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// Copyright 2019 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 ext
import (
"io"
"gvisor.dev/gvisor/pkg/syserror"
)
// symlink represents a symlink inode.
type symlink struct {
inode inode
target string // immutable
}
// newSymlink is the symlink constructor. It reads out the symlink target from
// the inode (however it might have been stored).
//
// Preconditions: Must hold the mutex of the filesystem containing dev.
func newSymlink(dev io.ReadSeeker, blkSize uint64, inode inode) (*symlink, error) {
var file *symlink
var link []byte
// If the symlink target is lesser than 60 bytes, its stores in inode.Data().
// Otherwise either extents or block maps will be used to store the link.
size := inode.diskInode.Size()
if size < 60 {
link = inode.diskInode.Data()[:size]
} else {
// Create a regular file out of this inode and read out the target.
regFile, err := newRegularFile(dev, blkSize, inode)
if err != nil {
return nil, err
}
link = make([]byte, size)
reader := regFile.impl.getFileReader(dev, blkSize, 0)
if _, err := io.ReadFull(reader, link); err != nil {
return nil, syserror.EIO
}
}
file = &symlink{inode: inode, target: string(link)}
file.inode.impl = file
return file, nil
}
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