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

I have come here to ask for your guidance.

I tried searches on line and even tried joining the mailing list for emperl embperl-subscribe@perl.apache.org I don't think it is available anymore.

I have a sample program in 2 formats perl & embperl

The perl version works as a CGI but the embperl version does not work.

Any suggestions or pointers to solutions would be appreciated

OS: Linux version 2.6.35.6-48.fc14.i686.PAE (...) (gcc version 4.5.1 20100924 (Red Hat 4.5.1-4) (GCC) ) #1 SMP Fri Oct 22 15:27:53 UTC 2010

perl working script

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

print "Content-type: text/plain\n\n";

my $cmd = 'ls';

my $pid = open3(*HIS_IN, *HIS_OUT, *HIS_ERR, $cmd);
close(HIS_IN);  # give end of file to kid, or feed him
my @outlines = <HIS_OUT>;              # read till EOF
my @errlines = <HIS_ERR>;              # XXX: block potential if massi
+ve
print "STDOUT: ", @outlines, "\n";
print "STDERR: ", @errlines, "\n";

waitpid( $pid, 0 );
my $child_exit_status = $? >> 8;

print "child_exit_status: $child_exit_status\n";

[download]

embperl non-working script

Here is the output I receive.
STDERR: ls: write error: Bad file descriptor

child_exit_status: 2
 
[-
use warnings;
use strict;
use IPC::Open3;
use Symbol 'gensym'; 

$escmode = 0;
$http_headers_out{'Content-Type'} = "text/plain";

my $cmd = 'ls';

my $pid = open3(*HIS_IN, *HIS_OUT, *HIS_ERR, $cmd);

close(HIS_IN);  # give end of file to kid, or feed him

my @outlines = <HIS_OUT>;              # read till EOF
my @errlines = <HIS_ERR>;              # XXX: block potential if massi
+ve
print OUT "STDOUT: ", @outlines, "\n";
print OUT "STDERR: ", @errlines, "\n";

waitpid( $pid, 0 );
my $child_exit_status = $? >> 8;

print OUT "child_exit_status: $child_exit_status\n";
-]

[download]

Replies are listed 'Best First'.
Re: perl / embperl -- IPC::Open3;
by zentara (Cardinal) on May 17, 2014 at 14:09 UTC
    Just looking at your embperl script, and assuming you copy&pasted it properly, it should fail because you have use strict enabled, but have a few variables without scope. 
    Global symbol "$escmode" requires explicit package name at ./1086395.p
+l line 7.
Global symbol "%http_headers_out" requires explicit package name at ./
+1086395.pl line 8.

    [download]

    It's conceivable that the cgi is trying to print this error, but it gives your bad filedescriptor error instead. Sometimes error reporting can be deceiving.

    I'm not really a human, but I play one on earth.
    Old Perl Programmer Haiku ................... flash japh
[reply]
[d/l]

      $escmode and %http_headers_out are a part of and used in embperl. I don't think they need to be defined separately.

      Either way I removed them both from the script and I still get the same error

[reply]

        With the help of user ikegami over at stackoverflow. The following solutions works. 

        [-
  use warnings;
  use strict;
  use IPC::Open3;
  use POSIX;

  $http_headers_out{'Content-Type'} = "text/plain";

  my $cmd = 'ls';

  open(my $fh, '>', '/dev/null') or die $!; 

  dup2(fileno($fh), 1) or die $! if fileno($fh) != 1;

  local *STDOUT;
  open(STDOUT, '>&=', 1) or die $!;

  my $pid = open3(*HIS_IN, *HIS_OUT, *HIS_ERR, $cmd);

  close(HIS_IN);  # give end of file to kid, or feed him

  my @outlines = <HIS_OUT>;              # read till EOF
  my @errlines = <HIS_ERR>;              # XXX: block potential if mas
+sive
  print OUT "STDOUT: ", @outlines, "\n";
  print OUT "STDERR: ", @errlines, "\n";

  waitpid( $pid, 0 );
  my $child_exit_status = $? >> 8;

  print OUT "child_exit_status: $child_exit_status\n";
-]

        [download]
[reply]
[d/l]

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