{-# OPTIONS_GHC -optc-DBTRFS_RAW_PATHS=1 #-}
{-# LINE 1 "System/Linux/Btrfs/ByteString.hsc" #-}

{-# LINE 2 "System/Linux/Btrfs/ByteString.hsc" #-}
{- |
Module      : System.Linux.Btrfs

Stability   : provisional
Portability : non-portable (requires Linux)

Most functions in this module come in two flavors: one that operates on
file descriptors and another one that operates on file paths. The former
can be distinguished by the @Fd@ suffix in their names.
-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE RecordWildCards #-}


{-# LINE 17 "System/Linux/Btrfs/ByteString.hsc" #-}
#define FILEPATH RawFilePath
module System.Linux.Btrfs.ByteString

{-# LINE 23 "System/Linux/Btrfs/ByteString.hsc" #-}
    (
    -- * Basic types
      FileSize, ObjectType, ObjectId, InodeNum, SubvolId, CompressionType(..)
    -- * File cloning
    , cloneFd, clone, cloneNew
    , cloneRangeFd, cloneRange
    , CloneResult(..)
    , cloneRangeIfSameFd, cloneRangeIfSame
    -- * Subvolumes and snapshots
    , createSubvol
    , destroySubvol
    , snapshotFd, snapshot
    , getSubvolReadOnlyFd, getSubvolReadOnly
    , setSubvolReadOnlyFd, setSubvolReadOnly
    , getSubvolFd, getSubvol
    , lookupSubvolFd, lookupSubvol
    , resolveSubvolFd, resolveSubvol
    , rootSubvol
    , listSubvolsFd, listSubvols
    , listSubvolPathsFd, listSubvolPaths
    , childSubvolsFd, childSubvols
    , childSubvolPathsFd, childSubvolPaths
    , SubvolInfo(..)
    , getSubvolInfoFd, getSubvolInfo
    , getSubvolByUuidFd, getSubvolByUuid
    , getSubvolByReceivedUuidFd, getSubvolByReceivedUuid
    -- * Defragging
    , defragFd, defrag
    , DefragRangeArgs(..), defaultDefragRangeArgs
    , defragRangeFd, defragRange
    -- * Sync
    , syncFd, sync
    , startSyncFd, startSync
    , waitSyncFd, waitSync
    -- * Inspect internal
    , resolveLogicalFd, resolveLogical
    , resolveInodeFd, resolveInode
    , lookupInodeFd, lookupInode
    -- * Miscellaneous
    , getFileNoCOWFd, getFileNoCOW
    , setFileNoCOWFd, setFileNoCOW
    -- * Tree search
    -- | Low-level API for tree search using the @BTRFS_IOC_TREE_SEARCH@
    -- @ioctl@.
    , SearchKey(..)
    , defaultSearchKey
    , SearchHeader(..)
    , treeSearchFd, treeSearch
    , treeSearchListFd, treeSearchList
    , findFirstItemFd, findFirstItem
    ) where

import System.Posix.Types
import System.Posix.IO hiding (openFd)
import System.Posix.Files
import System.Posix.Signals
import System.IO.Error
import Control.Exception
import Control.Monad
import Data.IORef
import Data.Time.Clock (UTCTime)
import Data.Monoid
import System.Linux.Btrfs.FilePathLike

import Foreign
import Foreign.C.Types
import Foreign.C.String (CStringLen)
import Foreign.C.Error

import Data.Word.Endian
import System.Linux.Btrfs.Time
import System.Linux.Btrfs.UUID


{-# LINE 97 "System/Linux/Btrfs/ByteString.hsc" #-}

{-# LINE 98 "System/Linux/Btrfs/ByteString.hsc" #-}

{-# LINE 99 "System/Linux/Btrfs/ByteString.hsc" #-}


{-# LINE 101 "System/Linux/Btrfs/ByteString.hsc" #-}

foreign import ccall safe
    ioctl :: Fd -> CULong -> Ptr a -> IO CInt
foreign import ccall unsafe "ioctl"
    ioctl_fast :: Fd -> CULong -> Ptr a -> IO CInt

type FileSize = Word64

type ObjectType = Word8

type ObjectId = Word64

type InodeNum = ObjectId

type SubvolId = ObjectId

data CompressionType = Zlib | LZO
    deriving (Show, Read, Eq, Enum, Bounded)

--------------------------------------------------------------------------------

cloneFd :: Fd -> Fd -> IO ()
cloneFd srcFd dstFd =
    throwErrnoIfMinus1_ "cloneFd" $
        ioctl_fast dstFd (1074041865) srcFdP
{-# LINE 126 "System/Linux/Btrfs/ByteString.hsc" #-}
  where
    srcFdP = intPtrToPtr (fromIntegral srcFd)

-- | Clone an entire file to an existing file.
--
-- Note: calls the @BTRFS_IOC_CLONE@ @ioctl@.
clone
    :: FILEPATH -- ^ The source file.
    -> FILEPATH -- ^ The destination file.
    -> IO ()
clone srcPath dstPath =
    withFd srcPath ReadOnly $ \srcFd ->
    withFd dstPath WriteOnly $ \dstFd ->
        cloneFd srcFd dstFd

-- | Like 'clone' except that it will create or truncate the destination
-- file if necessary. This is similar to @cp --reflink=always@.
--
-- Note: calls the @BTRFS_IOC_CLONE@ @ioctl@.
cloneNew :: FILEPATH -> FILEPATH -> IO ()
cloneNew srcPath dstPath =
    withFd srcPath ReadOnly $ \srcFd -> do
        stat <- getFdStatus srcFd
        let mode = fileMode stat
        bracket (openFd dstPath WriteOnly (Just mode) defaultFileFlags {trunc = True}) closeFd $ \dstFd ->
            cloneFd srcFd dstFd

cloneRangeFd :: Fd -> FileSize -> FileSize -> Fd -> FileSize -> IO ()
cloneRangeFd srcFd srcOff srcLen dstFd dstOff =
    allocaBytesZero ((32)) $ \cra -> do
{-# LINE 156 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) cra (fromIntegral srcFd :: Int64)
{-# LINE 157 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) cra (srcOff :: Word64)
{-# LINE 158 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) cra (srcLen :: Word64)
{-# LINE 159 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 24)) cra (dstOff :: Word64)
{-# LINE 160 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "cloneRangeFd" $
            ioctl_fast dstFd (1075876877) cra
{-# LINE 162 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Clones a range of bytes from a file to another file. All ranges must
-- be block-aligned.
--
-- Note: calls the @BTRFS_IOC_CLONE_RANGE@ @ioctl@.
cloneRange
    :: FILEPATH -- ^ The source file.
    -> FileSize -- ^ The offset within the source file.
    -> FileSize -- ^ The length of the range. A length of 0 selects the range
                -- from the source offset to the end.
    -> FILEPATH -- ^ The destination file.
    -> FileSize -- ^ The offset within the destination file.
    -> IO ()
cloneRange srcPath srcOff srcLen dstPath dstOff =
    withFd srcPath ReadOnly $ \srcFd ->
    withFd dstPath WriteOnly $ \dstFd ->
        cloneRangeFd srcFd srcOff srcLen dstFd dstOff


{-# LINE 181 "System/Linux/Btrfs/ByteString.hsc" #-}
data SameExtentInfoIn = SameExtentInfoIn
    Fd       -- file descriptor (stored as Int64)
    FileSize -- offset

instance Storable SameExtentInfoIn where
    sizeOf _ = ((32))
{-# LINE 187 "System/Linux/Btrfs/ByteString.hsc" #-}
    alignment _ = alignment (undefined :: CInt)
    poke ptr (SameExtentInfoIn dstFd dstOff) = do
        memset ptr 0 ((32))
{-# LINE 190 "System/Linux/Btrfs/ByteString.hsc" #-}
        let dstFd' = fromIntegral dstFd :: Int64
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) ptr dstFd'
{-# LINE 192 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) ptr dstOff
{-# LINE 193 "System/Linux/Btrfs/ByteString.hsc" #-}
    peek _ = error "not implemented"

data SameExtentInfoOut = SameExtentInfoOut
    Int32    -- status
    FileSize -- bytes deduped

instance Storable SameExtentInfoOut where
    sizeOf _ = ((32))
{-# LINE 201 "System/Linux/Btrfs/ByteString.hsc" #-}
    alignment _ = alignment (undefined :: CInt)
    poke _ _ = error "not implemented"
    peek ptr = do
        status <- ((\hsc_ptr -> peekByteOff hsc_ptr 24)) ptr
{-# LINE 205 "System/Linux/Btrfs/ByteString.hsc" #-}
        bytes  <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) ptr
{-# LINE 206 "System/Linux/Btrfs/ByteString.hsc" #-}
        return (SameExtentInfoOut status bytes)

{-# LINE 208 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | The result of a 'cloneRangeIfSame' operation.
data CloneResult
    = CRError IOError    -- ^ Cloning failed because of an error.
    | CRDataDiffers      -- ^ No cloning was performed because the contents
                         -- of the source and the destination file differ.
    | CRSuccess FileSize -- ^ Cloning succeeded, the returned integer
                         -- indicates the number of bytes that were
                         -- deduped.
    deriving (Show, Eq)

cloneRangeIfSameFd :: Fd -> FileSize -> FileSize -> [(Fd, FileSize)] -> IO [CloneResult]

{-# LINE 224 "System/Linux/Btrfs/ByteString.hsc" #-}
cloneRangeIfSameFd srcFd srcOff srcLen dsts = do
    unless (dstCount <= maxCount) $
        ioError $ flip ioeSetErrorString ("too many destination files (more than " ++
                                          show maxCount ++ ")")
                $ mkIOError illegalOperationErrorType "cloneRangeIfSameFd" Nothing Nothing
    allocaBytes saSize $ \sa -> do
        memset sa 0 ((24))
{-# LINE 231 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) sa srcOff
{-# LINE 232 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) sa srcLen
{-# LINE 233 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) sa dstCount'
{-# LINE 234 "System/Linux/Btrfs/ByteString.hsc" #-}
        let info = ((\hsc_ptr -> hsc_ptr `plusPtr` 24)) sa
{-# LINE 235 "System/Linux/Btrfs/ByteString.hsc" #-}
        pokeArray info (map (uncurry SameExtentInfoIn) dsts)
        throwErrnoIfMinus1_ "cloneRangeIfSameFd" $
            ioctl srcFd (3222836278) sa
{-# LINE 238 "System/Linux/Btrfs/ByteString.hsc" #-}
        res <- peekArray dstCount info
        return $ flip map res $ \(SameExtentInfoOut status bytes) ->
            if status == 0 then
                CRSuccess bytes
            else if status == (1) then
{-# LINE 243 "System/Linux/Btrfs/ByteString.hsc" #-}
                CRDataDiffers
            else if status <= 0 then
                CRError $ errnoToIOError "cloneRangeIfSameFd"
                                         (Errno $ fromIntegral $ -status)
                                         Nothing Nothing
            else
                error $ "unknown status value (" ++ show status ++ ")"
  where
    saSize = ((24)) +
{-# LINE 252 "System/Linux/Btrfs/ByteString.hsc" #-}
             dstCount * ((32))
{-# LINE 253 "System/Linux/Btrfs/ByteString.hsc" #-}
    dstCount = length dsts
    dstCount' = fromIntegral dstCount :: Word64
    maxCount = fromIntegral (maxBound :: Word16)

{-# LINE 257 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Similar to 'cloneRange' except that it performs the cloning only if
-- the data ranges contain identical data.
-- Additionally, it accepts multiple destination files. The same thing can
-- be accomplished with 'cloneRange' in conjunction with file locking but
-- this function uses in-kernel locking to guarantee that the deduplicated
-- data is identical at the time of the operation. On the other hand, this
-- function will not clone arbitrarily large ranges; the kernel has an upper
-- limit for the length and if cloning bigger ranges is desired then it
-- has to be called multiple times. Note that cloning may succeed for some
-- of the destination files and fail for others. Because of that, this
-- function returns a list of outcomes, one for each destination file, and
-- no exceptions will be raised for the failed files.
--
-- Note: calls the @BTRFS_IOC_FILE_EXTENT_SAME@ @ioctl@.
--
-- /Requires Linux 3.12 or later./
cloneRangeIfSame
    :: FILEPATH               -- ^ The source file.
    -> FileSize               -- ^ The offset within the source file.
    -> FileSize               -- ^ The length of the range.
    -> [(FILEPATH, FileSize)] -- ^ The destination files and corresponding offsets.
    -> IO [CloneResult]
cloneRangeIfSame srcPath srcOff srcLen dstsP0 =
    withFd srcPath ReadOnly $ \srcFd ->
        loop srcFd (reverse dstsP0) []
  where
    loop srcFd ((dstPath, dstOff) : dstsP) dsts =
        withFd dstPath WriteOnly $ \fd ->
            loop srcFd dstsP ((fd, dstOff) : dsts)
    loop srcFd [] dsts =
        cloneRangeIfSameFd srcFd srcOff srcLen dsts

--------------------------------------------------------------------------------

simpleSubvolOp :: String -> FILEPATH -> CULong -> IO ()
simpleSubvolOp loc path req =
    withSplitPathOpenParent loc (4087) path $ \(cName, l) dirFd ->
{-# LINE 295 "System/Linux/Btrfs/ByteString.hsc" #-}
        allocaBytesZero ((4096)) $ \iva -> do
{-# LINE 296 "System/Linux/Btrfs/ByteString.hsc" #-}
            let ivaName = ((\hsc_ptr -> hsc_ptr `plusPtr` 8)) iva
{-# LINE 297 "System/Linux/Btrfs/ByteString.hsc" #-}
            copyBytes ivaName cName l
            throwErrnoIfMinus1_ loc $
                ioctl dirFd req iva

-- | Create an (initially) empty new subvolume.
--
-- Note: calls the @BTRFS_IOC_SUBVOL_CREATE@ @ioctl@.
createSubvol :: FILEPATH -> IO ()
createSubvol path =
    simpleSubvolOp "createSubvol" path (1342215182)
{-# LINE 307 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Destroy (delete) a subvolume.
--
-- Note: calls the @BTRFS_IOC_SNAP_DESTROY@ @ioctl@.
destroySubvol :: FILEPATH -> IO ()
destroySubvol path =
    simpleSubvolOp "destroySubvol" path (1342215183)
{-# LINE 314 "System/Linux/Btrfs/ByteString.hsc" #-}

snapshotFd :: Fd -> FILEPATH -> Bool -> IO ()
snapshotFd srcFd dstPath readOnly =
    withSplitPathOpenParent "snapshotFd" (4039) dstPath $ \(cName, l) dirFd ->
{-# LINE 318 "System/Linux/Btrfs/ByteString.hsc" #-}
        allocaBytesZero ((4096)) $ \iva -> do
{-# LINE 319 "System/Linux/Btrfs/ByteString.hsc" #-}
            let ivaName = ((\hsc_ptr -> hsc_ptr `plusPtr` 56)) iva
{-# LINE 320 "System/Linux/Btrfs/ByteString.hsc" #-}
            copyBytes ivaName cName l
            ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) iva (fromIntegral srcFd :: Int64)
{-# LINE 322 "System/Linux/Btrfs/ByteString.hsc" #-}
            when readOnly $
                setFlags (((\hsc_ptr -> hsc_ptr `plusPtr` 16)) iva)
{-# LINE 324 "System/Linux/Btrfs/ByteString.hsc" #-}
                    ((2) :: Word64)
{-# LINE 325 "System/Linux/Btrfs/ByteString.hsc" #-}
            throwErrnoIfMinus1_ "snapshotFd" $
                ioctl dirFd (1342215191) iva
{-# LINE 327 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Create a snapshot of an existing subvolume.
--
-- Note: calls the @BTRFS_IOC_SNAP_CREATE_V2@ @ioctl@.
snapshot
    :: FILEPATH -- ^ The source subvolume.
    -> FILEPATH -- ^ The destination subvolume (must not exist).
    -> Bool     -- ^ Create a read-only snapshot?
    -> IO ()
snapshot srcPath dstPath readOnly =
    withFd srcPath ReadOnly $ \srcFd ->
        snapshotFd srcFd dstPath readOnly

getSubvolReadOnlyFd :: Fd -> IO Bool
getSubvolReadOnlyFd fd =
    alloca $ \flagsPtr -> do
        throwErrnoIfMinus1_ "getSubvolReadOnlyFd" $
            ioctl fd (2148045849) flagsPtr
{-# LINE 345 "System/Linux/Btrfs/ByteString.hsc" #-}
        flags <- peek flagsPtr :: IO Word64
        return (flags .&. (2) /= 0)
{-# LINE 347 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Is the subvolume read-only?
--
-- Note: calls the @BTRFS_IOC_SUBVOL_GETFLAGS@ @ioctl@.
getSubvolReadOnly :: FILEPATH -> IO Bool
getSubvolReadOnly path = withFd path ReadOnly getSubvolReadOnlyFd

setSubvolReadOnlyFd :: Fd -> Bool -> IO ()
setSubvolReadOnlyFd fd readOnly =
    alloca $ \flagsPtr -> do
        throwErrnoIfMinus1_ "setSubvolReadOnlyFd" $
            ioctl fd (2148045849) flagsPtr
{-# LINE 359 "System/Linux/Btrfs/ByteString.hsc" #-}
        if readOnly then
            setFlags flagsPtr ((2) :: Word64)
{-# LINE 361 "System/Linux/Btrfs/ByteString.hsc" #-}
        else
            clearFlags flagsPtr ((2) :: Word64)
{-# LINE 363 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "setSubvolReadOnlyFd" $
            ioctl fd (1074304026) flagsPtr
{-# LINE 365 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Make a subvolume read-only (or read-write).
--
-- Note: calls the @BTRFS_IOC_SUBVOL_GETFLAGS@ and
-- @BTRFS_IOC_SUBVOL_SETFLAGS@ @ioctl@s.
setSubvolReadOnly :: FILEPATH -> Bool -> IO ()
setSubvolReadOnly path readOnly =
    withFd path ReadOnly $ \fd -> setSubvolReadOnlyFd fd readOnly

getSubvolFd :: Fd -> IO SubvolId
getSubvolFd fd = do
    (subvolId, _) <- lookupInodeFd fd 0 (256)
{-# LINE 377 "System/Linux/Btrfs/ByteString.hsc" #-}
    return subvolId

-- | Find the id of the subvolume where the given file resides. This is
-- merely a wrapper around 'lookupInode' provided for convenience.
getSubvol :: FILEPATH -> IO SubvolId
getSubvol path = withFd path ReadOnly getSubvolFd

lookupSubvolFd :: Fd -> SubvolId -> IO (SubvolId, InodeNum, FILEPATH)
lookupSubvolFd fd subvolId = do
    let sk = defaultSearchKey
            { skTreeId      = (1)
{-# LINE 388 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMinObjectId = subvolId
            , skMaxObjectId = subvolId
            , skMinType     = (144)
{-# LINE 391 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMaxType     = (144)
{-# LINE 392 "System/Linux/Btrfs/ByteString.hsc" #-}
            }
    findFirstItemFd fd sk $ \sh rr -> do
        (dirId, name) <- peekRootRef rr
        return (shOffset sh, dirId, name)

-- | Given the id of a subvolume, find the id of the parent subvolume, the
-- inode number of the directory containing it, and its name. This is
-- a wrapper around 'treeSearch'.
lookupSubvol
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> SubvolId -- ^ The id of the subvolume.
    -> IO (SubvolId, InodeNum, FILEPATH)
lookupSubvol path subvolId =
    withFd path ReadOnly $ \fd ->
        lookupSubvolFd fd subvolId

resolveSubvolFd :: Fd -> SubvolId -> IO FILEPATH
resolveSubvolFd fd subvolId
    | subvolId == rootSubvol = return mempty
    | otherwise = do
        (parentId, dirId, name) <- lookupSubvolFd fd subvolId
        parentPath <- resolveSubvolFd fd parentId
        if dirId == (256) then
{-# LINE 415 "System/Linux/Btrfs/ByteString.hsc" #-}
            return (parentPath </> name)
        else do
            (_, dirName) <- lookupInodeFd fd parentId dirId
            return (parentPath </> dirName </> name)

-- | Given the id of a subvolume, find its path relative to the root of the
-- volume. This function calls 'lookupSubvol' recursively.
resolveSubvol
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> SubvolId -- ^ The id of the subvolume.
    -> IO FILEPATH
resolveSubvol path subvolId =
    withFd path ReadOnly $ \fd ->
        resolveSubvolFd fd subvolId

-- | The id the root subvolume.
rootSubvol :: SubvolId
rootSubvol = (5)
{-# LINE 433 "System/Linux/Btrfs/ByteString.hsc" #-}

listSubvolsFd :: Fd -> IO [(SubvolId, SubvolId, InodeNum, FILEPATH)]
listSubvolsFd fd = do
    let sk = defaultSearchKey
            { skTreeId      = (1)
{-# LINE 438 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMinObjectId = (256)
{-# LINE 439 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMaxObjectId = (18446744073709551360)
{-# LINE 440 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMinType     = (144)
{-# LINE 441 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMaxType     = (144)
{-# LINE 442 "System/Linux/Btrfs/ByteString.hsc" #-}
            }
    treeSearchListFd fd sk unpack
  where
    unpack sh rr
        | shType sh /= (144) =
{-# LINE 447 "System/Linux/Btrfs/ByteString.hsc" #-}
            return Nothing
        | otherwise = do
            (dirId, name) <- peekRootRef rr
            return $ Just (shObjectId sh, shOffset sh, dirId, name)

-- | Find all subvolumes of the given volume. For each subvolume found, it
-- returns: its id, the id of its parent subvolume, the inode number of the
-- directory containing it, and its name. This is a wrapper around
-- 'treeSearch'.
listSubvols :: FILEPATH -> IO [(SubvolId, SubvolId, InodeNum, FILEPATH)]
listSubvols path =
    withFd path ReadOnly listSubvolsFd

listSubvolPathsFd :: Fd -> IO [(SubvolId, SubvolId, FILEPATH)]
listSubvolPathsFd fd = do
    subvols <- listSubvolsFd fd
    forM subvols $ \(subvolId, parentId, _, _) -> do
        path <- resolveSubvolFd fd subvolId
        return (subvolId, parentId, path)

-- | Find all subvolumes of the given volume. For each subvolume found, it
-- returns: its id, the id of its parent subvolume, and its path relative
-- to the root of the volume. This is a wrapper around 'treeSearch' and
-- 'resolveSubvol'.
listSubvolPaths :: FILEPATH -> IO [(SubvolId, SubvolId, FILEPATH)]
listSubvolPaths path =
    withFd path ReadOnly listSubvolPathsFd

childSubvolsFd :: Fd -> SubvolId -> IO [(SubvolId, InodeNum, FILEPATH)]
childSubvolsFd fd subvolId = do
    let sk = defaultSearchKey
            { skTreeId      = (1)
{-# LINE 479 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMinObjectId = subvolId
            , skMaxObjectId = subvolId
            , skMinType     = (156)
{-# LINE 482 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMaxType     = (156)
{-# LINE 483 "System/Linux/Btrfs/ByteString.hsc" #-}
            }
    treeSearchListFd fd sk unpack
  where
    unpack sh rr
        | shType sh /= (156) =
{-# LINE 488 "System/Linux/Btrfs/ByteString.hsc" #-}
            return Nothing
        | otherwise = do
            (dirId, name) <- peekRootRef rr
            return $ Just (shOffset sh, dirId, name)

-- | Find all child subvolumes of the given subvolume. For each child,
-- returns its id, the inode number of the directory containing it, and its
-- name. This is a wrapper around 'treeSearch'.
childSubvols
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> SubvolId -- ^ The id of the subvolume.
    -> IO [(SubvolId, InodeNum, FILEPATH)]
childSubvols path subvolId =
    withFd path ReadOnly $ \fd ->
        childSubvolsFd fd subvolId

childSubvolPathsFd :: Fd -> SubvolId -> IO [(SubvolId, FILEPATH)]
childSubvolPathsFd fd subvolId = do
    childs <- childSubvolsFd fd subvolId
    forM childs $ \(childId, dirId, name) ->
        if dirId == (256) then
{-# LINE 509 "System/Linux/Btrfs/ByteString.hsc" #-}
            return (childId, name)
        else do
            (_, dirName) <- lookupInodeFd fd subvolId dirId
            return (childId, dirName </> name)

-- | Find all child subvolumes of the given subvolume. For each child,
-- returns its id and its path relative to the root of the parent.
-- This is a wrapper around 'treeSearch' and 'lookupInode'.
childSubvolPaths
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> SubvolId -- ^ The id of the subvolume.
    -> IO [(SubvolId, FILEPATH)]
childSubvolPaths path subvolId =
    withFd path ReadOnly $ \fd ->
        childSubvolPathsFd fd subvolId

-- | Information about a subvolume.
data SubvolInfo = SubvolInfo
    { siGeneration :: Word64
        -- ^ The generation when the subvolume was last modified.
    , siLastSnapshot :: Maybe Word64
        -- ^ The generation when the most recent snapshot of this subvolume was taken.
    , siParSnapGen :: Maybe Word64
        -- ^ The generation of the snapshot parent at the time when the snapshot
        -- was taken. Defined if only if this is a snapshot.
    , siReadOnly :: Bool
        -- ^ Is this a read-only subvolume?
    , siUuid :: Maybe UUID
        -- ^ The UUID of the subvolume.
    , siPUuid :: Maybe UUID
        -- ^ The UUID of the snapshot parent.
    , siReceivedUuid :: Maybe UUID
        -- ^ The UUID of the source subvolume that this subvolume was
        -- received from. This is always defined for received subvolumes.
    , siCTransId :: Maybe Word64
        -- ^ The generation when an inode was last modified.
    , siOTransId :: Maybe Word64
        -- ^ The generation when the subvolume was created.
    , siSTransId :: Maybe Word64
        -- ^ The generation of the source subvolume that this subvolume was
        -- received from. This is always defined for received subvolumes.
    , siRTransId :: Maybe Word64
        -- ^ The generation when the subvolume was received. This is always
        -- defined for received subvolumes.
    , siCTime :: Maybe UTCTime
        -- ^ The time when an inode was last modified.
    , siOTime :: Maybe UTCTime
        -- ^ The time when the subvolume was created.
    , siSTime :: Maybe UTCTime
        -- ^ The timestamp that corresponds to 'siSTransId'.
    , siRTime :: Maybe UTCTime
        -- ^ The time when the subvolume was received. This is always
        -- defined for received subvolumes.
    }
  deriving (Show, Eq)

getSubvolInfoFd :: Fd -> SubvolId -> IO SubvolInfo
getSubvolInfoFd fd subvolId
    | subvolId /= rootSubvol &&
        (subvolId < (256) || subvolId > (18446744073709551360)) =
{-# LINE 569 "System/Linux/Btrfs/ByteString.hsc" #-}
          ioError $ mkIOError doesNotExistErrorType
                              "getSubvolInfoFd"
                              Nothing Nothing
    | otherwise = do
        let sk = defaultSearchKey
                { skTreeId      = (1)
{-# LINE 575 "System/Linux/Btrfs/ByteString.hsc" #-}
                , skMinObjectId = subvolId
                , skMaxObjectId = subvolId
                , skMinType     = (132)
{-# LINE 578 "System/Linux/Btrfs/ByteString.hsc" #-}
                , skMaxType     = (132)
{-# LINE 579 "System/Linux/Btrfs/ByteString.hsc" #-}
                }
        findFirstItemFd fd sk unpack
  where
    unpack sh ri = do
        LE64 generation <- ((\hsc_ptr -> peekByteOff hsc_ptr 160)) ri
{-# LINE 584 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 lastSnapshot <- ((\hsc_ptr -> peekByteOff hsc_ptr 200)) ri
{-# LINE 585 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 flags <- ((\hsc_ptr -> peekByteOff hsc_ptr 208)) ri
{-# LINE 586 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 generationV2 <- ((\hsc_ptr -> peekByteOff hsc_ptr 239)) ri
{-# LINE 587 "System/Linux/Btrfs/ByteString.hsc" #-}
        let nv2 = generationV2 < generation -- not version 2
        uuid <- ((\hsc_ptr -> peekByteOff hsc_ptr 247)) ri :: IO UUID
{-# LINE 589 "System/Linux/Btrfs/ByteString.hsc" #-}
        pUuid <- ((\hsc_ptr -> peekByteOff hsc_ptr 263)) ri :: IO UUID
{-# LINE 590 "System/Linux/Btrfs/ByteString.hsc" #-}
        receivedUuid <- ((\hsc_ptr -> peekByteOff hsc_ptr 279)) ri :: IO UUID
{-# LINE 591 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 cTransId <- ((\hsc_ptr -> peekByteOff hsc_ptr 295)) ri
{-# LINE 592 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 oTransId <- ((\hsc_ptr -> peekByteOff hsc_ptr 303)) ri
{-# LINE 593 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 sTransId <- ((\hsc_ptr -> peekByteOff hsc_ptr 311)) ri
{-# LINE 594 "System/Linux/Btrfs/ByteString.hsc" #-}
        LE64 rTransId <- ((\hsc_ptr -> peekByteOff hsc_ptr 319)) ri
{-# LINE 595 "System/Linux/Btrfs/ByteString.hsc" #-}
        BtrfsTime cTime <- ((\hsc_ptr -> peekByteOff hsc_ptr 327)) ri
{-# LINE 596 "System/Linux/Btrfs/ByteString.hsc" #-}
        BtrfsTime oTime <- ((\hsc_ptr -> peekByteOff hsc_ptr 339)) ri
{-# LINE 597 "System/Linux/Btrfs/ByteString.hsc" #-}
        BtrfsTime sTime <- ((\hsc_ptr -> peekByteOff hsc_ptr 351)) ri
{-# LINE 598 "System/Linux/Btrfs/ByteString.hsc" #-}
        BtrfsTime rTime <- ((\hsc_ptr -> peekByteOff hsc_ptr 363)) ri
{-# LINE 599 "System/Linux/Btrfs/ByteString.hsc" #-}
        return $ SubvolInfo
            { siGeneration = generation
            , siLastSnapshot = nothingIf (lastSnapshot == 0) $ lastSnapshot
            , siParSnapGen = nothingIf (shOffset sh == 0) $ shOffset sh
            , siReadOnly = flags .&. (2) /= 0
{-# LINE 604 "System/Linux/Btrfs/ByteString.hsc" #-}
            , siUuid = nothingIf nv2 uuid
            , siPUuid = nothingIf (nv2 || shOffset sh == 0) pUuid
            , siReceivedUuid = nothingIf (nv2 || sTransId == 0) receivedUuid
            , siCTransId = nothingIf nv2 cTransId
            , siOTransId = nothingIf (nv2 || oTransId == 0) oTransId
            , siSTransId = nothingIf (nv2 || sTransId == 0) sTransId
            , siRTransId = nothingIf (nv2 || rTransId == 0) rTransId
            , siCTime = nothingIf nv2 cTime
            , siOTime = nothingIf (nv2 || oTransId == 0) oTime
            , siSTime = nothingIf (nv2 || sTransId == 0) sTime
            , siRTime = nothingIf (nv2 || rTransId == 0) rTime
            }

-- | Retrieve information about a subvolume.
getSubvolInfo
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> SubvolId -- ^ The id of the subvolume.
    -> IO SubvolInfo
getSubvolInfo path subvolId =
    withFd path ReadOnly $ \fd ->
        getSubvolInfoFd fd subvolId

searchByUuidFd :: ObjectType -> Fd -> UUID -> IO SubvolId
searchByUuidFd typ fd (UUID hBE lBE) = do
    let sk = defaultSearchKey
            { skTreeId      = (9)
{-# LINE 630 "System/Linux/Btrfs/ByteString.hsc" #-}
            , skMinObjectId = hLE
            , skMaxObjectId = hLE
            , skMinType     = typ
            , skMaxType     = typ
            , skMinOffset   = lLE
            , skMaxOffset   = lLE
            }
    findFirstItemFd fd sk $ \_ ptr ->
        liftM fromLE64 $ peek ptr
  where
    -- UUID is stored as two big-endian integers
    -- but in the UUID tree, little-endian integers are used
    lLE = invert64 lBE
    hLE = invert64 hBE

getSubvolByUuidFd :: Fd -> UUID -> IO SubvolId
getSubvolByUuidFd =
    searchByUuidFd (251)
{-# LINE 648 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Find the id of a subvolume, given its UUID.
--
-- /Requires Linux 3.12 or later./
getSubvolByUuid
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> UUID     -- ^ The UUID of the subvolume.
    -> IO SubvolId
getSubvolByUuid path uuid =
    withFd path ReadOnly $ \fd ->
        getSubvolByUuidFd fd uuid

getSubvolByReceivedUuidFd :: Fd -> UUID -> IO SubvolId
getSubvolByReceivedUuidFd =
    searchByUuidFd (252)
{-# LINE 663 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Find the id of a subvolume, given its 'siReceivedUuid'.
--
-- /Requires Linux 3.12 or later./
getSubvolByReceivedUuid
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> UUID     -- ^ The 'siReceivedUuid' of the subvolume.
    -> IO SubvolId
getSubvolByReceivedUuid path uuid =
    withFd path ReadOnly $ \fd ->
        getSubvolByReceivedUuidFd fd uuid

--------------------------------------------------------------------------------

defragFd :: Fd -> IO ()
defragFd fd =
    throwErrnoIfMinus1_ "defragFd" $
        withBlockSIGVTALRM $ -- this is probably a bad idea
            ioctl fd (1342215170) nullPtr
{-# LINE 682 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Defrag a single file.
--
-- Note: calls the @BTRFS_IOC_DEFRAG@ @ioctl@.
defrag :: FILEPATH -> IO ()
defrag path = withFd path ReadWrite defragFd

-- | Argument to the 'defragRange' operation.
data DefragRangeArgs = DefragRangeArgs
    { draStart :: FileSize
        -- ^ Beginning of the defrag range.
    , draLength :: FileSize
        -- ^ Number of bytes to defrag, use 'maxBound' to say all.
    , draExtentThreshold :: Word32
        -- ^ Any extent bigger than this size will be considered already
        -- defragged. Use 0 to take the kernel default, use 1 to say every
        -- single extent must be rewritten.
    , draCompress :: Maybe CompressionType
        -- ^ Compress the file while defragmenting.
    , draFlush :: Bool
        -- ^ Flush data to disk immediately after defragmenting.
    }

-- | Defaults for 'defragRange'. Selects the entire file, no compression,
-- and no flushing.
defaultDefragRangeArgs :: DefragRangeArgs
defaultDefragRangeArgs = DefragRangeArgs
    { draStart = 0
    , draLength = maxBound
    , draExtentThreshold = 0
    , draCompress = Nothing
    , draFlush = False
    }

defragRangeFd :: Fd -> DefragRangeArgs -> IO ()
defragRangeFd fd DefragRangeArgs{..} =
    allocaBytesZero ((48)) $ \args -> do
{-# LINE 719 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) args draStart
{-# LINE 720 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) args draLength
{-# LINE 721 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) args flags
{-# LINE 722 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 24)) args draExtentThreshold
{-# LINE 723 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 28)) args comp_type
{-# LINE 724 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "defragRangeFd" $
            withBlockSIGVTALRM $ -- this is probably a bad idea
                ioctl fd (1076925456) args
{-# LINE 727 "System/Linux/Btrfs/ByteString.hsc" #-}
  where
    flags = comp_flags .|. if draFlush then (2) else 0
{-# LINE 729 "System/Linux/Btrfs/ByteString.hsc" #-}
    comp_flags :: Word64
    comp_type :: Word32
    (comp_flags, comp_type) =
        case draCompress of
            Nothing -> (0, 0)
            Just Zlib -> ((1), (1))
{-# LINE 735 "System/Linux/Btrfs/ByteString.hsc" #-}
            Just LZO  -> ((1), (2))
{-# LINE 736 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Defrag a range within a single file.
--
-- Note: calls the @BTRFS_IOC_DEFRAG_RANGE@ @ioctl@.
defragRange :: FILEPATH -> DefragRangeArgs -> IO ()
defragRange path args =
    withFd path ReadWrite $ \fd ->
        defragRangeFd fd args

--------------------------------------------------------------------------------

syncFd :: Fd -> IO ()
syncFd fd =
    throwErrnoIfMinus1_ "syncFd" $
        ioctl fd (37896) nullPtr
{-# LINE 751 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Sync the file system identified by the supplied path.
-- The 'FilePath' can refer to any file in the file system.
--
-- Note: calls the @BTRFS_IOC_SYNC@ @ioctl@.
sync :: FILEPATH -> IO ()
sync path = withFd path ReadOnly syncFd

startSyncFd :: Fd -> IO ()
startSyncFd fd =
    throwErrnoIfMinus1_ "startSyncFd" $
        ioctl_fast fd (2148045848) nullPtr
{-# LINE 763 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Initiate a sync for the file system identified by the supplied path.
--
-- Note: calls the @BTRFS_IOC_START_SYNC@ @ioctl@.
startSync :: FILEPATH -> IO ()
startSync path = withFd path ReadOnly startSyncFd

waitSyncFd :: Fd -> IO ()
waitSyncFd fd =
    throwErrnoIfMinus1_ "waitSyncFd" $
        ioctl fd (1074304022) nullPtr
{-# LINE 774 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Wait until the sync operation completes.
--
-- Note: calls the @BTRFS_IOC_WAIT_SYNC@ @ioctl@.
waitSync :: FILEPATH -> IO ()
waitSync path = withFd path ReadOnly waitSyncFd

--------------------------------------------------------------------------------

resolveLogicalFd :: Fd -> FileSize -> IO ([(InodeNum, FileSize, SubvolId)], Int)
resolveLogicalFd rootFd logical =
    allocaBytes inodesSize $ \inodes ->
    allocaBytesZero ((56)) $ \lia -> do
{-# LINE 787 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) lia logical
{-# LINE 788 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) lia (fromIntegral inodesSize :: Word64)
{-# LINE 789 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 48)) lia inodes
{-# LINE 790 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "resolveLogical" $ ioctl rootFd (3224933412) lia
{-# LINE 791 "System/Linux/Btrfs/ByteString.hsc" #-}
        elemMissed <- ((\hsc_ptr -> peekByteOff hsc_ptr 12)) inodes :: IO Word32
{-# LINE 792 "System/Linux/Btrfs/ByteString.hsc" #-}
        count      <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) inodes :: IO Word32
{-# LINE 793 "System/Linux/Btrfs/ByteString.hsc" #-}
        let val = ((\hsc_ptr -> hsc_ptr `plusPtr` 16)) inodes :: Ptr Word64
{-# LINE 794 "System/Linux/Btrfs/ByteString.hsc" #-}
        vals <- peekArray (fromIntegral count) val
        return (extractTriplets vals, fromIntegral elemMissed)
  where
    inodesSize = 64 * 1024 + ((16))
{-# LINE 798 "System/Linux/Btrfs/ByteString.hsc" #-}
    extractTriplets (x1 : x2 : x3 : xs) = (x1, x2, x3) : extractTriplets xs
    extractTriplets [] = []
    extractTriplets _ = error "extractTriplets: The length of the list must be a multiple of 3"

-- | Given a physical offset, look for any inodes that this byte belongs
-- to. For each inode, it returns the inode number, the logical offset
-- (i.e. the offset within the inode), and the subvolume id. If a large
-- number of inodes is found, then not all of them will be returned by this
-- function. This is due to a current limitation in the kernel. The integer
-- returned along with list of inodes indicates the number of inodes found
-- but not included in the list.
--
-- Note: calls the @BTRFS_IOC_LOGICAL_INO@ @ioctl@.
resolveLogical
    :: FILEPATH -- ^ The mount point of the volume (or any file in that volume).
    -> FileSize -- ^ The physical byte offset in the underlying block device.
    -> IO ([(InodeNum, FileSize, SubvolId)], Int)
resolveLogical rootPath logical =
    withFd rootPath ReadOnly $ \fd ->
        resolveLogicalFd fd logical

resolveInodeFd :: Fd -> InodeNum -> IO ([FILEPATH], Int)
resolveInodeFd subvolFd inum =
    allocaBytes fspathSize $ \fspath ->
    allocaBytesZero ((56)) $ \ipa -> do
{-# LINE 823 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) ipa inum
{-# LINE 824 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) ipa (fromIntegral fspathSize :: Word64)
{-# LINE 825 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 48)) ipa fspath
{-# LINE 826 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "resolveInode" $ ioctl subvolFd (3224933411) ipa
{-# LINE 827 "System/Linux/Btrfs/ByteString.hsc" #-}
        elemMissed <- ((\hsc_ptr -> peekByteOff hsc_ptr 12)) fspath :: IO Word32
{-# LINE 828 "System/Linux/Btrfs/ByteString.hsc" #-}
        count      <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) fspath :: IO Word32
{-# LINE 829 "System/Linux/Btrfs/ByteString.hsc" #-}
        let val = ((\hsc_ptr -> hsc_ptr `plusPtr` 16)) fspath :: Ptr Word64
{-# LINE 830 "System/Linux/Btrfs/ByteString.hsc" #-}
        vals <- peekArray (fromIntegral count) val
        paths <- mapM (peekCString . plusPtr val . fromIntegral) vals
        return (paths, fromIntegral elemMissed)
  where
    fspathSize = 2 * 1024 + ((16))
{-# LINE 835 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Find the file path(s) given an inode number. Returns a list of file paths
-- and an integer indicating the number of paths found but not included in
-- the resulting list. This is because of a limitation in the kernel (it
-- will not return an arbitrarily large list). The paths returned are
-- relative to the root of the subvolume.
--
-- Note: calls the @BTRFS_IOC_INO_PATHS@ @ioctl@.
resolveInode
    :: FILEPATH -- ^ The path to the subvolume (or any file in that subvolume).
    -> InodeNum -- ^ The inode number.
    -> IO ([FILEPATH], Int)
resolveInode subvolPath inum =
    withFd subvolPath ReadOnly $ \subvolFd ->
        resolveInodeFd subvolFd inum

lookupInodeFd :: Fd -> SubvolId -> InodeNum -> IO (SubvolId, FILEPATH)
lookupInodeFd fd treeId inum =
    allocaBytesZero ((4096)) $ \ila -> do
{-# LINE 854 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) ila treeId
{-# LINE 855 "System/Linux/Btrfs/ByteString.hsc" #-}
        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) ila inum
{-# LINE 856 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "lookupInodeFd" $
            ioctl_fast fd (3489698834) ila
{-# LINE 858 "System/Linux/Btrfs/ByteString.hsc" #-}
        treeId' <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) ila :: IO Word64
{-# LINE 859 "System/Linux/Btrfs/ByteString.hsc" #-}
        let cName = ((\hsc_ptr -> hsc_ptr `plusPtr` 16)) ila
{-# LINE 860 "System/Linux/Btrfs/ByteString.hsc" #-}
        name <- peekCString cName
        return (treeId', dropTrailingSlash name)

-- | Find the path of a file given its inode number and the id of the
-- subvolume. If multiple files share the same inode number, only one of
-- them is returned. The id of the subvolume is also returned. This is
-- useful when 0 is given for the 'SubvolId' argument (also see
-- 'getSubvol' for this case).
--
-- Note: calls the @BTRFS_IOC_INO_LOOKUP@ @ioctl@.
lookupInode
    :: FILEPATH -- ^ The path to any file in the volume. The subvolume where
                -- this file resides is ignored unless no 'SubvolId' is
                -- provided (see below).
    -> SubvolId -- ^ The id of the subvolume. Can be 0. In that case, the
                -- subvolume of the 'FilePath' is used (see above).
    -> InodeNum -- ^ The inode number.
    -> IO (SubvolId, FILEPATH)
lookupInode path treeId inum =
    withFd path ReadOnly $ \fd -> lookupInodeFd fd treeId inum

--------------------------------------------------------------------------------

getFileNoCOWFd :: Fd -> IO Bool
getFileNoCOWFd fd =
    alloca $ \flagsPtr -> do
        throwErrnoIfMinus1_ "getFileNoCOWFd" $
            ioctl fd (2148034049) flagsPtr
{-# LINE 888 "System/Linux/Btrfs/ByteString.hsc" #-}
        flags <- peek flagsPtr :: IO CUInt
        return (flags .&. (8388608) /= 0)
{-# LINE 890 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Determine whether the NOCOW flag is enabled for the specified file.
--
-- Note: calls the @FS_IOC_GETFLAGS@ @ioctl@.
getFileNoCOW :: FILEPATH -> IO Bool
getFileNoCOW path =
    withFd path ReadOnly getFileNoCOWFd

setFileNoCOWFd :: Fd -> Bool -> IO ()
setFileNoCOWFd fd noCOW = do
    alloca $ \flagsPtr -> do
        throwErrnoIfMinus1_ "setFileNoCOWFd" $
            ioctl fd (2148034049) flagsPtr
{-# LINE 903 "System/Linux/Btrfs/ByteString.hsc" #-}
        if noCOW then
            setFlags flagsPtr ((8388608) :: CUInt)
{-# LINE 905 "System/Linux/Btrfs/ByteString.hsc" #-}
        else
            clearFlags flagsPtr ((8388608) :: CUInt)
{-# LINE 907 "System/Linux/Btrfs/ByteString.hsc" #-}
        throwErrnoIfMinus1_ "setFileNoCOWFd" $
            ioctl fd (1074292226) flagsPtr
{-# LINE 909 "System/Linux/Btrfs/ByteString.hsc" #-}

-- | Set or clear the NOCOW flag for the specified file. If the file is not
-- empty, this has no effect and no error will be reported.
--
-- Note: calls the @FS_IOC_GETFLAGS@ and @FS_IOC_GETFLAGS@ @ioctl@s.
setFileNoCOW :: FILEPATH -> Bool -> IO ()
setFileNoCOW path noCOW = do
    withFd path ReadOnly $ \fd ->
        setFileNoCOWFd fd noCOW

--------------------------------------------------------------------------------

data SearchKey = SearchKey
    { skTreeId      :: ObjectId
    , skMinObjectId :: ObjectId
    , skMinType     :: ObjectType
    , skMinOffset   :: Word64
    , skMaxObjectId :: ObjectId
    , skMaxType     :: ObjectType
    , skMaxOffset   :: Word64
    , skMinTransId  :: Word64
    , skMaxTransId  :: Word64
    }
  deriving (Show, Eq)

defaultSearchKey :: SearchKey
defaultSearchKey = SearchKey
    { skTreeId      = 0
    , skMinObjectId = minBound
    , skMinType     = minBound
    , skMinOffset   = minBound
    , skMaxObjectId = maxBound
    , skMaxType     = maxBound
    , skMaxOffset   = maxBound
    , skMinTransId  = minBound
    , skMaxTransId  = maxBound
    }

data SearchHeader = SearchHeader
    { shTransId  :: Word64
    , shObjectId :: ObjectId
    , shOffset   :: Word64
    , shType     :: ObjectType
    , shLen      :: Word32
    }
  deriving (Show, Eq)

treeSearchFd :: Fd -> SearchKey -> Int -> (SearchHeader -> Ptr i -> IO ()) -> IO ()
treeSearchFd fd sk maxItemCount0 callback =
    allocaBytesZero ((4096)) $ \saPtr -> do
{-# LINE 959 "System/Linux/Btrfs/ByteString.hsc" #-}
        let skPtr = ((\hsc_ptr -> hsc_ptr `plusPtr` 0)) saPtr
{-# LINE 960 "System/Linux/Btrfs/ByteString.hsc" #-}
        pokeSearchKey skPtr sk
        loopSingleSearch saPtr skPtr maxItemCount0
  where
    loopSingleSearch saPtr skPtr maxItemCount
        | maxItemCount <= 0 = return ()
        | otherwise = do
            let nrItems = fromIntegral (min 4096 maxItemCount) :: Word32
            ((\hsc_ptr -> pokeByteOff hsc_ptr 64)) skPtr nrItems
{-# LINE 968 "System/Linux/Btrfs/ByteString.hsc" #-}
            throwErrnoIfMinus1_ "treeSearchFd" $
                ioctl fd (3489698833) saPtr
{-# LINE 970 "System/Linux/Btrfs/ByteString.hsc" #-}
            itemsFound <- ((\hsc_ptr -> peekByteOff hsc_ptr 64)) skPtr :: IO Word32
{-# LINE 971 "System/Linux/Btrfs/ByteString.hsc" #-}
            when (itemsFound > 0) $ do
                let shPtr = ((\hsc_ptr -> hsc_ptr `plusPtr` 104)) saPtr
{-# LINE 973 "System/Linux/Btrfs/ByteString.hsc" #-}
                lastSh <- loopItems shPtr itemsFound
                case nextKey (shObjectId lastSh, shType lastSh, shOffset lastSh) of
                    Nothing -> return ()
                    Just (objectId, iType, offset) -> do
                        ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) skPtr objectId
{-# LINE 978 "System/Linux/Btrfs/ByteString.hsc" #-}
                        ((\hsc_ptr -> pokeByteOff hsc_ptr 56)) skPtr (fromIntegral iType :: Word32)
{-# LINE 979 "System/Linux/Btrfs/ByteString.hsc" #-}
                        ((\hsc_ptr -> pokeByteOff hsc_ptr 24)) skPtr offset
{-# LINE 980 "System/Linux/Btrfs/ByteString.hsc" #-}
                        loopSingleSearch saPtr skPtr (maxItemCount - fromIntegral itemsFound)
    -- itemsFound must be at least 1
    loopItems shPtr itemsFound = do
        (sh, itemPtr) <- peekSearchItem shPtr
        callback sh itemPtr
        if itemsFound <= 1 then
            return sh
        else do
            let shPtr' = itemPtr `plusPtr` fromIntegral (shLen sh)
            loopItems shPtr' (itemsFound - 1)
    -- items are indexed by keys which are (objectId, iType, offset)
    -- they are returned in lexicographical order wrt the keys
    nextKey (objectId, iType, offset)
        | offset   < maxBound         = Just (objectId, iType, offset + 1)
        | iType    < skMaxType sk     = Just (objectId, iType + 1, skMinOffset sk)
        | objectId < skMaxObjectId sk = Just (objectId + 1, skMinType sk, skMinOffset sk)
        | otherwise                   = Nothing

treeSearch :: FILEPATH -> SearchKey -> Int -> (SearchHeader -> Ptr i -> IO ()) -> IO ()
treeSearch path sk maxItemCount callback =
    withFd path ReadOnly $ \fd ->
        treeSearchFd fd sk maxItemCount callback

treeSearchListFd :: Fd -> SearchKey -> (SearchHeader -> Ptr i -> IO (Maybe a)) -> IO [a]
treeSearchListFd fd sk unpack = do
    res <- newIORef []
    treeSearchFd fd sk maxBound $ \sh itemPtr -> do
        r <- unpack sh itemPtr
        case r of
            Nothing -> return ()
            Just x -> modifyIORef' res (x :)
    liftM reverse $ readIORef res

treeSearchList :: FILEPATH -> SearchKey -> (SearchHeader -> Ptr i -> IO (Maybe a)) -> IO [a]
treeSearchList path sk unpack =
    withFd path ReadOnly $ \fd ->
        treeSearchListFd fd sk unpack

findFirstItemFd :: Fd -> SearchKey -> (SearchHeader -> Ptr i -> IO a) -> IO a
findFirstItemFd fd sk unpack = do
    res <- newIORef Nothing
    treeSearchFd fd sk 1 $ \sh ptr -> do
        r <- unpack sh ptr
        modifyIORef' res (`mplus` Just r)
    resV <- readIORef res
    case resV of
        Just x -> return x
        Nothing ->
            ioError $ mkIOError doesNotExistErrorType
                                "findFirstItemFd"
                                Nothing Nothing

findFirstItem :: FILEPATH -> SearchKey -> (SearchHeader -> Ptr i -> IO a) -> IO a
findFirstItem path sk unpack =
    withFd path ReadOnly $ \fd ->
        findFirstItemFd fd sk unpack

-- does not initialize nr_items
pokeSearchKey :: Ptr a -> SearchKey -> IO ()
pokeSearchKey ptr sk = do
    ((\hsc_ptr -> pokeByteOff hsc_ptr 0)) ptr (skTreeId      sk)
{-# LINE 1041 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 8)) ptr (skMinObjectId sk)
{-# LINE 1042 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 56)) ptr (fromIntegral (skMinType sk) :: Word32)
{-# LINE 1043 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 24)) ptr (skMinOffset   sk)
{-# LINE 1044 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 16)) ptr (skMaxObjectId sk)
{-# LINE 1045 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 60)) ptr (fromIntegral (skMaxType sk) :: Word32)
{-# LINE 1046 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 32)) ptr (skMaxOffset   sk)
{-# LINE 1047 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 40)) ptr (skMinTransId  sk)
{-# LINE 1048 "System/Linux/Btrfs/ByteString.hsc" #-}
    ((\hsc_ptr -> pokeByteOff hsc_ptr 48)) ptr (skMaxTransId  sk)
{-# LINE 1049 "System/Linux/Btrfs/ByteString.hsc" #-}

peekSearchItem :: Ptr a -> IO (SearchHeader, Ptr i)
peekSearchItem shPtr = do
    transId  <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) shPtr :: IO Word64
{-# LINE 1053 "System/Linux/Btrfs/ByteString.hsc" #-}
    objectId <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) shPtr :: IO Word64
{-# LINE 1054 "System/Linux/Btrfs/ByteString.hsc" #-}
    offset   <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) shPtr :: IO Word64
{-# LINE 1055 "System/Linux/Btrfs/ByteString.hsc" #-}
    iType    <- ((\hsc_ptr -> peekByteOff hsc_ptr 24)) shPtr :: IO Word32
{-# LINE 1056 "System/Linux/Btrfs/ByteString.hsc" #-}
    len      <- ((\hsc_ptr -> peekByteOff hsc_ptr 28)) shPtr :: IO Word32
{-# LINE 1057 "System/Linux/Btrfs/ByteString.hsc" #-}
    let itemPtr = shPtr `plusPtr` ((32))
{-# LINE 1058 "System/Linux/Btrfs/ByteString.hsc" #-}
    return (SearchHeader transId objectId offset (fromIntegral iType) len, itemPtr)

peekRootRef :: Ptr a -> IO (InodeNum, FILEPATH)
peekRootRef rrPtr = do
    LE64 dirId   <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) rrPtr
{-# LINE 1063 "System/Linux/Btrfs/ByteString.hsc" #-}
    LE16 nameLen <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) rrPtr
{-# LINE 1064 "System/Linux/Btrfs/ByteString.hsc" #-}
    let cName = rrPtr `plusPtr` ((18))
{-# LINE 1065 "System/Linux/Btrfs/ByteString.hsc" #-}
    name <- peekCStringLen (cName, fromIntegral nameLen)
    return (dirId, name)

--------------------------------------------------------------------------------

withFd :: FILEPATH -> OpenMode -> (Fd -> IO r) -> IO r
withFd path openMode action =
    bracket (openFd path openMode Nothing defaultFileFlags {nonBlock = True})
            closeFd action

withSplitPathOpenParent :: String -> Int -> FILEPATH -> (CStringLen -> Fd -> IO r) -> IO r
withSplitPathOpenParent loc maxLen path action =
    unsafeWithCStringLen name $ \cName @ (_, l) -> do
        unless (l <= maxLen) $
            ioError $ flip ioeSetErrorString "the subvolume name is too long"
                    $ mkIOError illegalOperationErrorType loc Nothing (Just (asString name))
        withFd dir ReadOnly $ action cName
  where
    (dir, name) = splitFileName (dropTrailingSlash path)

withBlockSIGVTALRM :: IO a -> IO a
withBlockSIGVTALRM =
    bracket_ (blockSignals s) (unblockSignals s)
  where
    s = addSignal sigVTALRM emptySignalSet

nothingIf :: Bool -> a -> Maybe a
nothingIf f v = if f then Nothing else Just v
{-# INLINE nothingIf #-}

modifyPtr :: Storable a => Ptr a -> (a -> a) -> IO ()
modifyPtr ptr f = do
    peek ptr >>= (poke ptr . f)

setFlags :: (Storable a, Bits a) => Ptr a -> a -> IO ()
setFlags ptr flags =
    modifyPtr ptr (.|. flags)

clearFlags :: (Storable a, Bits a) => Ptr a -> a -> IO ()
clearFlags ptr flags =
    modifyPtr ptr (.&. complement flags)

allocaBytesZero :: Int -> (Ptr a -> IO b) -> IO b
allocaBytesZero size action =
    allocaBytes size $ \ptr -> do
        memset ptr 0 size
        action ptr

memset :: Ptr a -> Word8 -> Int -> IO ()
memset p b l = do
    _ <- c_memset p (fromIntegral b) (fromIntegral l)
    return ()
{-# INLINE memset #-}

foreign import ccall unsafe "string.h memset"
    c_memset :: Ptr a -> CInt -> CSize -> IO (Ptr a)