2018-10-19 23:34:09 +00:00
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// Copyright 2018 Google LLC
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2018-04-27 17:37:02 +00:00
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package linux
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import (
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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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)
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// Stat implements linux syscall stat(2).
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func Stat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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addr := args[0].Pointer()
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statAddr := args[1].Pointer()
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path, dirPath, err := copyInPath(t, addr, false /* allowEmpty */)
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if err != nil {
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return 0, nil, err
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}
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return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
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return stat(t, d, dirPath, statAddr)
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})
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}
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// Fstatat implements linux syscall newfstatat, i.e. fstatat(2).
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func Fstatat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := kdefs.FD(args[0].Int())
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addr := args[1].Pointer()
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statAddr := args[2].Pointer()
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flags := args[3].Int()
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path, dirPath, err := copyInPath(t, addr, flags&linux.AT_EMPTY_PATH != 0)
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if err != nil {
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return 0, nil, err
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}
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if path == "" {
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// Annoying. What's wrong with fstat?
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file := t.FDMap().GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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return 0, nil, stat(t, file.Dirent, false, statAddr)
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}
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return 0, nil, fileOpOn(t, fd, path, flags&linux.AT_SYMLINK_NOFOLLOW == 0, func(root *fs.Dirent, d *fs.Dirent) error {
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return stat(t, d, dirPath, statAddr)
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})
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}
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// Lstat implements linux syscall lstat(2).
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func Lstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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addr := args[0].Pointer()
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statAddr := args[1].Pointer()
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path, dirPath, err := copyInPath(t, addr, false /* allowEmpty */)
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if err != nil {
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return 0, nil, err
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}
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return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, false /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
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return stat(t, d, dirPath, statAddr)
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})
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}
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// Fstat implements linux syscall fstat(2).
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func Fstat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := kdefs.FD(args[0].Int())
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statAddr := args[1].Pointer()
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file := t.FDMap().GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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return 0, nil, stat(t, file.Dirent, false /* dirPath */, statAddr)
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}
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// stat implements stat from the given *fs.Dirent.
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func stat(t *kernel.Task, d *fs.Dirent, dirPath bool, statAddr usermem.Addr) error {
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if dirPath && !fs.IsDir(d.Inode.StableAttr) {
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return syserror.ENOTDIR
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}
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uattr, err := d.Inode.UnstableAttr(t)
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if err != nil {
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return err
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}
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var mode uint32
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switch d.Inode.StableAttr.Type {
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case fs.RegularFile, fs.SpecialFile:
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mode |= linux.ModeRegular
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case fs.Symlink:
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mode |= linux.ModeSymlink
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case fs.Directory, fs.SpecialDirectory:
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mode |= linux.ModeDirectory
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case fs.Pipe:
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mode |= linux.ModeNamedPipe
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case fs.CharacterDevice:
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mode |= linux.ModeCharacterDevice
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case fs.BlockDevice:
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mode |= linux.ModeBlockDevice
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case fs.Socket:
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mode |= linux.ModeSocket
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}
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_, err = t.CopyOut(statAddr, linux.Stat{
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Dev: uint64(d.Inode.StableAttr.DeviceID),
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Rdev: uint64(linux.MakeDeviceID(d.Inode.StableAttr.DeviceFileMajor, d.Inode.StableAttr.DeviceFileMinor)),
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Ino: uint64(d.Inode.StableAttr.InodeID),
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Nlink: uattr.Links,
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Mode: mode | uint32(uattr.Perms.LinuxMode()),
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UID: uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()),
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GID: uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()),
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Size: uattr.Size,
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Blksize: d.Inode.StableAttr.BlockSize,
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Blocks: uattr.Usage / 512,
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ATime: uattr.AccessTime.Timespec(),
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MTime: uattr.ModificationTime.Timespec(),
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CTime: uattr.StatusChangeTime.Timespec(),
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})
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return err
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}
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// Statfs implements linux syscall statfs(2).
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func Statfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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addr := args[0].Pointer()
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statfsAddr := args[1].Pointer()
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path, _, err := copyInPath(t, addr, false /* allowEmpty */)
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if err != nil {
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return 0, nil, err
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}
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return 0, nil, fileOpOn(t, linux.AT_FDCWD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent) error {
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return statfsImpl(t, d, statfsAddr)
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})
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}
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// Fstatfs implements linux syscall fstatfs(2).
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func Fstatfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := kdefs.FD(args[0].Int())
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statfsAddr := args[1].Pointer()
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file := t.FDMap().GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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return 0, nil, statfsImpl(t, file.Dirent, statfsAddr)
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}
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// statfsImpl implements the linux syscall statfs and fstatfs based on a Dirent,
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// copying the statfs structure out to addr on success, otherwise an error is
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// returned.
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func statfsImpl(t *kernel.Task, d *fs.Dirent, addr usermem.Addr) error {
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info, err := d.Inode.StatFS(t)
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if err != nil {
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return err
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}
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// Construct the statfs structure and copy it out.
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statfs := linux.Statfs{
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Type: info.Type,
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// Treat block size and fragment size as the same, as
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// most consumers of this structure will expect one
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// or the other to be filled in.
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BlockSize: d.Inode.StableAttr.BlockSize,
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Blocks: info.TotalBlocks,
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// We don't have the concept of reserved blocks, so
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// report blocks free the same as available blocks.
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// This is a normal thing for filesystems, to do, see
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// udf, hugetlbfs, tmpfs, among others.
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BlocksFree: info.FreeBlocks,
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BlocksAvailable: info.FreeBlocks,
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Files: info.TotalFiles,
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FilesFree: info.FreeFiles,
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// Same as Linux for simple_statfs, see fs/libfs.c.
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2018-10-08 18:38:02 +00:00
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NameLength: linux.NAME_MAX,
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2018-04-27 17:37:02 +00:00
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FragmentSize: d.Inode.StableAttr.BlockSize,
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// Leave other fields 0 like simple_statfs does.
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}
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if _, err := t.CopyOut(addr, &statfs); err != nil {
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return err
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}
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return nil
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}
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