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Subject: Perl Win32::Shortcut screws up fork
Date: Thu, 7 Jul 2005 18:10:17 +0100
Message-ID: <7231C15EAC2F164CA6DC326D97493C8BA1C3F1@exchange35.fed.cclrc.ac.uk>
From: "Adye, TJ \(Tim\)" <T DOT J DOT Adye AT rl DOT ac DOT uk>
To: <cygwin AT cygwin DOT com>
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X-MIME-Autoconverted: from quoted-printable to 8bit by delorie.com id j67HAYQ0004629

Hi,

In an attempt to work round the problem with readshortcut I reported
earlier, I thought I'd use a Perl script. Unfortunately the
Win32::Shortcut package seems to cause problems with process forking
(unlike the readshortcut error, this one isn't specific to the latest
cygwin DLL). I get an error

C:\cygwin\bin\perl.exe (3088): *** unable to remap
C:\cygwin\lib\perl5\vendor_perl\5.8\cygwin\auto\Win32\Shortcut\Shortcut.
dll to same address as parent(0xBF0000) != 0x1110000
     13 [main] perl 3716 fork_parent: child 3088 died waiting for dll
loading

Here's an example that demonstrates the problem.

#!/usr/bin/perl -w
use strict;
use Win32::Shortcut;

if (my $pid= open (my $pipe, '-|')) {
  print "forked child process $pid\n";
  while (<$pipe>) { print "from child: $_"; }
  close ($pipe) or die;
} elsif (defined $pid) {
  print "this is the child\n";
  exit;
} else {
  print "fork failed: $!\n";
}

Without the "use Win32::Shortcut", the script runs fine. With the
package the fork fails with the error message I gave. Win32::Shortcut
works fine if I don't fork or don't do it until after the package is
loaded (eg. I can eval "require Win32::Shortcut" after the fork). I see
this behaviour with Perl 5.8.6 and 5.8.7 and Cygwin 1.5.17-1 and
1.5.18-1.

This error makes it a tricky to convert the Win32::Shortcut output to
Cygwin-style paths with cygpath -u (without resorting to a separate
program to parse the results). Or is there a Perl module that can do the
cygpath conversion? That would be even nicer!

Thanks,
Tim.

==============================  cut here  ==============================
Tim Adye, BaBar Group, Particle Physics Dept.,             _   /|
          Rutherford Appleton Laboratory, UK.              \'o.O'   Oop!
e-mail:   T DOT J DOT Adye AT rl DOT ac DOT uk                                =(___)=  Ack!
WWW:      http://hepwww.rl.ac.uk/Delphi/Adye/homepage.html    U  Thphft!

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