Warningf("unknown error: %v", err)
+		return &Rlerror{Error: uint32(syscall.EIO)}
+	}
+}
+
+// handler is implemented for server-handled messages.
+//
+// See server.go for call information.
+type handler interface {
+	// Handle handles the given message.
+	//
+	// This may modify the server state. The handle function must return a
+	// message which will be sent back to the client. It may be useful to
+	// use newErr to automatically extract an error message.
+	handle(cs *connState) message
+}
+
+// handle implements handler.handle.
+func (t *Tversion) handle(cs *connState) message {
+	if t.MSize == 0 {
+		return newErr(syscall.EINVAL)
+	}
+	if t.MSize > maximumLength {
+		return newErr(syscall.EINVAL)
+	}
+	atomic.StoreUint32(&cs.messageSize, t.MSize)
+	requested, ok := parseVersion(t.Version)
+	if !ok {
+		return newErr(syscall.EINVAL)
+	}
+	// The server cannot support newer versions that it doesn't know about.  In this
+	// case we return EAGAIN to tell the client to try again with a lower version.
+	if requested > highestSupportedVersion {
+		return newErr(syscall.EAGAIN)
+	}
+	// From Tversion(9P): "The server may respond with the client’s version
+	// string, or a version string identifying an earlier defined protocol version".
+	atomic.StoreUint32(&cs.version, requested)
+	return &Rversion{
+		MSize:   t.MSize,
+		Version: t.Version,
+	}
+}
+
+// handle implements handler.handle.
+func (t *Tflush) handle(cs *connState) message {
+	cs.WaitTag(t.OldTag)
+	return &Rflush{}
+}
+
+// handle implements handler.handle.
+func (t *Twalk) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Has it been opened already?
+	if _, opened := ref.OpenFlags(); opened {
+		return newErr(syscall.EBUSY)
+	}
+
+	// Do the walk.
+	qids, sf, err := ref.file.Walk(t.Names)
+	if err != nil {
+		return newErr(err)
+	}
+
+	// Install the new FID.
+	cs.InsertFID(t.NewFID, &fidRef{file: sf})
+
+	return &Rwalk{QIDs: qids}
+}
+
+// handle implements handler.handle.
+func (t *Tclunk) handle(cs *connState) message {
+	if !cs.DeleteFID(t.FID) {
+		return newErr(syscall.EBADF)
+	}
+	return &Rclunk{}
+}
+
+// handle implements handler.handle.
+func (t *Tremove) handle(cs *connState) message {
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// "The remove request asks the file server both to remove the file
+	// represented by fid and to clunk the fid, even if the remove fails."
+	//
+	// "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
+	err := ref.file.Remove()
+
+	// Clunk the FID regardless of Remove error.
+	if !cs.DeleteFID(t.FID) {
+		return newErr(syscall.EBADF)
+	}
+
+	if err != nil {
+		return newErr(err)
+	}
+	return &Rremove{}
+}
+
+// handle implements handler.handle.
+//
+// We don't support authentication, so this just returns ENOSYS.
+func (t *Tauth) handle(cs *connState) message {
+	return newErr(syscall.ENOSYS)
+}
+
+// handle implements handler.handle.
+func (t *Tattach) handle(cs *connState) message {
+	// Ensure no authentication FID is provided.
+	if t.Auth.AuthenticationFID != NoFID {
+		return newErr(syscall.EINVAL)
+	}
+
+	// Do the attach.
+	sf, err := cs.server.attacher.Attach(t.Auth.AttachName)
+	if err != nil {
+		return newErr(err)
+	}
+	cs.InsertFID(t.FID, &fidRef{file: sf})
+
+	// Return an empty QID.
+	return &Rattach{}
+}
+
+// handle implements handler.handle.
+func (t *Tlopen) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	ref.openedMu.Lock()
+	defer ref.openedMu.Unlock()
+
+	// Has it been opened already?
+	if ref.opened {
+		return newErr(syscall.EINVAL)
+	}
+
+	// Do the open.
+	osFile, qid, ioUnit, err := ref.file.Open(t.Flags)
+	if err != nil {
+		return newErr(err)
+	}
+
+	// Mark file as opened and set open mode.
+	ref.opened = true
+	ref.openFlags = t.Flags
+
+	return &Rlopen{QID: qid, IoUnit: ioUnit, File: osFile}
+}
+
+func (t *Tlcreate) do(cs *connState, uid UID) (*Rlcreate, error) {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return nil, syscall.EBADF
+	}
+	defer ref.DecRef()
+
+	// Do the create.
+	osFile, nsf, qid, ioUnit, err := ref.file.Create(t.Name, t.OpenFlags, t.Permissions, uid, t.GID)
+	if err != nil {
+		return nil, err
+	}
+
+	// Replace the FID reference.
+	//
+	// The new file will be opened already.
+	cs.InsertFID(t.FID, &fidRef{file: nsf, opened: true, openFlags: t.OpenFlags})
+
+	return &Rlcreate{Rlopen: Rlopen{QID: qid, IoUnit: ioUnit, File: osFile}}, nil
+}
+
+// handle implements handler.handle.
+func (t *Tlcreate) handle(cs *connState) message {
+	rlcreate, err := t.do(cs, NoUID)
+	if err != nil {
+		return newErr(err)
+	}
+	return rlcreate
+}
+
+// handle implements handler.handle.
+func (t *Tsymlink) handle(cs *connState) message {
+	rsymlink, err := t.do(cs, NoUID)
+	if err != nil {
+		return newErr(err)
+	}
+	return rsymlink
+}
+
+func (t *Tsymlink) do(cs *connState, uid UID) (*Rsymlink, error) {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return nil, syscall.EBADF
+	}
+	defer ref.DecRef()
+
+	// Do the symlink.
+	qid, err := ref.file.Symlink(t.Target, t.Name, uid, t.GID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Rsymlink{QID: qid}, nil
+}
+
+// handle implements handler.handle.
+func (t *Tlink) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Lookup the other FID.
+	refTarget, ok := cs.LookupFID(t.Target)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer refTarget.DecRef()
+
+	// Do the link.
+	if err := ref.file.Link(refTarget.file, t.Name); err != nil {
+		return newErr(err)
+	}
+
+	return &Rlink{}
+}
+
+// handle implements handler.handle.
+func (t *Trenameat) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.OldDirectory)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Lookup the other FID.
+	refTarget, ok := cs.LookupFID(t.NewDirectory)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer refTarget.DecRef()
+
+	// Do the rename.
+	if err := ref.file.RenameAt(t.OldName, refTarget.file, t.NewName); err != nil {
+		return newErr(err)
+	}
+
+	return &Rrenameat{}
+}
+
+// handle implements handler.handle.
+func (t *Tunlinkat) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Do the unlink.
+	if err := ref.file.UnlinkAt(t.Name, t.Flags); err != nil {
+		return newErr(err)
+	}
+
+	return &Runlinkat{}
+}
+
+// handle implements handler.handle.
+func (t *Trename) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Lookup the target.
+	refTarget, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer refTarget.DecRef()
+
+	// Call the rename method.
+	if err := ref.file.Rename(refTarget.file, t.Name); err != nil {
+		return newErr(err)
+	}
+
+	return &Rrename{}
+}
+
+// handle implements handler.handle.
+func (t *Treadlink) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Do the read.
+	target, err := ref.file.Readlink()
+	if err != nil {
+		return newErr(err)
+	}
+
+	return &Rreadlink{target}
+}
+
+// handle implements handler.handle.
+func (t *Tread) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Has it been opened already?
+	openFlags, opened := ref.OpenFlags()
+	if !opened {
+		return newErr(syscall.EINVAL)
+	}
+
+	// Can it be read? Check permissions.
+	if openFlags&OpenFlagsModeMask == WriteOnly {
+		return newErr(syscall.EPERM)
+	}
+
+	// Constrain the size of the read buffer.
+	if int(t.Count) > int(maximumLength) {
+		return newErr(syscall.ENOBUFS)
+	}
+
+	// Do the read.
+	data := make([]byte, t.Count)
+	n, err := ref.file.ReadAt(data, t.Offset)
+	if err != nil && err != io.EOF {
+		return newErr(err)
+	}
+
+	return &Rread{Data: data[:n]}
+}
+
+// handle implements handler.handle.
+func (t *Twrite) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Has it been opened already?
+	openFlags, opened := ref.OpenFlags()
+	if !opened {
+		return newErr(syscall.EINVAL)
+	}
+
+	// Can it be write? Check permissions.
+	if openFlags&OpenFlagsModeMask == ReadOnly {
+		return newErr(syscall.EPERM)
+	}
+
+	// Do the write.
+	n, err := ref.file.WriteAt(t.Data, t.Offset)
+	if err != nil {
+		return newErr(err)
+	}
+
+	return &Rwrite{Count: uint32(n)}
+}
+
+// handle implements handler.handle.
+func (t *Tmknod) handle(cs *connState) message {
+	rmknod, err := t.do(cs, NoUID)
+	if err != nil {
+		return newErr(err)
+	}
+	return rmknod
+}
+
+func (t *Tmknod) do(cs *connState, uid UID) (*Rmknod, error) {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return nil, syscall.EBADF
+	}
+	defer ref.DecRef()
+
+	// Do the mknod.
+	qid, err := ref.file.Mknod(t.Name, t.Permissions, t.Major, t.Minor, uid, t.GID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Rmknod{QID: qid}, nil
+}
+
+// handle implements handler.handle.
+func (t *Tmkdir) handle(cs *connState) message {
+	rmkdir, err := t.do(cs, NoUID)
+	if err != nil {
+		return newErr(err)
+	}
+	return rmkdir
+}
+
+func (t *Tmkdir) do(cs *connState, uid UID) (*Rmkdir, error) {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return nil, syscall.EBADF
+	}
+	defer ref.DecRef()
+
+	// Do the mkdir.
+	qid, err := ref.file.Mkdir(t.Name, t.Permissions, uid, t.GID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Rmkdir{QID: qid}, nil
+}
+
+// handle implements handler.handle.
+func (t *Tgetattr) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Get attributes.
+	qid, valid, attr, err := ref.file.GetAttr(t.AttrMask)
+	if err != nil {
+		return newErr(err)
+	}
+
+	return &Rgetattr{QID: qid, Valid: valid, Attr: attr}
+}
+
+// handle implements handler.handle.
+func (t *Tsetattr) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Set attributes.
+	if err := ref.file.SetAttr(t.Valid, t.SetAttr); err != nil {
+		return newErr(err)
+	}
+
+	return &Rsetattr{}
+}
+
+// handle implements handler.handle.
+func (t *Txattrwalk) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// We don't support extended attributes.
+	return newErr(syscall.ENODATA)
+}
+
+// handle implements handler.handle.
+func (t *Txattrcreate) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// We don't support extended attributes.
+	return newErr(syscall.ENOSYS)
+}
+
+// handle implements handler.handle.
+func (t *Treaddir) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.Directory)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Has it been opened already?
+	if _, opened := ref.OpenFlags(); !opened {
+		return newErr(syscall.EINVAL)
+	}
+
+	// Read the entries.
+	entries, err := ref.file.Readdir(t.Offset, t.Count)
+	if err != nil && err != io.EOF {
+		return newErr(err)
+	}
+
+	return &Rreaddir{Count: t.Count, Entries: entries}
+}
+
+// handle implements handler.handle.
+func (t *Tfsync) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Has it been opened already?
+	if _, opened := ref.OpenFlags(); !opened {
+		return newErr(syscall.EINVAL)
+	}
+
+	err := ref.file.FSync()
+	if err != nil {
+		return newErr(err)
+	}
+
+	return &Rfsync{}
+}
+
+// handle implements handler.handle.
+func (t *Tstatfs) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	st, err := ref.file.StatFS()
+	if err != nil {
+		return newErr(err)
+	}
+
+	return &Rstatfs{st}
+}
+
+// handle implements handler.handle.
+func (t *Tflushf) handle(cs *connState) message {
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	if err := ref.file.Flush(); err != nil {
+		return newErr(err)
+	}
+
+	return &Rflushf{}
+}
+
+// handle implements handler.handle.
+func (t *Twalkgetattr) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Has it been opened already?
+	if _, opened := ref.OpenFlags(); opened {
+		return newErr(syscall.EBUSY)
+	}
+
+	// Do the walk.
+	qids, sf, valid, attr, err := ref.file.WalkGetAttr(t.Names)
+	if err == syscall.ENOSYS {
+		qids, sf, err = ref.file.Walk(t.Names)
+		if err != nil {
+			return newErr(err)
+		}
+		_, valid, attr, err = sf.GetAttr(AttrMaskAll())
+	}
+	if err != nil {
+		return newErr(err)
+	}
+
+	// Install the new FID.
+	cs.InsertFID(t.NewFID, &fidRef{file: sf})
+
+	return &Rwalkgetattr{QIDs: qids, Valid: valid, Attr: attr}
+}
+
+// handle implements handler.handle.
+func (t *Tucreate) handle(cs *connState) message {
+	rlcreate, err := t.Tlcreate.do(cs, t.UID)
+	if err != nil {
+		return newErr(err)
+	}
+	return &Rucreate{*rlcreate}
+}
+
+// handle implements handler.handle.
+func (t *Tumkdir) handle(cs *connState) message {
+	rmkdir, err := t.Tmkdir.do(cs, t.UID)
+	if err != nil {
+		return newErr(err)
+	}
+	return &Rumkdir{*rmkdir}
+}
+
+// handle implements handler.handle.
+func (t *Tusymlink) handle(cs *connState) message {
+	rsymlink, err := t.Tsymlink.do(cs, t.UID)
+	if err != nil {
+		return newErr(err)
+	}
+	return &Rusymlink{*rsymlink}
+}
+
+// handle implements handler.handle.
+func (t *Tumknod) handle(cs *connState) message {
+	rmknod, err := t.Tmknod.do(cs, t.UID)
+	if err != nil {
+		return newErr(err)
+	}
+	return &Rumknod{*rmknod}
+}
+
+// handle implements handler.handle.
+func (t *Tlconnect) handle(cs *connState) message {
+	// Lookup the FID.
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(syscall.EBADF)
+	}
+	defer ref.DecRef()
+
+	// Do the connect.
+	osFile, err := ref.file.Connect(t.Flags)
+	if err != nil {
+		return newErr(err)
+	}
+
+	return &Rlconnect{File: osFile}
+}