Remove fs.Handle, ramfs.Entry, and all the DeprecatedFileOperations.

More helper structs have been added to the fsutil package to make it easier to
implement fs.InodeOperations and fs.FileOperations.

PiperOrigin-RevId: 229305982
Change-Id: Ib6f8d3862f4216745116857913dbfa351530223b

6 files changed, 151 insertions, 79 deletions

diff --git a/pkg/sentry/fs/dev/BUILD b/pkg/sentry/fs/dev/BUILD
index b17b5202c..b9cfae05f 100644
--- a/pkg/sentry/fs/dev/BUILD
+++ b/pkg/sentry/fs/dev/BUILD
@@ -32,5 +32,6 @@ go_library(
         "//pkg/sentry/safemem",
         "//pkg/sentry/usermem",
         "//pkg/syserror",
+        "//pkg/waiter",
     ],
 )
diff --git a/pkg/sentry/fs/dev/dev.go b/pkg/sentry/fs/dev/dev.go
index 3e127bf04..f8e8099f7 100644
--- a/pkg/sentry/fs/dev/dev.go
+++ b/pkg/sentry/fs/dev/dev.go
@@ -16,6 +16,8 @@
 package dev
 
 import (
+	"math"
+
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ashmem"
@@ -26,13 +28,6 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 )
 
-// Dev is the root node.
-//
-// +stateify savable
-type Dev struct {
-	ramfs.Dir
-}
-
 func newCharacterDevice(iops fs.InodeOperations, msrc *fs.MountSource) *fs.Inode {
 	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
@@ -43,8 +38,7 @@ func newCharacterDevice(iops fs.InodeOperations, msrc *fs.MountSource) *fs.Inode
 }
 
 func newDirectory(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
-	iops := &ramfs.Dir{}
-	iops.InitDir(ctx, map[string]*fs.Inode{}, fs.RootOwner, fs.FilePermsFromMode(0555))
+	iops := ramfs.NewDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555))
 	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
@@ -54,8 +48,7 @@ func newDirectory(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
 }
 
 func newSymlink(ctx context.Context, target string, msrc *fs.MountSource) *fs.Inode {
-	iops := &ramfs.Symlink{}
-	iops.InitSymlink(ctx, fs.RootOwner, target)
+	iops := ramfs.NewSymlink(ctx, fs.RootOwner, target)
 	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
@@ -66,8 +59,6 @@ func newSymlink(ctx context.Context, target string, msrc *fs.MountSource) *fs.In
 
 // New returns the root node of a device filesystem.
 func New(ctx context.Context, msrc *fs.MountSource, binderEnabled bool, ashmemEnabled bool) *fs.Inode {
-	d := &Dev{}
-
 	contents := map[string]*fs.Inode{
 		"fd":     newSymlink(ctx, "/proc/self/fd", msrc),
 		"stdin":  newSymlink(ctx, "/proc/self/fd/0", msrc),
@@ -114,11 +105,19 @@ func New(ctx context.Context, msrc *fs.MountSource, binderEnabled bool, ashmemEn
 		contents["ashmem"] = newCharacterDevice(ashmem, msrc)
 	}
 
-	d.InitDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
-	return fs.NewInode(d, msrc, fs.StableAttr{
+	iops := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
+	return fs.NewInode(iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
 		BlockSize: usermem.PageSize,
 		Type:      fs.Directory,
 	})
 }
+
+// readZeros implements fs.FileOperations.Read with infinite null bytes.
+type readZeros struct{}
+
+// Read implements fs.FileOperations.Read.
+func (readZeros) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
+	return dst.ZeroOut(ctx, math.MaxInt64)
+}
diff --git a/pkg/sentry/fs/dev/fs.go b/pkg/sentry/fs/dev/fs.go
index d96f4f423..abfe689f0 100644
--- a/pkg/sentry/fs/dev/fs.go
+++ b/pkg/sentry/fs/dev/fs.go
@@ -33,6 +33,8 @@ const ashmemEnabledKey = "ashmem_enabled"
 // +stateify savable
 type filesystem struct{}
 
+var _ fs.Filesystem = (*filesystem)(nil)
+
 func init() {
 	fs.RegisterFilesystem(&filesystem{})
 }
diff --git a/pkg/sentry/fs/dev/full.go b/pkg/sentry/fs/dev/full.go
index eeda646ab..cbdd40161 100644
--- a/pkg/sentry/fs/dev/full.go
+++ b/pkg/sentry/fs/dev/full.go
@@ -15,41 +15,64 @@
 package dev
 
 import (
-	"math"
-
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 // fullDevice is used to implement /dev/full.
 //
 // +stateify savable
 type fullDevice struct {
-	ramfs.Entry
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*fullDevice)(nil)
+
 func newFullDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *fullDevice {
-	f := &fullDevice{}
-	f.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	f := &fullDevice{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
 	return f
 }
 
-// DeprecatedPwritev implements fs.InodeOperations.DeprecatedPwritev by
-// returining ENOSPC.
-func (f *fullDevice) DeprecatedPwritev(_ context.Context, _ usermem.IOSequence, _ int64) (int64, error) {
-	return 0, syserror.ENOSPC
+// GetFile implements fs.InodeOperations.GetFile.
+func (f *fullDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	flags.Pread = true
+	return fs.NewFile(ctx, dirent, flags, &fullFileOperations{}), nil
 }
 
-// DeprecatedPreadv implements fs.InodeOperations.DeprecatedPreadv.
-func (f *fullDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, _ int64) (int64, error) {
-	return dst.ZeroOut(ctx, math.MaxInt64)
+// +stateify savable
+type fullFileOperations struct {
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	readZeros                `state:"nosave"`
 }
 
-// Truncate should be simply ignored for character devices on linux.
-func (f *fullDevice) Truncate(context.Context, *fs.Inode, int64) error {
-	return nil
+var _ fs.FileOperations = (*fullFileOperations)(nil)
+
+// Write implements FileOperations.Write.
+func (fullFileOperations) Write(context.Context, *fs.File, usermem.IOSequence, int64) (int64, error) {
+	return 0, syserror.ENOSPC
 }
diff --git a/pkg/sentry/fs/dev/null.go b/pkg/sentry/fs/dev/null.go
index 68090f353..73fd09058 100644
--- a/pkg/sentry/fs/dev/null.go
+++ b/pkg/sentry/fs/dev/null.go
@@ -15,78 +15,104 @@
 package dev
 
 import (
-	"io"
-	"math"
-
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"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/fs/ramfs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/memmap"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/mm"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 // +stateify savable
 type nullDevice struct {
-	ramfs.Entry
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*nullDevice)(nil)
+
 func newNullDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *nullDevice {
-	n := &nullDevice{}
-	n.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	n := &nullDevice{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
 	return n
 }
 
-// DeprecatedPreadv reads data from the device.
-func (n *nullDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
-	return 0, io.EOF
-}
+// GetFile implements fs.FileOperations.GetFile.
+func (n *nullDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	flags.Pread = true
+	flags.Pwrite = true
 
-// DeprecatedPwritev discards writes.
-func (n *nullDevice) DeprecatedPwritev(_ context.Context, src usermem.IOSequence, offset int64) (int64, error) {
-	return src.NumBytes(), nil
+	return fs.NewFile(ctx, dirent, flags, &nullFileOperations{}), nil
 }
 
-// Truncate should be simply ignored for character devices on linux.
-func (n *nullDevice) Truncate(context.Context, *fs.Inode, int64) error {
-	return nil
+// +stateify savable
+type nullFileOperations struct {
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopRead      `state:"nosave"`
+	fsutil.FileNoopWrite     `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
 }
 
+var _ fs.FileOperations = (*nullFileOperations)(nil)
+
 // +stateify savable
 type zeroDevice struct {
 	nullDevice
 }
 
+var _ fs.InodeOperations = (*zeroDevice)(nil)
+
 func newZeroDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *zeroDevice {
-	zd := &zeroDevice{}
-	zd.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	zd := &zeroDevice{
+		nullDevice: nullDevice{
+			InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+		},
+	}
 	return zd
 }
 
-// DeprecatedPreadv implements fs.InodeOperations.DeprecatedPreadv.
-func (zd *zeroDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
-	return dst.ZeroOut(ctx, math.MaxInt64)
-}
-
-// GetFile overrides ramfs.Entry.GetFile and returns a zeroFile instead.
+// GetFile implements fs.FileOperations.GetFile.
 func (zd *zeroDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
-	// Allow pread(2) and pwrite(2) on this file.
 	flags.Pread = true
 	flags.Pwrite = true
 
-	return fs.NewFile(ctx, dirent, flags, &zeroFileOperations{
-		FileOperations: &fsutil.Handle{HandleOperations: dirent.Inode.HandleOps()},
-	}), nil
+	return fs.NewFile(ctx, dirent, flags, &zeroFileOperations{}), nil
 }
 
 // +stateify savable
 type zeroFileOperations struct {
-	fs.FileOperations
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNoopWrite     `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	readZeros                `state:"nosave"`
 }
 
+var _ fs.FileOperations = (*zeroFileOperations)(nil)
+
 // ConfigureMMap implements fs.FileOperations.ConfigureMMap.
 func (*zeroFileOperations) ConfigureMMap(ctx context.Context, file *fs.File, opts *memmap.MMapOpts) error {
 	m, err := mm.NewSharedAnonMappable(opts.Length, platform.FromContext(ctx))
diff --git a/pkg/sentry/fs/dev/random.go b/pkg/sentry/fs/dev/random.go
index 33e4913e4..837b7793a 100644
--- a/pkg/sentry/fs/dev/random.go
+++ b/pkg/sentry/fs/dev/random.go
@@ -19,37 +19,58 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/rand"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/safemem"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
 )
 
 // +stateify savable
 type randomDevice struct {
-	ramfs.Entry
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
 }
 
+var _ fs.InodeOperations = (*randomDevice)(nil)
+
 func newRandomDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *randomDevice {
-	r := &randomDevice{}
-	r.InitEntry(ctx, owner, fs.FilePermsFromMode(mode))
+	r := &randomDevice{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
 	return r
 }
 
-// DeprecatedPreadv reads random data.
-func (*randomDevice) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
-	return dst.CopyOutFrom(ctx, safemem.FromIOReader{rand.Reader})
+// GetFile implements fs.InodeOperations.GetFile.
+func (randomDevice) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	return fs.NewFile(ctx, dirent, flags, &randomFileOperations{}), nil
 }
 
-// DeprecatedPwritev implements fs.HandleOperations.DeprecatedPwritev.
-func (*randomDevice) DeprecatedPwritev(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
-	// On Linux, "Writing to /dev/random or /dev/urandom will update the
-	// entropy pool with the data written, but this will not result in a higher
-	// entropy count" - random(4). We don't need to support this, but we do
-	// need to support the write, so just make it a no-op a la /dev/null.
-	return src.NumBytes(), nil
+// +stateify savable
+type randomFileOperations struct {
+	waiter.AlwaysReady       `state:"nosave"`
+	fsutil.FileGenericSeek   `state:"nosave"`
+	fsutil.FileNotDirReaddir `state:"nosave"`
+	fsutil.FileNoMMap        `state:"nosave"`
+	fsutil.FileNoopFsync     `state:"nosave"`
+	fsutil.FileNoopFlush     `state:"nosave"`
+	fsutil.FileNoIoctl       `state:"nosave"`
+	fsutil.FileNoopRelease   `state:"nosave"`
+	fsutil.FileNoopWrite     `state:"nosave"`
 }
 
-// Truncate should be simply ignored for character devices on linux.
-func (r *randomDevice) Truncate(context.Context, *fs.Inode, int64) error {
-	return nil
+var _ fs.FileOperations = (*randomFileOperations)(nil)
+
+// Read implements fs.FileOperations.Read.
+func (randomFileOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
+	return dst.CopyOutFrom(ctx, safemem.FromIOReader{rand.Reader})
 }