Subject: Re: canonpath in perl as it relates to cygwin
From: "Gerrit P. Haase" <[email-masked]>
To: [email-masked], "Christopher Murray" <[email-masked]>
Date: Mon, 6 May 2002 17:05:56 +0200

Christopher schrieb:

> My question concerns the use of File::Spec->canonpath in perl (for cygwin).
> I did a search of the relevant mailing list archives, as well as google
> newsgroups, but did not seem to come across any hits that seem to discuss
> this specific issue.

> As it currently stands, canonpath will not strip out multiple occurrences
> of // in file paths when the script is executed from within a cygwin shell.
> The relevant line from /usr/lib/perl5/5.6.1/File/Spec/Unix.pm that strips
> out multiple /'s is

> $path =~ s|/+|/|g unless ($^O eq 'cygwin');

> I assume this regexp substitution is ignored for cygwin because we would
> not want to munge instances where // refers to a network share (something
> regular unix doesn't need to worry about), but is it wise to also ignore
> all multiple forward slashes when they occur in the middle of a path?  Or
> is this simply a non-issue because, for the most part, it seems like most
> (if not all?)  programs don't really seem to care about multiple path
> separators?

> For what it's worth, canonpath in ExtUtils::MM_Unix (and MM_Cygwin), uses

> $path =~ s|(?<=[^/])/+|/|g;

> which seems to do what I expect (leaves // at the front of a path alone,
> but replaces all remaining // with /).  The only weakness I see with this
> is that it will not replace ///shareName/path with //shareName/path, but
> that is a minor matter, at least as it concerns me.

> Any thoughts on this matter would be most appreciated.

Perl 5.8:
=========
sub canonpath {
    my ($self,$path) = @_;
    
    # Handle POSIX-style node names beginning with double slash
    my $node = '';
    if ( $^O =~ m/^(?:qnx|nto)$/ && $path =~ s:^(//[^/]+)(/|\z):/:s ) {
      $node = $1;
    }
    # This used to be
    # $path =~ s|/+|/|g unless($^O eq 'cygwin');
    # but that made tests 29, 30, 35, 46, and 213 (as of #13272) to fail
    # (Mainly because trailing "" directories didn't get stripped).
    # Why would cygwin avoid collapsing multiple slashes into one? --jhi
    $path =~ s|/+|/|g;                             # xx////xx  -> xx/xx
    $path =~ s@(/\.)+(/|\Z(?!\n))@/@g;             # xx/././xx -> xx/xx
    $path =~ s|^(\./)+||s unless $path eq "./";    # ./xx      -> xx
    $path =~ s|^/(\.\./)+|/|s;                     # /../../xx -> xx
    $path =~ s|/\Z(?!\n)|| unless $path eq "/";          # xx/       -> xx
    return "$node$path";
}

Looks more sophisticated?

Gerrit
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