blob: feeee9ffab48ff873e139aaf41e26cedb3ff0456 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
{-# LANGUAGE NondecreasingIndentation #-}
import Control.Monad
import Control.Monad.Fix
import Control.Monad.IO.Class
import Data.Char
import Network.Socket as Socket
import System.Console.Haskeline
import System.Environment
import System.Exit
import System.IO
import System.IO.Unsafe
import qualified Data.ByteString as B
-- | Reads one character. If it is not a digit,
-- then it is discarded and 'Nothing' is returned.
hReadDigit :: Handle -> IO (Maybe Char)
hReadDigit h = do c <- hGetChar h
return $ guard (isDigit c) >> pure c
-- | Expected input: "nnn:..."
-- Here we read the digit sequence "nnn" and drop the colon
-- as it is the first non-digit.
hReadInt :: Handle -> IO Int
hReadInt h = do
nstr <- fix $ \readDigits ->
maybe (return []) -- dropped non-digit character
(($ unsafeInterleaveIO readDigits) . fmap . (:))
=<< hReadDigit h
readIO nstr :: IO Int
-- | Read a length prefixed string from a handle.
-- The format is "nnn:..." where /nnn/ is an ascii-encoded character count
-- and /.../ is the sequence of characters
--
-- Note: The first byte after the count is ignored and discarded.
readResponse :: Handle -> IO String
readResponse h = do
n <- hReadInt h
sequence $ replicate n (hGetChar h)
-- | Send a command to the dhtd daemon and then print the response.
sendCommand :: Handle -> String -> InputT IO ()
sendCommand h cmd = do resp <- liftIO $ do hPutStrLn h cmd
readResponse h
outputStrLn resp
-- | Get one line of input and send it to the daemon, then run the
-- passed continuation if it wasn't "quit".
interactiveMode :: Handle -> InputT IO () -> InputT IO ()
interactiveMode h repl = do
minput <- getInputLine "dht> "
case minput of
Nothing -> return ()
Just "quit" -> sendCommand h "quit" >> return ()
Just cmd -> sendCommand h cmd >> repl
main :: IO ()
main = do
-- Open the control socket to the daemon.
h <- liftIO $ handle (\e -> do hPutStrLn stderr (show (e ::IOError))
exitFailure)
$ do sock <- socket AF_UNIX Stream defaultProtocol
connect sock (SockAddrUnix "dht.sock")
socketToHandle sock ReadWriteMode
-- Haskeline's default looks only at our stdin and not our stdout.
-- That's a bad idea because we can take input from the command line.
behavior <- do
useTerminal <- and <$> mapM hIsTerminalDevice [stdin,stdout]
return $ if useTerminal then preferTerm else useFileHandle stdin
runInputTBehaviorWithPrefs behavior defaultPrefs defaultSettings $ do
-- A command may be specified on the command line
-- or else we enter an interactive shell.
args <- dropWhile isSpace . unwords <$> liftIO getArgs
case args of
(_:_) -> sendCommand h args >> sendCommand h "quit"
_ -> fix $ interactiveMode h
|
