[GHC] #8844: Pseudo terminal and process-1.2.0.0

[GHC]

#8844: Pseudo terminal and process-1.2.0.0
--------------------------------------+------------------------------------
        Reporter:  ksamborski         |            Owner:
            Type:  feature request    |           Status:  new
        Priority:  normal             |        Milestone:
       Component:  libraries/process  |          Version:  7.6.3
      Resolution:                     |         Keywords:  pty
Operating System:  Unknown/Multiple   |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown       |       Difficulty:  Unknown
       Test Case:                     |       Blocked By:
        Blocking:                     |  Related Tickets:
--------------------------------------+------------------------------------

Old description:

> Hello,
>
> I'm writing simple app which execute process and communicate with it
> via pseudo terminal. Here is some sample code:
>
> import System.Posix.Terminal
> import System.Process
>
> main = do
>   (master, slave) <- openPseudoTerminal
>   hslave <- fdToHandle slave
>   hSetBuffering hslave NoBuffering
>   (_,_,_,ph) <- createProcess (shell "mc"){ env = Just [("TERM",
> "xterm")]
>                                           , std_in = UseHandle hslave
>                                           , std_out = UseHandle hslave
>                                           , std_err = UseHandle hslave
>                                           , close_fds = True
>                                           }
>   forkIO $ readTerm master -- my function which reads output from process
>   waitForProcess ph
>
> The problem is that mc still wants some input from stdin but not
> from slave terminal.
> But when I changed function runIteractiveProcess from runProcess.c like
> this:
>
> ...
>         /* Reset the SIGINT/SIGQUIT signal handlers in the child, if
> requested
>          */
>         if (reset_int_quit_handlers) {
>             struct sigaction dfl;
>             (void)sigemptyset(&dfl.sa_
> mask);
>             dfl.sa_flags = 0;
>             dfl.sa_handler = SIG_DFL;
>             (void)sigaction(SIGINT,  &dfl, NULL);
>             (void)sigaction(SIGQUIT, &dfl, NULL);
>         }
>
> /********************************************************************************/
>         setsid(); //Make the current process a new session leader
>         ioctl(0, TIOCSCTTY, 1); //As the child is a session leader,
> set the controlling terminal to be the slave side of the PTY
> /********************************************************************************/
>         /* the child */
>         if (environment) {
>             // XXX Check result
>             execvpe(args[0], args, environment);
>         } else {
>             // XXX Check result
>             execvp(args[0], args);
>         }
>
>         childFailed(forkCommunicationFds[1], forkExecFailed);
> ...
>
> it worked as expected, I'm not proposing patch or solution but is there
> any chance to add support for pseudo terminals in the process library?
> Maybe just add another record field in CreateProcess like pty :: Bool and
> then call these two additional instructions in runIteractiveProcess?
>
> Best regards,
> Karol Samborski

New description:

 Hello,

 I'm writing simple app which execute process and communicate with it
 via pseudo terminal. Here is some sample code:

 {{{#!haskell
 import System.Posix.Terminal
 import System.Process

 main = do
   (master, slave) <- openPseudoTerminal
   hslave <- fdToHandle slave
   hSetBuffering hslave NoBuffering
   (_,_,_,ph) <- createProcess (shell "mc"){ env = Just [("TERM", "xterm")]
                                           , std_in = UseHandle hslave
                                           , std_out = UseHandle hslave
                                           , std_err = UseHandle hslave
                                           , close_fds = True
                                           }
   forkIO $ readTerm master -- my function which reads output from process
   waitForProcess ph
 }}}

 The problem is that mc still wants some input from stdin but not
 from slave terminal.
 But when I changed function `runIteractiveProcess` from `runProcess.c`
 like this:

 {{{#!c
 ...
         /* Reset the SIGINT/SIGQUIT signal handlers in the child, if
 requested
          */
         if (reset_int_quit_handlers) {
             struct sigaction dfl;
             (void)sigemptyset(&dfl.sa_
 mask);
             dfl.sa_flags = 0;
             dfl.sa_handler = SIG_DFL;
             (void)sigaction(SIGINT,  &dfl, NULL);
             (void)sigaction(SIGQUIT, &dfl, NULL);
         }

 /********************************************************************************/
         setsid(); //Make the current process a new session leader
         ioctl(0, TIOCSCTTY, 1); //As the child is a session leader,
 set the controlling terminal to be the slave side of the PTY
 /********************************************************************************/
         /* the child */
         if (environment) {
             // XXX Check result
             execvpe(args[0], args, environment);
         } else {
             // XXX Check result
             execvp(args[0], args);
         }

         childFailed(forkCommunicationFds[1], forkExecFailed);
 ...
 }}}

 it worked as expected, I'm not proposing patch or solution but is there
 any chance to add support for pseudo terminals in the process library?
 Maybe just add another record field in `CreateProcess` like `pty :: Bool`
 and then call these two additional instructions in `runIteractiveProcess`?

 Best regards,
 Karol Samborski

--

Comment (by hvr):

 improved wiki markup of description

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8844#comment:1>
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