Hello,
with the build 819 from ActivePerl I recently received the error
Directory //phchbs-w26786/wsdisk/tmp/a changed before chdir, aborting at
...
when I try to remove a directory tree using an UNC path. I peeked into
File::Path and saw that the routine checks for a race condition "where a
directory may be replaced by a symlink between the initial lstat and the
chdir". This fails always for UNC paths as after doing the chdir the stat
yields a device number of -1 (it would not fail if one would start from an
UNC path as the cwd but that is probably rarely the case ... ;-) ).
This can be reproduced by the small program below. The drive z: mounts the
share //phchbs-w26786/wsdisk. Removing the $dDir works, that of $uDir
fails.
#!perl -w
use strict;
use File::Path;
use Cwd 'getcwd';
my $dDir = 'z:/tmp/a';
my $uDir = '//phchbs-w26786/wsdisk/tmp/a';
my $dir = $uDir;
my $oldpwd = getcwd or die $!;
my ($dev, $ino, $perm) = lstat $dir;
print "dev $dev, ino $ino, perm $perm\n";
chdir $dir or die $!;
my ($new_dev, $new_ino) = stat '.';
print "new_dev $new_dev, new_ino $new_ino\n";
chdir $oldpwd or die $!;
rmtree($dir,1,1) or die $!;
For now I found a solution by patching my version of Path.pm in the
following way:
--- Path.pm.orig 2006-01-04 08:55:28.000000000 +0100
+++ Path.pm 2007-02-13 19:10:47.534437500 +0100
@@ -205,8 +205,10 @@
# avoid a race condition where a directory may be replaced by a
# symlink between the initial lstat and the chdir
+ my $pathIsUNC = $path =~ m|^[/\\]{2}| ? 1 : 0;
my ($new_dev, $new_ino) = stat '.';
- unless ("$new_dev:$new_ino" eq "$dev:$ino")
+ unless ( ( $new_ino == $ino ) &&
+ ( ($new_dev == $dev) || ( ($new_dev == -1) && $pathIsUNC) ) )
{
croak "Directory $prefix$path changed before chdir, aborting";
}
Would that be a reasonable way to account for UNC paths? It seems to work
fine.
Ekkehard
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