file.pm

package URI::file;

use strict;
use vars qw(@ISA);

require URI::_generic;
@ISA = qw(URI::_generic);

# Map from $^O values to implementation classes.  The Unix
# class is the default.
my %os_class = (
     os2     => "OS2",
     mac     => "Mac",
     MacOS   => "Mac",
     MSWin32 => "Win32",
     win32   => "Win32",
     msdos   => "FAT",
     dos     => "FAT",
);

sub os_class
{
    my($OS) = shift || $^O;

    my $class = "URI::file::" . ($os_class{$OS} || "Unix");
    no strict 'refs';
    unless (defined %{"$class\::"}) {
	eval "require $class";
	die $@ if $@;
    }
    $class;
}

sub path { shift->path_query(@_) }
sub host { shift->authority(@_)  }

sub new
{
    my($class, $path, $os) = @_;
    os_class($os)->new($path);
}

sub new_abs
{
    my $class = shift;
    my $file = $class->new(shift);
    return $file->abs($class->cwd) unless $$file =~ /^file:/;
    $file;
}

sub cwd
{
    my $class = shift;
    require Cwd;
    my $cwd = $class->new(Cwd::cwd());
    $cwd .= "/" unless substr($cwd, -1, 1) eq "/";
    $cwd;
}

sub file
{
    my($self, $os) = @_;
    os_class($os)->file($self);
}

sub dir
{
    my($self, $os) = @_;
    os_class($os)->dir($self);
}

1;

__END__

file://foo/bar/baz  --> //foo/bar/baz  (unix)
                        \\foo\bar\baz  (win32)
                        foo:bar:baz    (mac)

file://localhost/bar/baz

volume, device --> authority
hostname       --> authority

file://<host>/foo/bar  --> /foo/bar if current hostname is <host> or
                                       <host> is "localhost"

It makes good sense to map drive volume to the authority field as this
make the resolving of relative references do the right thing.  The
main problem with this is that this might conflict with cases where
one wants to put the hostname here.

RFC 1630

   [...]

   There is clearly a danger of confusion that a link made to a local
   file should be followed by someone on a different system, with
   unexpected and possibly harmful results.  Therefore, the convention
   is that even a "file" URL is provided with a host part.  This allows
   a client on another system to know that it cannot access the file
   system, or perhaps to use some other local mecahnism to access the
   file.

   The special value "localhost" is used in the host field to indicate
   that the filename should really be used on whatever host one is.
   This for example allows links to be made to files which are
   distribted on many machines, or to "your unix local password file"
   subject of course to consistency across the users of the data.

   A void host field is equivalent to "localhost".