ghcup-hs/lib/GHCup/Utils/Windows.hs

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2021-10-17 18:39:49 +00:00
{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE OverloadedStrings #-}
module GHCup.Utils.Windows where
import Control.Exception.Safe
import Control.Monad
#if !MIN_VERSION_base(4,13,0)
import Control.Monad.Fail ( MonadFail )
#endif
import Data.Bits
import System.Win32.Console
import System.Win32.File hiding ( copyFile )
import System.Win32.Types
-- | Enables ANSI support on windows, does nothing on unix.
--
-- Returns 'Left str' on errors and 'Right bool' on success, where
-- 'bool' markes whether ansi support was already enabled.
--
-- This function never crashes.
--
-- Rip-off of https://docs.rs/ansi_term/0.12.1/x86_64-pc-windows-msvc/src/ansi_term/windows.rs.html#10-61
enableAnsiSupport :: IO (Either String Bool)
enableAnsiSupport = handleIO (pure . Left . displayException) $ do
-- ref: https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilew
-- Using `CreateFileW("CONOUT$", ...)` to retrieve the console handle works correctly even if STDOUT and/or STDERR are redirected
h <- createFile "CONOUT$" (gENERIC_WRITE .|. gENERIC_READ)
fILE_SHARE_WRITE Nothing oPEN_EXISTING 0 Nothing
when (h == iNVALID_HANDLE_VALUE ) $ fail "invalid handle value"
-- ref: https://docs.microsoft.com/en-us/windows/console/getconsolemode
m <- getConsoleMode h
-- VT processing not already enabled?
if m .&. eNABLE_VIRTUAL_TERMINAL_PROCESSING == 0
-- https://docs.microsoft.com/en-us/windows/console/setconsolemode
then setConsoleMode h (m .|. eNABLE_VIRTUAL_TERMINAL_PROCESSING)
>> pure (Right False)
else pure (Right True)