hackage-security-0.6.3.2: Hackage security library

Safe Haskell | None
Language | Haskell2010

Hackage.Security.Util.Path

Contents

- Paths
- FilePath-like operations on paths with arbitrary roots
- Unrooted paths
- File-system paths
  - Conversions
  - Wrappers around System.IO
  - Wrappers around Data.ByteString
  - Wrappers around System.Directory
- Wrappers around Codec.Archive.Tar
- Wrappers around Network.URI
- Re-exports

Description

A more type-safe version of file paths

This module is intended to replace imports of System.FilePath, and additionally exports thin wrappers around common IO functions. To facilitate importing this module unqualified we also re-export some definitions from System.IO (importing both would likely lead to name clashes).

Note that his module does not import any other modules from Hackage.Security; everywhere else we use Path instead of FilePath directly.

Synopsis

- newtype Path a = Path FilePath
- castRoot :: Path root -> Path root'
- takeDirectory :: Path a -> Path a
- takeFileName :: Path a -> String
- (<.>) :: Path a -> String -> Path a
- splitExtension :: Path a -> (Path a, String)
- takeExtension :: Path a -> String
- data Unrooted
- (</>) :: Path a -> Path Unrooted -> Path a
- rootPath :: Path Unrooted -> Path root
- unrootPath :: Path root -> Path Unrooted
- toUnrootedFilePath :: Path Unrooted -> FilePath
- fromUnrootedFilePath :: FilePath -> Path Unrooted
- fragment :: String -> Path Unrooted
- joinFragments :: [String] -> Path Unrooted
- splitFragments :: Path Unrooted -> [String]
- isPathPrefixOf :: Path Unrooted -> Path Unrooted -> Bool
- data Relative
- data Absolute
- data HomeDir
- class FsRoot root where
  - toAbsoluteFilePath :: Path root -> IO FilePath
- data FsPath = FsRoot root => FsPath (Path root)
- toFilePath :: Path Absolute -> FilePath
- fromFilePath :: FilePath -> FsPath
- makeAbsolute :: FsPath -> IO (Path Absolute)
- fromAbsoluteFilePath :: FilePath -> Path Absolute
- withFile :: FsRoot root => Path root -> IOMode -> (Handle -> IO r) -> IO r
- openTempFile' :: FsRoot root => Path root -> String -> IO (Path Absolute, Handle)
- readLazyByteString :: FsRoot root => Path root -> IO ByteString
- readStrictByteString :: FsRoot root => Path root -> IO ByteString
- writeLazyByteString :: FsRoot root => Path root -> ByteString -> IO ()
- writeStrictByteString :: FsRoot root => Path root -> ByteString -> IO ()
- copyFile :: (FsRoot root, FsRoot root') => Path root -> Path root' -> IO ()
- createDirectory :: FsRoot root => Path root -> IO ()
- createDirectoryIfMissing :: FsRoot root => Bool -> Path root -> IO ()
- removeDirectory :: FsRoot root => Path root -> IO ()
- doesFileExist :: FsRoot root => Path root -> IO Bool
- doesDirectoryExist :: FsRoot root => Path root -> IO Bool
- getModificationTime :: FsRoot root => Path root -> IO UTCTime
- removeFile :: FsRoot root => Path root -> IO ()
- getTemporaryDirectory :: IO (Path Absolute)
- getDirectoryContents :: FsRoot root => Path root -> IO [Path Unrooted]
- getRecursiveContents :: FsRoot root => Path root -> IO [Path Unrooted]
- renameFile :: (FsRoot root, FsRoot root') => Path root -> Path root' -> IO ()
- getCurrentDirectory :: IO (Path Absolute)
- data Tar
- tarIndexLookup :: TarIndex -> Path Tar -> Maybe TarIndexEntry
- tarAppend :: (FsRoot root, FsRoot root') => Path root -> Path root' -> [Path Tar] -> IO ()
- data Web
- toURIPath :: FilePath -> Path Web
- fromURIPath :: Path Web -> FilePath
- uriPath :: URI -> Path Web
- modifyUriPath :: URI -> (Path Web -> Path Web) -> URI
- data IOMode
  - = ReadMode
  - | WriteMode
  - | AppendMode
  - | ReadWriteMode
- data BufferMode
  - = NoBuffering
  - | LineBuffering
  - | BlockBuffering (Maybe Int)
- data Handle
- data SeekMode
  - = AbsoluteSeek
  - | RelativeSeek
  - | SeekFromEnd
- hSetBuffering :: Handle -> BufferMode -> IO ()
- hClose :: Handle -> IO ()
- hFileSize :: Handle -> IO Integer
- hSeek :: Handle -> SeekMode -> Integer -> IO ()

# Paths

newtype Path a Source #

Paths

A `Path` is simply a `FilePath` with a type-level tag indicating where this path is rooted (relative to the current directory, absolute path, relative to a web domain, whatever). Most operations on `Path` are just lifted versions of the operations on the underlying `FilePath`. The tag however allows us to give a lot of operations a more meaningful type. For instance, it does not make sense to append two absolute paths together; instead, we can only append an unrooted path to another path. It also means we avoid bugs where we use one kind of path where we expect another.

Constructors

Path FilePath |

#### Instances

Instances details

Monad m => FromObjectKey m (Path root) Source # |
Instance details Defined in Hackage.Security.Util.JSON Methods fromObjectKey :: String -> m (Maybe (Path root)) Source #
Monad m => ToObjectKey m (Path root) Source # |
Instance details Defined in Hackage.Security.Util.JSON Methods toObjectKey :: Path root -> m String Source #
Show (Path a) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods showsPrec :: Int -> Path a -> ShowS Source # show :: Path a -> String Source # showList :: [Path a] -> ShowS Source #
Eq (Path a) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods (==) :: Path a -> Path a -> Bool Source # (/=) :: Path a -> Path a -> Bool Source #
Ord (Path a) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods compare :: Path a -> Path a -> Ordering Source # (<) :: Path a -> Path a -> Bool Source # (<=) :: Path a -> Path a -> Bool Source # (>) :: Path a -> Path a -> Bool Source # (>=) :: Path a -> Path a -> Bool Source # max :: Path a -> Path a -> Path a Source # min :: Path a -> Path a -> Path a Source #
Pretty (Path CacheRoot) Source # |
Instance details Defined in Hackage.Security.TUF.Paths Methods pretty :: Path CacheRoot -> String Source #
Pretty (Path IndexRoot) Source # |
Instance details Defined in Hackage.Security.TUF.Paths Methods pretty :: Path IndexRoot -> String Source #
Pretty (Path RepoRoot) Source # |
Instance details Defined in Hackage.Security.TUF.Paths Methods pretty :: Path RepoRoot -> String Source #
Pretty (Path Absolute) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Absolute -> String Source #
Pretty (Path HomeDir) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path HomeDir -> String Source #
Pretty (Path Relative) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Relative -> String Source #
Pretty (Path Tar) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Tar -> String Source #
Pretty (Path Unrooted) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Unrooted -> String Source #

castRoot :: Path root -> Path root' Source #

Reinterpret the root of a path

This literally just changes the type-level tag; use with caution!

# FilePath-like operations on paths with arbitrary roots

takeDirectory :: Path a -> Path a Source #

takeFileName :: Path a -> String Source #

(<.>) :: Path a -> String -> Path a Source #

splitExtension :: Path a -> (Path a, String) Source #

takeExtension :: Path a -> String Source #

# Unrooted paths

data Unrooted Source #

Type-level tag for unrooted paths

Unrooted paths need a root before they can be interpreted.

#### Instances

Instances details

Pretty (Path Unrooted) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Unrooted -> String Source #

(</>) :: Path a -> Path Unrooted -> Path a Source #

rootPath :: Path Unrooted -> Path root Source #

Reinterpret an unrooted path

This is an alias for `castRoot`; see comments there.

unrootPath :: Path root -> Path Unrooted Source #

Forget a path's root

This is an alias for `castRoot`; see comments there.

toUnrootedFilePath :: Path Unrooted -> FilePath Source #

Convert a relative/unrooted Path to a FilePath (using POSIX style directory separators).

See also `toAbsoluteFilePath`

fromUnrootedFilePath :: FilePath -> Path Unrooted Source #

Convert from a relative/unrooted FilePath (using POSIX style directory separators).

fragment :: String -> Path Unrooted Source #

A path fragment (like a single directory or filename)

joinFragments :: [String] -> Path Unrooted Source #

splitFragments :: Path Unrooted -> [String] Source #

isPathPrefixOf :: Path Unrooted -> Path Unrooted -> Bool Source #

# File-system paths

data Relative Source #

#### Instances

Instances details

FsRoot Relative Source # |
Instance details Defined in Hackage.Security.Util.Path Methods toAbsoluteFilePath :: Path Relative -> IO FilePath Source #
Pretty (Path Relative) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Relative -> String Source #

data Absolute Source #

#### Instances

Instances details

FsRoot Absolute Source # |
Instance details Defined in Hackage.Security.Util.Path Methods toAbsoluteFilePath :: Path Absolute -> IO FilePath Source #
Pretty (Path Absolute) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Absolute -> String Source #

data HomeDir Source #

#### Instances

Instances details

FsRoot HomeDir Source # |
Instance details Defined in Hackage.Security.Util.Path Methods toAbsoluteFilePath :: Path HomeDir -> IO FilePath Source #
Pretty (Path HomeDir) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path HomeDir -> String Source #

class FsRoot root where Source #

A file system root can be interpreted as an (absolute) FilePath

Methods

toAbsoluteFilePath :: Path root -> IO FilePath Source #

Convert a Path to an absolute FilePath (using native style directory separators).

#### Instances

Instances details

FsRoot Absolute Source # |
Instance details Defined in Hackage.Security.Util.Path Methods toAbsoluteFilePath :: Path Absolute -> IO FilePath Source #
FsRoot HomeDir Source # |
Instance details Defined in Hackage.Security.Util.Path Methods toAbsoluteFilePath :: Path HomeDir -> IO FilePath Source #
FsRoot Relative Source # |
Instance details Defined in Hackage.Security.Util.Path Methods toAbsoluteFilePath :: Path Relative -> IO FilePath Source #

data FsPath Source #

Abstract over a file system root

see `fromFilePath`

Constructors

FsRoot root => FsPath (Path root) |

## Conversions

toFilePath :: Path Absolute -> FilePath Source #

fromFilePath :: FilePath -> FsPath Source #

makeAbsolute :: FsPath -> IO (Path Absolute) Source #

fromAbsoluteFilePath :: FilePath -> Path Absolute Source #

## Wrappers around System.IO

withFile :: FsRoot root => Path root -> IOMode -> (Handle -> IO r) -> IO r Source #

Wrapper around `withFile`

openTempFile' :: FsRoot root => Path root -> String -> IO (Path Absolute, Handle) Source #

Wrapper around `openBinaryTempFileWithDefaultPermissions`

NOTE: The caller is responsible for cleaning up the temporary file.

## Wrappers around Data.ByteString

readLazyByteString :: FsRoot root => Path root -> IO ByteString Source #

readStrictByteString :: FsRoot root => Path root -> IO ByteString Source #

writeLazyByteString :: FsRoot root => Path root -> ByteString -> IO () Source #

writeStrictByteString :: FsRoot root => Path root -> ByteString -> IO () Source #

## Wrappers around System.Directory

copyFile :: (FsRoot root, FsRoot root') => Path root -> Path root' -> IO () Source #

createDirectory :: FsRoot root => Path root -> IO () Source #

createDirectoryIfMissing :: FsRoot root => Bool -> Path root -> IO () Source #

removeDirectory :: FsRoot root => Path root -> IO () Source #

doesFileExist :: FsRoot root => Path root -> IO Bool Source #

doesDirectoryExist :: FsRoot root => Path root -> IO Bool Source #

getModificationTime :: FsRoot root => Path root -> IO UTCTime Source #

removeFile :: FsRoot root => Path root -> IO () Source #

getTemporaryDirectory :: IO (Path Absolute) Source #

getDirectoryContents :: FsRoot root => Path root -> IO [Path Unrooted] Source #

Return the immediate children of a directory

Filters out `"."` and `".."`.

getRecursiveContents :: FsRoot root => Path root -> IO [Path Unrooted] Source #

Recursive traverse a directory structure

Returns a set of paths relative to the directory specified. The list is lazily constructed, so that directories are only read when required. (This is also essential to ensure that this function does not build the entire result in memory before returning, potentially running out of heap.)

renameFile Source #

Arguments

:: (FsRoot root, FsRoot root') |
=> Path root | Old
-> Path root' | New
-> IO () |

getCurrentDirectory :: IO (Path Absolute) Source #

# Wrappers around Codec.Archive.Tar

data Tar Source #

#### Instances

Instances details

Pretty (Path Tar) Source # |
Instance details Defined in Hackage.Security.Util.Path Methods pretty :: Path Tar -> String Source #

tarIndexLookup :: TarIndex -> Path Tar -> Maybe TarIndexEntry Source #

tarAppend Source #

Arguments

:: (FsRoot root, FsRoot root') |
=> Path root | Path of the `.tar` file
-> Path root' | Base directory
-> [Path Tar] | Files to add, relative to the base dir
-> IO () |

# Wrappers around Network.URI

data Web Source #

toURIPath :: FilePath -> Path Web Source #

fromURIPath :: Path Web -> FilePath Source #

uriPath :: URI -> Path Web Source #

modifyUriPath :: URI -> (Path Web -> Path Web) -> URI Source #

# Re-exports

data IOMode Source #

See `openFile`

Constructors

ReadMode |
WriteMode |
AppendMode |
ReadWriteMode |

#### Instances

Instances details

Enum IOMode | Since: base-4.2.0.0

Instance details

Defined in GHC.Internal.IO.IOMode

Methods

succ :: IOMode -> IOMode Source #

pred :: IOMode -> IOMode Source #

toEnum :: Int -> IOMode Source #

fromEnum :: IOMode -> Int Source #

enumFrom :: IOMode -> [IOMode] Source #

enumFromThen :: IOMode -> IOMode -> [IOMode] Source #

enumFromTo :: IOMode -> IOMode -> [IOMode] Source #

enumFromThenTo :: IOMode -> IOMode -> IOMode -> [IOMode] Source #

Ix IOMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.IOMode Methods range :: (IOMode, IOMode) -> [IOMode] Source # index :: (IOMode, IOMode) -> IOMode -> Int Source # unsafeIndex :: (IOMode, IOMode) -> IOMode -> Int Source # inRange :: (IOMode, IOMode) -> IOMode -> Bool Source # rangeSize :: (IOMode, IOMode) -> Int Source # unsafeRangeSize :: (IOMode, IOMode) -> Int Source #
Read IOMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.IOMode Methods readsPrec :: Int -> ReadS IOMode Source # readList :: ReadS [IOMode] Source # readPrec :: ReadPrec IOMode Source # readListPrec :: ReadPrec [IOMode] Source #
Show IOMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.IOMode Methods showsPrec :: Int -> IOMode -> ShowS Source # show :: IOMode -> String Source # showList :: [IOMode] -> ShowS Source #
Eq IOMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.IOMode Methods (==) :: IOMode -> IOMode -> Bool Source # (/=) :: IOMode -> IOMode -> Bool Source #
Ord IOMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.IOMode Methods compare :: IOMode -> IOMode -> Ordering Source # (<) :: IOMode -> IOMode -> Bool Source # (<=) :: IOMode -> IOMode -> Bool Source # (>) :: IOMode -> IOMode -> Bool Source # (>=) :: IOMode -> IOMode -> Bool Source # max :: IOMode -> IOMode -> IOMode Source # min :: IOMode -> IOMode -> IOMode Source #

data BufferMode Source #

Three kinds of buffering are supported: line-buffering, block-buffering or no-buffering. These modes have the following effects. For output, items are written out, or flushed, from the internal buffer according to the buffer mode:

- line-buffering: the entire output buffer is flushed whenever a newline is output, the buffer overflows, a `hFlush` is issued, or the handle is closed.
- block-buffering: the entire buffer is written out whenever it overflows, a `hFlush` is issued, or the handle is closed.
- no-buffering: output is written immediately, and never stored in the buffer.

An implementation is free to flush the buffer more frequently, but not less frequently, than specified above. The output buffer is emptied as soon as it has been written out.

Similarly, input occurs according to the buffer mode for the handle:

- line-buffering: when the buffer for the handle is not empty, the next item is obtained from the buffer; otherwise, when the buffer is empty, characters up to and including the next newline character are read into the buffer. No characters are available until the newline character is available or the buffer is full.
- block-buffering: when the buffer for the handle becomes empty, the next block of data is read into the buffer.
- no-buffering: the next input item is read and returned. The `hLookAhead` operation implies that even a no-buffered handle may require a one-character buffer.

The default buffering mode when a handle is opened is implementation-dependent and may depend on the file system object which is attached to that handle. For most implementations, physical files will normally be block-buffered and terminals will normally be line-buffered.

Constructors

NoBuffering | buffering is disabled if possible.
LineBuffering | line-buffering should be enabled if possible.
BlockBuffering (Maybe Int) | block-buffering should be enabled if possible. The size of the buffer is `n` items if the argument is `Just` `n` and is otherwise implementation-dependent.

#### Instances

Instances details

Read BufferMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Handle.Types Methods readsPrec :: Int -> ReadS BufferMode Source # readList :: ReadS [BufferMode] Source # readPrec :: ReadPrec BufferMode Source # readListPrec :: ReadPrec [BufferMode] Source #
Show BufferMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Handle.Types Methods showsPrec :: Int -> BufferMode -> ShowS Source # show :: BufferMode -> String Source # showList :: [BufferMode] -> ShowS Source #
Eq BufferMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Handle.Types Methods (==) :: BufferMode -> BufferMode -> Bool Source # (/=) :: BufferMode -> BufferMode -> Bool Source #
Ord BufferMode | Since: base-4.2.0.0

Instance details

Defined in GHC.Internal.IO.Handle.Types

Methods

compare :: BufferMode -> BufferMode -> Ordering Source #

(<) :: BufferMode -> BufferMode -> Bool Source #

(<=) :: BufferMode -> BufferMode -> Bool Source #

(>) :: BufferMode -> BufferMode -> Bool Source #

(>=) :: BufferMode -> BufferMode -> Bool Source #

max :: BufferMode -> BufferMode -> BufferMode Source #

min :: BufferMode -> BufferMode -> BufferMode Source #

data Handle Source #

Haskell defines operations to read and write characters from and to files, represented by values of type `Handle`. Each value of this type is a handle: a record used by the Haskell run-time system to manage I/O with file system objects. A handle has at least the following properties:

- whether it manages input or output or both;
- whether it is open, closed or semi-closed;
- whether the object is seekable;
- whether buffering is disabled, or enabled on a line or block basis;
- a buffer (whose length may be zero).

Most handles will also have a current I/O position indicating where the next input or output operation will occur. A handle is readable if it manages only input or both input and output; likewise, it is writable if it manages only output or both input and output. A handle is open when first allocated. Once it is closed it can no longer be used for either input or output, though an implementation cannot re-use its storage while references remain to it. Handles are in the `Show` and `Eq` classes. The string produced by showing a handle is system dependent; it should include enough information to identify the handle for debugging. A handle is equal according to `==` only to itself; no attempt is made to compare the internal state of different handles for equality.

#### Instances

Instances details

Show Handle | Since: base-4.1.0.0
Instance details Defined in GHC.Internal.IO.Handle.Types Methods showsPrec :: Int -> Handle -> ShowS Source # show :: Handle -> String Source # showList :: [Handle] -> ShowS Source #
Eq Handle | Since: base-4.1.0.0
Instance details Defined in GHC.Internal.IO.Handle.Types Methods (==) :: Handle -> Handle -> Bool Source # (/=) :: Handle -> Handle -> Bool Source #

data SeekMode Source #

A mode that determines the effect of `hSeek` `hdl mode i`.

Constructors

AbsoluteSeek | the position of `hdl` is set to `i`.
RelativeSeek | the position of `hdl` is set to offset `i` from the current position.
SeekFromEnd | the position of `hdl` is set to offset `i` from the end of the file.

#### Instances

Instances details

Enum SeekMode | Since: base-4.2.0.0

Instance details

Defined in GHC.Internal.IO.Device

Methods

succ :: SeekMode -> SeekMode Source #

pred :: SeekMode -> SeekMode Source #

toEnum :: Int -> SeekMode Source #

fromEnum :: SeekMode -> Int Source #

enumFrom :: SeekMode -> [SeekMode] Source #

enumFromThen :: SeekMode -> SeekMode -> [SeekMode] Source #

enumFromTo :: SeekMode -> SeekMode -> [SeekMode] Source #

enumFromThenTo :: SeekMode -> SeekMode -> SeekMode -> [SeekMode] Source #

Ix SeekMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Device Methods range :: (SeekMode, SeekMode) -> [SeekMode] Source # index :: (SeekMode, SeekMode) -> SeekMode -> Int Source # unsafeIndex :: (SeekMode, SeekMode) -> SeekMode -> Int Source # inRange :: (SeekMode, SeekMode) -> SeekMode -> Bool Source # rangeSize :: (SeekMode, SeekMode) -> Int Source # unsafeRangeSize :: (SeekMode, SeekMode) -> Int Source #
Read SeekMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Device Methods readsPrec :: Int -> ReadS SeekMode Source # readList :: ReadS [SeekMode] Source # readPrec :: ReadPrec SeekMode Source # readListPrec :: ReadPrec [SeekMode] Source #
Show SeekMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Device Methods showsPrec :: Int -> SeekMode -> ShowS Source # show :: SeekMode -> String Source # showList :: [SeekMode] -> ShowS Source #
Eq SeekMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Device Methods (==) :: SeekMode -> SeekMode -> Bool Source # (/=) :: SeekMode -> SeekMode -> Bool Source #
Ord SeekMode | Since: base-4.2.0.0
Instance details Defined in GHC.Internal.IO.Device Methods compare :: SeekMode -> SeekMode -> Ordering Source # (<) :: SeekMode -> SeekMode -> Bool Source # (<=) :: SeekMode -> SeekMode -> Bool Source # (>) :: SeekMode -> SeekMode -> Bool Source # (>=) :: SeekMode -> SeekMode -> Bool Source # max :: SeekMode -> SeekMode -> SeekMode Source # min :: SeekMode -> SeekMode -> SeekMode Source #

hSetBuffering :: Handle -> BufferMode -> IO () Source #

Computation `hSetBuffering` `hdl mode` sets the mode of buffering for handle `hdl` on subsequent reads and writes.

If the buffer mode is changed from `BlockBuffering` or `LineBuffering` to `NoBuffering`, then

- if `hdl` is writable, the buffer is flushed as for `hFlush`;
- if `hdl` is not writable, the contents of the buffer are discarded.

This operation may fail with:

- `isPermissionError` if the handle has already been used for reading or writing and the implementation does not allow the buffering mode to be changed.

hClose :: Handle -> IO () Source #

Computation `hClose` `hdl` makes handle `hdl` closed. Before the computation finishes, if `hdl` is writable its buffer is flushed as for `hFlush`. Performing `hClose` on a handle that has already been closed has no effect; doing so is not an error. All other operations on a closed handle will fail. If `hClose` fails for any reason, any further operations (apart from `hClose`) on the handle will still fail as if `hdl` had been successfully closed.

`hClose` is an interruptible operation in the sense described in Control.Exception. If `hClose` is interrupted by an asynchronous exception in the process of flushing its buffers, then the I/O device (e.g., file) will be closed anyway.

hFileSize :: Handle -> IO Integer Source #

For a handle `hdl` which attached to a physical file, `hFileSize` `hdl` returns the size of that file in 8-bit bytes.

hSeek :: Handle -> SeekMode -> Integer -> IO () Source #

Computation `hSeek` `hdl mode i` sets the position of handle `hdl` depending on `mode`. The offset `i` is given in terms of 8-bit bytes.

If `hdl` is block- or line-buffered, then seeking to a position which is not in the current buffer will first cause any items in the output buffer to be written to the device, and then cause the input buffer to be discarded. Some handles may not be seekable (see `hIsSeekable`), or only support a subset of the possible positioning operations (for instance, it may only be possible to seek to the end of a tape, or to a positive offset from the beginning or current position). It is not possible to set a negative I/O position, or for a physical file, an I/O position beyond the current end-of-file.

This operation may fail with:

- `isIllegalOperationError` if the Handle is not seekable, or does not support the requested seek mode.
- `isPermissionError` if a system resource limit would be exceeded.