Copyright	(c) The University of Glasgow 2002
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	[email protected]
Stability	provisional
Portability	non-portable (requires POSIX)
Safe Haskell	Safe
Language	Haskell2010

Input / Output

Standard file descriptors

stdInput :: Fd Source

stdOutput :: Fd Source

stdError :: Fd Source

Opening and closing files

data OpenMode Source

data OpenFileFlags Source

Correspond to some of the int flags from C's fcntl.h.

defaultFileFlags :: OpenFileFlags Source

Default values for the OpenFileFlags type. False for each of append, exclusive, noctty, nonBlock, and trunc.

openFd Source

Open and optionally create this file. See Files for information on how to use the FileMode type.

createFile :: FilePath -> FileMode -> IO Fd Source

Create and open this file in WriteOnly mode. A special case of openFd. See Files for information on how to use the FileMode type.

closeFd :: Fd -> IO () Source

Close this file descriptor. May throw an exception if this is an invalid descriptor.

Reading/writing data

Programmers using the fdRead and fdWrite API should be aware that EAGAIN exceptions may occur for non-blocking IO!

fdRead Source

Read data from an Fd and convert it to a String using the locale encoding. Throws an exception if this is an invalid descriptor, or EOF has been reached.

fdWrite :: Fd -> String -> IO ByteCount Source

Write a String to an Fd using the locale encoding.

fdReadBuf Source

Read data from an Fd into memory. This is exactly equivalent to the POSIX read function.

fdWriteBuf Source

Write data from memory to an Fd. This is exactly equivalent to the POSIX write function.

Seeking

fdSeek :: Fd -> SeekMode -> FileOffset -> IO FileOffset Source

May throw an exception if this is an invalid descriptor.

File options

data FdOption Source

queryFdOption :: Fd -> FdOption -> IO Bool Source

May throw an exception if this is an invalid descriptor.

setFdOption :: Fd -> FdOption -> Bool -> IO () Source

May throw an exception if this is an invalid descriptor.

Locking

type FileLock = (LockRequest, SeekMode, FileOffset, FileOffset) Source

data LockRequest Source

getLock :: Fd -> FileLock -> IO (Maybe (ProcessID, FileLock)) Source

May throw an exception if this is an invalid descriptor.

setLock :: Fd -> FileLock -> IO () Source

May throw an exception if this is an invalid descriptor.

waitToSetLock :: Fd -> FileLock -> IO () Source

May throw an exception if this is an invalid descriptor.

Pipes

createPipe :: IO (Fd, Fd) Source

The createPipe function creates a pair of connected file descriptors. The first component is the fd to read from, the second is the write end. Although pipes may be bidirectional, this behaviour is not portable and programmers should use two separate pipes for this purpose. May throw an exception if this is an invalid descriptor.

Duplicating file descriptors

dup :: Fd -> IO Fd Source

May throw an exception if this is an invalid descriptor.

dupTo :: Fd -> Fd -> IO Fd Source

May throw an exception if this is an invalid descriptor.

Converting file descriptors to/from Handles

handleToFd :: Handle -> IO Fd Source

Extracts the Fd from a Handle. This function has the side effect of closing the Handle and flushing its write buffer, if necessary.

fdToHandle :: Fd -> IO Handle Source

Converts an Fd into a Handle that can be used with the standard Haskell IO library (see System.IO).