112 lines
3.5 KiB
Go
112 lines
3.5 KiB
Go
// Copyright 2019 The gVisor Authors.
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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 ext
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import (
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/sentry/memmap"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/syserror"
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"gvisor.dev/gvisor/pkg/usermem"
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)
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// symlink represents a symlink inode.
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type symlink struct {
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inode inode
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target string // immutable
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}
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// newSymlink is the symlink constructor. It reads out the symlink target from
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// the inode (however it might have been stored).
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func newSymlink(args inodeArgs) (*symlink, error) {
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var link []byte
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// If the symlink target is lesser than 60 bytes, its stores in inode.Data().
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// Otherwise either extents or block maps will be used to store the link.
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size := args.diskInode.Size()
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if size < 60 {
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link = args.diskInode.Data()[:size]
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} else {
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// Create a regular file out of this inode and read out the target.
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regFile, err := newRegularFile(args)
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if err != nil {
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return nil, err
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}
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link = make([]byte, size)
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if n, err := regFile.impl.ReadAt(link, 0); uint64(n) < size {
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return nil, err
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}
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}
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file := &symlink{target: string(link)}
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file.inode.init(args, file)
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return file, nil
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}
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func (in *inode) isSymlink() bool {
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_, ok := in.impl.(*symlink)
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return ok
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}
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// symlinkFD represents a symlink file description and implements implements
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// vfs.FileDescriptionImpl. which may only be used if open options contains
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// O_PATH. For this reason most of the functions return EBADF.
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type symlinkFD struct {
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fileDescription
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vfs.NoLockFD
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}
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// Compiles only if symlinkFD implements vfs.FileDescriptionImpl.
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var _ vfs.FileDescriptionImpl = (*symlinkFD)(nil)
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// Release implements vfs.FileDescriptionImpl.Release.
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func (fd *symlinkFD) Release(context.Context) {}
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// PRead implements vfs.FileDescriptionImpl.PRead.
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func (fd *symlinkFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
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return 0, syserror.EBADF
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}
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// Read implements vfs.FileDescriptionImpl.Read.
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func (fd *symlinkFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
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return 0, syserror.EBADF
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}
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// PWrite implements vfs.FileDescriptionImpl.PWrite.
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func (fd *symlinkFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
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return 0, syserror.EBADF
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}
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// Write implements vfs.FileDescriptionImpl.Write.
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func (fd *symlinkFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
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return 0, syserror.EBADF
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}
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// IterDirents implements vfs.FileDescriptionImpl.IterDirents.
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func (fd *symlinkFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback) error {
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return syserror.ENOTDIR
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}
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// Seek implements vfs.FileDescriptionImpl.Seek.
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func (fd *symlinkFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
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return 0, syserror.EBADF
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}
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// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
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func (fd *symlinkFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
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return syserror.EBADF
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}
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