Lee writes:
> Mark Castoe <[log in to unmask]> wrote:
> > I am working on an application which will run under both the MPE CI and
> > the POSIX shell.  I need to be able to determine whether or not the app
> > has been launched under the shell.  Is there an easy way to do this?  I
> > have considered using HPFOPEN to open a file with an HFS filename and
> > checking to see if it fails.
>
> Look at either AIFPROCGET or PROCINFO which will return the PIN of the
> processes father and then the program file name which you can then compare
> to CI.PUB.SYS or SH.HPBIN.SYS.

Unfortunately, that doesn't help much if you're running under something
else!  (E.g., CI -> QEDIT -> FOO (your program))
or (sh -> ??? -> FOO)

For a trivial check, which only says "you're under the CI" if you are
indeed the top-level process in the session, try:


Pascal:

   const
      ccG           = 0;
      ccL           = 1;
      ccE           = 2;

   var
      i_am_under_ci : boolean;
      parent_pin    : shortint;
   ...
   Function father : shortint; intrinsic;
   ...
   parent_pin := father;
   if ccode = ccG then
      i_am_under_ci := true
   else
      i_am_under_ci := false;   {well, we aren't the top-level child}

This works because, according to CSEQ, father() returns a condition
code as follows:

   CSEQ [2.1] - LPS Toolbox [A.01q]        (c) 1995 Lund Performance Solutions

   Function FATHER := pin : UInt16    {R28}
         { CCE: parent is user process                              }
         { CCG: parent is job/session main (CI) process             }
         { CCL: parent is system process                            }

Otherwise, to do it "right", you'd need pseudo-code like:

   i_am_under_ci := true;                     {initial assumption}

   pin := father;
   loops := 0;

   while not done do
      loops := loops + 1;
      get program name (pin)                  <--- via PROCINFO, probably
      if name = "CI.PUB.SYS" then
         done := true;
         i_am_under_ci := true;
      else if name = "SH.HPBIN.SYS" then
         done :+ true;
         i_am_under_ci := false;
      else
         begin
         pin := parent of pin;                <--- via PROCINFO, probably
         if pin <= 1 then                     <--- run off end? (shouldn't happen)
            done := true;
         if loops > 9999 then                 <--- prevent bug from causing inf loop
            done := true;
         end;

Also, what answer do you *want* if the process tree is:

   CI
      sh
         CI
            ???
               foo  (your program)

You may want to specify *why* you want to determine your environment!

If it's because you're writing a C program, and want to be able to
handle open-old-file requests in a friendly manner (e.g., user
enters "fum" ... if under CI, you want to open ./FUM, if under
the shell, you want to open ./fum) ... that's relatively easy.
If the file name doesn't start with "/" or "./", and you're
using FOPEN/HPFOPEN do:

   1) try opening as given
   2) if that fails, put "./" in front, and try opening it again
   3) if that fails, complain to user: no such file

if you're using fopen() (from POSIX C library), do:

   1) try opening as given
   2) if filename has any periods in it (e.g., "fum.fie.foe"),
      extract and convert to MPE style:  /FOE/FIE/FUM
      and try again.

If you're opening a NEW disk file based on user input, then it's
a harder task :)

--
Stan Sieler                                          [log in to unmask]
                                     http://www.allegro.com/sieler.html