Update
  • IO reduces is a needs for content-filter on smtp servers
  • Postfix don't use redirection on call after-queue
  • It's work with redirection, but don't with my needs :(
    I'm working on a content filter on Postfix, and need exec antivirus, anti spam and usualy write content to debug, but it's a heavy host and need to reduce disk io.

    On my tests seek and tell functions working on STDIN, when exec with redirect, but a question "is it correct or can fail on future" ?

    My relevant code:

    filter.pl < filter.pl 

      print "." while ( <STDIN> );  print "\n";
  seek(STDIN,0,0);
  print "," while ( <STDIN> );  print "\n";

    [download]
    Code more complex:

    My code need this reduce io... 

    use strict;
 my ( $dfrom, $dsubj );
 my $from = shift;

  while ( defined( $_ = <STDIN> ) ) {
      if ( substr($_,0,5) eq 'From:' ) {
         chomp($dfrom = substr($_,6);)
         last;
      }
  }

  if ( $dfrom && $from ne $dfrom ) {
       seek(STDIN,0,0);
       ... save copy and log ...
  }

  seek(STDIN,0,0);
  ... Clamav call by stream ...
  if ( ... virus found ... ) {
     ... warn mail ...
     exit;
  }

  seek(STDIN,0,0);
  open(AS, "| ... anti spam binary") or die " ... error string ";
  syswrite(AS, $buf) while ( read(STDIN, $buf, 32768) );
  close(AS);
  }

    [download]

    It don't work if called with cat filter.pl | ./filter.pl or input from keyboard.

    --
    Marco Antonio
    Rio-PM

    In reply to Redirect data and Filehandle manipulation (STDIN x Disk IO) by mda2

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