Refactor tty codebase to use master-replica terminology.

Updates #2972

PiperOrigin-RevId: 329584905

9 files changed, 79 insertions, 78 deletions

diff --git a/pkg/sentry/fs/tty/BUILD b/pkg/sentry/fs/tty/BUILD
index b3f5a8244..fdd5a40d5 100644
--- a/pkg/sentry/fs/tty/BUILD
+++ b/pkg/sentry/fs/tty/BUILD
@@ -10,7 +10,7 @@ go_library(
         "line_discipline.go",
         "master.go",
         "queue.go",
-        "slave.go",
+        "replica.go",
         "terminal.go",
     ],
     visibility = ["//pkg/sentry:internal"],
diff --git a/pkg/sentry/fs/tty/dir.go b/pkg/sentry/fs/tty/dir.go
index 463f6189e..c2da80bc2 100644
--- a/pkg/sentry/fs/tty/dir.go
+++ b/pkg/sentry/fs/tty/dir.go
@@ -37,14 +37,14 @@ import (
 // This indirectly manages all terminals within the mount.
 //
 // New Terminals are created by masterInodeOperations.GetFile, which registers
-// the slave Inode in the this directory for discovery via Lookup/Readdir. The
-// slave inode is unregistered when the master file is Released, as the slave
+// the replica Inode in the this directory for discovery via Lookup/Readdir. The
+// replica inode is unregistered when the master file is Released, as the replica
 // is no longer discoverable at that point.
 //
 // References on the underlying Terminal are held by masterFileOperations and
-// slaveInodeOperations.
+// replicaInodeOperations.
 //
-// masterInodeOperations and slaveInodeOperations hold a pointer to
+// masterInodeOperations and replicaInodeOperations hold a pointer to
 // dirInodeOperations, which is reference counted by the refcount their
 // corresponding Dirents hold on their parent (this directory).
 //
@@ -76,16 +76,16 @@ type dirInodeOperations struct {
 	// master is the master PTY inode.
 	master *fs.Inode
 
-	// slaves contains the slave inodes reachable from the directory.
+	// replicas contains the replica inodes reachable from the directory.
 	//
-	// A new slave is added by allocateTerminal and is removed by
+	// A new replica is added by allocateTerminal and is removed by
 	// masterFileOperations.Release.
 	//
-	// A reference is held on every slave in the map.
-	slaves map[uint32]*fs.Inode
+	// A reference is held on every replica in the map.
+	replicas map[uint32]*fs.Inode
 
 	// dentryMap is a SortedDentryMap used to implement Readdir containing
-	// the master and all entries in slaves.
+	// the master and all entries in replicas.
 	dentryMap *fs.SortedDentryMap
 
 	// next is the next pty index to use.
@@ -101,7 +101,7 @@ func newDir(ctx context.Context, m *fs.MountSource) *fs.Inode {
 	d := &dirInodeOperations{
 		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, fs.RootOwner, fs.FilePermsFromMode(0555), linux.DEVPTS_SUPER_MAGIC),
 		msrc:                  m,
-		slaves:                make(map[uint32]*fs.Inode),
+		replicas:              make(map[uint32]*fs.Inode),
 		dentryMap:             fs.NewSortedDentryMap(nil),
 	}
 	// Linux devpts uses a default mode of 0000 for ptmx which can be
@@ -133,7 +133,7 @@ func (d *dirInodeOperations) Release(ctx context.Context) {
 	defer d.mu.Unlock()
 
 	d.master.DecRef(ctx)
-	if len(d.slaves) != 0 {
+	if len(d.replicas) != 0 {
 		panic(fmt.Sprintf("devpts directory still contains active terminals: %+v", d))
 	}
 }
@@ -149,14 +149,14 @@ func (d *dirInodeOperations) Lookup(ctx context.Context, dir *fs.Inode, name str
 		return fs.NewDirent(ctx, d.master, name), nil
 	}
 
-	// Slave number?
+	// Replica number?
 	n, err := strconv.ParseUint(name, 10, 32)
 	if err != nil {
 		// Not found.
 		return nil, syserror.ENOENT
 	}
 
-	s, ok := d.slaves[uint32(n)]
+	s, ok := d.replicas[uint32(n)]
 	if !ok {
 		return nil, syserror.ENOENT
 	}
@@ -236,7 +236,7 @@ func (d *dirInodeOperations) allocateTerminal(ctx context.Context) (*Terminal, e
 		return nil, syserror.ENOMEM
 	}
 
-	if _, ok := d.slaves[n]; ok {
+	if _, ok := d.replicas[n]; ok {
 		panic(fmt.Sprintf("pty index collision; index %d already exists", n))
 	}
 
@@ -244,19 +244,19 @@ func (d *dirInodeOperations) allocateTerminal(ctx context.Context) (*Terminal, e
 	d.next++
 
 	// The reference returned by newTerminal is returned to the caller.
-	// Take another for the slave inode.
+	// Take another for the replica inode.
 	t.IncRef()
 
 	// Create a pts node. The owner is based on the context that opens
 	// ptmx.
 	creds := auth.CredentialsFromContext(ctx)
 	uid, gid := creds.EffectiveKUID, creds.EffectiveKGID
-	slave := newSlaveInode(ctx, d, t, fs.FileOwner{uid, gid}, fs.FilePermsFromMode(0666))
+	replica := newReplicaInode(ctx, d, t, fs.FileOwner{uid, gid}, fs.FilePermsFromMode(0666))
 
-	d.slaves[n] = slave
+	d.replicas[n] = replica
 	d.dentryMap.Add(strconv.FormatUint(uint64(n), 10), fs.DentAttr{
-		Type:    slave.StableAttr.Type,
-		InodeID: slave.StableAttr.InodeID,
+		Type:    replica.StableAttr.Type,
+		InodeID: replica.StableAttr.InodeID,
 	})
 
 	return t, nil
@@ -267,18 +267,18 @@ func (d *dirInodeOperations) masterClose(ctx context.Context, t *Terminal) {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 
-	// The slave end disappears from the directory when the master end is
-	// closed, even if the slave end is open elsewhere.
+	// The replica end disappears from the directory when the master end is
+	// closed, even if the replica end is open elsewhere.
 	//
 	// N.B. since we're using a backdoor method to remove a directory entry
 	// we won't properly fire inotify events like Linux would.
-	s, ok := d.slaves[t.n]
+	s, ok := d.replicas[t.n]
 	if !ok {
 		panic(fmt.Sprintf("Terminal %+v doesn't exist in %+v?", t, d))
 	}
 
 	s.DecRef(ctx)
-	delete(d.slaves, t.n)
+	delete(d.replicas, t.n)
 	d.dentryMap.Remove(strconv.FormatUint(uint64(t.n), 10))
 }
 
diff --git a/pkg/sentry/fs/tty/fs.go b/pkg/sentry/fs/tty/fs.go
index 2d4d44bf3..13f4901db 100644
--- a/pkg/sentry/fs/tty/fs.go
+++ b/pkg/sentry/fs/tty/fs.go
@@ -79,8 +79,8 @@ type superOperations struct{}
 //
 // It always returns true, forcing a Lookup for all entries.
 //
-// Slave entries are dropped from dir when their master is closed, so an
-// existing slave Dirent in the tree is not sufficient to guarantee that it
+// Replica entries are dropped from dir when their master is closed, so an
+// existing replica Dirent in the tree is not sufficient to guarantee that it
 // still exists on the filesystem.
 func (superOperations) Revalidate(context.Context, string, *fs.Inode, *fs.Inode) bool {
 	return true
diff --git a/pkg/sentry/fs/tty/line_discipline.go b/pkg/sentry/fs/tty/line_discipline.go
index b6bc011a9..b34f4a0eb 100644
--- a/pkg/sentry/fs/tty/line_discipline.go
+++ b/pkg/sentry/fs/tty/line_discipline.go
@@ -44,7 +44,7 @@ const (
 )
 
 // lineDiscipline dictates how input and output are handled between the
-// pseudoterminal (pty) master and slave. It can be configured to alter I/O,
+// pseudoterminal (pty) master and replica. It can be configured to alter I/O,
 // modify control characters (e.g. Ctrl-C for SIGINT), etc. The following man
 // pages are good resources for how to affect the line discipline:
 //
@@ -55,8 +55,8 @@ const (
 //
 // lineDiscipline has a simple structure but supports a multitude of options
 // (see the above man pages). It consists of two queues of bytes: one from the
-// terminal master to slave (the input queue) and one from slave to master (the
-// output queue). When bytes are written to one end of the pty, the line
+// terminal master to replica (the input queue) and one from replica to master
+// (the output queue). When bytes are written to one end of the pty, the line
 // discipline reads the bytes, modifies them or takes special action if
 // required, and enqueues them to be read by the other end of the pty:
 //
@@ -65,7 +65,7 @@ const (
 //    |   (inputQueueWrite)     +-------------+     (inputQueueRead)      |
 //    |                                                                   |
 //    |                                                                   v
-// masterFD                                                            slaveFD
+// masterFD                                                           replicaFD
 //    ^                                                                   |
 //    |                                                                   |
 //    |   output to terminal   +--------------+    output from process    |
@@ -104,8 +104,8 @@ type lineDiscipline struct {
 	// masterWaiter is used to wait on the master end of the TTY.
 	masterWaiter waiter.Queue `state:"zerovalue"`
 
-	// slaveWaiter is used to wait on the slave end of the TTY.
-	slaveWaiter waiter.Queue `state:"zerovalue"`
+	// replicaWaiter is used to wait on the replica end of the TTY.
+	replicaWaiter waiter.Queue `state:"zerovalue"`
 }
 
 func newLineDiscipline(termios linux.KernelTermios) *lineDiscipline {
@@ -143,7 +143,7 @@ func (l *lineDiscipline) setTermios(task *kernel.Task, args arch.SyscallArgument
 		l.inQueue.pushWaitBufLocked(l)
 		l.inQueue.readable = true
 		l.inQueue.mu.Unlock()
-		l.slaveWaiter.Notify(waiter.EventIn)
+		l.replicaWaiter.Notify(waiter.EventIn)
 	}
 
 	return 0, err
@@ -169,7 +169,7 @@ func (l *lineDiscipline) masterReadiness() waiter.EventMask {
 	return l.inQueue.writeReadiness(&linux.MasterTermios) | l.outQueue.readReadiness(&linux.MasterTermios)
 }
 
-func (l *lineDiscipline) slaveReadiness() waiter.EventMask {
+func (l *lineDiscipline) replicaReadiness() waiter.EventMask {
 	l.termiosMu.RLock()
 	defer l.termiosMu.RUnlock()
 	return l.outQueue.writeReadiness(&l.termios) | l.inQueue.readReadiness(&l.termios)
@@ -189,7 +189,7 @@ func (l *lineDiscipline) inputQueueRead(ctx context.Context, dst usermem.IOSeque
 	if n > 0 {
 		l.masterWaiter.Notify(waiter.EventOut)
 		if pushed {
-			l.slaveWaiter.Notify(waiter.EventIn)
+			l.replicaWaiter.Notify(waiter.EventIn)
 		}
 		return n, nil
 	}
@@ -204,7 +204,7 @@ func (l *lineDiscipline) inputQueueWrite(ctx context.Context, src usermem.IOSequ
 		return 0, err
 	}
 	if n > 0 {
-		l.slaveWaiter.Notify(waiter.EventIn)
+		l.replicaWaiter.Notify(waiter.EventIn)
 		return n, nil
 	}
 	return 0, syserror.ErrWouldBlock
@@ -222,7 +222,7 @@ func (l *lineDiscipline) outputQueueRead(ctx context.Context, dst usermem.IOSequ
 		return 0, err
 	}
 	if n > 0 {
-		l.slaveWaiter.Notify(waiter.EventOut)
+		l.replicaWaiter.Notify(waiter.EventOut)
 		if pushed {
 			l.masterWaiter.Notify(waiter.EventIn)
 		}
diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go
index 175457297..bebf90ffa 100644
--- a/pkg/sentry/fs/tty/master.go
+++ b/pkg/sentry/fs/tty/master.go
@@ -166,11 +166,11 @@ func (mf *masterFileOperations) Ioctl(ctx context.Context, _ *fs.File, io userme
 		return 0, mf.t.ld.outputQueueReadSize(t, args)
 	case linux.TCGETS:
 		// N.B. TCGETS on the master actually returns the configuration
-		// of the slave end.
+		// of the replica end.
 		return mf.t.ld.getTermios(t, args)
 	case linux.TCSETS:
 		// N.B. TCSETS on the master actually affects the configuration
-		// of the slave end.
+		// of the replica end.
 		return mf.t.ld.setTermios(t, args)
 	case linux.TCSETSW:
 		// TODO(b/29356795): This should drain the output queue first.
diff --git a/pkg/sentry/fs/tty/queue.go b/pkg/sentry/fs/tty/queue.go
index f0a18c75a..e070a1b71 100644
--- a/pkg/sentry/fs/tty/queue.go
+++ b/pkg/sentry/fs/tty/queue.go
@@ -34,7 +34,7 @@ import (
 const waitBufMaxBytes = 131072
 
 // queue represents one of the input or output queues between a pty master and
-// slave. Bytes written to a queue are added to the read buffer until it is
+// replica. Bytes written to a queue are added to the read buffer until it is
 // full, at which point they are written to the wait buffer. Bytes are
 // processed (i.e. undergo termios transformations) as they are added to the
 // read buffer. The read buffer is readable when its length is nonzero and
diff --git a/pkg/sentry/fs/tty/slave.go b/pkg/sentry/fs/tty/replica.go
index 933d2c3ff..cb6cd6864 100644
--- a/pkg/sentry/fs/tty/slave.go
+++ b/pkg/sentry/fs/tty/replica.go
@@ -29,11 +29,11 @@ import (
 
 // LINT.IfChange
 
-// slaveInodeOperations are the fs.InodeOperations for the slave end of the
+// replicaInodeOperations are the fs.InodeOperations for the replica end of the
 // Terminal (pts file).
 //
 // +stateify savable
-type slaveInodeOperations struct {
+type replicaInodeOperations struct {
 	fsutil.SimpleFileInode
 
 	// d is the containing dir.
@@ -43,13 +43,13 @@ type slaveInodeOperations struct {
 	t *Terminal
 }
 
-var _ fs.InodeOperations = (*slaveInodeOperations)(nil)
+var _ fs.InodeOperations = (*replicaInodeOperations)(nil)
 
-// newSlaveInode creates an fs.Inode for the slave end of a terminal.
+// newReplicaInode creates an fs.Inode for the replica end of a terminal.
 //
-// newSlaveInode takes ownership of t.
-func newSlaveInode(ctx context.Context, d *dirInodeOperations, t *Terminal, owner fs.FileOwner, p fs.FilePermissions) *fs.Inode {
-	iops := &slaveInodeOperations{
+// newReplicaInode takes ownership of t.
+func newReplicaInode(ctx context.Context, d *dirInodeOperations, t *Terminal, owner fs.FileOwner, p fs.FilePermissions) *fs.Inode {
+	iops := &replicaInodeOperations{
 		SimpleFileInode: *fsutil.NewSimpleFileInode(ctx, owner, p, linux.DEVPTS_SUPER_MAGIC),
 		d:               d,
 		t:               t,
@@ -66,18 +66,18 @@ func newSlaveInode(ctx context.Context, d *dirInodeOperations, t *Terminal, owne
 		Type:    fs.CharacterDevice,
 		// See fs/devpts/inode.c:devpts_fill_super.
 		BlockSize:       1024,
-		DeviceFileMajor: linux.UNIX98_PTY_SLAVE_MAJOR,
+		DeviceFileMajor: linux.UNIX98_PTY_REPLICA_MAJOR,
 		DeviceFileMinor: t.n,
 	})
 }
 
 // Release implements fs.InodeOperations.Release.
-func (si *slaveInodeOperations) Release(ctx context.Context) {
+func (si *replicaInodeOperations) Release(ctx context.Context) {
 	si.t.DecRef(ctx)
 }
 
 // Truncate implements fs.InodeOperations.Truncate.
-func (*slaveInodeOperations) Truncate(context.Context, *fs.Inode, int64) error {
+func (*replicaInodeOperations) Truncate(context.Context, *fs.Inode, int64) error {
 	return nil
 }
 
@@ -85,14 +85,15 @@ func (*slaveInodeOperations) Truncate(context.Context, *fs.Inode, int64) error {
 //
 // This may race with destruction of the terminal. If the terminal is gone, it
 // returns ENOENT.
-func (si *slaveInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
-	return fs.NewFile(ctx, d, flags, &slaveFileOperations{si: si}), nil
+func (si *replicaInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	return fs.NewFile(ctx, d, flags, &replicaFileOperations{si: si}), nil
 }
 
-// slaveFileOperations are the fs.FileOperations for the slave end of a terminal.
+// replicaFileOperations are the fs.FileOperations for the replica end of a
+// terminal.
 //
 // +stateify savable
-type slaveFileOperations struct {
+type replicaFileOperations struct {
 	fsutil.FilePipeSeek             `state:"nosave"`
 	fsutil.FileNotDirReaddir        `state:"nosave"`
 	fsutil.FileNoFsync              `state:"nosave"`
@@ -102,42 +103,42 @@ type slaveFileOperations struct {
 	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
 
 	// si is the inode operations.
-	si *slaveInodeOperations
+	si *replicaInodeOperations
 }
 
-var _ fs.FileOperations = (*slaveFileOperations)(nil)
+var _ fs.FileOperations = (*replicaFileOperations)(nil)
 
 // Release implements fs.FileOperations.Release.
-func (sf *slaveFileOperations) Release(context.Context) {
+func (sf *replicaFileOperations) Release(context.Context) {
 }
 
 // EventRegister implements waiter.Waitable.EventRegister.
-func (sf *slaveFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
-	sf.si.t.ld.slaveWaiter.EventRegister(e, mask)
+func (sf *replicaFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
+	sf.si.t.ld.replicaWaiter.EventRegister(e, mask)
 }
 
 // EventUnregister implements waiter.Waitable.EventUnregister.
-func (sf *slaveFileOperations) EventUnregister(e *waiter.Entry) {
-	sf.si.t.ld.slaveWaiter.EventUnregister(e)
+func (sf *replicaFileOperations) EventUnregister(e *waiter.Entry) {
+	sf.si.t.ld.replicaWaiter.EventUnregister(e)
 }
 
 // Readiness implements waiter.Waitable.Readiness.
-func (sf *slaveFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
-	return sf.si.t.ld.slaveReadiness()
+func (sf *replicaFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
+	return sf.si.t.ld.replicaReadiness()
 }
 
 // Read implements fs.FileOperations.Read.
-func (sf *slaveFileOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
+func (sf *replicaFileOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
 	return sf.si.t.ld.inputQueueRead(ctx, dst)
 }
 
 // Write implements fs.FileOperations.Write.
-func (sf *slaveFileOperations) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, _ int64) (int64, error) {
+func (sf *replicaFileOperations) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, _ int64) (int64, error) {
 	return sf.si.t.ld.outputQueueWrite(ctx, src)
 }
 
 // Ioctl implements fs.FileOperations.Ioctl.
-func (sf *slaveFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+func (sf *replicaFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
 	t := kernel.TaskFromContext(ctx)
 	if t == nil {
 		// ioctl(2) may only be called from a task goroutine.
@@ -182,4 +183,4 @@ func (sf *slaveFileOperations) Ioctl(ctx context.Context, _ *fs.File, io usermem
 	}
 }
 
-// LINT.ThenChange(../../fsimpl/devpts/slave.go)
+// LINT.ThenChange(../../fsimpl/devpts/replica.go)
diff --git a/pkg/sentry/fs/tty/terminal.go b/pkg/sentry/fs/tty/terminal.go
index 56b59632d..c9dbf1f3b 100644
--- a/pkg/sentry/fs/tty/terminal.go
+++ b/pkg/sentry/fs/tty/terminal.go
@@ -44,19 +44,19 @@ type Terminal struct {
 	// this terminal. This field is immutable.
 	masterKTTY *kernel.TTY
 
-	// slaveKTTY contains the controlling process of the slave end of this
+	// replicaKTTY contains the controlling process of the replica end of this
 	// terminal. This field is immutable.
-	slaveKTTY *kernel.TTY
+	replicaKTTY *kernel.TTY
 }
 
 func newTerminal(ctx context.Context, d *dirInodeOperations, n uint32) *Terminal {
-	termios := linux.DefaultSlaveTermios
+	termios := linux.DefaultReplicaTermios
 	t := Terminal{
-		d:          d,
-		n:          n,
-		ld:         newLineDiscipline(termios),
-		masterKTTY: &kernel.TTY{Index: n},
-		slaveKTTY:  &kernel.TTY{Index: n},
+		d:           d,
+		n:           n,
+		ld:          newLineDiscipline(termios),
+		masterKTTY:  &kernel.TTY{Index: n},
+		replicaKTTY: &kernel.TTY{Index: n},
 	}
 	t.EnableLeakCheck("tty.Terminal")
 	return &t
@@ -123,7 +123,7 @@ func (tm *Terminal) tty(isMaster bool) *kernel.TTY {
 	if isMaster {
 		return tm.masterKTTY
 	}
-	return tm.slaveKTTY
+	return tm.replicaKTTY
 }
 
 // LINT.ThenChange(../../fsimpl/devpts/terminal.go)
diff --git a/pkg/sentry/fs/tty/tty_test.go b/pkg/sentry/fs/tty/tty_test.go
index 2cbc05678..49edee83d 100644
--- a/pkg/sentry/fs/tty/tty_test.go
+++ b/pkg/sentry/fs/tty/tty_test.go
@@ -22,8 +22,8 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
-func TestSimpleMasterToSlave(t *testing.T) {
-	ld := newLineDiscipline(linux.DefaultSlaveTermios)
+func TestSimpleMasterToReplica(t *testing.T) {
+	ld := newLineDiscipline(linux.DefaultReplicaTermios)
 	ctx := contexttest.Context(t)
 	inBytes := []byte("hello, tty\n")
 	src := usermem.BytesIOSequence(inBytes)