| Copyright | (c) The University of Glasgow 1994-2008 | 
|---|---|
| License | see libraries/base/LICENSE | 
| Maintainer | libraries@haskell.org | 
| Stability | internal | 
| Portability | non-portable | 
| Safe Haskell | Trustworthy | 
| Language | Haskell2010 | 
GHC.IO.Handle.FD
Description
Handle operations implemented by file descriptors (FDs)
Synopsis
- stdin :: Handle
- stdout :: Handle
- stderr :: Handle
- openFile :: FilePath -> IOMode -> IO Handle
- withFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r
- openBinaryFile :: FilePath -> IOMode -> IO Handle
- withBinaryFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r
- openFileBlocking :: FilePath -> IOMode -> IO Handle
- withFileBlocking :: FilePath -> IOMode -> (Handle -> IO r) -> IO r
- mkHandleFromFD :: FD -> IODeviceType -> FilePath -> IOMode -> Bool -> Maybe TextEncoding -> IO Handle
- fdToHandle :: FD -> IO Handle
- fdToHandle' :: CInt -> Maybe IODeviceType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
- handleToFd :: Handle -> IO FD
Documentation
openFile :: FilePath -> IOMode -> IO Handle Source #
Computation openFile file mode allocates and returns a new, open
 handle to manage the file file.  It manages input if mode
 is ReadMode, output if mode is WriteMode or AppendMode,
 and both input and output if mode is ReadWriteMode.
If the file does not exist and it is opened for output, it should be
 created as a new file.  If mode is WriteMode and the file
 already exists, then it should be truncated to zero length.
 Some operating systems delete empty files, so there is no guarantee
 that the file will exist following an openFile with mode
 WriteMode unless it is subsequently written to successfully.
 The handle is positioned at the end of the file if mode is
 AppendMode, and otherwise at the beginning (in which case its
 internal position is 0).
 The initial buffer mode is implementation-dependent.
This operation may fail with:
- isAlreadyInUseErrorif the file is already open and cannot be reopened;
- isDoesNotExistErrorif the file does not exist or (on POSIX systems) is a FIFO without a reader and- WriteModewas requested; or
- isPermissionErrorif the user does not have permission to open the file.
On POSIX systems, openFile is an interruptible operation as
 described in Control.Exception.
Note: if you will be working with files containing binary data, you'll want to
 be using openBinaryFile.
withFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r Source #
withFile name mode actopenFile and passes
 the resulting handle to the computation act.  The handle will be
 closed on exit from withFile, whether by normal termination or by
 raising an exception.  If closing the handle raises an exception, then
 this exception will be raised by withFile rather than any exception
 raised by act.
openBinaryFile :: FilePath -> IOMode -> IO Handle Source #
Like openFile, but open the file in binary mode.
 On Windows, reading a file in text mode (which is the default)
 will translate CRLF to LF, and writing will translate LF to CRLF.
 This is usually what you want with text files.  With binary files
 this is undesirable; also, as usual under Microsoft operating systems,
 text mode treats control-Z as EOF.  Binary mode turns off all special
 treatment of end-of-line and end-of-file characters.
 (See also hSetBinaryMode.)
withBinaryFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r Source #
A version of openBinaryFile that takes an action to perform
 with the handle. If an exception occurs in the action, then
 the file will be closed automatically. The action should
 close the file when finished with it so the file does not remain
 open until the garbage collector collects the handle.
openFileBlocking :: FilePath -> IOMode -> IO Handle Source #
Like openFile, but opens the file in ordinary blocking mode.
 This can be useful for opening a FIFO for writing: if we open in
 non-blocking mode then the open will fail if there are no readers,
 whereas a blocking open will block until a reader appear.
Note: when blocking happens, an OS thread becomes tied up with the processing, so the program must have at least another OS thread if it wants to unblock itself. By corollary, a non-threaded runtime will need a process-external trigger in order to become unblocked.
On POSIX systems, openFileBlocking is an interruptible operation as
 described in Control.Exception.
Since: base-4.4.0.0
withFileBlocking :: FilePath -> IOMode -> (Handle -> IO r) -> IO r Source #
withFileBlocking name mode actopenFileBlocking
 and passes the resulting handle to the computation act.  The handle will
 be closed on exit from withFileBlocking, whether by normal termination or
 by raising an exception.  If closing the handle raises an exception, then
 this exception will be raised by withFile rather than any exception raised
 by act.
mkHandleFromFD :: FD -> IODeviceType -> FilePath -> IOMode -> Bool -> Maybe TextEncoding -> IO Handle Source #
fdToHandle :: FD -> IO Handle Source #
Turn an existing file descriptor into a Handle. This is used by various external libraries to make Handles.
Makes a binary Handle. This is for historical reasons; it should probably be a text Handle with the default encoding and newline translation instead.