unix-2.8.5.1: POSIX functionality
Copyright(c) The University of Glasgow 2002
LicenseBSD-style (see the file libraries/base/LICENSE)
Maintainerlibraries@haskell.org
Stabilityprovisional
Portabilitynon-portable (requires POSIX)
Safe HaskellSafe
LanguageHaskell2010

System.Posix.Files

Description

Functions defined by the POSIX standards for manipulating and querying the file system. Names of underlying POSIX functions are indicated whenever possible. A more complete documentation of the POSIX functions together with a more detailed description of different error conditions are usually available in the system's manual pages or from http://www.unix.org/version3/online.html (free registration required).

When a function that calls an underlying POSIX function fails, the errno code is converted to an IOError using errnoToIOError. For a list of which errno codes may be generated, consult the POSIX documentation for the underlying function.

Synopsis

File modes

unionFileModes :: FileMode -> FileMode -> FileMode Source #

Combines the two file modes into one that contains modes that appear in either.

intersectFileModes :: FileMode -> FileMode -> FileMode Source #

Combines two file modes into one that only contains modes that appear in both.

nullFileMode :: FileMode Source #

No permissions.

ownerReadMode :: FileMode Source #

Owner has read permission.

ownerWriteMode :: FileMode Source #

Owner has write permission.

ownerExecuteMode :: FileMode Source #

Owner has execute permission.

ownerModes :: FileMode Source #

Owner has read, write and execute permission.

groupReadMode :: FileMode Source #

Group has read permission.

groupWriteMode :: FileMode Source #

Group has write permission.

groupExecuteMode :: FileMode Source #

Group has execute permission.

groupModes :: FileMode Source #

Group has read, write and execute permission.

otherReadMode :: FileMode Source #

Others have read permission.

otherWriteMode :: FileMode Source #

Others have write permission.

otherExecuteMode :: FileMode Source #

Others have execute permission.

otherModes :: FileMode Source #

Others have read, write and execute permission.

setUserIDMode :: FileMode Source #

Set user ID on execution.

setGroupIDMode :: FileMode Source #

Set group ID on execution.

stdFileMode :: FileMode Source #

Owner, group and others have read and write permission.

accessModes :: FileMode Source #

Owner, group and others have read, write and execute permission.

fileTypeModes :: FileMode Source #

namedPipeMode :: FileMode Source #

directoryMode :: FileMode Source #

socketMode :: FileMode Source #

Setting file modes

setFileMode :: FilePath -> FileMode -> IO () Source #

setFileMode path mode changes permission of the file given by path to mode. This operation may fail with throwErrnoPathIfMinus1_ if path doesn't exist or if the effective user ID of the current process is not that of the file's owner.

Note: calls chmod.

setFdMode :: Fd -> FileMode -> IO () Source #

setFdMode fd mode acts like setFileMode but uses a file descriptor fd instead of a FilePath.

Note: calls fchmod.

setFileCreationMask :: FileMode -> IO FileMode Source #

setFileCreationMask mode sets the file mode creation mask to mode. Modes set by this operation are subtracted from files and directories upon creation. The previous file creation mask is returned.

Note: calls umask.

Checking file existence and permissions

fileAccess :: FilePath -> Bool -> Bool -> Bool -> IO Bool Source #

fileAccess name read write exec checks if the file (or other file system object) name can be accessed for reading, writing and/or executing. To check a permission set the corresponding argument to True.

Note: calls access.

fileExist :: FilePath -> IO Bool Source #

Checks for the existence of the file.

Note: calls access.

File status

newtype FileStatus Source #

POSIX defines operations to get information, such as owner, permissions, size and access times, about a file. This information is represented by the FileStatus type.

Note: see chmod.

Limitations: Support for high resolution timestamps is filesystem dependent:

  • HFS+ volumes on OS X only support whole-second times.

Constructors

FileStatus (ForeignPtr CStat)

The constructor is considered internal and may change.

Obtaining file status

getFileStatus :: FilePath -> IO FileStatus Source #

getFileStatus path calls gets the FileStatus information (user ID, size, access times, etc.) for the file path.

Note: calls stat.

getFdStatus :: Fd -> IO FileStatus Source #

getFdStatus fd acts as getFileStatus but uses a file descriptor fd.

Note: calls fstat.

getSymbolicLinkStatus :: FilePath -> IO FileStatus Source #

Acts as getFileStatus except when the FilePath refers to a symbolic link. In that case the FileStatus information of the symbolic link itself is returned instead of that of the file it points to.

Note: calls lstat.

Querying file status

deviceID :: FileStatus -> DeviceID Source #

ID of the device on which this file resides.

fileID :: FileStatus -> FileID Source #

inode number

fileMode :: FileStatus -> FileMode Source #

File mode (such as permissions).

linkCount :: FileStatus -> LinkCount Source #

Number of hard links to this file.

fileOwner :: FileStatus -> UserID Source #

ID of owner.

fileGroup :: FileStatus -> GroupID Source #

ID of group.

specialDeviceID :: FileStatus -> DeviceID Source #

Describes the device that this file represents.

fileSize :: FileStatus -> FileOffset Source #

Size of the file in bytes. If this file is a symbolic link the size is the length of the pathname it contains.

accessTime :: FileStatus -> EpochTime Source #

Time of last access.

modificationTime :: FileStatus -> EpochTime Source #

Time of last modification.

statusChangeTime :: FileStatus -> EpochTime Source #

Time of last status change (i.e. owner, group, link count, mode, etc.).

accessTimeHiRes :: FileStatus -> POSIXTime Source #

Time of last access in sub-second resolution. Depends on the timestamp resolution of the underlying filesystem.

modificationTimeHiRes :: FileStatus -> POSIXTime Source #

Time of last modification in sub-second resolution. Depends on the timestamp resolution of the underlying filesystem.

statusChangeTimeHiRes :: FileStatus -> POSIXTime Source #

Time of last status change (i.e. owner, group, link count, mode, etc.) in sub-second resolution. Depends on the timestamp resolution of the underlying filesystem.

isBlockDevice :: FileStatus -> Bool Source #

Checks if this file is a block device.

isCharacterDevice :: FileStatus -> Bool Source #

Checks if this file is a character device.

isNamedPipe :: FileStatus -> Bool Source #

Checks if this file is a named pipe device.

isRegularFile :: FileStatus -> Bool Source #

Checks if this file is a regular file device.

isDirectory :: FileStatus -> Bool Source #

Checks if this file is a directory device.

isSymbolicLink :: FileStatus -> Bool Source #

Checks if this file is a symbolic link device.

isSocket :: FileStatus -> Bool Source #

Checks if this file is a socket device.

fileBlockSize :: FileStatus -> Maybe CBlkSize Source #

Gives the preferred block size for efficient filesystem I/O in bytes. Returns Nothing if st_blocksize is not supported on this platform.

fileBlocks :: FileStatus -> Maybe CBlkCnt Source #

Number of blocks allocated for this file, in units of 512-bytes. Returns Nothing if st_blocks is not supported on this platform.

Extended file status

newtype ExtendedFileStatus Source #

Constructors

ExtendedFileStatus (ForeignPtr CStatx)

The constructor is considered internal and may change.

newtype CAttributes Source #

Constructors

CAttributes Word64 

Instances

Instances details
Bits CAttributes Source # 
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Storable CAttributes Source # 
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Num CAttributes Source # 
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Read CAttributes Source # 
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Show CAttributes Source # 
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Eq CAttributes Source # 
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Ord CAttributes Source # 
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haveStatx :: Bool Source #

Whether statx is available on this platform and getExtendedFileStatus and related functions will work.

Obtaining extended file status

getExtendedFileStatus Source #

Arguments

:: Maybe Fd

Optional directory file descriptor (dirfd)

-> FilePath

pathname to open

-> StatxFlags

flags

-> StatxMask

mask

-> IO ExtendedFileStatus 

Gets extended file status information.

The target file to open is identified in one of the following ways:

  • If pathname begins with a slash, then it is an absolute pathname that identifies the target file. In this case, dirfd is ignored
  • If pathname is a string that begins with a character other than a slash and dirfd is a file descriptor that refers to a directory, then pathname is a relative pathname that is interpreted relative to the directory referred to by dirfd. (See openat(2) for an explanation of why this is useful.)
  • If pathname is an empty string and the EmptyPath flag is specified in flags (see below), then the target file is the one referred to by the file descriptor dirfd.

Note: calls statx.

Flags

newtype StatxFlags Source #

Statx flags.

See the pattern synonyms for possible flags. These are combined via (<>). Flags can be tested via (.&.).

The following flags influence pathname-based lookup:

The following flags can be used to control what sort of synchronization the kernel will do when querying a file on a remote filesystem:

Constructors

StatxFlags CInt 

Instances

Instances details
Monoid StatxFlags Source # 
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Semigroup StatxFlags Source #

ORs the flags.

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Bits StatxFlags Source # 
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Enum StatxFlags Source # 
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Num StatxFlags Source # 
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Read StatxFlags Source # 
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Integral StatxFlags Source # 
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Real StatxFlags Source # 
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Show StatxFlags Source # 
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Eq StatxFlags Source # 
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Ord StatxFlags Source # 
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pattern EmptyPath :: StatxFlags Source #

If pathname to getExtendedFileStatus is an empty string, operate on the file referred to by the 'Maybe Fd' argument.

In this case, it can refer to any type of file, not just a directory.

pattern NoAutoMount :: StatxFlags Source #

Don't automount the terminal ("basename") component of pathname if it is a directory that is an automount point. This allows the caller to gather attributes of an automount point (rather than the location it would mount). This flag can be used in tools that scan directories to prevent mass-automounting of a directory of automount points. This flag has no effect if the mount point has already been mounted over.

pattern SymlinkNoFollow :: StatxFlags Source #

If pathname is a symbolic link, do not dereference it: instead return information about the link itself, like lstat(2).

pattern SyncAsStat :: StatxFlags Source #

Do whatever stat(2) does. This is the default and is very much filesystem-specific.

pattern ForceSync :: StatxFlags Source #

Force the attributes to be synchronized with the server. This may require that a network filesystem perform a data writeback to get the timestamps correct.

pattern DontSync :: StatxFlags Source #

Don't synchronize anything, but rather just take whatever the system has cached if possible. This may mean that the information returned is approximate, but, on a network filesystem, it may not involve a round trip to the server - even if no lease is held.

Mask

newtype StatxMask Source #

Mask argument to statx. It's used to tell the kernel which fields the caller is interested in.

See the pattern synonyms for possible masks. These are combined via (<>). Masks can be tested via (.&.).

Constructors

StatxMask CInt 

Instances

Instances details
Monoid StatxMask Source # 
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Semigroup StatxMask Source #

ORs the masks.

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Bits StatxMask Source # 
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Enum StatxMask Source # 
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Num StatxMask Source # 
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Read StatxMask Source # 
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Integral StatxMask Source # 
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Real StatxMask Source # 
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Show StatxMask Source # 
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Eq StatxMask Source # 
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Ord StatxMask Source # 
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pattern StatxType :: StatxMask Source #

Want stx_mode & S_IFMT.

pattern StatxMode :: StatxMask Source #

Want stx_mode & ~S_IFMT.

pattern StatxNlink :: StatxMask Source #

Want stx_nlink.

pattern StatxUid :: StatxMask Source #

Want stx_uid.

pattern StatxGid :: StatxMask Source #

Want stx_gid.

pattern StatxAtime :: StatxMask Source #

Want stx_atime.

pattern StatxMtime :: StatxMask Source #

Want stx_mtime.

pattern StatxCtime :: StatxMask Source #

Want stx_ctime.

pattern StatxIno :: StatxMask Source #

Want stx_ino.

pattern StatxSize :: StatxMask Source #

Want stx_size.

pattern StatxBlocks :: StatxMask Source #

Want stx_blocks.

pattern StatxBasicStats :: StatxMask Source #

Want all of the above.

pattern StatxBtime :: StatxMask Source #

Want stx_btime.

pattern StatxMntId :: StatxMask Source #

Want stx_mnt_id.

pattern StatxAll :: StatxMask Source #

Want all currently available fields.

Querying extended file status

fileBlockSizeX :: ExtendedFileStatus -> CBlkSize Source #

The "preferred" block size for efficient filesystem I/O. (Writing to a file in smaller chunks may cause an inefficient read-mod‐ify-rewrite.)

linkCountX :: ExtendedFileStatus -> CNlink Source #

The number of hard links on a file.

fileOwnerX :: ExtendedFileStatus -> UserID Source #

Te user ID of the owner of the file.

fileGroupX :: ExtendedFileStatus -> GroupID Source #

The ID of the group owner of the file.

fileModeX :: ExtendedFileStatus -> FileMode Source #

The file type and mode. See inode(7) for details.

fileIDX :: ExtendedFileStatus -> FileID Source #

The inode number of the file.

fileSizeX :: ExtendedFileStatus -> Word64 Source #

The size of the file (if it is a regular file or a symbolic link) in bytes. The size of a symbolic link is the length of the pathname it contains, without a terminating null byte.

fileBlocksX :: ExtendedFileStatus -> Word64 Source #

The number of blocks allocated to the file on the medium, in 512-byte units. (This may be smaller than stx_size/512 when the file has holes.)

accessTimeHiResX :: ExtendedFileStatus -> POSIXTime Source #

The file's last access timestamp.

creationTimeHiResX :: ExtendedFileStatus -> POSIXTime Source #

The file's creation timestamp.

statusChangeTimeHiResX :: ExtendedFileStatus -> POSIXTime Source #

The file's last status change timestamp.

modificationTimeHiResX :: ExtendedFileStatus -> POSIXTime Source #

The file's last modification timestamp.

deviceIDX :: ExtendedFileStatus -> DeviceID Source #

ID of the device on which this file resides.

specialDeviceIDX :: ExtendedFileStatus -> DeviceID Source #

Describes the device that this file represents.

mountIDX :: ExtendedFileStatus -> Word64 Source #

The mount ID of the mount containing the file. This is the same number reported by name_to_handle_at(2) and corresponds to the number in the first field in one of the records in procself/mountinfo.

fileCompressedX :: ExtendedFileStatus -> Bool Source #

The file is compressed by the filesystem and may take extra resources to access. This is an extended attribute.

fileImmutableX :: ExtendedFileStatus -> Bool Source #

The file cannot be modified: it cannot be deleted or renamed, no hard links can be created to this file and no data can be written to it. See chattr(1). This is an extended attribute.

fileAppendX :: ExtendedFileStatus -> Bool Source #

The file can only be opened in append mode for writing. Random access writing is not permitted. See chattr(1). This is an extended attribute.

fileNoDumpX :: ExtendedFileStatus -> Bool Source #

File is not a candidate for backup when a backup program such as dump(8) is run. See chattr(1). This is an extended attribute.

fileEncryptedX :: ExtendedFileStatus -> Bool Source #

A key is required for the file to be encrypted by the filesystem. This is an extended attribute.

fileVerityX :: ExtendedFileStatus -> Bool Source #

The file has fs-verity enabled. It cannot be written to, and all reads from it will be verified against a cryptographic hash that covers the entire file (e.g., via a Merkle tree). This is an extended attribute. Since Linux 5.5.

fileDaxX :: ExtendedFileStatus -> Bool Source #

The file is in the DAX (cpu direct access) state. This is an extended attribute. Since Linux 5.8.

isBlockDeviceX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a block device.

isCharacterDeviceX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a character device.

isNamedPipeX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a named pipe device.

isRegularFileX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a regular file device.

isDirectoryX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a directory device.

isSymbolicLinkX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a symbolic link device.

isSocketX :: ExtendedFileStatus -> Bool Source #

Checks if this file is a socket device.

Creation

createNamedPipe :: FilePath -> FileMode -> IO () Source #

createNamedPipe fifo mode creates a new named pipe, fifo, with permissions based on mode. May fail with throwErrnoPathIfMinus1_ if a file named name already exists or if the effective user ID of the current process doesn't have permission to create the pipe.

Note: calls mkfifo.

createDevice :: FilePath -> FileMode -> DeviceID -> IO () Source #

createDevice path mode dev creates either a regular or a special file depending on the value of mode (and dev). mode will normally be either blockSpecialMode or characterSpecialMode. May fail with throwErrnoPathIfMinus1_ if a file named name already exists or if the effective user ID of the current process doesn't have permission to create the file.

Note: calls mknod.

Hard links

createLink :: FilePath -> FilePath -> IO () Source #

createLink old new creates a new path, new, linked to an existing file, old.

Note: calls link.

removeLink :: FilePath -> IO () Source #

removeLink path removes the link named path.

Note: calls unlink.

Symbolic links

createSymbolicLink :: FilePath -> FilePath -> IO () Source #

createSymbolicLink name1 name2 creates a symbolic link named name2 which points to the file name1.

Symbolic links are interpreted at run-time as if the contents of the link had been substituted into the path being followed to find a file or directory.

Note: calls symlink.

readSymbolicLink :: FilePath -> IO FilePath Source #

Reads the FilePath pointed to by the symbolic link and returns it.

Note: calls readlink.

Renaming files

rename :: FilePath -> FilePath -> IO () Source #

rename old new renames a file or directory from old to new.

Note: calls rename.

Changing file ownership

setOwnerAndGroup :: FilePath -> UserID -> GroupID -> IO () Source #

setOwnerAndGroup path uid gid changes the owner and group of path to uid and gid, respectively.

If uid or gid is specified as -1, then that ID is not changed.

Note: calls chown.

setFdOwnerAndGroup :: Fd -> UserID -> GroupID -> IO () Source #

Acts as setOwnerAndGroup but uses a file descriptor instead of a FilePath.

Note: calls fchown.

setSymbolicLinkOwnerAndGroup :: FilePath -> UserID -> GroupID -> IO () Source #

Acts as setOwnerAndGroup but does not follow symlinks (and thus changes permissions on the link itself).

Note: calls lchown.

Changing file timestamps

setFileTimes :: FilePath -> EpochTime -> EpochTime -> IO () Source #

setFileTimes path atime mtime sets the access and modification times associated with file path to atime and mtime, respectively.

Note: calls utime.

setFileTimesHiRes :: FilePath -> POSIXTime -> POSIXTime -> IO () Source #

Like setFileTimes but timestamps can have sub-second resolution.

Note: calls utimensat or utimes. Support for high resolution timestamps is filesystem dependent with the following limitations:

  • HFS+ volumes on OS X truncate the sub-second part of the timestamp.

Since: unix-2.7.0.0

setFdTimesHiRes :: Fd -> POSIXTime -> POSIXTime -> IO () Source #

Like setFileTimesHiRes but uses a file descriptor instead of a path. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls futimens or futimes. Support for high resolution timestamps is filesystem dependent with the following limitations:

  • HFS+ volumes on OS X truncate the sub-second part of the timestamp.

Since: unix-2.7.0.0

setSymbolicLinkTimesHiRes :: FilePath -> POSIXTime -> POSIXTime -> IO () Source #

Like setFileTimesHiRes but does not follow symbolic links. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls utimensat or lutimes. Support for high resolution timestamps is filesystem dependent with the following limitations:

  • HFS+ volumes on OS X truncate the sub-second part of the timestamp.

Since: unix-2.7.0.0

touchFile :: FilePath -> IO () Source #

touchFile path sets the access and modification times associated with file path to the current time.

Note: calls utime.

touchFd :: Fd -> IO () Source #

Like touchFile but uses a file descriptor instead of a path. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls futimes.

Since: unix-2.7.0.0

touchSymbolicLink :: FilePath -> IO () Source #

Like touchFile but does not follow symbolic links. This operation is not supported on all platforms. On these platforms, this function will raise an exception.

Note: calls lutimes.

Since: unix-2.7.0.0

Setting file sizes

setFileSize :: FilePath -> FileOffset -> IO () Source #

Truncates the file down to the specified length. If the file was larger than the given length before this operation was performed the extra is lost.

Note: calls truncate.

setFdSize :: Fd -> FileOffset -> IO () Source #

Acts as setFileSize but uses a file descriptor instead of a FilePath.

Note: calls ftruncate.

Find system-specific limits for a file

getPathVar :: FilePath -> PathVar -> IO Limit Source #

getPathVar var path obtains the dynamic value of the requested configurable file limit or option associated with file or directory path. For defined file limits, getPathVar returns the associated value. For defined file options, the result of getPathVar is undefined, but not failure.

Note: calls pathconf.

getFdPathVar :: Fd -> PathVar -> IO Limit Source #

getFdPathVar var fd obtains the dynamic value of the requested configurable file limit or option associated with the file or directory attached to the open channel fd. For defined file limits, getFdPathVar returns the associated value. For defined file options, the result of getFdPathVar is undefined, but not failure.

Note: calls fpathconf.