Re: Ada & Scripting

[sk <noname@myob.com>]

Hi,

  > I have some C sources for 'popen' which show how this is
  > supposed to work. Now I "only" have to map the function to Ada.

...

  > I saw them. As I said 'popen' ony returns one of the
  > pipes - so I have to program my own version of 'popen'.

... and as I said, the method is 2 PIPES (not 'popen')

The routine (algorithm) goes, roughly, like so ...

<algorithm>

Create a PIPE for stdin
Create a PIPE for stdout
Create a PIPE for stderr

FORK

if child process

      DUP the stdin, stdout and stderr pipes

      Close the write end of the stdin pipe
      Close the read end of the stdout pipe
      Close the read end of the stderr pipe

      EXECUTE the program you choose to talk
           to through pipes.

else -- parent process

      Close the read end of the stdin pipe
      Close the write end of the stdout pipe
      Close the write end of the stderr pipe

      Read from the stdout or stderr pipes.

      Write to stdin pipe.

end if;

</algorithm>

Use the "select" or "poll" system calls in the parent
process to determine if the pipes are open, open but
blocked or closed.

There is no difficulty in implementing this algorithm
in Ada, but it is a very "C" way to do it. A more Ada
solution is to use Ada tasks or protected objects, but
there is still a 'fork' and 'exec' call involved since
this is the way a Linux system (and Windows I think)
implements the "pipe" concept. So, I tend to stick
to the parent/child fork and exec method retaining the
"C" way to do things.

-- 
-------------------------------------------------
-- Merge vertically for real address
--
--     s n p @ t . o
--      k i e k c c m
-------------------------------------------------