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

1 files changed, 57 insertions, 31 deletions

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))