System.Nix.Nar

Encoding and Decoding NAR archives

buildNarIO :: NarEffects IO -> FilePath -> Handle -> IO ()

Pack the filesystem object at FilePath into a NAR and stream it into the IO.Handle The handle should aleady be open and in WriteMode.

unpackNarIO :: NarEffects IO -> Handle -> FilePath -> IO (Either String ())

Read NAR formatted bytes from the IO.Handle and unpack them into file system object(s) at the supplied FilePath

Experimental

parseNar :: (MonadIO m, MonadFail m) => NarParser m ()

Parse a NAR byte string, producing (). Parsing a NAR is mostly used for its side-effect: producing the file system objects packed in the NAR. That's why we pure ()

testParser :: m ~ IO => NarParser m a -> ByteString -> m (Either String a)

testParser' :: m ~ IO => FilePath -> IO (Either String ())

Filesystem capabilities used by NAR encoder/decoder

data NarEffects (m :: Type -> Type)

Constructors

NarEffects

Fields

• narReadFile :: FilePath -> m ByteString
• narWriteFile :: FilePath -> ByteString -> m ()
• narStreamFile :: FilePath -> m (Maybe ByteString) -> m ()
• narListDir :: FilePath -> m [FilePath]
• narCreateDir :: FilePath -> m ()
• narCreateLink :: FilePath -> FilePath -> m ()
• narGetPerms :: FilePath -> m Permissions
• narSetPerms :: FilePath -> Permissions -> m ()
• narIsDir :: FilePath -> m Bool
• narIsSymLink :: FilePath -> m Bool
• narFileSize :: FilePath -> m Int64
• narReadLink :: FilePath -> m FilePath
• narDeleteDir :: FilePath -> m ()
• narDeleteFile :: FilePath -> m ()

narEffectsIO :: (MonadIO m, MonadFail m, MonadBaseControl IO m) => NarEffects m

A particular NarEffects that uses regular POSIX for file manipulation You would replace this with your own NarEffects if you wanted a different backend

data NarOptions

Options for configuring how NAR files are encoded and decoded.

Constructors

NarOptions

Fields

• optUseCaseHack :: Bool

  Whether to enable a case hack to support case-insensitive filesystems. Equivalent to the 'use-case-hack' option in the Nix client.

  The case hack rewrites file names to avoid collisions on case-insensitive file systems, e.g. APFS and HFS+ on macOS. Enabled by default on macOS (Darwin).

defaultNarOptions :: NarOptions

Internal

streamNarIO :: forall m. MonadIO m => NarEffects IO -> FilePath -> NarSource m

This implementation of Nar encoding takes an arbitrary yield function from any streaming library, and repeatedly calls it while traversing the filesystem object to Nar encode

streamNarIOWithOptions :: forall m. MonadIO m => NarOptions -> NarEffects IO -> FilePath -> NarSource m

runParser

Arguments

:: forall m a. (MonadIO m, MonadBaseControl IO m)

=> NarEffects m

Provide the effects set, usually narEffectsIO

-> NarParser m a

A parser to run, such as parseNar

-> Handle

A handle the stream containg the NAR. It should already be open and in ReadMode

-> FilePath

The root file system object to be created by the NAR

-> m (Either String a)

Run a NarParser over a byte stream This is suitable for testing the top-level NAR parser, or any of the smaller utilities parsers, if you have bytes appropriate for them

runParserWithOptions

Arguments

:: forall m a. (MonadIO m, MonadBaseControl IO m)

=> NarOptions

-> NarEffects m

Provide the effects set, usually narEffectsIO

-> NarParser m a

A parser to run, such as parseNar

-> Handle

A handle the stream containg the NAR. It should already be open and in ReadMode

-> FilePath

The root file system object to be created by the NAR

-> m (Either String a)

dumpString

Arguments

:: forall m. MonadIO m

=> ByteString

the string you want to dump

-> NarSource m

The nar result in CPS style

dumpString dump a string to nar in CPS style. The function takes in a ByteString, and build a `NarSource m`.

dumpPath

Arguments

:: forall m. MonadIO m

=> FilePath

path for the file you want to dump to nar

-> NarSource m

the nar result in CPS style

dumpPath shorthand build a Source that turn file path to nar using the default narEffectsIO.

Type

type NarSource m = (ByteString -> m ()) -> m ()

NarSource The source to provide nar to the handler `(ByteString -> m ())`. It is isomorphic to ByteString by Yoneda lemma if the result is meant to be m (). It is done in CPS style so IO can be chunks.