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, 82 insertions, 56 deletions

diff --git a/pkg/sentry/fs/proc/fds.go b/pkg/sentry/fs/proc/fds.go
index 5acbce75e..b8a0a5eff 100644
--- a/pkg/sentry/fs/proc/fds.go
+++ b/pkg/sentry/fs/proc/fds.go
@@ -21,11 +21,11 @@ import (
 
 	"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/proc/device"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
-	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
 )
 
@@ -55,7 +55,7 @@ func walkDescriptors(t *kernel.Task, p string, toInode func(*fs.File, kernel.FDF
 // readDescriptors reads fds in the task starting at offset, and calls the
 // toDentAttr callback for each to get a DentAttr, which it then emits. This is
 // a helper for implementing fs.InodeOperations.Readdir.
-func readDescriptors(t *kernel.Task, c *fs.DirCtx, offset int, toDentAttr func(int) fs.DentAttr) (int, error) {
+func readDescriptors(t *kernel.Task, c *fs.DirCtx, offset int64, toDentAttr func(int) fs.DentAttr) (int64, error) {
 	var fds kernel.FDs
 	t.WithMuLocked(func(t *kernel.Task) {
 		if fdm := t.FDMap(); fdm != nil {
@@ -69,7 +69,7 @@ func readDescriptors(t *kernel.Task, c *fs.DirCtx, offset int, toDentAttr func(i
 	}
 
 	// Find the fd to start at.
-	idx := sort.SearchInts(fdInts, offset)
+	idx := sort.SearchInts(fdInts, int(offset))
 	if idx == len(fdInts) {
 		return offset, nil
 	}
@@ -80,28 +80,32 @@ func readDescriptors(t *kernel.Task, c *fs.DirCtx, offset int, toDentAttr func(i
 		name := strconv.FormatUint(uint64(fd), 10)
 		if err := c.DirEmit(name, toDentAttr(fd)); err != nil {
 			// Returned offset is the next fd to serialize.
-			return fd, err
+			return int64(fd), err
 		}
 	}
 	// We serialized them all.  Next offset should be higher than last
 	// serialized fd.
-	return fd + 1, nil
+	return int64(fd + 1), nil
 }
 
-// fd is a single file in /proc/TID/fd/.
+// fd implements fs.InodeOperations for a file in /proc/TID/fd/.
 type fd struct {
 	ramfs.Symlink
 	*fs.File
 }
 
+var _ fs.InodeOperations = (*fd)(nil)
+
 // newFd returns a new fd based on an existing file.
 //
 // This inherits one reference to the file.
 func newFd(t *kernel.Task, f *fs.File, msrc *fs.MountSource) *fs.Inode {
-	fd := &fd{File: f}
-	// RootOwner by default, is overridden in UnstableAttr()
-	fd.InitSymlink(t, fs.RootOwner, "")
-	return newFile(fd, msrc, fs.Symlink, t)
+	fd := &fd{
+		// RootOwner overridden by taskOwnedInodeOps.UnstableAttrs().
+		Symlink: *ramfs.NewSymlink(t, fs.RootOwner, ""),
+		File:    f,
+	}
+	return newProcInode(fd, msrc, fs.Symlink, t)
 }
 
 // GetFile returns the fs.File backing this fd.  The dirent and flags
@@ -142,7 +146,7 @@ func (f *fd) Close() error {
 	return nil
 }
 
-// fdDir implements /proc/TID/fd.
+// fdDir is an InodeOperations for /proc/TID/fd.
 //
 // +stateify savable
 type fdDir struct {
@@ -154,11 +158,15 @@ type fdDir struct {
 	t *kernel.Task
 }
 
+var _ fs.InodeOperations = (*fdDir)(nil)
+
 // newFdDir creates a new fdDir.
 func newFdDir(t *kernel.Task, msrc *fs.MountSource) *fs.Inode {
-	f := &fdDir{t: t}
-	f.InitDir(t, nil, fs.RootOwner, fs.FilePermissions{User: fs.PermMask{Read: true, Execute: true}})
-	return newFile(f, msrc, fs.SpecialDirectory, t)
+	f := &fdDir{
+		Dir: *ramfs.NewDir(t, nil, fs.RootOwner, fs.FilePermissions{User: fs.PermMask{Read: true, Execute: true}}),
+		t:   t,
+	}
+	return newProcInode(f, msrc, fs.SpecialDirectory, t)
 }
 
 // Check implements InodeOperations.Check.
@@ -191,49 +199,55 @@ func (f *fdDir) Lookup(ctx context.Context, dir *fs.Inode, p string) (*fs.Dirent
 	return fs.NewDirent(n, p), nil
 }
 
-// DeprecatedReaddir lists fds in /proc/TID/fd.
-func (f *fdDir) DeprecatedReaddir(ctx context.Context, dirCtx *fs.DirCtx, offset int) (int, error) {
-	return readDescriptors(f.t, dirCtx, offset, func(fd int) fs.DentAttr {
-		return fs.GenericDentAttr(fs.Symlink, device.ProcDevice)
+// GetFile implements fs.FileOperations.GetFile.
+func (f *fdDir) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	fops := &fdDirFile{
+		isInfoFile: false,
+		t:          f.t,
+	}
+	return fs.NewFile(ctx, dirent, flags, fops), nil
+}
+
+// +stateify savable
+type fdDirFile struct {
+	fsutil.DirFileOperations `state:"nosave"`
+
+	isInfoFile bool
+
+	t *kernel.Task
+}
+
+var _ fs.FileOperations = (*fdDirFile)(nil)
+
+// Readdir implements fs.FileOperations.Readdir.
+func (f *fdDirFile) Readdir(ctx context.Context, file *fs.File, ser fs.DentrySerializer) (int64, error) {
+	dirCtx := &fs.DirCtx{
+		Serializer: ser,
+	}
+	typ := fs.RegularFile
+	if f.isInfoFile {
+		typ = fs.Symlink
+	}
+	return readDescriptors(f.t, dirCtx, file.Offset(), func(fd int) fs.DentAttr {
+		return fs.GenericDentAttr(typ, device.ProcDevice)
 	})
 }
 
-// fdInfo is a single file in /proc/TID/fdinfo/.
+// fdInfoInode is a single file in /proc/TID/fdinfo/.
 //
 // +stateify savable
-type fdInfo struct {
-	ramfs.File
+type fdInfoInode struct {
+	staticFileInodeOps
 
 	file    *fs.File
 	flags   fs.FileFlags
 	fdFlags kernel.FDFlags
 }
 
-// newFdInfo returns a new fdInfo based on an existing file.
-func newFdInfo(t *kernel.Task, file *fs.File, fdFlags kernel.FDFlags, msrc *fs.MountSource) *fs.Inode {
-	fdi := &fdInfo{file: file, flags: file.Flags(), fdFlags: fdFlags}
-	fdi.InitFile(t, fs.RootOwner, fs.FilePermissions{User: fs.PermMask{Read: true}})
-	// TODO: Get pos, locks, and other data.  For now we only
-	// have flags.
-	// See https://www.kernel.org/doc/Documentation/filesystems/proc.txt
-
-	flags := file.Flags().ToLinux() | fdFlags.ToLinuxFileFlags()
-	fdi.Append([]byte(fmt.Sprintf("flags:\t0%o\n", flags)))
-	return newFile(fdi, msrc, fs.SpecialFile, t)
-}
-
-// DeprecatedPwritev implements fs.HandleOperations.DeprecatedPwritev.
-func (*fdInfo) DeprecatedPwritev(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
-	return 0, ramfs.ErrInvalidOp
-}
-
-// Truncate implements fs.InodeOperations.Truncate.
-func (*fdInfo) Truncate(ctx context.Context, inode *fs.Inode, size int64) error {
-	return ramfs.ErrInvalidOp
-}
+var _ fs.InodeOperations = (*fdInfoInode)(nil)
 
-func (f *fdInfo) Release(ctx context.Context) {
-	f.File.Release(ctx)
+// Release implements fs.InodeOperations.Release.
+func (f *fdInfoInode) Release(ctx context.Context) {
 	f.file.DecRef()
 }
 
@@ -249,25 +263,37 @@ type fdInfoDir struct {
 
 // newFdInfoDir creates a new fdInfoDir.
 func newFdInfoDir(t *kernel.Task, msrc *fs.MountSource) *fs.Inode {
-	fdid := &fdInfoDir{t: t}
-	fdid.InitDir(t, nil, fs.RootOwner, fs.FilePermsFromMode(0500))
-	return newFile(fdid, msrc, fs.SpecialDirectory, t)
+	fdid := &fdInfoDir{
+		Dir: *ramfs.NewDir(t, nil, fs.RootOwner, fs.FilePermsFromMode(0500)),
+		t:   t,
+	}
+	return newProcInode(fdid, msrc, fs.SpecialDirectory, t)
 }
 
 // Lookup loads an fd in /proc/TID/fdinfo into a Dirent.
 func (fdid *fdInfoDir) Lookup(ctx context.Context, dir *fs.Inode, p string) (*fs.Dirent, error) {
-	n, err := walkDescriptors(fdid.t, p, func(file *fs.File, fdFlags kernel.FDFlags) *fs.Inode {
-		return newFdInfo(fdid.t, file, fdFlags, dir.MountSource)
+	inode, err := walkDescriptors(fdid.t, p, func(file *fs.File, fdFlags kernel.FDFlags) *fs.Inode {
+		// TODO: Using a static inode here means that the
+		// data can be out-of-date if, for instance, the flags on the
+		// FD change before we read this file. We should switch to
+		// generating the data on Read(). Also, we should include pos,
+		// locks, and other data.  For now we only have flags.
+		// See https://www.kernel.org/doc/Documentation/filesystems/proc.txt
+		flags := file.Flags().ToLinux() | fdFlags.ToLinuxFileFlags()
+		contents := []byte(fmt.Sprintf("flags:\t0%o\n", flags))
+		return newStaticProcInode(ctx, dir.MountSource, contents)
 	})
 	if err != nil {
 		return nil, err
 	}
-	return fs.NewDirent(n, p), nil
+	return fs.NewDirent(inode, p), nil
 }
 
-// DeprecatedReaddir lists fds in /proc/TID/fdinfo.
-func (fdid *fdInfoDir) DeprecatedReaddir(ctx context.Context, dirCtx *fs.DirCtx, offset int) (int, error) {
-	return readDescriptors(fdid.t, dirCtx, offset, func(fd int) fs.DentAttr {
-		return fs.GenericDentAttr(fs.RegularFile, device.ProcDevice)
-	})
+// GetFile implements fs.FileOperations.GetFile.
+func (fdid *fdInfoDir) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	fops := &fdDirFile{
+		isInfoFile: true,
+		t:          fdid.t,
+	}
+	return fs.NewFile(ctx, dirent, flags, fops), nil
 }