1 files changed, 220 insertions, 0 deletions
diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go
new file mode 100644
index 000000000..afdf44cd1
--- /dev/null
+++ b/pkg/sentry/fs/tty/master.go
@@ -0,0 +1,220 @@
+// Copyright 2018 The gVisor Authors.
+//
+// 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 tty
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/unimpl"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/syserror"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// masterInodeOperations are the fs.InodeOperations for the master end of the
+// Terminal (ptmx file).
+//
+// +stateify savable
+type masterInodeOperations struct {
+	fsutil.SimpleFileInode
+
+	// d is the containing dir.
+	d *dirInodeOperations
+}
+
+var _ fs.InodeOperations = (*masterInodeOperations)(nil)
+
+// newMasterInode creates an Inode for the master end of a terminal.
+func newMasterInode(ctx context.Context, d *dirInodeOperations, owner fs.FileOwner, p fs.FilePermissions) *fs.Inode {
+	iops := &masterInodeOperations{
+		SimpleFileInode: *fsutil.NewSimpleFileInode(ctx, owner, p, linux.DEVPTS_SUPER_MAGIC),
+		d:               d,
+	}
+
+	return fs.NewInode(iops, d.msrc, fs.StableAttr{
+		DeviceID: ptsDevice.DeviceID(),
+		// N.B. Linux always uses inode id 2 for ptmx. See
+		// fs/devpts/inode.c:mknod_ptmx.
+		//
+		// TODO(b/75267214): Since ptsDevice must be shared between
+		// different mounts, we must not assign fixed numbers.
+		InodeID: ptsDevice.NextIno(),
+		Type:    fs.CharacterDevice,
+		// See fs/devpts/inode.c:devpts_fill_super.
+		BlockSize: 1024,
+		// The PTY master effectively has two different major/minor
+		// device numbers.
+		//
+		// This one is returned by stat for both opened and unopened
+		// instances of this inode.
+		//
+		// When the inode is opened (GetFile), a new device number is
+		// allocated based on major UNIX98_PTY_MASTER_MAJOR and the tty
+		// index as minor number. However, this device number is only
+		// accessible via ioctl(TIOCGDEV) and /proc/TID/stat.
+		DeviceFileMajor: linux.TTYAUX_MAJOR,
+		DeviceFileMinor: linux.PTMX_MINOR,
+	})
+}
+
+// Release implements fs.InodeOperations.Release.
+func (mi *masterInodeOperations) Release(ctx context.Context) {
+}
+
+// GetFile implements fs.InodeOperations.GetFile.
+//
+// It allocates a new terminal.
+func (mi *masterInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	t, err := mi.d.allocateTerminal(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	return fs.NewFile(ctx, d, flags, &masterFileOperations{
+		d: mi.d,
+		t: t,
+	}), nil
+}
+
+// masterFileOperations are the fs.FileOperations for the master end of a terminal.
+//
+// +stateify savable
+type masterFileOperations struct {
+	fsutil.FilePipeSeek             `state:"nosave"`
+	fsutil.FileNotDirReaddir        `state:"nosave"`
+	fsutil.FileNoFsync              `state:"nosave"`
+	fsutil.FileNoMMap               `state:"nosave"`
+	fsutil.FileNoSplice             `state:"nosave"`
+	fsutil.FileNoopFlush            `state:"nosave"`
+	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
+
+	// d is the containing dir.
+	d *dirInodeOperations
+
+	// t is the connected Terminal.
+	t *Terminal
+}
+
+var _ fs.FileOperations = (*masterFileOperations)(nil)
+
+// Release implements fs.FileOperations.Release.
+func (mf *masterFileOperations) Release() {
+	mf.d.masterClose(mf.t)
+	mf.t.DecRef()
+}
+
+// EventRegister implements waiter.Waitable.EventRegister.
+func (mf *masterFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
+	mf.t.ld.masterWaiter.EventRegister(e, mask)
+}
+
+// EventUnregister implements waiter.Waitable.EventUnregister.
+func (mf *masterFileOperations) EventUnregister(e *waiter.Entry) {
+	mf.t.ld.masterWaiter.EventUnregister(e)
+}
+
+// Readiness implements waiter.Waitable.Readiness.
+func (mf *masterFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
+	return mf.t.ld.masterReadiness()
+}
+
+// Read implements fs.FileOperations.Read.
+func (mf *masterFileOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
+	return mf.t.ld.outputQueueRead(ctx, dst)
+}
+
+// Write implements fs.FileOperations.Write.
+func (mf *masterFileOperations) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, _ int64) (int64, error) {
+	return mf.t.ld.inputQueueWrite(ctx, src)
+}
+
+// Ioctl implements fs.FileOperations.Ioctl.
+func (mf *masterFileOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	switch cmd := args[1].Uint(); cmd {
+	case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ
+		// Get the number of bytes in the output queue read buffer.
+		return 0, mf.t.ld.outputQueueReadSize(ctx, io, args)
+	case linux.TCGETS:
+		// N.B. TCGETS on the master actually returns the configuration
+		// of the slave end.
+		return mf.t.ld.getTermios(ctx, io, args)
+	case linux.TCSETS:
+		// N.B. TCSETS on the master actually affects the configuration
+		// of the slave end.
+		return mf.t.ld.setTermios(ctx, io, args)
+	case linux.TCSETSW:
+		// TODO(b/29356795): This should drain the output queue first.
+		return mf.t.ld.setTermios(ctx, io, args)
+	case linux.TIOCGPTN:
+		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), uint32(mf.t.n), usermem.IOOpts{
+			AddressSpaceActive: true,
+		})
+		return 0, err
+	case linux.TIOCSPTLCK:
+		// TODO(b/29356795): Implement pty locking. For now just pretend we do.
+		return 0, nil
+	case linux.TIOCGWINSZ:
+		return 0, mf.t.ld.windowSize(ctx, io, args)
+	case linux.TIOCSWINSZ:
+		return 0, mf.t.ld.setWindowSize(ctx, io, args)
+	default:
+		maybeEmitUnimplementedEvent(ctx, cmd)
+		return 0, syserror.ENOTTY
+	}
+}
+
+// maybeEmitUnimplementedEvent emits unimplemented event if cmd is valid.
+func maybeEmitUnimplementedEvent(ctx context.Context, cmd uint32) {
+	switch cmd {
+	case linux.TCGETS,
+		linux.TCSETS,
+		linux.TCSETSW,
+		linux.TCSETSF,
+		linux.TIOCGPGRP,
+		linux.TIOCSPGRP,
+		linux.TIOCGWINSZ,
+		linux.TIOCSWINSZ,
+		linux.TIOCSETD,
+		linux.TIOCSBRK,
+		linux.TIOCCBRK,
+		linux.TCSBRK,
+		linux.TCSBRKP,
+		linux.TIOCSTI,
+		linux.TIOCCONS,
+		linux.FIONBIO,
+		linux.TIOCEXCL,
+		linux.TIOCNXCL,
+		linux.TIOCGEXCL,
+		linux.TIOCNOTTY,
+		linux.TIOCSCTTY,
+		linux.TIOCGSID,
+		linux.TIOCGETD,
+		linux.TIOCVHANGUP,
+		linux.TIOCGDEV,
+		linux.TIOCMGET,
+		linux.TIOCMSET,
+		linux.TIOCMBIC,
+		linux.TIOCMBIS,
+		linux.TIOCGICOUNT,
+		linux.TCFLSH,
+		linux.TIOCSSERIAL,
+		linux.TIOCGPTPEER:
+
+		unimpl.EmitUnimplementedEvent(ctx)
+	}
+}