MissingH-1.3.0.1: Large utility library

Copyright | Copyright (C) 2004-2011 John Goerzen
License | BSD3
Maintainer | John Goerzen <jgoerzen@complete.org>
Stability | provisional
Portability | portable
Safe Haskell | None
Language | Haskell98

System.IO.HVFS

Contents

- Implementation Classes / Types
- Re-exported types from other modules

Description

Haskell Virtual FS -- generic support for real or virtual filesystem in Haskell

Copyright (c) 2004-2005 John Goerzen, jgoerzen@complete.org

The idea of this module is to provide virtualization of filesystem calls. In addition to the "real" system filesystem, you can also provide access to other, virtual, filesystems using the same set of calls. Examples of such virtual filesystems might include a remote FTP server, WebDAV server, a local Hashtable, a ConfigParser object, or any other data structure you can represent as a tree of named nodes containing strings.

Each `HVFS` function takes a `HVFS` "handle" (`HVFS` instance) as its first parameter. If you wish to operate on the standard system filesystem, you can just use `SystemFS`.

The MissingH.HVFS.IO.InstanceHelpers module contains some code to help you make your own HVFS instances.

The `HVFSOpenable` class works together with the System.IO.HVIO module to provide a complete virtual filesystem and I/O model that allows you to open up virtual filesystem files and act upon them in a manner similar to standard Handles.

Synopsis

- class Show a => HVFS a where
  - vGetCurrentDirectory :: a -> IO FilePath
  - vSetCurrentDirectory :: a -> FilePath -> IO ()
  - vGetDirectoryContents :: a -> FilePath -> IO [FilePath]
  - vDoesFileExist :: a -> FilePath -> IO Bool
  - vDoesDirectoryExist :: a -> FilePath -> IO Bool
  - vDoesExist :: a -> FilePath -> IO Bool
  - vCreateDirectory :: a -> FilePath -> IO ()
  - vRemoveDirectory :: a -> FilePath -> IO ()
  - vRenameDirectory :: a -> FilePath -> FilePath -> IO ()
  - vRemoveFile :: a -> FilePath -> IO ()
  - vRenameFile :: a -> FilePath -> FilePath -> IO ()
  - vGetFileStatus :: a -> FilePath -> IO HVFSStatEncap
  - vGetSymbolicLinkStatus :: a -> FilePath -> IO HVFSStatEncap
  - vGetModificationTime :: a -> FilePath -> IO ClockTime
  - vRaiseError :: a -> IOErrorType -> String -> Maybe FilePath -> IO c
  - vCreateSymbolicLink :: a -> FilePath -> FilePath -> IO ()
  - vReadSymbolicLink :: a -> FilePath -> IO FilePath
  - vCreateLink :: a -> FilePath -> FilePath -> IO ()
- class Show a => HVFSStat a where
  - vDeviceID :: a -> DeviceID
  - vFileID :: a -> FileID
  - vFileMode :: a -> FileMode
  - vLinkCount :: a -> LinkCount
  - vFileOwner :: a -> UserID
  - vFileGroup :: a -> GroupID
  - vSpecialDeviceID :: a -> DeviceID
  - vFileSize :: a -> FileOffset
  - vAccessTime :: a -> EpochTime
  - vModificationTime :: a -> EpochTime
  - vStatusChangeTime :: a -> EpochTime
  - vIsBlockDevice :: a -> Bool
  - vIsCharacterDevice :: a -> Bool
  - vIsNamedPipe :: a -> Bool
  - vIsRegularFile :: a -> Bool
  - vIsDirectory :: a -> Bool
  - vIsSymbolicLink :: a -> Bool
  - vIsSocket :: a -> Bool
- class HVFS a => HVFSOpenable a where
  - vOpen :: a -> FilePath -> IOMode -> IO HVFSOpenEncap
  - vReadFile :: a -> FilePath -> IO String
  - vWriteFile :: a -> FilePath -> String -> IO ()
  - vOpenBinaryFile :: a -> FilePath -> IOMode -> IO HVFSOpenEncap
- data HVFSOpenEncap = forall a . HVIO a => HVFSOpenEncap a
- data HVFSStatEncap = forall a . HVFSStat a => HVFSStatEncap a
- withStat :: forall b. HVFSStatEncap -> (forall a. HVFSStat a => a -> b) -> b
- withOpen :: forall b. HVFSOpenEncap -> (forall a. HVIO a => a -> b) -> b
- data SystemFS = SystemFS
- type FilePath = String
- type DeviceID = CDev
- type FileID = CIno
- type FileMode = CMode
- type LinkCount = CNlink
- type UserID = CUid
- type GroupID = CGid
- type FileOffset = COff
- type EpochTime = CTime
- data IOMode :: *

# Implementation Classes / Types

class Show a => HVFS a where Source

The main HVFS class.

Default implementations of these functions are provided:

- `vGetModificationTime` -- implemented in terms of `vGetFileStatus`
- `vRaiseError`
- `vDoesFileExist` -- implemented in terms of `vGetFileStatus`
- `vDoesDirectoryExist` -- implemented in terms of `vGetFileStatus`
- `vDoesExist` -- implemented in terms of `vGetSymbolicLinkStatus`
- `vGetSymbolicLinkStatus` -- set to call `vGetFileStatus`.

Default implementations of all other functions will generate an isIllegalOperation error, since they are assumed to be un-implemented.

You should always provide at least a `vGetFileStatus` call, and almost certainly several of the others.

Most of these functions correspond to functions in System.Directory or System.Posix.Files. Please see detailed documentation on them there.

Minimal complete definition

vGetFileStatus

Methods

vGetCurrentDirectory :: a -> IO FilePath Source

vSetCurrentDirectory :: a -> FilePath -> IO () Source

vGetDirectoryContents :: a -> FilePath -> IO [FilePath] Source

vDoesFileExist :: a -> FilePath -> IO Bool Source

vDoesDirectoryExist :: a -> FilePath -> IO Bool Source

vDoesExist :: a -> FilePath -> IO Bool Source

True if the file exists, regardless of what type it is. This is even True if the given path is a broken symlink.

vCreateDirectory :: a -> FilePath -> IO () Source

vRemoveDirectory :: a -> FilePath -> IO () Source

vRenameDirectory :: a -> FilePath -> FilePath -> IO () Source

vRemoveFile :: a -> FilePath -> IO () Source

vRenameFile :: a -> FilePath -> FilePath -> IO () Source

vGetFileStatus :: a -> FilePath -> IO HVFSStatEncap Source

vGetSymbolicLinkStatus :: a -> FilePath -> IO HVFSStatEncap Source

vGetModificationTime :: a -> FilePath -> IO ClockTime Source

vRaiseError :: a -> IOErrorType -> String -> Maybe FilePath -> IO c Source

Raise an error relating to actions on this class.

vCreateSymbolicLink :: a -> FilePath -> FilePath -> IO () Source

vReadSymbolicLink :: a -> FilePath -> IO FilePath Source

vCreateLink :: a -> FilePath -> FilePath -> IO () Source

Instances

HVFS SystemFS Source |
HVFS MemoryVFS Source |
HVFS a => HVFS (HVFSChroot a) Source |
HVFS a => HVFS (HVFSReadOnly a) Source |

class Show a => HVFSStat a where Source

Evaluating types of files and information about them.

This corresponds to the System.Posix.Types.FileStatus type, and indeed, that is one instance of this class.

Inplementators must, at minimum, implement `vIsDirectory` and `vIsRegularFile`.

Default implementations of everything else are provided, returning reasonable values.

A default implementation of this is not currently present on Windows.

Minimal complete definition

vIsRegularFile, vIsDirectory

Methods

vDeviceID :: a -> DeviceID Source

vFileID :: a -> FileID Source

vFileMode :: a -> FileMode Source

Refers to file permissions, NOT the st_mode field from stat(2)

vLinkCount :: a -> LinkCount Source

vFileOwner :: a -> UserID Source

vFileGroup :: a -> GroupID Source

vSpecialDeviceID :: a -> DeviceID Source

vFileSize :: a -> FileOffset Source

vAccessTime :: a -> EpochTime Source

vModificationTime :: a -> EpochTime Source

vStatusChangeTime :: a -> EpochTime Source

vIsBlockDevice :: a -> Bool Source

vIsCharacterDevice :: a -> Bool Source

vIsNamedPipe :: a -> Bool Source

vIsRegularFile :: a -> Bool Source

vIsDirectory :: a -> Bool Source

vIsSymbolicLink :: a -> Bool Source

vIsSocket :: a -> Bool Source

Instances

HVFSStat FileStatus Source |
HVFSStat SimpleStat Source |

class HVFS a => HVFSOpenable a where Source

Types that can open a HVIO object should be instances of this class. You need only implement `vOpen`.

Minimal complete definition

vOpen

Methods

vOpen :: a -> FilePath -> IOMode -> IO HVFSOpenEncap Source

vReadFile :: a -> FilePath -> IO String Source

vWriteFile :: a -> FilePath -> String -> IO () Source

vOpenBinaryFile :: a -> FilePath -> IOMode -> IO HVFSOpenEncap Source

Instances

HVFSOpenable SystemFS Source |
HVFSOpenable MemoryVFS Source |
HVFSOpenable a => HVFSOpenable (HVFSChroot a) Source |
HVFSOpenable a => HVFSOpenable (HVFSReadOnly a) Source |

data HVFSOpenEncap Source

Similar to `HVFSStatEncap`, but for `vOpen` result.

Constructors

forall a . HVIO a => HVFSOpenEncap a |

data HVFSStatEncap Source

Encapsulate a `HVFSStat` result. This is required due to Haskell typing restrictions. You can get at it with:

    case encap of
       HVFSStatEncap x -> -- now use x

Constructors

forall a . HVFSStat a => HVFSStatEncap a |

withStat :: forall b. HVFSStatEncap -> (forall a. HVFSStat a => a -> b) -> b Source

Convenience function for working with stat -- takes a stat result and a function that uses it, and returns the result.

Here is an example from the HVFS source:

       vGetModificationTime fs fp =
          do s <- vGetFileStatus fs fp
             return $ epochToClockTime (withStat s vModificationTime)

See `epochToClockTime` for more information.

withOpen :: forall b. HVFSOpenEncap -> (forall a. HVIO a => a -> b) -> b Source

Similar to `withStat`, but for the `vOpen` result.

data SystemFS Source

Constructors

SystemFS |

Instances

Eq SystemFS Source |
Show SystemFS Source |
HVFSOpenable SystemFS Source |
HVFS SystemFS Source |

# Re-exported types from other modules

type FilePath = String

File and directory names are values of type `String`, whose precise meaning is operating system dependent. Files can be opened, yielding a handle which can then be used to operate on the contents of that file.

type DeviceID = CDev

type FileID = CIno

type FileMode = CMode

type LinkCount = CNlink

type UserID = CUid

type GroupID = CGid

type FileOffset = COff

type EpochTime = CTime

data IOMode :: *

See `openFile`

Instances

Enum IOMode |
Eq IOMode |
Ord IOMode |
Read IOMode |
Show IOMode |
Ix IOMode |