Hello Monks

I have a need to execute long processes through CGI and had successfully tested the code provided by merlyn by executing a series of sleep commands few weeks back in Apache 1.3.33 in Unix.

Now, I wanted to make some modifications to execute some actual commands and before modifying, I checked the same script and found it to be acting differently. The code has not changed even a line but I can't figure out what is going wrong now

The execution enters into the 1st loop (i.e.. picking up the session data ) and returns a value of "1" for $data->[0] and a value for $session. Hence, the execution never enters the loop which does the forking.

I am clueless as to how it is getting a value when I start it the first time. I have checked the /tmp directory under which the FileCache folder is created but couldn't figure out what is going wrong.

Would appreciate your help/ suggestions.

Below is the code with some minor modifications from the original version 

1 use CGI qw(:all delete_all escapeHTML);
2
3 my $redirect_page = "display_page.cgi";
4
5 # The execution enters this loop in the first pass whereas 6 it shou
+ld not!!!
7 if (my $session = param('session')) { # returning to pick 8 up sessi
+on data
9  my $cache = get_cache_handle();
10  my $data = $cache->get($session);
11  unless ($data and ref $data eq "ARRAY") { # something is wrong
12    show_form();
13    exit 0;
14  }
15  print header;
16  if ( $data->[0] ){
17  print start_html(-title=>'Sleep Results Done',-bgcolor=>'white');
18  # Checking.... print $session and $data->[0] to screen
20  print h2("$session");
21     print h2("$data->[0]");
22  # End of checking
23  print start_form(-name=>'data',-action=>$redirect_page);
24  print end_form();
25  print script("setTimeout(\"document.data.submit();\",2000);");
26  }
27  else{
28  print start_html(-title => "Sleep Results",
29                   ($data->[0] ? () :
30                    (-head => ["<meta http-equiv=refresh content=5>"
+])));
31  print h1("Sleep Results");
32  print pre(escapeHTML($data->[0]));
33  print pre(escapeHTML($data->[1]));
34  print p(i("... continuing ...")) unless $data->[0];  
35  
36  }
37  print end_html;
38 } 
39 elsif ( (my $slp = param('sleep')) eq 'sleep') {
40     my $session = get_session_id();
41    my $cache = get_cache_handle();
42    $cache->set($session, [0, ""]); # no data yet
43
44    if (my $pid = fork) {       # parent does
45      delete_all();             # clear parameters
46      param('session', $session);
47      print redirect(self_url());
48    } 
49    elsif (defined $pid) {    # child does
50      close STDOUT;             # so parent can go on
51      unless (open F, "-|") {
52        open STDERR, ">&=1";
53        exec "/path/to/run_sleep_commands.sh";
54        die "Cannot execute Sleep: $!";
55      }
56      my $buf = "";
57      while (<F>) {
58        $buf .= $_;
59        $cache->set($session, [0, $buf]);
60      }
61      $cache->set($session, [1, $buf]);
62      exit 0;
63    } 
64    else {
65      die "Cannot fork: $!";
66    }
67 }
68 else {                        # display form
69  show_form();
70 }
71
72 exit 0;

sub show_form {
  print header, start_html("Sleep"), h1("Sleep");
  print start_form;
  #print submit('traceroute to this host:'), " ", textfield('host');
  print submit('Run Sleep Process:'), " ", textfield('sleep');
  print end_form, end_html;
}

sub get_cache_handle {
  require Cache::FileCache;

  Cache::FileCache->new
      ({
        namespace => 'sleep',
        username => 'sara2005',
        default_expires_in => '30 minutes',
        auto_purge_interval => '4 hours',
       });
}

sub get_session_id {
    require Digest::MD5;

    Digest::MD5::md5_hex(Digest::MD5::md5_hex(time().{}.rand().$$));
}

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In reply to Issue with Running Long Processes thru CGI by sara2005

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