Merge release-20210419.0-39-g26adb3c47 (automated)

6 files changed, 218 insertions, 6 deletions

diff --git a/pkg/p9/client_file.go b/pkg/p9/client_file.go
index 7abc82e1b..28396b0ea 100644
--- a/pkg/p9/client_file.go
+++ b/pkg/p9/client_file.go
@@ -121,6 +121,22 @@ func (c *clientFile) WalkGetAttr(components []string) ([]QID, File, AttrMask, At
 	return rwalkgetattr.QIDs, c.client.newFile(FID(fid)), rwalkgetattr.Valid, rwalkgetattr.Attr, nil
 }
 
+func (c *clientFile) MultiGetAttr(names []string) ([]FullStat, error) {
+	if atomic.LoadUint32(&c.closed) != 0 {
+		return nil, unix.EBADF
+	}
+
+	if !versionSupportsTmultiGetAttr(c.client.version) {
+		return DefaultMultiGetAttr(c, names)
+	}
+
+	rmultigetattr := Rmultigetattr{}
+	if err := c.client.sendRecv(&Tmultigetattr{FID: c.fid, Names: names}, &rmultigetattr); err != nil {
+		return nil, err
+	}
+	return rmultigetattr.Stats, nil
+}
+
 // StatFS implements File.StatFS.
 func (c *clientFile) StatFS() (FSStat, error) {
 	if atomic.LoadUint32(&c.closed) != 0 {
diff --git a/pkg/p9/file.go b/pkg/p9/file.go
index c59c6a65b..97e0231d6 100644
--- a/pkg/p9/file.go
+++ b/pkg/p9/file.go
@@ -15,6 +15,8 @@
 package p9
 
 import (
+	"errors"
+
 	"golang.org/x/sys/unix"
 	"gvisor.dev/gvisor/pkg/fd"
 )
@@ -72,6 +74,15 @@ type File interface {
 	// On the server, WalkGetAttr has a read concurrency guarantee.
 	WalkGetAttr([]string) ([]QID, File, AttrMask, Attr, error)
 
+	// MultiGetAttr batches up multiple calls to GetAttr(). names is a list of
+	// path components similar to Walk(). If the first component name is empty,
+	// the current file is stat'd and included in the results. If the walk reaches
+	// a file that doesn't exist or not a directory, MultiGetAttr returns the
+	// partial result with no error.
+	//
+	// On the server, MultiGetAttr has a read concurrency guarantee.
+	MultiGetAttr(names []string) ([]FullStat, error)
+
 	// StatFS returns information about the file system associated with
 	// this file.
 	//
@@ -306,6 +317,53 @@ func (DisallowClientCalls) SetAttrClose(SetAttrMask, SetAttr) error {
 type DisallowServerCalls struct{}
 
 // Renamed implements File.Renamed.
-func (*clientFile) Renamed(File, string) {
+func (*DisallowServerCalls) Renamed(File, string) {
 	panic("Renamed should not be called on the client")
 }
+
+// DefaultMultiGetAttr implements File.MultiGetAttr() on top of File.
+func DefaultMultiGetAttr(start File, names []string) ([]FullStat, error) {
+	stats := make([]FullStat, 0, len(names))
+	parent := start
+	mask := AttrMaskAll()
+	for i, name := range names {
+		if len(name) == 0 && i == 0 {
+			qid, valid, attr, err := parent.GetAttr(mask)
+			if err != nil {
+				return nil, err
+			}
+			stats = append(stats, FullStat{
+				QID:   qid,
+				Valid: valid,
+				Attr:  attr,
+			})
+			continue
+		}
+		qids, child, valid, attr, err := parent.WalkGetAttr([]string{name})
+		if parent != start {
+			_ = parent.Close()
+		}
+		if err != nil {
+			if errors.Is(err, unix.ENOENT) {
+				return stats, nil
+			}
+			return nil, err
+		}
+		stats = append(stats, FullStat{
+			QID:   qids[0],
+			Valid: valid,
+			Attr:  attr,
+		})
+		if attr.Mode.FileType() != ModeDirectory {
+			// Doesn't need to continue if entry is not a dir. Including symlinks
+			// that cannot be followed.
+			_ = child.Close()
+			break
+		}
+		parent = child
+	}
+	if parent != start {
+		_ = parent.Close()
+	}
+	return stats, nil
+}
diff --git a/pkg/p9/handlers.go b/pkg/p9/handlers.go
index 58312d0cc..758e11b13 100644
--- a/pkg/p9/handlers.go
+++ b/pkg/p9/handlers.go
@@ -1421,3 +1421,31 @@ func (t *Tchannel) handle(cs *connState) message {
 	}
 	return rchannel
 }
+
+// handle implements handler.handle.
+func (t *Tmultigetattr) handle(cs *connState) message {
+	for i, name := range t.Names {
+		if len(name) == 0 && i == 0 {
+			// Empty name is allowed on the first entry to indicate that the current
+			// FID needs to be included in the result.
+			continue
+		}
+		if err := checkSafeName(name); err != nil {
+			return newErr(err)
+		}
+	}
+	ref, ok := cs.LookupFID(t.FID)
+	if !ok {
+		return newErr(unix.EBADF)
+	}
+	defer ref.DecRef()
+
+	var stats []FullStat
+	if err := ref.safelyRead(func() (err error) {
+		stats, err = ref.file.MultiGetAttr(t.Names)
+		return err
+	}); err != nil {
+		return newErr(err)
+	}
+	return &Rmultigetattr{Stats: stats}
+}
diff --git a/pkg/p9/messages.go b/pkg/p9/messages.go
index cf13cbb69..2ff4694c0 100644
--- a/pkg/p9/messages.go
+++ b/pkg/p9/messages.go
@@ -254,8 +254,8 @@ func (r *Rwalk) decode(b *buffer) {
 // encode implements encoder.encode.
 func (r *Rwalk) encode(b *buffer) {
 	b.Write16(uint16(len(r.QIDs)))
-	for _, q := range r.QIDs {
-		q.encode(b)
+	for i := range r.QIDs {
+		r.QIDs[i].encode(b)
 	}
 }
 
@@ -2243,8 +2243,8 @@ func (r *Rwalkgetattr) encode(b *buffer) {
 	r.Valid.encode(b)
 	r.Attr.encode(b)
 	b.Write16(uint16(len(r.QIDs)))
-	for _, q := range r.QIDs {
-		q.encode(b)
+	for i := range r.QIDs {
+		r.QIDs[i].encode(b)
 	}
 }
 
@@ -2552,6 +2552,80 @@ func (r *Rchannel) String() string {
 	return fmt.Sprintf("Rchannel{Offset: %d, Length: %d}", r.Offset, r.Length)
 }
 
+// Tmultigetattr is a multi-getattr request.
+type Tmultigetattr struct {
+	// FID is the FID to be walked.
+	FID FID
+
+	// Names are the set of names to be walked.
+	Names []string
+}
+
+// decode implements encoder.decode.
+func (t *Tmultigetattr) decode(b *buffer) {
+	t.FID = b.ReadFID()
+	n := b.Read16()
+	t.Names = t.Names[:0]
+	for i := 0; i < int(n); i++ {
+		t.Names = append(t.Names, b.ReadString())
+	}
+}
+
+// encode implements encoder.encode.
+func (t *Tmultigetattr) encode(b *buffer) {
+	b.WriteFID(t.FID)
+	b.Write16(uint16(len(t.Names)))
+	for _, name := range t.Names {
+		b.WriteString(name)
+	}
+}
+
+// Type implements message.Type.
+func (*Tmultigetattr) Type() MsgType {
+	return MsgTmultigetattr
+}
+
+// String implements fmt.Stringer.
+func (t *Tmultigetattr) String() string {
+	return fmt.Sprintf("Tmultigetattr{FID: %d, Names: %v}", t.FID, t.Names)
+}
+
+// Rmultigetattr is a multi-getattr response.
+type Rmultigetattr struct {
+	// Stats are the set of FullStat returned for each of the names in the
+	// request.
+	Stats []FullStat
+}
+
+// decode implements encoder.decode.
+func (r *Rmultigetattr) decode(b *buffer) {
+	n := b.Read16()
+	r.Stats = r.Stats[:0]
+	for i := 0; i < int(n); i++ {
+		var fs FullStat
+		fs.decode(b)
+		r.Stats = append(r.Stats, fs)
+	}
+}
+
+// encode implements encoder.encode.
+func (r *Rmultigetattr) encode(b *buffer) {
+	b.Write16(uint16(len(r.Stats)))
+	for i := range r.Stats {
+		r.Stats[i].encode(b)
+	}
+}
+
+// Type implements message.Type.
+func (*Rmultigetattr) Type() MsgType {
+	return MsgRmultigetattr
+}
+
+// String implements fmt.Stringer.
+func (r *Rmultigetattr) String() string {
+	return fmt.Sprintf("Rmultigetattr{Stats: %v}", r.Stats)
+}
+
 const maxCacheSize = 3
 
 // msgFactory is used to reduce allocations by caching messages for reuse.
@@ -2717,6 +2791,8 @@ func init() {
 	msgRegistry.register(MsgRallocate, func() message { return &Rallocate{} })
 	msgRegistry.register(MsgTsetattrclunk, func() message { return &Tsetattrclunk{} })
 	msgRegistry.register(MsgRsetattrclunk, func() message { return &Rsetattrclunk{} })
+	msgRegistry.register(MsgTmultigetattr, func() message { return &Tmultigetattr{} })
+	msgRegistry.register(MsgRmultigetattr, func() message { return &Rmultigetattr{} })
 	msgRegistry.register(MsgTchannel, func() message { return &Tchannel{} })
 	msgRegistry.register(MsgRchannel, func() message { return &Rchannel{} })
 }
diff --git a/pkg/p9/p9.go b/pkg/p9/p9.go
index 648cf4b49..3d452a0bd 100644
--- a/pkg/p9/p9.go
+++ b/pkg/p9/p9.go
@@ -402,6 +402,8 @@ const (
 	MsgRallocate     MsgType = 139
 	MsgTsetattrclunk MsgType = 140
 	MsgRsetattrclunk MsgType = 141
+	MsgTmultigetattr MsgType = 142
+	MsgRmultigetattr MsgType = 143
 	MsgTchannel      MsgType = 250
 	MsgRchannel      MsgType = 251
 )
@@ -1178,3 +1180,29 @@ func (a *AllocateMode) encode(b *buffer) {
 	}
 	b.Write32(mask)
 }
+
+// FullStat is used in the result of a MultiGetAttr call.
+type FullStat struct {
+	QID   QID
+	Valid AttrMask
+	Attr  Attr
+}
+
+// String implements fmt.Stringer.
+func (f *FullStat) String() string {
+	return fmt.Sprintf("FullStat{QID: %v, Valid: %v, Attr: %v}", f.QID, f.Valid, f.Attr)
+}
+
+// decode implements encoder.decode.
+func (f *FullStat) decode(b *buffer) {
+	f.QID.decode(b)
+	f.Valid.decode(b)
+	f.Attr.decode(b)
+}
+
+// encode implements encoder.encode.
+func (f *FullStat) encode(b *buffer) {
+	f.QID.encode(b)
+	f.Valid.encode(b)
+	f.Attr.encode(b)
+}
diff --git a/pkg/p9/version.go b/pkg/p9/version.go
index 8d7168ef5..950236162 100644
--- a/pkg/p9/version.go
+++ b/pkg/p9/version.go
@@ -26,7 +26,7 @@ const (
 	//
 	// Clients are expected to start requesting this version number and
 	// to continuously decrement it until a Tversion request succeeds.
-	highestSupportedVersion uint32 = 12
+	highestSupportedVersion uint32 = 13
 
 	// lowestSupportedVersion is the lowest supported version X in a
 	// version string of the format 9P2000.L.Google.X.
@@ -179,3 +179,9 @@ func versionSupportsListRemoveXattr(v uint32) bool {
 func versionSupportsTsetattrclunk(v uint32) bool {
 	return v >= 12
 }
+
+// versionSupportsTmultiGetAttr returns true if version v supports
+// the TmultiGetAttr message.
+func versionSupportsTmultiGetAttr(v uint32) bool {
+	return v >= 13
+}