ext4

package
v1.5.2 Latest Latest
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 Go to latest Published: Mar 10, 2025 License: MIT Imports: 22 Imported by: 0

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Constants

View Source 
const (
	HashVersionLegacy          = 0
	HashVersionHalfMD4         = 1
	HashVersionTEA             = 2
	HashVersionLegacyUnsigned  = 3
	HashVersionHalfMD4Unsigned = 4
	HashVersionTEAUnsigned     = 5
	HashVersionSIP             = 6
)
View Source 
const (
	// SectorSize512 is a sector size of 512 bytes, used as the logical size for all ext4 filesystems
	SectorSize512 SectorSize = 512

	BootSectorSize               SectorSize = 2 * SectorSize512
	SuperblockSize               SectorSize = 2 * SectorSize512
	BlockGroupFactor             int        = 8
	DefaultInodeRatio            int64      = 8192
	DefaultInodeSize             int64      = 256
	DefaultReservedBlocksPercent uint8      = 5
	DefaultVolumeName                       = "diskfs_ext4"
)
View Source 
const (
	// KB represents one KB
	KB int64 = 1024
	// MB represents one MB
	MB int64 = 1024 * KB
	// GB represents one GB
	GB int64 = 1024 * MB
	// TB represents one TB
	TB int64 = 1024 * GB
	// PB represents one TB
	PB int64 = 1024 * TB
	// XB represents one Exabyte
	XB int64 = 1024 * PB

	// Ext4MinSize is minimum size for an ext4 filesystem
	//   it assumes a single block group with:
	//   blocksize = 2 sectors = 1KB
	//   1 block for boot code
	//   1 block for superblock
	//   1 block for block group descriptors
	//   1 block for bock and inode bitmaps and inode table
	//   1 block for data
	//   total = 5 blocks
	Ext4MinSize int64 = 5 * int64(SectorSize512)
)

Variables

This section is empty.

Functions

func TEATransform 

func TEATransform(buf [4]uint32, in []uint32) [4]uint32

Types

type BlockSize 

type BlockSize uint8

BlockSize indicates how many sectors are in a block

type Directory 

type Directory struct {
	// contains filtered or unexported fields
}

Directory represents a single directory in an ext4 filesystem

type FeatureOpt 

type FeatureOpt func(*featureFlags)

func WithFeatureBTreeDirectory 

func WithFeatureBTreeDirectory(enable bool) FeatureOpt

func WithFeatureBigalloc 

func WithFeatureBigalloc(enable bool) FeatureOpt

func WithFeatureCompression 

func WithFeatureCompression(enable bool) FeatureOpt

func WithFeatureDataInDirectoryEntries 

func WithFeatureDataInDirectoryEntries(enable bool) FeatureOpt

func WithFeatureDataInInode 

func WithFeatureDataInInode(enable bool) FeatureOpt

func WithFeatureDirectoryEntriesRecordFileType 

func WithFeatureDirectoryEntriesRecordFileType(enable bool) FeatureOpt

func WithFeatureDirectoryIndices 

func WithFeatureDirectoryIndices(enable bool) FeatureOpt

func WithFeatureDirectoryPreAllocate 

func WithFeatureDirectoryPreAllocate(enable bool) FeatureOpt

func WithFeatureEncryptInodes 

func WithFeatureEncryptInodes(enable bool) FeatureOpt

func WithFeatureExcludeBitmap 

func WithFeatureExcludeBitmap(enable bool) FeatureOpt

func WithFeatureExcludeInode 

func WithFeatureExcludeInode(enable bool) FeatureOpt

func WithFeatureExtendedAttributeInodes 

func WithFeatureExtendedAttributeInodes(enable bool) FeatureOpt

func WithFeatureExtendedAttributes 

func WithFeatureExtendedAttributes(enable bool) FeatureOpt

func WithFeatureExtents 

func WithFeatureExtents(enable bool) FeatureOpt

func WithFeatureFS64Bit 

func WithFeatureFS64Bit(enable bool) FeatureOpt

func WithFeatureFlexBlockGroups 

func WithFeatureFlexBlockGroups(enable bool) FeatureOpt

func WithFeatureGDTChecksum 

func WithFeatureGDTChecksum(enable bool) FeatureOpt

func WithFeatureHasJournal 

func WithFeatureHasJournal(enable bool) FeatureOpt

func WithFeatureHugeFile 

func WithFeatureHugeFile(enable bool) FeatureOpt

func WithFeatureImagicInodes 

func WithFeatureImagicInodes(enable bool) FeatureOpt

func WithFeatureLargeDirectory 

func WithFeatureLargeDirectory(enable bool) FeatureOpt

func WithFeatureLargeFile 

func WithFeatureLargeFile(enable bool) FeatureOpt

func WithFeatureLargeInodes 

func WithFeatureLargeInodes(enable bool) FeatureOpt

func WithFeatureLargeSubdirectoryCount 

func WithFeatureLargeSubdirectoryCount(enable bool) FeatureOpt

func WithFeatureLazyBlockGroup 

func WithFeatureLazyBlockGroup(enable bool) FeatureOpt

func WithFeatureMetaBlockGroups 

func WithFeatureMetaBlockGroups(enable bool) FeatureOpt

func WithFeatureMetadataChecksumSeedInSuperblock 

func WithFeatureMetadataChecksumSeedInSuperblock(enable bool) FeatureOpt

func WithFeatureMetadataChecksums 

func WithFeatureMetadataChecksums(enable bool) FeatureOpt

func WithFeatureMultipleMountProtection 

func WithFeatureMultipleMountProtection(enable bool) FeatureOpt

func WithFeatureProjectQuotas 

func WithFeatureProjectQuotas(enable bool) FeatureOpt

func WithFeatureQuota 

func WithFeatureQuota(enable bool) FeatureOpt

func WithFeatureReadOnly 

func WithFeatureReadOnly(enable bool) FeatureOpt

func WithFeatureRecoveryNeeded 

func WithFeatureRecoveryNeeded(enable bool) FeatureOpt

func WithFeatureReplicas 

func WithFeatureReplicas(enable bool) FeatureOpt

func WithFeatureReservedGDTBlocksForExpansion 

func WithFeatureReservedGDTBlocksForExpansion(enable bool) FeatureOpt

func WithFeatureSeparateJournalDevice 

func WithFeatureSeparateJournalDevice(enable bool) FeatureOpt

func WithFeatureSnapshot 

func WithFeatureSnapshot(enable bool) FeatureOpt

func WithFeatureSparseSuperBlockV2 

func WithFeatureSparseSuperBlockV2(enable bool) FeatureOpt

func WithFeatureSparseSuperblock 

func WithFeatureSparseSuperblock(enable bool) FeatureOpt

type File 

type File struct {
	// contains filtered or unexported fields
}

File represents a single file in an ext4 filesystem

func (*File) Close 

func (fl *File) Close() error

Close close a file that is being read

func (*File) Read 

func (fl *File) Read(b []byte) (int, error)

Read reads up to len(b) bytes from the File. It returns the number of bytes read and any error encountered. At end of file, Read returns 0, io.EOF reads from the last known offset in the file from last read or write use Seek() to set at a particular point

func (*File) Seek 

func (fl *File) Seek(offset int64, whence int) (int64, error)

Seek set the offset to a particular point in the file

func (*File) Write 

func (fl *File) Write(b []byte) (int, error)

Write writes len(b) bytes to the File. It returns the number of bytes written and an error, if any. returns a non-nil error when n != len(b) writes to the last known offset in the file from last read or write use Seek() to set at a particular point

type FileInfo 

type FileInfo struct {
	// contains filtered or unexported fields
}

FileInfo represents the information for an individual file it fulfills os.FileInfo interface

func (*FileInfo) IsDir 

func (fi *FileInfo) IsDir() bool

IsDir abbreviation for Mode().IsDir()

func (*FileInfo) ModTime 

func (fi *FileInfo) ModTime() time.Time

ModTime modification time

func (*FileInfo) Mode 

func (fi *FileInfo) Mode() os.FileMode

Mode returns file mode

func (*FileInfo) Name 

func (fi *FileInfo) Name() string

Name base name of the file 

will return the long name of the file. If none exists, returns the shortname and extension

func (*FileInfo) Size 

func (fi *FileInfo) Size() int64

Size length in bytes for regular files

func (*FileInfo) Sys 

func (fi *FileInfo) Sys() interface{}

Sys underlying data source - not supported yet and so will return nil

type FileSystem 

type FileSystem struct {
	// contains filtered or unexported fields
}

FileSystem implememnts the FileSystem interface

func Create 

func Create(b backend.Storage, size, start, sectorsize int64, p *Params) (*FileSystem, error)

Create creates an ext4 filesystem in a given file or device

requires the backend.Storage where to create the filesystem, size is the size of the filesystem in bytes, start is how far in bytes from the beginning of the backend.Storage to create the filesystem, and sectorsize is is the logical sector size to use for creating the filesystem

blocksize is the size of the ext4 blocks, and is calculated as sectorsPerBlock * sectorsize. By ext4 specification, it must be between 512 and 4096 bytes, where sectorsize is the provided parameter, and sectorsPerBlock is part of `p *Params`. If either sectorsize or p.SectorsPerBlock is 0, it will calculate the optimal size for both.

note that you are *not* required to create the filesystem on the entire disk. You could have a disk of size 20GB, and create a small filesystem of size 50MB that begins 2GB into the disk. This is extremely useful for creating filesystems on disk partitions.

Note, however, that it is much easier to do this using the higher-level APIs at github.com/diskfs/go-diskfs which allow you to work directly with partitions, rather than having to calculate (and hopefully not make any errors) where a partition starts and ends.

If the provided blocksize is 0, it will use the default of 512 bytes. If it is any number other than 0 or 512, it will return an error.

func Read 

func Read(b backend.Storage, size, start, sectorsize int64) (*FileSystem, error)

Read reads a filesystem from a given disk.

requires the backend.File where to read the filesystem, size is the size of the filesystem in bytes, start is how far in bytes from the beginning of the backend.File the filesystem is expected to begin, and blocksize is is the logical blocksize to use for creating the filesystem

note that you are *not* required to read a filesystem on the entire disk. You could have a disk of size 20GB, and a small filesystem of size 50MB that begins 2GB into the disk. This is extremely useful for working with filesystems on disk partitions.

Note, however, that it is much easier to do this using the higher-level APIs at github.com/diskfs/go-diskfs which allow you to work directly with partitions, rather than having to calculate (and hopefully not make any errors) where a partition starts and ends.

If the provided blocksize is 0, it will use the default of 512 bytes. If it is any number other than 0 or 512, it will return an error.

func (*FileSystem) Chmod added in v1.5.0 

func (fs *FileSystem) Chmod(name string, mode os.FileMode) error

Chmod changes the mode of the named file to mode. If the file is a symbolic link, it changes the mode of the link's target.

func (*FileSystem) Chown added in v1.5.0 

func (fs *FileSystem) Chown(name string, uid, gid int) error

Chown changes the numeric uid and gid of the named file. If the file is a symbolic link, it changes the uid and gid of the link's target. A uid or gid of -1 means to not change that value

func (*FileSystem) Close added in v1.5.2 

func (fs *FileSystem) Close() error

Do cleaning job for ext4. Note that ext4 does not have side-effects so we do not do anything.

func (*FileSystem) Equal 

func (fs *FileSystem) Equal(a *FileSystem) bool

Equal compare if two filesystems are equal

func (*FileSystem) Label 

func (fs *FileSystem) Label() string

Label read the volume label 

func (fs *FileSystem) Link(oldpath, newpath string) error

creates a new link (also known as a hard link) to an existing file.

func (*FileSystem) Mkdir 

func (fs *FileSystem) Mkdir(p string) error

Mkdir make a directory at the given path. It is equivalent to `mkdir -p`, i.e. idempotent, in that:

* It will make the entire tree path if it does not exist * It will not return an error if the path already exists

func (*FileSystem) Mknod added in v1.5.0 

func (fs *FileSystem) Mknod(pathname string, mode uint32, dev int) error

creates a filesystem node (file, device special file, or named pipe) named pathname, with attributes specified by mode and dev

func (*FileSystem) OpenFile 

func (fs *FileSystem) OpenFile(p string, flag int) (filesystem.File, error)

OpenFile returns an io.ReadWriter from which you can read the contents of a file or write contents to the file

accepts normal os.OpenFile flags

returns an error if the file does not exist

func (*FileSystem) ReadDir 

func (fs *FileSystem) ReadDir(p string) ([]os.FileInfo, error)

ReadDir return the contents of a given directory in a given filesystem.

Returns a slice of os.FileInfo with all of the entries in the directory.

Will return an error if the directory does not exist or is a regular file and not a directory

func (*FileSystem) Remove added in v1.5.0 

func (fs *FileSystem) Remove(p string) error

Removes file or directory at path. If path is directory, it only will remove if it is empty. If path is a file, it will remove the file. Will not remove any parents. Error if the file does not exist or is not an empty directory

func (*FileSystem) Rename added in v1.5.0 

func (fs *FileSystem) Rename(oldpath, newpath string) error

Rename renames (moves) oldpath to newpath. If newpath already exists and is not a directory, Rename replaces it.

func (*FileSystem) Rm deprecated 

func (fs *FileSystem) Rm(p string) error

Deprecated: use filesystem.Remove(p string) instead

func (*FileSystem) SetLabel 

func (fs *FileSystem) SetLabel(label string) error

SetLabel changes the label on the writable filesystem. Different file system may hav different length constraints.

func (*FileSystem) Stat 

func (fs *FileSystem) Stat(p string) (iofs.FileInfo, error)

Stat return fs.FileInfo about a specific file path. 

func (fs *FileSystem) Symlink(oldpath, newpath string) error

creates a symbolic link named linkpath which contains the string target.

func (*FileSystem) Truncate 

func (fs *FileSystem) Truncate(p string, size int64) error

func (*FileSystem) Type 

func (fs *FileSystem) Type() filesystem.Type

Type returns the type code for the filesystem. Always returns filesystem.TypeExt4

type MountOpt 

type MountOpt func(*mountOptions)

func WithDefaultMountOptionBlockValidity 

func WithDefaultMountOptionBlockValidity(enable bool) MountOpt

func WithDefaultMountOptionDisableDelayedAllocation 

func WithDefaultMountOptionDisableDelayedAllocation(enable bool) MountOpt

func WithDefaultMountOptionDisableWriteFlushes 

func WithDefaultMountOptionDisableWriteFlushes(enable bool) MountOpt

func WithDefaultMountOptionDiscardSupport 

func WithDefaultMountOptionDiscardSupport(enable bool) MountOpt

func WithDefaultMountOptionGIDFromDirectory 

func WithDefaultMountOptionGIDFromDirectory(enable bool) MountOpt

func WithDefaultMountOptionJournalModeData 

func WithDefaultMountOptionJournalModeData(enable bool) MountOpt

func WithDefaultMountOptionJournalModeOrdered 

func WithDefaultMountOptionJournalModeOrdered(enable bool) MountOpt

func WithDefaultMountOptionJournalModeWriteback 

func WithDefaultMountOptionJournalModeWriteback(enable bool) MountOpt

func WithDefaultMountOptionPOSIXACLs 

func WithDefaultMountOptionPOSIXACLs(enable bool) MountOpt

func WithDefaultMountOptionPrintDebuggingInfo 

func WithDefaultMountOptionPrintDebuggingInfo(enable bool) MountOpt

func WithDefaultMountOptionUID16Bit 

func WithDefaultMountOptionUID16Bit(enable bool) MountOpt

func WithDefaultMountOptionUserspaceXattrs 

func WithDefaultMountOptionUserspaceXattrs(enable bool) MountOpt

type Params 

type Params struct {
	UUID                  *uuid.UUID
	SectorsPerBlock       uint8
	BlocksPerGroup        uint32
	InodeRatio            int64
	InodeCount            uint32
	SparseSuperVersion    uint8
	Checksum              bool
	ClusterSize           int64
	ReservedBlocksPercent uint8
	VolumeName            string
	// JournalDevice external journal device, only checked if WithFeatureSeparateJournalDevice(true) is set
	JournalDevice      string
	LogFlexBlockGroups int
	Features           []FeatureOpt
	DefaultMountOpts   []MountOpt
}

type SectorSize 

type SectorSize uint16

SectorSize indicates what the sector size in bytes is

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