Running gpg thru IPC, fileno problem

zentara has asked for the wisdom of the Perl Monks concerning the following question:

Hi, Someone asked on the perl.beginners maillist, a question about running gpg thru a script. Well I thought It could be run thru IPC::Open3, but there is a complication. Gpg grabs the tty of the perlscript, preventing IPC from operating.

If you run the script below(modified to edit a suitable name for your system), gpg, grabs the tty. If you enter "trust" followed by Enter, a new menu appears. That is the functionality I'm trying to perform thru the script.

If I print to the IN filehandle, it does nothing. I've noticed that the Crypt::GPG module uses IPC::Run and an undocumented gpg option called "--no-tty", but that aside, I just want to know how to access the STDIN to gpg.

On my system gpg is shown using /dev/pts/5, and I can't seem to be able to print to it. Is it possible thru some sort of fileno magic?

#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;
use POSIX;

my $childpid = open3(\*IN, \*OUT, \*ERR, 'gpg --edit zentara');

#gpg grabs control of the tty here 

my $tty0 = ttyname(0); #STDIN 
my $tty1 = ttyname(1); #STDOUT 
print "$tty0  $tty1\n";
#  they are /dev/pts/5  on my machine 
#how do I print to STDIN of /dev/pts/5 ? 

print IN "trust\n";
 chomp(my $answer = <OUT>);
 print $answer;
 if ($answer =~ /Your decision/) {
 print IN "5\n";
 }else {
    print "decision error $!\n";
    exit;
}
[download]

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Comment on Running gpg thru IPC, fileno problem Download Code

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Re: Running gpg thru IPC, fileno problem
by Fletch (Bishop) on Jun 09, 2005 at 14:36 UTC

You need to look at either IPC::Run or Expect as they'll let you run a child on a pty.

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[reply]

Re: Running gpg thru IPC, fileno problem
by PodMaster (Abbot) on Jun 09, 2005 at 15:18 UTC

GnuPG/GPG:
- http://search.cpan.org/src/MILES/GPG-0.06/GPG.pm - uses IPC::Open3
- http://search.cpan.org/src/AGUL/Crypt-GPG-1.52/GPG.pm - uses IPC::Run
- GnuPG::Interface - uses interprocess communication methods similar to those used in IPC::Open3
- GnuPG - uses fileno :)

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[reply]

Re^2: Running gpg thru IPC, fileno problem

by kaif (Friar) on Jun 09, 2005 at 17:44 UTC

A recent thread suggests that you should not necessarily trust GnuPG, but at least the thread provides a fix so that the package actually compiles.

[reply]

Re^2: Running gpg thru IPC, fileno problem

by perrin (Chancellor) on Jun 09, 2005 at 15:22 UTC

I explored CPAN's GPG/PGP modules a while back. Most of them either don't compile or fail their tests on Fedora Core 3. The GPG interfaces on CPAN seem to have been left to rot, which means doing your own IPC to the executable is probably the safest choice at the moment. (Or put in the effort to clean one of them up, if you have the time and interest.)

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Re^3: Running gpg thru IPC, fileno problem

by PodMaster (Abbot) on Jun 09, 2005 at 15:26 UTC

Most of them either don't compile or fail their tests on Fedora Core 3.

update: also, a lot of those FAILS are a case of Can't exec "gpg": No such file or directory , which means the test suite isn't the best (assumes you have gpg installed), but doesn't indicate an actual failure.

[reply]

Re^4: Running gpg thru IPC, fileno problem

by perrin (Chancellor) on Jun 09, 2005 at 18:13 UTC

Re: Running gpg thru IPC, fileno problem
by zentara (Archbishop) on Jun 09, 2005 at 20:33 UTC

#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;

local $SIG{CHLD} = 'IGNORE';
local $SIG{PIPE} = 'IGNORE';

my $childpid = open3(\*IN, \*OUT, \*ERR,
     'gpg  -v --no-greeting --no-tty  --command-fd 0 --status-fd 1 --e
+dit zentara');

print IN "trust\n5\ny\n";
close IN;

my(@answer,@err);

 @answer = <OUT>;
 print "out->@answer\n";

 @err = <ERR>;
 print "err->@err\n";
[download]

I'm not really a human, but I play one on earth. flash japh

[reply]
[d/l]

Re^2: Running gpg thru IPC, fileno problem

by cbrandtbuffalo (Deacon) on Jun 09, 2005 at 20:42 UTC

I played around with the file descriptor option with gpg a while ago and never got it to work. Thanks for posting your snippet of working code!


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