Portability | portable |
---|---|
Stability | provisional |
Maintainer | John Goerzen <jgoerzen@complete.org> |
System.IO.HVFS
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.
- 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
The main HVFS class.
Default implementations of these functions are provided:
-
vGetModificationTime
-- implemented in terms ofvGetFileStatus
-
vRaiseError
-
vDoesFileExist
-- implemented in terms ofvGetFileStatus
-
vDoesDirectoryExist
-- implemented in terms ofvGetFileStatus
-
vDoesExist
-- implemented in terms ofvGetSymbolicLinkStatus
-
vGetSymbolicLinkStatus
-- set to callvGetFileStatus
.
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.
Methods
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
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 ()
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
Raise an error relating to actions on this class.
vCreateSymbolicLink :: a -> FilePath -> FilePath -> IO ()
vReadSymbolicLink :: a -> FilePath -> IO FilePath
vCreateLink :: a -> FilePath -> FilePath -> IO ()
Instances
HVFS SystemFS | |
HVFS MemoryVFS | |
HVFS a => HVFS (HVFSChroot a) | |
HVFS a => HVFS (HVFSReadOnly a) |
class Show a => HVFSStat a where
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.
Methods
Refers to file permissions, NOT the st_mode field from stat(2)
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
Instances
class HVFS a => HVFSOpenable a where
Types that can open a HVIO object should be instances of this class.
You need only implement vOpen
.
Methods
vOpen :: a -> FilePath -> IOMode -> IO HVFSOpenEncap
vReadFile :: a -> FilePath -> IO String
vWriteFile :: a -> FilePath -> String -> IO ()
vOpenBinaryFile :: a -> FilePath -> IOMode -> IO HVFSOpenEncap
Instances
data HVFSOpenEncap
Similar to HVFSStatEncap
, but for vOpen
result.
Constructors
forall a . HVIO a => HVFSOpenEncap a |
data HVFSStatEncap
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
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
Re-exported types from other modules
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 FileOffset = COff