73 lines
2.6 KiB
Go
73 lines
2.6 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 disklayout
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import (
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"gvisor.dev/gvisor/pkg/sentry/fs"
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)
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const (
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// MaxFileName is the maximum length of an ext fs file's name.
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MaxFileName = 255
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// DirentSize is the size of ext dirent structures.
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DirentSize = 263
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)
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var (
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// inodeTypeByFileType maps ext4 file types to vfs inode types.
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//
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// See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#ftype.
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inodeTypeByFileType = map[uint8]fs.InodeType{
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0: fs.Anonymous,
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1: fs.RegularFile,
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2: fs.Directory,
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3: fs.CharacterDevice,
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4: fs.BlockDevice,
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5: fs.Pipe,
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6: fs.Socket,
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7: fs.Symlink,
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}
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)
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// The Dirent interface should be implemented by structs representing ext
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// directory entries. These are for the linear classical directories which
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// just store a list of dirent structs. A directory is a series of data blocks
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// where is each data block contains a linear array of dirents. The last entry
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// of the block has a record size that takes it to the end of the block. The
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// end of the directory is when you read dirInode.Size() bytes from the blocks.
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//
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// See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#linear-classic-directories.
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type Dirent interface {
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// Inode returns the absolute inode number of the underlying inode.
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// Inode number 0 signifies an unused dirent.
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Inode() uint32
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// RecordSize returns the record length of this dirent on disk. The next
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// dirent in the dirent list should be read after these many bytes from
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// the current dirent. Must be a multiple of 4.
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RecordSize() uint16
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// FileName returns the name of the file. Can be at most 255 is length.
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FileName() string
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// FileType returns the inode type of the underlying inode. This is a
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// performance hack so that we do not have to read the underlying inode struct
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// to know the type of inode. This will only work when the SbDirentFileType
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// feature is set. If not, the second returned value will be false indicating
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// that user code has to use the inode mode to extract the file type.
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FileType() (fs.InodeType, bool)
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}
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