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-rw-r--r--pkg/sentry/fs/host/util.go12
-rw-r--r--pkg/sentry/fsimpl/host/BUILD27
-rw-r--r--pkg/sentry/fsimpl/host/default_file.go233
-rw-r--r--pkg/sentry/fsimpl/host/host.go286
-rw-r--r--pkg/sentry/fsimpl/host/util.go86
-rw-r--r--pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go2
-rw-r--r--pkg/sentry/fsimpl/kernfs/fd_impl_util.go18
-rw-r--r--pkg/sentry/fsimpl/kernfs/filesystem.go6
-rw-r--r--pkg/sentry/fsimpl/kernfs/inode_impl_util.go54
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs.go7
-rw-r--r--pkg/sentry/fsimpl/proc/subtasks.go13
-rw-r--r--pkg/sentry/fsimpl/proc/task.go23
-rw-r--r--pkg/sentry/fsimpl/proc/tasks.go19
-rw-r--r--pkg/sentry/vfs/BUILD4
-rw-r--r--pkg/sentry/vfs/file_description_impl_util.go4
15 files changed, 731 insertions, 63 deletions
diff --git a/pkg/sentry/fs/host/util.go b/pkg/sentry/fs/host/util.go
index e37e687c6..7c60dc1db 100644
--- a/pkg/sentry/fs/host/util.go
+++ b/pkg/sentry/fs/host/util.go
@@ -24,7 +24,7 @@ import (
"gvisor.dev/gvisor/pkg/sentry/device"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
- ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
+ "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/syserror"
)
@@ -152,9 +152,9 @@ func unstableAttr(mo *superOperations, s *syscall.Stat_t) fs.UnstableAttr {
Usage: s.Blocks * 512,
Perms: fs.FilePermsFromMode(linux.FileMode(s.Mode)),
Owner: owner(mo, s),
- AccessTime: ktime.FromUnix(s.Atim.Sec, s.Atim.Nsec),
- ModificationTime: ktime.FromUnix(s.Mtim.Sec, s.Mtim.Nsec),
- StatusChangeTime: ktime.FromUnix(s.Ctim.Sec, s.Ctim.Nsec),
+ AccessTime: time.FromUnix(s.Atim.Sec, s.Atim.Nsec),
+ ModificationTime: time.FromUnix(s.Mtim.Sec, s.Mtim.Nsec),
+ StatusChangeTime: time.FromUnix(s.Ctim.Sec, s.Ctim.Nsec),
Links: uint64(s.Nlink),
}
}
@@ -165,6 +165,8 @@ type dirInfo struct {
bufp int // location of next record in buf.
}
+// LINT.IfChange
+
// isBlockError unwraps os errors and checks if they are caused by EAGAIN or
// EWOULDBLOCK. This is so they can be transformed into syserror.ErrWouldBlock.
func isBlockError(err error) bool {
@@ -177,6 +179,8 @@ func isBlockError(err error) bool {
return false
}
+// LINT.ThenChange(../../fsimpl/host/util.go)
+
func hostEffectiveKIDs() (uint32, []uint32, error) {
gids, err := os.Getgroups()
if err != nil {
diff --git a/pkg/sentry/fsimpl/host/BUILD b/pkg/sentry/fsimpl/host/BUILD
new file mode 100644
index 000000000..731f192b3
--- /dev/null
+++ b/pkg/sentry/fsimpl/host/BUILD
@@ -0,0 +1,27 @@
+load("//tools:defs.bzl", "go_library")
+
+licenses(["notice"])
+
+go_library(
+ name = "host",
+ srcs = [
+ "default_file.go",
+ "host.go",
+ "util.go",
+ ],
+ deps = [
+ "//pkg/abi/linux",
+ "//pkg/context",
+ "//pkg/log",
+ "//pkg/refs",
+ "//pkg/safemem",
+ "//pkg/sentry/fsimpl/kernfs",
+ "//pkg/sentry/kernel/auth",
+ "//pkg/sentry/memmap",
+ "//pkg/sentry/vfs",
+ "//pkg/sync",
+ "//pkg/syserror",
+ "//pkg/usermem",
+ "@org_golang_x_sys//unix:go_default_library",
+ ],
+)
diff --git a/pkg/sentry/fsimpl/host/default_file.go b/pkg/sentry/fsimpl/host/default_file.go
new file mode 100644
index 000000000..172cdb161
--- /dev/null
+++ b/pkg/sentry/fsimpl/host/default_file.go
@@ -0,0 +1,233 @@
+// Copyright 2020 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 host
+
+import (
+ "math"
+ "syscall"
+
+ "golang.org/x/sys/unix"
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/safemem"
+ "gvisor.dev/gvisor/pkg/sentry/memmap"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+ "gvisor.dev/gvisor/pkg/sync"
+ "gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
+)
+
+// defaultFileFD implements FileDescriptionImpl for non-socket, non-TTY files.
+type defaultFileFD struct {
+ fileDescription
+
+ // canMap specifies whether we allow the file to be memory mapped.
+ canMap bool
+
+ // mu protects the fields below.
+ mu sync.Mutex
+
+ // offset specifies the current file offset.
+ offset int64
+}
+
+// TODO(gvisor.dev/issue/1672): Implement Waitable interface.
+
+// PRead implements FileDescriptionImpl.
+func (f *defaultFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
+ // TODO(b/34716638): Some char devices do support offsets, e.g. /dev/null.
+ if f.inode.isStream {
+ return 0, syserror.ESPIPE
+ }
+
+ return readFromHostFD(ctx, f.inode.hostFD, dst, offset, int(opts.Flags))
+}
+
+// Read implements FileDescriptionImpl.
+func (f *defaultFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
+ // TODO(b/34716638): Some char devices do support offsets, e.g. /dev/null.
+ if f.inode.isStream {
+ // These files can't be memory mapped, assert this.
+ if f.canMap {
+ panic("files that can return EWOULDBLOCK (sockets, pipes, etc.) cannot be memory mapped")
+ }
+
+ f.mu.Lock()
+ n, err := readFromHostFD(ctx, f.inode.hostFD, dst, -1, int(opts.Flags))
+ f.mu.Unlock()
+ if isBlockError(err) {
+ // If we got any data at all, return it as a "completed" partial read
+ // rather than retrying until complete.
+ if n != 0 {
+ err = nil
+ } else {
+ err = syserror.ErrWouldBlock
+ }
+ }
+ return n, err
+ }
+ // TODO(gvisor.dev/issue/1672): Cache pages, when forced to do so.
+ f.mu.Lock()
+ n, err := readFromHostFD(ctx, f.inode.hostFD, dst, f.offset, int(opts.Flags))
+ f.offset += n
+ f.mu.Unlock()
+ return n, err
+}
+
+func readFromHostFD(ctx context.Context, fd int, dst usermem.IOSequence, offset int64, flags int) (int64, error) {
+ if flags&^(linux.RWF_VALID) != 0 {
+ return 0, syserror.EOPNOTSUPP
+ }
+
+ reader := safemem.FromVecReaderFunc{
+ func(srcs [][]byte) (int64, error) {
+ n, err := unix.Preadv2(fd, srcs, offset, flags)
+ return int64(n), err
+ },
+ }
+ n, err := dst.CopyOutFrom(ctx, reader)
+ return int64(n), err
+}
+
+// PWrite implements FileDescriptionImpl.
+func (f *defaultFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
+ // TODO(b/34716638): Some char devices do support offsets, e.g. /dev/null.
+ if f.inode.isStream {
+ return 0, syserror.ESPIPE
+ }
+
+ return writeToHostFD(ctx, f.inode.hostFD, src, offset, int(opts.Flags))
+}
+
+// Write implements FileDescriptionImpl.
+func (f *defaultFileFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
+ // TODO(b/34716638): Some char devices do support offsets, e.g. /dev/null.
+ if f.inode.isStream {
+ // These files can't be memory mapped, assert this.
+ if f.canMap {
+ panic("files that can return EWOULDBLOCK (sockets, pipes, etc.) cannot be memory mapped")
+ }
+
+ f.mu.Lock()
+ n, err := writeToHostFD(ctx, f.inode.hostFD, src, -1, int(opts.Flags))
+ f.mu.Unlock()
+ if isBlockError(err) {
+ err = syserror.ErrWouldBlock
+ }
+ return n, err
+ }
+ // TODO(gvisor.dev/issue/1672): Cache pages, when forced to do so.
+ // TODO(gvisor.dev/issue/1672): Write to end of file and update offset if O_APPEND is set on this file.
+ f.mu.Lock()
+ n, err := writeToHostFD(ctx, f.inode.hostFD, src, f.offset, int(opts.Flags))
+ f.offset += n
+ f.mu.Unlock()
+ return n, err
+}
+
+func writeToHostFD(ctx context.Context, fd int, src usermem.IOSequence, offset int64, flags int) (int64, error) {
+ if flags&^(linux.RWF_VALID) != 0 {
+ return 0, syserror.EOPNOTSUPP
+ }
+
+ writer := safemem.FromVecWriterFunc{
+ func(srcs [][]byte) (int64, error) {
+ n, err := unix.Pwritev2(fd, srcs, offset, flags)
+ return int64(n), err
+ },
+ }
+ n, err := src.CopyInTo(ctx, writer)
+ return int64(n), err
+}
+
+// Seek implements FileDescriptionImpl.
+//
+// Note that we do not support seeking on directories, since we do not even
+// allow directory fds to be imported at all.
+func (f *defaultFileFD) Seek(_ context.Context, offset int64, whence int32) (int64, error) {
+ // TODO(b/34716638): Some char devices do support seeking, e.g. /dev/null.
+ if f.inode.isStream {
+ return 0, syserror.ESPIPE
+ }
+
+ f.mu.Lock()
+ defer f.mu.Unlock()
+
+ switch whence {
+ case linux.SEEK_SET:
+ if offset < 0 {
+ return f.offset, syserror.EINVAL
+ }
+ f.offset = offset
+
+ case linux.SEEK_CUR:
+ // Check for overflow. Note that underflow cannot occur, since f.offset >= 0.
+ if offset > math.MaxInt64-f.offset {
+ return f.offset, syserror.EOVERFLOW
+ }
+ if f.offset+offset < 0 {
+ return f.offset, syserror.EINVAL
+ }
+ f.offset += offset
+
+ case linux.SEEK_END:
+ var s syscall.Stat_t
+ if err := syscall.Fstat(f.inode.hostFD, &s); err != nil {
+ return f.offset, err
+ }
+ size := s.Size
+
+ // Check for overflow. Note that underflow cannot occur, since size >= 0.
+ if offset > math.MaxInt64-size {
+ return f.offset, syserror.EOVERFLOW
+ }
+ if size+offset < 0 {
+ return f.offset, syserror.EINVAL
+ }
+ f.offset = size + offset
+
+ case linux.SEEK_DATA, linux.SEEK_HOLE:
+ // Modifying the offset in the host file table should not matter, since
+ // this is the only place where we use it.
+ //
+ // For reading and writing, we always rely on our internal offset.
+ n, err := unix.Seek(f.inode.hostFD, offset, int(whence))
+ if err != nil {
+ return f.offset, err
+ }
+ f.offset = n
+
+ default:
+ // Invalid whence.
+ return f.offset, syserror.EINVAL
+ }
+
+ return f.offset, nil
+}
+
+// Sync implements FileDescriptionImpl.
+func (f *defaultFileFD) Sync(context.Context) error {
+ // TODO(gvisor.dev/issue/1672): Currently we do not support the SyncData optimization, so we always sync everything.
+ return unix.Fsync(f.inode.hostFD)
+}
+
+// ConfigureMMap implements FileDescriptionImpl.
+func (f *defaultFileFD) ConfigureMMap(_ context.Context, opts *memmap.MMapOpts) error {
+ if !f.canMap {
+ return syserror.ENODEV
+ }
+ // TODO(gvisor.dev/issue/1672): Implement ConfigureMMap and Mappable interface.
+ return syserror.ENODEV
+}
diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go
new file mode 100644
index 000000000..c205e6a0b
--- /dev/null
+++ b/pkg/sentry/fsimpl/host/host.go
@@ -0,0 +1,286 @@
+// Copyright 2020 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 host provides a filesystem implementation for host files imported as
+// file descriptors.
+package host
+
+import (
+ "errors"
+ "fmt"
+ "syscall"
+
+ "golang.org/x/sys/unix"
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/log"
+ "gvisor.dev/gvisor/pkg/refs"
+ "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
+ "gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+ "gvisor.dev/gvisor/pkg/sync"
+ "gvisor.dev/gvisor/pkg/syserror"
+)
+
+// filesystem implements vfs.FilesystemImpl.
+type filesystem struct {
+ kernfs.Filesystem
+}
+
+// ImportFD sets up and returns a vfs.FileDescription from a donated fd.
+func ImportFD(mnt *vfs.Mount, hostFD int, ownerUID auth.KUID, ownerGID auth.KGID, isTTY bool) (*vfs.FileDescription, error) {
+ // Must be importing to a mount of host.filesystem.
+ fs, ok := mnt.Filesystem().Impl().(*filesystem)
+ if !ok {
+ return nil, fmt.Errorf("can't import host FDs into filesystems of type %T", mnt.Filesystem().Impl())
+ }
+
+ // Retrieve metadata.
+ var s syscall.Stat_t
+ if err := syscall.Fstat(hostFD, &s); err != nil {
+ return nil, err
+ }
+
+ fileMode := linux.FileMode(s.Mode)
+ fileType := fileMode.FileType()
+ // Pipes, character devices, and sockets can return EWOULDBLOCK for
+ // operations that would block.
+ isStream := fileType == syscall.S_IFIFO || fileType == syscall.S_IFCHR || fileType == syscall.S_IFSOCK
+
+ i := &inode{
+ hostFD: hostFD,
+ isStream: isStream,
+ isTTY: isTTY,
+ ino: fs.NextIno(),
+ mode: fileMode,
+ uid: ownerUID,
+ gid: ownerGID,
+ }
+
+ d := &kernfs.Dentry{}
+ d.Init(i)
+ // i.open will take a reference on d.
+ defer d.DecRef()
+
+ return i.open(d.VFSDentry(), mnt)
+}
+
+// inode implements kernfs.Inode.
+type inode struct {
+ kernfs.InodeNotDirectory
+ kernfs.InodeNotSymlink
+
+ // When the reference count reaches zero, the host fd is closed.
+ refs.AtomicRefCount
+
+ // hostFD contains the host fd that this file was originally created from,
+ // which must be available at time of restore.
+ //
+ // This field is initialized at creation time and is immutable.
+ hostFD int
+
+ // isStream is true if the host fd points to a file representing a stream,
+ // e.g. a socket or a pipe. Such files are not seekable and can return
+ // EWOULDBLOCK for I/O operations.
+ //
+ // This field is initialized at creation time and is immutable.
+ isStream bool
+
+ // isTTY is true if this file represents a TTY.
+ //
+ // This field is initialized at creation time and is immutable.
+ isTTY bool
+
+ // ino is an inode number unique within this filesystem.
+ ino uint64
+
+ // mu protects the inode metadata below.
+ mu sync.Mutex
+
+ // mode is the file mode of this inode. Note that this value may become out
+ // of date if the mode is changed on the host, e.g. with chmod.
+ mode linux.FileMode
+
+ // uid and gid of the file owner. Note that these refer to the owner of the
+ // file created on import, not the fd on the host.
+ uid auth.KUID
+ gid auth.KGID
+}
+
+// Note that these flags may become out of date, since they can be modified
+// on the host, e.g. with fcntl.
+func fileFlagsFromHostFD(fd int) (int, error) {
+ flags, err := unix.FcntlInt(uintptr(fd), syscall.F_GETFL, 0)
+ if err != nil {
+ log.Warningf("Failed to get file flags for donated FD %d: %v", fd, err)
+ return 0, err
+ }
+ // TODO(gvisor.dev/issue/1672): implement behavior corresponding to these allowed flags.
+ flags &= syscall.O_ACCMODE | syscall.O_DIRECT | syscall.O_NONBLOCK | syscall.O_DSYNC | syscall.O_SYNC | syscall.O_APPEND
+ return flags, nil
+}
+
+// CheckPermissions implements kernfs.Inode.
+func (i *inode) CheckPermissions(ctx context.Context, creds *auth.Credentials, atx vfs.AccessTypes) error {
+ return vfs.GenericCheckPermissions(creds, atx, false /* isDir */, uint16(i.mode), i.uid, i.gid)
+}
+
+// Mode implements kernfs.Inode.
+func (i *inode) Mode() linux.FileMode {
+ return i.mode
+}
+
+// Stat implements kernfs.Inode.
+func (i *inode) Stat(_ *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+ var s unix.Statx_t
+ if err := unix.Statx(i.hostFD, "", int(unix.AT_EMPTY_PATH|opts.Sync), int(opts.Mask), &s); err != nil {
+ return linux.Statx{}, err
+ }
+ ls := unixToLinuxStatx(s)
+
+ // Use our own internal inode number and file owner.
+ //
+ // TODO(gvisor.dev/issue/1672): Use a kernfs-specific device number as well.
+ // If we use the device number from the host, it may collide with another
+ // sentry-internal device number. We handle device/inode numbers without
+ // relying on the host to prevent collisions.
+ ls.Ino = i.ino
+ ls.UID = uint32(i.uid)
+ ls.GID = uint32(i.gid)
+
+ // Update file mode from the host.
+ i.mode = linux.FileMode(ls.Mode)
+
+ return ls, nil
+}
+
+// SetStat implements kernfs.Inode.
+func (i *inode) SetStat(_ *vfs.Filesystem, opts vfs.SetStatOptions) error {
+ s := opts.Stat
+
+ m := s.Mask
+ if m == 0 {
+ return nil
+ }
+ if m&(linux.STATX_UID|linux.STATX_GID) != 0 {
+ return syserror.EPERM
+ }
+ if m&linux.STATX_MODE != 0 {
+ if err := syscall.Fchmod(i.hostFD, uint32(s.Mode)); err != nil {
+ return err
+ }
+ i.mode = linux.FileMode(s.Mode)
+ }
+ if m&linux.STATX_SIZE != 0 {
+ if err := syscall.Ftruncate(i.hostFD, int64(s.Size)); err != nil {
+ return err
+ }
+ }
+ if m&(linux.STATX_ATIME|linux.STATX_MTIME) != 0 {
+ timestamps := []unix.Timespec{
+ toTimespec(s.Atime, m&linux.STATX_ATIME == 0),
+ toTimespec(s.Mtime, m&linux.STATX_MTIME == 0),
+ }
+ if err := unix.UtimesNanoAt(i.hostFD, "", timestamps, unix.AT_EMPTY_PATH); err != nil {
+ return err
+ }
+ }
+ return nil
+}
+
+// DecRef implements kernfs.Inode.
+func (i *inode) DecRef() {
+ i.AtomicRefCount.DecRefWithDestructor(i.Destroy)
+}
+
+// Destroy implements kernfs.Inode.
+func (i *inode) Destroy() {
+ if err := unix.Close(i.hostFD); err != nil {
+ log.Warningf("failed to close host fd %d: %v", i.hostFD, err)
+ }
+}
+
+// Open implements kernfs.Inode.
+func (i *inode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
+ return i.open(vfsd, rp.Mount())
+}
+
+func (i *inode) open(d *vfs.Dentry, mnt *vfs.Mount) (*vfs.FileDescription, error) {
+
+ fileType := i.mode.FileType()
+ if fileType == syscall.S_IFSOCK {
+ if i.isTTY {
+ return nil, errors.New("cannot use host socket as TTY")
+ }
+ // TODO(gvisor.dev/issue/1672): support importing sockets.
+ return nil, errors.New("importing host sockets not supported")
+ }
+
+ if i.isTTY {
+ // TODO(gvisor.dev/issue/1672): support importing host fd as TTY.
+ return nil, errors.New("importing host fd as TTY not supported")
+ }
+
+ // For simplicity, set offset to 0. Technically, we should
+ // only set to 0 on files that are not seekable (sockets, pipes, etc.),
+ // and use the offset from the host fd otherwise.
+ fd := &defaultFileFD{
+ fileDescription: fileDescription{
+ inode: i,
+ },
+ canMap: canMap(uint32(fileType)),
+ mu: sync.Mutex{},
+ offset: 0,
+ }
+
+ vfsfd := &fd.vfsfd
+ flags, err := fileFlagsFromHostFD(i.hostFD)
+ if err != nil {
+ return nil, err
+ }
+
+ if err := vfsfd.Init(fd, uint32(flags), mnt, d, &vfs.FileDescriptionOptions{}); err != nil {
+ return nil, err
+ }
+ return vfsfd, nil
+}
+
+// fileDescription is embedded by host fd implementations of FileDescriptionImpl.
+type fileDescription struct {
+ vfsfd vfs.FileDescription
+ vfs.FileDescriptionDefaultImpl
+
+ // inode is vfsfd.Dentry().Impl().(*kernfs.Dentry).Inode().(*inode), but
+ // cached to reduce indirections and casting. fileDescription does not hold
+ // a reference on the inode through the inode field (since one is already
+ // held via the Dentry).
+ //
+ // inode is immutable after fileDescription creation.
+ inode *inode
+}
+
+// SetStat implements vfs.FileDescriptionImpl.
+func (f *fileDescription) SetStat(_ context.Context, opts vfs.SetStatOptions) error {
+ return f.inode.SetStat(nil, opts)
+}
+
+// Stat implements vfs.FileDescriptionImpl.
+func (f *fileDescription) Stat(_ context.Context, opts vfs.StatOptions) (linux.Statx, error) {
+ return f.inode.Stat(nil, opts)
+}
+
+// Release implements vfs.FileDescriptionImpl.
+func (f *fileDescription) Release() {
+ // noop
+}
diff --git a/pkg/sentry/fsimpl/host/util.go b/pkg/sentry/fsimpl/host/util.go
new file mode 100644
index 000000000..e1ccacb4d
--- /dev/null
+++ b/pkg/sentry/fsimpl/host/util.go
@@ -0,0 +1,86 @@
+// Copyright 2020 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 host
+
+import (
+ "syscall"
+
+ "golang.org/x/sys/unix"
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/syserror"
+)
+
+func toTimespec(ts linux.StatxTimestamp, omit bool) unix.Timespec {
+ if omit {
+ return unix.Timespec{
+ Sec: 0,
+ Nsec: unix.UTIME_OMIT,
+ }
+ }
+ return unix.Timespec{
+ Sec: int64(ts.Sec),
+ Nsec: int64(ts.Nsec),
+ }
+}
+
+func unixToLinuxStatx(s unix.Statx_t) linux.Statx {
+ return linux.Statx{
+ Mask: s.Mask,
+ Blksize: s.Blksize,
+ Attributes: s.Attributes,
+ Nlink: s.Nlink,
+ UID: s.Uid,
+ GID: s.Gid,
+ Mode: s.Mode,
+ Ino: s.Ino,
+ Size: s.Size,
+ Blocks: s.Blocks,
+ AttributesMask: s.Attributes_mask,
+ Atime: unixToLinuxStatxTimestamp(s.Atime),
+ Btime: unixToLinuxStatxTimestamp(s.Btime),
+ Ctime: unixToLinuxStatxTimestamp(s.Ctime),
+ Mtime: unixToLinuxStatxTimestamp(s.Mtime),
+ RdevMajor: s.Rdev_major,
+ RdevMinor: s.Rdev_minor,
+ DevMajor: s.Dev_major,
+ DevMinor: s.Dev_minor,
+ }
+}
+
+func unixToLinuxStatxTimestamp(ts unix.StatxTimestamp) linux.StatxTimestamp {
+ return linux.StatxTimestamp{Sec: ts.Sec, Nsec: ts.Nsec}
+}
+
+// wouldBlock returns true for file types that can return EWOULDBLOCK
+// for blocking operations, e.g. pipes, character devices, and sockets.
+func wouldBlock(fileType uint32) bool {
+ return fileType == syscall.S_IFIFO || fileType == syscall.S_IFCHR || fileType == syscall.S_IFSOCK
+}
+
+// canMap returns true if a file with fileType is allowed to be memory mapped.
+// This is ported over from VFS1, but it's probably not the best way for us
+// to check if a file can be memory mapped.
+func canMap(fileType uint32) bool {
+ // TODO(gvisor.dev/issue/1672): Also allow "special files" to be mapped (see fs/host:canMap()).
+ //
+ // TODO(b/38213152): Some obscure character devices can be mapped.
+ return fileType == syscall.S_IFREG
+}
+
+// isBlockError checks if an error is EAGAIN or EWOULDBLOCK.
+// If so, they can be transformed into syserror.ErrWouldBlock.
+func isBlockError(err error) bool {
+ return err == syserror.EAGAIN || err == syserror.EWOULDBLOCK
+}
diff --git a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
index d092ccb2a..1c026f4d8 100644
--- a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
+++ b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
@@ -122,7 +122,7 @@ func (fd *DynamicBytesFD) Release() {}
// Stat implements vfs.FileDescriptionImpl.Stat.
func (fd *DynamicBytesFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
fs := fd.vfsfd.VirtualDentry().Mount().Filesystem()
- return fd.inode.Stat(fs), nil
+ return fd.inode.Stat(fs, opts)
}
// SetStat implements vfs.FileDescriptionImpl.SetStat.
diff --git a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
index 5650512e0..da821d524 100644
--- a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
@@ -107,9 +107,13 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent
fs.mu.Lock()
defer fs.mu.Unlock()
+ opts := vfs.StatOptions{Mask: linux.STATX_INO}
// Handle ".".
if fd.off == 0 {
- stat := fd.inode().Stat(vfsFS)
+ stat, err := fd.inode().Stat(vfsFS, opts)
+ if err != nil {
+ return err
+ }
dirent := vfs.Dirent{
Name: ".",
Type: linux.DT_DIR,
@@ -125,7 +129,10 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent
// Handle "..".
if fd.off == 1 {
parentInode := vfsd.ParentOrSelf().Impl().(*Dentry).inode
- stat := parentInode.Stat(vfsFS)
+ stat, err := parentInode.Stat(vfsFS, opts)
+ if err != nil {
+ return err
+ }
dirent := vfs.Dirent{
Name: "..",
Type: linux.FileMode(stat.Mode).DirentType(),
@@ -146,7 +153,10 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent
childIdx := fd.off - 2
for it := fd.children.nthLocked(childIdx); it != nil; it = it.Next() {
inode := it.Dentry.Impl().(*Dentry).inode
- stat := inode.Stat(vfsFS)
+ stat, err := inode.Stat(vfsFS, opts)
+ if err != nil {
+ return err
+ }
dirent := vfs.Dirent{
Name: it.Name,
Type: linux.FileMode(stat.Mode).DirentType(),
@@ -190,7 +200,7 @@ func (fd *GenericDirectoryFD) Seek(ctx context.Context, offset int64, whence int
func (fd *GenericDirectoryFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
fs := fd.filesystem()
inode := fd.inode()
- return inode.Stat(fs), nil
+ return inode.Stat(fs, opts)
}
// SetStat implements vfs.FileDescriptionImpl.SetStat.
diff --git a/pkg/sentry/fsimpl/kernfs/filesystem.go b/pkg/sentry/fsimpl/kernfs/filesystem.go
index 292f58afd..1d7e04ad4 100644
--- a/pkg/sentry/fsimpl/kernfs/filesystem.go
+++ b/pkg/sentry/fsimpl/kernfs/filesystem.go
@@ -12,10 +12,10 @@
// See the License for the specific language governing permissions and
// limitations under the License.
-// This file implements vfs.FilesystemImpl for kernfs.
-
package kernfs
+// This file implements vfs.FilesystemImpl for kernfs.
+
import (
"fmt"
@@ -634,7 +634,7 @@ func (fs *Filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
if err != nil {
return linux.Statx{}, err
}
- return inode.Stat(fs.VFSFilesystem()), nil
+ return inode.Stat(fs.VFSFilesystem(), opts)
}
// StatFSAt implements vfs.FilesystemImpl.StatFSAt.
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index 099d70a16..d50018b18 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -36,20 +36,20 @@ type InodeNoopRefCount struct {
}
// IncRef implements Inode.IncRef.
-func (n *InodeNoopRefCount) IncRef() {
+func (InodeNoopRefCount) IncRef() {
}
// DecRef implements Inode.DecRef.
-func (n *InodeNoopRefCount) DecRef() {
+func (InodeNoopRefCount) DecRef() {
}
// TryIncRef implements Inode.TryIncRef.
-func (n *InodeNoopRefCount) TryIncRef() bool {
+func (InodeNoopRefCount) TryIncRef() bool {
return true
}
// Destroy implements Inode.Destroy.
-func (n *InodeNoopRefCount) Destroy() {
+func (InodeNoopRefCount) Destroy() {
}
// InodeDirectoryNoNewChildren partially implements the Inode interface.
@@ -58,27 +58,27 @@ func (n *InodeNoopRefCount) Destroy() {
type InodeDirectoryNoNewChildren struct{}
// NewFile implements Inode.NewFile.
-func (*InodeDirectoryNoNewChildren) NewFile(context.Context, string, vfs.OpenOptions) (*vfs.Dentry, error) {
+func (InodeDirectoryNoNewChildren) NewFile(context.Context, string, vfs.OpenOptions) (*vfs.Dentry, error) {
return nil, syserror.EPERM
}
// NewDir implements Inode.NewDir.
-func (*InodeDirectoryNoNewChildren) NewDir(context.Context, string, vfs.MkdirOptions) (*vfs.Dentry, error) {
+func (InodeDirectoryNoNewChildren) NewDir(context.Context, string, vfs.MkdirOptions) (*vfs.Dentry, error) {
return nil, syserror.EPERM
}
// NewLink implements Inode.NewLink.
-func (*InodeDirectoryNoNewChildren) NewLink(context.Context, string, Inode) (*vfs.Dentry, error) {
+func (InodeDirectoryNoNewChildren) NewLink(context.Context, string, Inode) (*vfs.Dentry, error) {
return nil, syserror.EPERM
}
// NewSymlink implements Inode.NewSymlink.
-func (*InodeDirectoryNoNewChildren) NewSymlink(context.Context, string, string) (*vfs.Dentry, error) {
+func (InodeDirectoryNoNewChildren) NewSymlink(context.Context, string, string) (*vfs.Dentry, error) {
return nil, syserror.EPERM
}
// NewNode implements Inode.NewNode.
-func (*InodeDirectoryNoNewChildren) NewNode(context.Context, string, vfs.MknodOptions) (*vfs.Dentry, error) {
+func (InodeDirectoryNoNewChildren) NewNode(context.Context, string, vfs.MknodOptions) (*vfs.Dentry, error) {
return nil, syserror.EPERM
}
@@ -90,62 +90,62 @@ type InodeNotDirectory struct {
}
// HasChildren implements Inode.HasChildren.
-func (*InodeNotDirectory) HasChildren() bool {
+func (InodeNotDirectory) HasChildren() bool {
return false
}
// NewFile implements Inode.NewFile.
-func (*InodeNotDirectory) NewFile(context.Context, string, vfs.OpenOptions) (*vfs.Dentry, error) {
+func (InodeNotDirectory) NewFile(context.Context, string, vfs.OpenOptions) (*vfs.Dentry, error) {
panic("NewFile called on non-directory inode")
}
// NewDir implements Inode.NewDir.
-func (*InodeNotDirectory) NewDir(context.Context, string, vfs.MkdirOptions) (*vfs.Dentry, error) {
+func (InodeNotDirectory) NewDir(context.Context, string, vfs.MkdirOptions) (*vfs.Dentry, error) {
panic("NewDir called on non-directory inode")
}
// NewLink implements Inode.NewLinkink.
-func (*InodeNotDirectory) NewLink(context.Context, string, Inode) (*vfs.Dentry, error) {
+func (InodeNotDirectory) NewLink(context.Context, string, Inode) (*vfs.Dentry, error) {
panic("NewLink called on non-directory inode")
}
// NewSymlink implements Inode.NewSymlink.
-func (*InodeNotDirectory) NewSymlink(context.Context, string, string) (*vfs.Dentry, error) {
+func (InodeNotDirectory) NewSymlink(context.Context, string, string) (*vfs.Dentry, error) {
panic("NewSymlink called on non-directory inode")
}
// NewNode implements Inode.NewNode.
-func (*InodeNotDirectory) NewNode(context.Context, string, vfs.MknodOptions) (*vfs.Dentry, error) {
+func (InodeNotDirectory) NewNode(context.Context, string, vfs.MknodOptions) (*vfs.Dentry, error) {
panic("NewNode called on non-directory inode")
}
// Unlink implements Inode.Unlink.
-func (*InodeNotDirectory) Unlink(context.Context, string, *vfs.Dentry) error {
+func (InodeNotDirectory) Unlink(context.Context, string, *vfs.Dentry) error {
panic("Unlink called on non-directory inode")
}
// RmDir implements Inode.RmDir.
-func (*InodeNotDirectory) RmDir(context.Context, string, *vfs.Dentry) error {
+func (InodeNotDirectory) RmDir(context.Context, string, *vfs.Dentry) error {
panic("RmDir called on non-directory inode")
}
// Rename implements Inode.Rename.
-func (*InodeNotDirectory) Rename(context.Context, string, string, *vfs.Dentry, *vfs.Dentry) (*vfs.Dentry, error) {
+func (InodeNotDirectory) Rename(context.Context, string, string, *vfs.Dentry, *vfs.Dentry) (*vfs.Dentry, error) {
panic("Rename called on non-directory inode")
}
// Lookup implements Inode.Lookup.
-func (*InodeNotDirectory) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) {
+func (InodeNotDirectory) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) {
panic("Lookup called on non-directory inode")
}
// IterDirents implements Inode.IterDirents.
-func (*InodeNotDirectory) IterDirents(ctx context.Context, callback vfs.IterDirentsCallback, offset, relOffset int64) (newOffset int64, err error) {
+func (InodeNotDirectory) IterDirents(ctx context.Context, callback vfs.IterDirentsCallback, offset, relOffset int64) (newOffset int64, err error) {
panic("IterDirents called on non-directory inode")
}
// Valid implements Inode.Valid.
-func (*InodeNotDirectory) Valid(context.Context) bool {
+func (InodeNotDirectory) Valid(context.Context) bool {
return true
}
@@ -157,17 +157,17 @@ func (*InodeNotDirectory) Valid(context.Context) bool {
type InodeNoDynamicLookup struct{}
// Lookup implements Inode.Lookup.
-func (*InodeNoDynamicLookup) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) {
+func (InodeNoDynamicLookup) Lookup(ctx context.Context, name string) (*vfs.Dentry, error) {
return nil, syserror.ENOENT
}
// IterDirents implements Inode.IterDirents.
-func (*InodeNoDynamicLookup) IterDirents(ctx context.Context, callback vfs.IterDirentsCallback, offset, relOffset int64) (int64, error) {
+func (InodeNoDynamicLookup) IterDirents(ctx context.Context, callback vfs.IterDirentsCallback, offset, relOffset int64) (int64, error) {
return offset, nil
}
// Valid implements Inode.Valid.
-func (*InodeNoDynamicLookup) Valid(ctx context.Context) bool {
+func (InodeNoDynamicLookup) Valid(ctx context.Context) bool {
return true
}
@@ -177,7 +177,7 @@ func (*InodeNoDynamicLookup) Valid(ctx context.Context) bool {
type InodeNotSymlink struct{}
// Readlink implements Inode.Readlink.
-func (*InodeNotSymlink) Readlink(context.Context) (string, error) {
+func (InodeNotSymlink) Readlink(context.Context) (string, error) {
return "", syserror.EINVAL
}
@@ -219,7 +219,7 @@ func (a *InodeAttrs) Mode() linux.FileMode {
// Stat partially implements Inode.Stat. Note that this function doesn't provide
// all the stat fields, and the embedder should consider extending the result
// with filesystem-specific fields.
-func (a *InodeAttrs) Stat(*vfs.Filesystem) linux.Statx {
+func (a *InodeAttrs) Stat(*vfs.Filesystem, vfs.StatOptions) (linux.Statx, error) {
var stat linux.Statx
stat.Mask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO | linux.STATX_NLINK
stat.Ino = atomic.LoadUint64(&a.ino)
@@ -230,7 +230,7 @@ func (a *InodeAttrs) Stat(*vfs.Filesystem) linux.Statx {
// TODO: Implement other stat fields like timestamps.
- return stat
+ return stat, nil
}
// SetStat implements Inode.SetStat.
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index c74fa999b..a8ab2a2ba 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -176,8 +176,6 @@ type Dentry struct {
vfsd vfs.Dentry
inode Inode
- refs uint64
-
// flags caches useful information about the dentry from the inode. See the
// dflags* consts above. Must be accessed by atomic ops.
flags uint32
@@ -302,7 +300,8 @@ type Inode interface {
// this inode. The returned file description should hold a reference on the
// inode for its lifetime.
//
- // Precondition: !rp.Done(). vfsd.Impl() must be a kernfs Dentry.
+ // Precondition: rp.Done(). vfsd.Impl() must be the kernfs Dentry containing
+ // the inode on which Open() is being called.
Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error)
}
@@ -328,7 +327,7 @@ type inodeMetadata interface {
// Stat returns the metadata for this inode. This corresponds to
// vfs.FilesystemImpl.StatAt.
- Stat(fs *vfs.Filesystem) linux.Statx
+ Stat(fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error)
// SetStat updates the metadata for this inode. This corresponds to
// vfs.FilesystemImpl.SetStatAt.
diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go
index f3f4e49b4..611645f3f 100644
--- a/pkg/sentry/fsimpl/proc/subtasks.go
+++ b/pkg/sentry/fsimpl/proc/subtasks.go
@@ -121,8 +121,13 @@ func (i *subtasksInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.O
}
// Stat implements kernfs.Inode.
-func (i *subtasksInode) Stat(vsfs *vfs.Filesystem) linux.Statx {
- stat := i.InodeAttrs.Stat(vsfs)
- stat.Nlink += uint32(i.task.ThreadGroup().Count())
- return stat
+func (i *subtasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+ stat, err := i.InodeAttrs.Stat(vsfs, opts)
+ if err != nil {
+ return linux.Statx{}, err
+ }
+ if opts.Mask&linux.STATX_NLINK != 0 {
+ stat.Nlink += uint32(i.task.ThreadGroup().Count())
+ }
+ return stat, nil
}
diff --git a/pkg/sentry/fsimpl/proc/task.go b/pkg/sentry/fsimpl/proc/task.go
index 18e5cd6f6..c0d643f51 100644
--- a/pkg/sentry/fsimpl/proc/task.go
+++ b/pkg/sentry/fsimpl/proc/task.go
@@ -154,12 +154,21 @@ func newTaskOwnedDir(task *kernel.Task, ino uint64, perm linux.FileMode, childre
}
// Stat implements kernfs.Inode.
-func (i *taskOwnedInode) Stat(fs *vfs.Filesystem) linux.Statx {
- stat := i.Inode.Stat(fs)
- uid, gid := i.getOwner(linux.FileMode(stat.Mode))
- stat.UID = uint32(uid)
- stat.GID = uint32(gid)
- return stat
+func (i *taskOwnedInode) Stat(fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+ stat, err := i.Inode.Stat(fs, opts)
+ if err != nil {
+ return linux.Statx{}, err
+ }
+ if opts.Mask&(linux.STATX_UID|linux.STATX_GID) != 0 {
+ uid, gid := i.getOwner(linux.FileMode(stat.Mode))
+ if opts.Mask&linux.STATX_UID != 0 {
+ stat.UID = uint32(uid)
+ }
+ if opts.Mask&linux.STATX_GID != 0 {
+ stat.GID = uint32(gid)
+ }
+ }
+ return stat, nil
}
// CheckPermissions implements kernfs.Inode.
@@ -236,7 +245,7 @@ func newNamespaceSymlink(task *kernel.Task, ino uint64, ns string) *kernfs.Dentr
// member, there is one entry containing three colon-separated fields:
// hierarchy-ID:controller-list:cgroup-path"
func newCgroupData(controllers map[string]string) dynamicInode {
- buf := bytes.Buffer{}
+ var buf bytes.Buffer
// The hierarchy ids must be positive integers (for cgroup v1), but the
// exact number does not matter, so long as they are unique. We can
diff --git a/pkg/sentry/fsimpl/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go
index 10c08fa90..b1e39c82f 100644
--- a/pkg/sentry/fsimpl/proc/tasks.go
+++ b/pkg/sentry/fsimpl/proc/tasks.go
@@ -211,17 +211,22 @@ func (i *tasksInode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.Open
return fd.VFSFileDescription(), nil
}
-func (i *tasksInode) Stat(vsfs *vfs.Filesystem) linux.Statx {
- stat := i.InodeAttrs.Stat(vsfs)
+func (i *tasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+ stat, err := i.InodeAttrs.Stat(vsfs, opts)
+ if err != nil {
+ return linux.Statx{}, err
+ }
- // Add dynamic children to link count.
- for _, tg := range i.pidns.ThreadGroups() {
- if leader := tg.Leader(); leader != nil {
- stat.Nlink++
+ if opts.Mask&linux.STATX_NLINK != 0 {
+ // Add dynamic children to link count.
+ for _, tg := range i.pidns.ThreadGroups() {
+ if leader := tg.Leader(); leader != nil {
+ stat.Nlink++
+ }
}
}
- return stat
+ return stat, nil
}
func cpuInfoData(k *kernel.Kernel) string {
diff --git a/pkg/sentry/vfs/BUILD b/pkg/sentry/vfs/BUILD
index 07c8383e6..cb4deb068 100644
--- a/pkg/sentry/vfs/BUILD
+++ b/pkg/sentry/vfs/BUILD
@@ -42,10 +42,13 @@ go_library(
deps = [
"//pkg/abi/linux",
"//pkg/context",
+ "//pkg/fd",
"//pkg/fspath",
"//pkg/gohacks",
"//pkg/log",
+ "//pkg/safemem",
"//pkg/sentry/arch",
+ "//pkg/sentry/fs",
"//pkg/sentry/fs/lock",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/memmap",
@@ -53,6 +56,7 @@ go_library(
"//pkg/syserror",
"//pkg/usermem",
"//pkg/waiter",
+ "@org_golang_x_sys//unix:go_default_library",
],
)
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index c2a52ec1b..45191d1c3 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -33,8 +33,8 @@ import (
// implementations to adapt:
// - Have a local fileDescription struct (containing FileDescription) which
// embeds FileDescriptionDefaultImpl and overrides the default methods
-// which are common to all fd implementations for that for that filesystem
-// like StatusFlags, SetStatusFlags, Stat, SetStat, StatFS, etc.
+// which are common to all fd implementations for that filesystem like
+// StatusFlags, SetStatusFlags, Stat, SetStat, StatFS, etc.
// - This should be embedded in all file description implementations as the
// first field by value.
// - Directory FDs would also embed DirectoryFileDescriptionDefaultImpl.
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 13:29:37 +0000