Hi,
I'm trying to use open3 to control input to an external program (in this
case gpg). I would use Expect, but I need to use packages that are
installed as standard with perl as this script will be running on many
platforms. I simply want to enter interactive mode of gpg, pass it 3
commands, then exit back to my script. The following code runs gpg in
interactive mode, but none of the commands get passed to it and it just
sits there till I exit manually, then it comes back to my script.
use IPC::;
local(*HIS_IN, *HISUT, *HIS_ERR);
$childpid = open3(*HIS_IN, *HISUT, *HIS_ERR, 'gpg root');
print HIS_IN "trust\n5\yes\n";
close (HIS_IN);
my @outlines = <HISUT>;
my @errlines = <HIS_ERR>;
close HISUT;
close HIS_ERR;
waitpid($childpid, 0);
if ($?) {
print "Child exited with status of $?\n";
}
If I remove the "close (HIS_IN)" statement
Is it possible to do what I want with open3, and how?
Thanks
Darren

Fri, 03 Jun 2005 08:35:32 +0100, darren (AT) birkett (DOT) com (D. J. Birkett)
wrote:

>I'm trying to use open3 to control input to an external program (in this
>case gpg). I would use Expect, but I need to use packages that are
>installed as standard with perl as this script will be running on many
>platforms. I simply want to enter interactive mode of gpg, pass it 3
>commands, then exit back to my script. The following code runs gpg in
>interactive mode, but none of the commands get passed to it and it just
>sits there till I exit manually, then it comes back to my script.

>use IPC::;
>
>local(*HIS_IN, *HISUT, *HIS_ERR);
>
>$childpid = open3(*HIS_IN, *HISUT, *HIS_ERR, 'gpg root');
>
>print HIS_IN "trust\n5\yes\n";
>close (HIS_IN);
>my @outlines = <HISUT>;
>my @errlines = <HIS_ERR>;
>close HISUT;
>close HIS_ERR;
>waitpid($childpid, 0);
>if ($?) {
print "Child exited with status of $?\n";
>}
>
>If I remove the "close (HIS_IN)" statement
>
>
>Is it possible to do what I want with open3, and how?

I'm not testing this locally, with gpg,
but from what I know from using IPC::, you may have to put delays
in your script, to allow
gpg to return, before giving the next command.
, gpg will get the 'trust\n5\yes\n' as 1 long command
and won't understand it.

Like:
print HIS_IN "trust\n";
sleep 1;
print HIS_IN "5\n";
sleep 1
print HIS_IN "yes\n";

but better yet, don't rely on delays because your
system may be overloaded and the delay may not work.

The best way is to print a command to HIS_IN and then read
the HISUT and HIS_ERR and use regexes to process the output.
If the expected output is there, print the next line and do the same.
Then you are making IPC:: run like Expect.

Something along these lines

print HIS_IN "trust\n";
chomp(my $answer = <HISUT>);
if( $answer =~ /^How many years?$/ )
{ print HIS_IN "5\n"; }else{print "years error $!\n"; exit}

chomp(my $answer1 = <HISUT>);
if( $answer1 =~ /^Are you sure?$/ )
{ print HIS_IN "yes\n"; }else{print "confirm error $!\n"; exit}

But you need to run the procedure yourself a few times, and
see what the regexes should be.

Zentara wrote:

Something along these lines

print HIS_IN "trust\n";
chomp(my $answer = <HISUT>);
if( $answer =~ /^How many years?$/ )
{ print HIS_IN "5\n"; }else{print "years error $!\n"; exit}

chomp(my $answer1 = <HISUT>);
if( $answer1 =~ /^Are you sure?$/ )
{ print HIS_IN "yes\n"; }else{print "confirm error $!\n"; exit}

But you need to run the procedure yourself a few times, and
see what the regexes should be.

K I've tried altering my code as you suggested, replacing the regexes
with ones that would work. gpg still just sits there as soon as it has
entered it's intereactive mode, and perl doesn't seem to be passing any
commands to it at all.

Any other ideas?

Tue, 07 Jun 2005 14:38:41 +0100, darren (AT) birkett (DOT) com (D. J. Birkett)
wrote:

>Zentara wrote:
>
>
>Something along these lines
>
>print HIS_IN "trust\n";
>chomp(my $answer = <HISUT>);
>if( $answer =~ /^How many years?$/ )
>{ print HIS_IN "5\n"; }else{print "years error $!\n"; exit}
>
>chomp(my $answer1 = <HISUT>);
>if( $answer1 =~ /^Are you sure?$/ )
>{ print HIS_IN "yes\n"; }else{print "confirm error $!\n"; exit}
>
>
>But you need to run the procedure yourself a few times, and
>see what the regexes should be.
>
>
>
>
>K I've tried altering my code as you suggested, replacing the regexes
>with ones that would work. gpg still just sits there as soon as it has
>entered it's intereactive mode, and perl doesn't seem to be passing any
>commands to it at all.
>
>Any other ideas?

Since you are not showing us your code, we can only guess.
My guess is that you are not setting up the gpg command properly.

The first thing that jumps out at me when I look at man gpg, is:

Please remember that option parsing stops as soon as a non
option is encountered, you can explicitly stop option
parsing by using the special option "--".

So gpg is just sitting there, waiting for more input, you need to find
out why.

Alot of little details can go wrong. Maybe you need to tweak the way
the filehandles are referenced.

But Thomas Baltzer's advice is right-on: look at the other modules, and
see how they do it.

Wed, 08 Jun 2005 06:39:29 -0400, zentara <zentara (AT) highstream (DOT) net>
wrote:

>>Any other ideas?
>
>Since you are not showing us your code, we can only guess.
>My guess is that you are not setting up the gpg command properly.
>
>The first thing that jumps out at me when I look at man gpg, is:
>
Please remember that option parsing stops as soon as a non
option is encountered, you can explicitly stop option
parsing by using the special option "--".
>
>So gpg is just sitting there, waiting for more input, you need to find
>out why.
>
>Alot of little details can go wrong. Maybe you need to tweak the way
>the filehandles are referenced.
>
>But Thomas Baltzer's advice is right-on: look at the other modules, and
>see how they do it.

Yeah, I've tried running gpg thru IPC:: and you are right, it
dosn't repond. Some apps are tricky the way they use
STDIN, STDUT and STDERR.

I looked at the modules that use it, and it looks like Crypt::GPG uses
IPC::Run and it gets quite involved. thing I did notice is that you
need to close the IN filehandle before gpg will return anything.

It all looks very complicated, and you should probably just use the
modules instead of trying to roll your own.

Here is an IPC:: script, which does coax gpg to return output,
but I see problems with having to close the IN filehandle, as shown in
the code below. Maybe there is a way to send and 'eof' thru IN, without
closing it, so you can send multiple commands? If I find it, I'll let
you know. Maybe print a null char?

#!/usr/bin/perl
use warnings;
use strict;
use IPC::;
use I::Select;
$|++;

my $pid1 = open3(\*IN, \*READ,\*ERRR,"gpg");
#if \*ERRR is false, STDERR is sent to STDUT

my $sel = new I::Select();

$sel->add(\*READ);
$sel->add(\*ERRR);

print IN "\n";
close IN;

get_output();

print IN "\n";
close IN;

get_output();

sub get_output{

if( $sel->can_read ){
foreach my $h ($sel->can_read){
my $buf = '';
if ($h eq \*ERRR){
$buf = <ERRR>;
if($buf){print "ERRR-$buf\n"}
}else{
$buf = <READ>;
if($buf){print "$buf\n"}
}
}
}

}
__END__

Zentara wrote:

Since you are not showing us your code, we can only guess.
My guess is that you are not setting up the gpg command properly.

Here is what I now have

use IPC::;

local(*HIS_IN, *HISUT, *HIS_ERR);

$childpid = open3(*HIS_IN, *HISUT, *HIS_ERR, 'gpg root');
sleep 5;

print HIS_IN "trust\n";
chomp(my $answer = <HISUT>);
print $answer;
if ($answer =~ /Your decision/) {
print HIS_IN "5\n";
}
else {
print "decision error $!\n";
exit;
}

chomp (my $answer1 = <HISUT>);
if ($answer1 =~ /^Do you really/) {
print HIS_IN "yes\n";
}
else {
print "sure error $!\n";
exit;
}

The first thing that jumps out at me when I look at man gpg, is:

Please remember that option parsing stops as soon as a non
option is encountered, you can explicitly stop option
parsing by using the special option "--".

So gpg is just sitting there, waiting for more input, you need to find
out why.

gpg is starting up fine. It is not a question of options that I'm
passing it to open it. It's the fact that my code is not interacting
with it once it's open

Alot of little details can go wrong. Maybe you need to tweak the way
the filehandles are referenced.

This is really where I am after help as my perl is not really that advanced.

But Thomas Baltzer's advice is right-on: look at the other modules, and
see how they do it.

yes I checked out Crypt::GPG, and that interacts with gpg by using
IPC::Run in an Expect like manner. Unfortunately, IPC::Run does not
come as part of the standard perl distro either.

Thanks
Darren

Here is what I now have
use IPC::;
use strict;
use warnings;
before IPC::
local(*HIS_IN, *HISUT, *HIS_ERR);
$childpid = open3(*HIS_IN, *HISUT, *HIS_ERR, 'gpg root');
Make sure open3 worked
open3() or die $!;

Wed, 08 Jun 2005 15:52:21 +0100, darren (AT) birkett (DOT) com (D. J. Birkett)
wrote:

>Here is what I now have
>
>gpg is starting up fine. It is not a question of options that I'm
>passing it to open it. It's the fact that my code is not interacting
>with it once it's open

>yes I checked out Crypt::GPG, and that interacts with gpg by using
>IPC::Run in an Expect like manner. Unfortunately, IPC::Run does not
>come as part of the standard perl distro either.
>
>Thanks
>Darren

I see what is happening but I don't know how to resolve it. I modified
your code above to run on my machine, and it works, but interactively.
When I first run the code, gpg grabs control of the tty away from the
perl script, and it works. This interferes with IPC::'s attempt to
sit between the terminal and gpg. I guess he does it for some security
reason?

I noticed in Crypt::GPG, that it uses the undocumented "" option
of gpg. If you use that option, gpg will not grab the tty, but then you
have another problemhow to talk to it, since you need to close HIS_IN
to get gpg going?

I see 2 choices: either find a way to use and put all the
options on the original command line like (guessing):
"gpg zentara"

or

find a way to intercept the tty which gpg is using. I noticed in the
modules, that they do some tricky things with fileno, and they are
probably using it, to grab the fileno's of the tty in order to read and
write to them directly.

#!/usr/bin/perl
use warnings;
use strict;
use IPC::;
use I::Select;
local(*HIS_IN, *HISUT, *HIS_ERR);

my $childpid = open3(*HIS_IN, *HISUT, *HIS_ERR, 'gpg zentara');
#my $childpid = open3(*HIS_IN, *HISUT, *HIS_ERR, 'gpg
zentara');

close HIS_IN;
#close HIS_IN;

print HIS_IN "trust\n";
chomp(my $answer = <HISUT>);
print $answer;
if ($answer =~ /Your decision/) {
print HIS_IN "5\n";
}else {
print "decision error $!\n";
exit;
}

chomp (my $answer1 = <HISUT>);
if ($answer1 =~ /^Do you really/) {
print HIS_IN "yes\n";
}else{
print "sure error $!\n";
exit;
}
__END__