Can not readLine about brick HOT 8 CLOSED

@Kaligule @simonmichael @jtdaugherty
I'm super late to the party here but I found a way past this for anyone running into this who is willing to use customMain instead of simpleMain. customMain allows you to override the underlying VTY configuration and give it the handle of the controlling terminal even when input originally comes from a pipe.

Reading stdin using getContents will put the handle into a semi closed state. Just read it, then close the handle. After this, using System.Posix.Terminal , you can make a call to getControllingTerminalName then open that descriptor using openFd in the System.Posix.IO.ByteString module, and then pass that descriptor to inputFd on the VTY value passed to customMain.

Here is a crude example that requires the unix, brick, vty, bytestring packages:

You can test this with your shell: $ echo 12345 | YourApp

module Main where

import           Brick
import           Brick.BChan
import           Control.Monad
import qualified Data.ByteString.Char8 as C
import           Graphics.Vty
import           Graphics.Vty.Config
import           System.IO
import           System.Posix.IO.ByteString
import           System.Posix.Terminal
import           System.Posix.Types

data AppState = AppState String
type ResourceName = ()

main :: IO ()
main = do
  stdin' <- getContents
  print stdin' -- no lazy plz
  _ <- hClose stdin
  terminalName <- getControllingTerminalName
  terminalFd <- openFd (C.pack terminalName) ReadOnly Nothing (OpenFileFlags False False False False False)
  channel <- newBChan 1000
  initialVty <- buildVty terminalFd
  _          <- customMain initialVty (buildVty terminalFd) (Just channel) app (AppState stdin')
  return ()
  where
    buildVty :: Fd -> IO Vty
    buildVty terminalFd' = do
          vtyCfg <- standardIOConfig
          v      <- mkVty $ vtyCfg { inputFd = Just terminalFd' }
          when (supportsMode (outputIface v) Mouse) $ setMode (outputIface v) Mouse True
          when (supportsMode (outputIface v) BracketedPaste) $ setMode (outputIface v) BracketedPaste True
          return v

app :: App AppState e ResourceName
app = App draw neverShowCursor handleEvent startEvent attributeMap

draw :: AppState -> [Widget ResourceName]
draw (AppState stdin) = [ str stdin ]

handleEvent :: AppState -> BrickEvent ResourceName e -> EventM ResourceName (Next AppState)
handleEvent s e = continue s

startEvent :: AppState -> EventM ResourceName AppState
startEvent = return

attributeMap :: AppState -> AttrMap
attributeMap = const $ attrMap Graphics.Vty.defAttr []

from brick.

I think the issue here is that invoking a program with standard input from the terminal is not the same as invoking a program with a pipe redirection. In the former case, stdin is a file descriptor from the terminal that supports different ioctl system calls (such as the ones needed by vty), while the file descriptor opened by the shell for the pipe redirection is not a terminal device and will not support the same ioctl operations. In the redirection case you get the error about an unsupported ioctl as a result.

from brick.

Here is something that sheds a little light on what I'm talking about:

http://unix.stackexchange.com/questions/68712/how-to-detect-if-a-program-is-not-run-from-a-terminal

from brick.

Here's another:

http://unix.stackexchange.com/questions/157852/echo-test-stty-echo-stty-standard-input-inappropriate-ioctl-for-device

from brick.

So, to sum up: this isn't a vty or brick problem; it's purely a consequence of using a pipe where none should be used because vty (and therefore brick) programs expect stdin to be a terminal.

from brick.

I see that this sort of thing could happen in a nonpure world of bash. Thanks for pointing that out. I am going to search for a workaround.

from brick.

@Kaligule did you find a workaround ? We'd like to make this work:

$ cat some.file | hledger-ui -f-   # 1. take initial input from stdin
# 2. continue in normal interactive mode

I guess some shuffling of handles could do it.

from brick.

@simonmichael I never found a way to make it work, sorry.

from brick.