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{-# LANGUAGE OverloadedStrings #-}

{-| Logical Volumer information parser

This module holds the definition of the parser that extracts status

information about the logical volumes (LVs) of the system from the output of the

@lvs@ command.

-}

{-

Copyright (C) 2013 Google Inc.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.

-}

module Ganeti.Storage.Lvm.LVParser (lvParser, lvCommand) where

import Control.Applicative ((<*>), (*>), (<*), (<$>), Applicative, )

import qualified Data.Attoparsec.Text as A

import qualified Data.Attoparsec.Combinator as AC

import Data.Attoparsec.Text (Parser)

import Data.Text (unpack)

import Ganeti.Storage.Lvm.Types

-- | The separator of the fields returned by @lvs@

lvsSeparator :: Char

lvsSeparator = ';'

-- * Utility functions

-- | Our own space-skipping function, because A.skipSpace also skips

-- newline characters. It skips ZERO or more spaces, so it does not

-- fail if there are no spaces.

skipSpaces :: Parser ()

skipSpaces = A.skipWhile A.isHorizontalSpace

-- | A parser recognizing a number of bytes, represented as a number preceeded

-- by a separator and followed by the "B" character.

bytesP :: Parser Int

bytesP = A.char lvsSeparator *> A.decimal <* A.char 'B'

-- | A parser recognizing a number discarding the preceeding separator

intP :: Parser Int

intP = A.char lvsSeparator *> A.signed A.decimal

-- | A parser recognizing a string starting with and closed by a separator (both

-- are discarded)

stringP :: Parser String

stringP =

  A.char lvsSeparator *> fmap unpack (A.takeWhile (`notElem`

    [ lvsSeparator

    , '\n']

    ))

-- * Parser implementation

-- | The command providing the data, in the format the parser expects

lvCommand :: [String]

lvCommand =

  [ "lvs"

  , "--noheadings"

  , "--units B"

  , "-- separator ;"

  , "-o lv_uuid,lv_name,lv_attr,lv_major,lv_minor,lv_kernel_major\

    \,lv_kernel_minor,lv_size,seg_count,lv_tags,modules,vg_uuid,vg_name,segtype\

    \,seg_start,seg_start_pe,seg_size,seg_tags,seg_pe_ranges,devices"

  ]

-- | The parser for one line of the diskstatus file.

oneLvParser :: Parser LVInfo

oneLvParser =

  let uuidP = skipSpaces *> fmap unpack (A.takeWhile (/= lvsSeparator))

      nameP = stringP

      attrP = stringP

      majorP = intP

      minorP = intP

      kernelMajorP = intP

      kernelMinorP = intP

      sizeP = bytesP

      segCountP = intP

      tagsP = stringP

      modulesP = stringP

      vgUuidP = stringP

      vgNameP = stringP

      segtypeP = stringP

      segStartP = bytesP

      segStartPeP = intP

      segSizeP = bytesP

      segTagsP = stringP

      segPeRangesP = stringP

      devicesP = stringP

    in

      LVInfo

        <$> uuidP <*> nameP <*> attrP <*> majorP <*> minorP <*> kernelMajorP

        <*> kernelMinorP <*> sizeP <*> segCountP <*> tagsP <*> modulesP

        <*> vgUuidP <*> vgNameP <*> segtypeP <*> segStartP <*> segStartPeP

        <*> segSizeP <*> segTagsP <*> segPeRangesP <*> devicesP <* A.endOfLine

-- | The parser for a whole diskstatus file.

lvParser :: Parser [LVInfo]

lvParser = oneLvParser `AC.manyTill` A.endOfInput