embperl - Using IPC::Open3 to call wkhtmltopdf. STDIN Not working

133 Views Asked by Donavon Lerman At 06 April 2025 at 10:08

From within embperl, I am trying to call wkhtmltopdf with the IPC::Open3 module.

I get output (thanks to ikegami ) from wkhtmltopdf but no input is going to wkhtmltopdf.

This is related to this question: perl / embperl — IPC::Open3

Here is the code:

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

  my $cmd = '/usr/local/bin/wkhtmltopdf - -';

  my $pdf = '';

  my $string = '<!DOCTYPE html>
  <html>
    <head>
      <title>Hello World</title>
     </head>
     <body>
       Hello World!!!
     </body>
     </html>';

  my $fhOUT = gensym();
  open($fhOUT, '>', '/dev/null') or die $!; 
  dup2(fileno($fhOUT), 1) or die $! if fileno($fhOUT) != 1;
  local *STDOUT;
  open(STDOUT, '>&=', 1) or die $!;

  my $pid = open3(*HIS_IN, *HIS_OUT, *HIS_ERR, $cmd)  or die "could not run cmd : $cmd : $!\n";

  print HIS_IN $string;
  close(HIS_IN);

  while( <HIS_OUT> ) {
    $pdf .= $_;
  }


  waitpid($pid, 0 ) or die "$!\n";
  my $retval =  $?;
  # print "retval-> $retval<br />\n";

  $http_headers_out{'Content-Type'}         = "application/pdf";
  $http_headers_out{'Content-Disposition'}  = "attachment; filename=pdfTest.pdf";

  $escmode = 0;
-]
[+ $pdf +]

Original Q&A

There are 1 best solutions below

ikegami On 26 May 2014 at 00:07

Same idea for STDIN, but fd 0 instead of 1.

 open(my $fhIN, '<', '/dev/null') or die $!;
 dup2(fileno($fhIN), 0) or die $! if fileno($fhIN) != 0;
 local *STDIN; open(STDIN, '<&=', 0) or die $!;

 open(my $fhOUT, '>', '/dev/null') or die $!;
 dup2(fileno($fhOUT), 1) or die $! if fileno($fhOUT) != 1;
 local *STDOUT; open(STDOUT, '>&=', 1) or die $!;

 my $pid = open3(
    local *HIS_IN,
    local *HIS_OUT,
    '>&STDERR',
    $cmd
 );

 ...

This assumes fd 0 and 1 are closed, as is the case here.

embperl - Using IPC::Open3 to call wkhtmltopdf. STDIN Not working

There are 1 best solutions below

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