Memfd

"memfd" (memory file descriptor) lets us open pseudo-"files" that are not actually stored in the "real" file system. This feature is only available on Linux.

This module is a small FFI wrapper around the memfd_create C system call. Some documentation in this package is copied/paraphrased from the Linux Programmer's Manual. Run "man 2 memfd_create" to see the full documentation.

Documentation

create :: CreateOptions -> IO Fd

Creates an anonymous file

The file behaves like a regular file, and so can be modified, truncated, memory-mapped, and so on. However, unlike a regular file, it lives in RAM and has a volatile backing storage. Once all references to the file are dropped, it is automatically released.

defaultCreateOptions :: Name -> CreateOptions

Default options for create, corresponding to what you get what you use the C library and don't set any flags.

• onExec = RemainOpenOnExec
• sealing = DoNotAllowSealing
• fileSystem = TemporaryFileSystem

data CreateOptions

Constructors

CreateOptions

Fields

• name :: Name
• onExec :: OnExec
• sealing :: Sealing
• fileSystem :: FileSystem

Instances

Eq CreateOptions

Defined in CreateOptionsType

Methods

(==) :: CreateOptions -> CreateOptions -> Bool

(/=) :: CreateOptions -> CreateOptions -> Bool

Ord CreateOptions

Defined in CreateOptionsType

Methods

compare :: CreateOptions -> CreateOptions -> Ordering

(<) :: CreateOptions -> CreateOptions -> Bool

(<=) :: CreateOptions -> CreateOptions -> Bool

(>) :: CreateOptions -> CreateOptions -> Bool

(>=) :: CreateOptions -> CreateOptions -> Bool

max :: CreateOptions -> CreateOptions -> CreateOptions

min :: CreateOptions -> CreateOptions -> CreateOptions

Show CreateOptions

Defined in CreateOptionsType

Methods

showsPrec :: Int -> CreateOptions -> ShowS

show :: CreateOptions -> String

showList :: [CreateOptions] -> ShowS

newtype Name

The name of an anonymous file

The name is used as a filename and will be displayed as the target of the corresponding symbolic link in the directory /proc/self/fd/. The displayed name is always prefixed with "memfd:" and serves only for debugging purposes. Names do not affect the behavior of the file descriptor, and as such multiple files can have the same name without any side effects.

Constructors

NameString

Fields

• nameString :: String

Instances

Eq Name

Defined in NameType

Methods

(==) :: Name -> Name -> Bool

(/=) :: Name -> Name -> Bool

Ord Name

Defined in NameType

Methods

compare :: Name -> Name -> Ordering

(<) :: Name -> Name -> Bool

(<=) :: Name -> Name -> Bool

(>) :: Name -> Name -> Bool

(>=) :: Name -> Name -> Bool

max :: Name -> Name -> Name

min :: Name -> Name -> Name

Show Name

Defined in NameType

Methods

showsPrec :: Int -> Name -> ShowS

show :: Name -> String

showList :: [Name] -> ShowS

IsString Name

Defined in NameType

Methods

fromString :: String -> Name

data OnExec

Constructors

CloseOnExec

The file descriptor will automatically be closed during a successful execve

RemainOpenOnExec

Instances

Bounded OnExec

Defined in OnExecType

Methods

minBound :: OnExec

maxBound :: OnExec

Enum OnExec

Defined in OnExecType

Methods

succ :: OnExec -> OnExec

pred :: OnExec -> OnExec

toEnum :: Int -> OnExec

fromEnum :: OnExec -> Int

enumFrom :: OnExec -> [OnExec]

enumFromThen :: OnExec -> OnExec -> [OnExec]

enumFromTo :: OnExec -> OnExec -> [OnExec]

enumFromThenTo :: OnExec -> OnExec -> OnExec -> [OnExec]

Eq OnExec

Defined in OnExecType

Methods

(==) :: OnExec -> OnExec -> Bool

(/=) :: OnExec -> OnExec -> Bool

Ord OnExec

Defined in OnExecType

Methods

compare :: OnExec -> OnExec -> Ordering

(<) :: OnExec -> OnExec -> Bool

(<=) :: OnExec -> OnExec -> Bool

(>) :: OnExec -> OnExec -> Bool

(>=) :: OnExec -> OnExec -> Bool

max :: OnExec -> OnExec -> OnExec

min :: OnExec -> OnExec -> OnExec

Show OnExec

Defined in OnExecType

Methods

showsPrec :: Int -> OnExec -> ShowS

show :: OnExec -> String

showList :: [OnExec] -> ShowS

data Sealing

Constructors

AllowSealing

File seals can be applied to the file descriptor

DoNotAllowSealing

Instances

Bounded Sealing

Defined in SealingType

Methods

minBound :: Sealing

maxBound :: Sealing

Enum Sealing

Defined in SealingType

Methods

succ :: Sealing -> Sealing

pred :: Sealing -> Sealing

toEnum :: Int -> Sealing

fromEnum :: Sealing -> Int

enumFrom :: Sealing -> [Sealing]

enumFromThen :: Sealing -> Sealing -> [Sealing]

enumFromTo :: Sealing -> Sealing -> [Sealing]

enumFromThenTo :: Sealing -> Sealing -> Sealing -> [Sealing]

Eq Sealing

Defined in SealingType

Methods

(==) :: Sealing -> Sealing -> Bool

(/=) :: Sealing -> Sealing -> Bool

Ord Sealing

Defined in SealingType

Methods

compare :: Sealing -> Sealing -> Ordering

(<) :: Sealing -> Sealing -> Bool

(<=) :: Sealing -> Sealing -> Bool

(>) :: Sealing -> Sealing -> Bool

(>=) :: Sealing -> Sealing -> Bool

max :: Sealing -> Sealing -> Sealing

min :: Sealing -> Sealing -> Sealing

Show Sealing

Defined in SealingType

Methods

showsPrec :: Int -> Sealing -> ShowS

show :: Sealing -> String

showList :: [Sealing] -> ShowS

data FileSystem

Constructors

TemporaryFileSystem

HugeTLBFileSystem HugeTLBOptions

Instances

Eq FileSystem

Defined in FileSystemType

Methods

(==) :: FileSystem -> FileSystem -> Bool

(/=) :: FileSystem -> FileSystem -> Bool

Ord FileSystem

Defined in FileSystemType

Methods

compare :: FileSystem -> FileSystem -> Ordering

(<) :: FileSystem -> FileSystem -> Bool

(<=) :: FileSystem -> FileSystem -> Bool

(>) :: FileSystem -> FileSystem -> Bool

(>=) :: FileSystem -> FileSystem -> Bool

max :: FileSystem -> FileSystem -> FileSystem

min :: FileSystem -> FileSystem -> FileSystem

Show FileSystem

Defined in FileSystemType

Methods

showsPrec :: Int -> FileSystem -> ShowS

show :: FileSystem -> String

showList :: [FileSystem] -> ShowS

data HugeTLBOptions

Not every HugeTLBSize may be available on your platform. If you select an unsupported page size, the system default page size will be used instead. See supportedHugeTLBSizes.

Constructors

DefaultHugeTLB

Use the system default hugetlb page size

HugeTLBSize HugeTLBSize

Prefer the given hugetlb page size

Instances

Eq HugeTLBOptions

Defined in HugeTLBOptionsType

Methods

(==) :: HugeTLBOptions -> HugeTLBOptions -> Bool

(/=) :: HugeTLBOptions -> HugeTLBOptions -> Bool

Ord HugeTLBOptions

Defined in HugeTLBOptionsType

Methods

compare :: HugeTLBOptions -> HugeTLBOptions -> Ordering

(<) :: HugeTLBOptions -> HugeTLBOptions -> Bool

(<=) :: HugeTLBOptions -> HugeTLBOptions -> Bool

(>) :: HugeTLBOptions -> HugeTLBOptions -> Bool

(>=) :: HugeTLBOptions -> HugeTLBOptions -> Bool

max :: HugeTLBOptions -> HugeTLBOptions -> HugeTLBOptions

min :: HugeTLBOptions -> HugeTLBOptions -> HugeTLBOptions

Show HugeTLBOptions

Defined in HugeTLBOptionsType

Methods

showsPrec :: Int -> HugeTLBOptions -> ShowS

show :: HugeTLBOptions -> String

showList :: [HugeTLBOptions] -> ShowS

data HugeTLBSize

These sizes may not all be available on your platform. See supportedHugeTLBSizes.

Constructors

HugeTLB_64KB

HugeTLB_512KB

HugeTLB_1MB

HugeTLB_2MB

HugeTLB_8MB

HugeTLB_16MB

HugeTLB_32MB

HugeTLB_256MB

HugeTLB_512MB

HugeTLB_1GB

HugeTLB_2GB

HugeTLB_16GB

Instances

Bounded HugeTLBSize

Defined in HugeTLBSizeType

Methods

minBound :: HugeTLBSize

maxBound :: HugeTLBSize

Enum HugeTLBSize

Defined in HugeTLBSizeType

Methods

succ :: HugeTLBSize -> HugeTLBSize

pred :: HugeTLBSize -> HugeTLBSize

toEnum :: Int -> HugeTLBSize

fromEnum :: HugeTLBSize -> Int

enumFrom :: HugeTLBSize -> [HugeTLBSize]

enumFromThen :: HugeTLBSize -> HugeTLBSize -> [HugeTLBSize]

enumFromTo :: HugeTLBSize -> HugeTLBSize -> [HugeTLBSize]

enumFromThenTo :: HugeTLBSize -> HugeTLBSize -> HugeTLBSize -> [HugeTLBSize]

Eq HugeTLBSize

Defined in HugeTLBSizeType

Methods

(==) :: HugeTLBSize -> HugeTLBSize -> Bool

(/=) :: HugeTLBSize -> HugeTLBSize -> Bool

Ord HugeTLBSize

Defined in HugeTLBSizeType

Methods

compare :: HugeTLBSize -> HugeTLBSize -> Ordering

(<) :: HugeTLBSize -> HugeTLBSize -> Bool

(<=) :: HugeTLBSize -> HugeTLBSize -> Bool

(>) :: HugeTLBSize -> HugeTLBSize -> Bool

(>=) :: HugeTLBSize -> HugeTLBSize -> Bool

max :: HugeTLBSize -> HugeTLBSize -> HugeTLBSize

min :: HugeTLBSize -> HugeTLBSize -> HugeTLBSize

Show HugeTLBSize

Defined in HugeTLBSizeType

Methods

showsPrec :: Int -> HugeTLBSize -> ShowS

show :: HugeTLBSize -> String

showList :: [HugeTLBSize] -> ShowS

supportedHugeTLBSizes :: [HugeTLBSize]

List of hugetlb sizes that are supported by your platform