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- package URI::file;
-
- use strict;
- use vars qw(@ISA $VERSION);
-
- require URI::_generic;
- @ISA = qw(URI::_generic);
- $VERSION = sprintf("%d.%02d", q$Revision: 4.14 $ =~ /(\d+)\.(\d+)/);
-
- use URI::Escape qw(uri_unescape);
-
- # Map from $^O values to implementation classes. The Unix
- # class is the default.
- my %os_class = (
- os2 => "OS2",
- mac => "Mac",
- MacOS => "Mac",
- MSWin32 => "Win32",
- win32 => "Win32",
- msdos => "FAT",
- dos => "FAT",
- qnx => "QNX",
- );
-
- sub os_class
- {
- my($OS) = shift || $^O;
-
- my $class = "URI::file::" . ($os_class{$OS} || "Unix");
- no strict 'refs';
- unless (%{"$class\::"}) {
- eval "require $class";
- die $@ if $@;
- }
- $class;
- }
-
- sub path { shift->path_query(@_) }
- sub host { uri_unescape(shift->authority(@_)) }
-
- sub new
- {
- my($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 = Cwd::cwd();
- $cwd = VMS::Filespec::unixpath($cwd) if $^O eq 'VMS';
- $cwd = $class->new($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__
-
- =head1 NAME
-
- URI::file - URI that maps to local file names
-
- =head1 SYNOPSIS
-
- use URI::file;
-
- $u1 = URI->new("file:/foo/bar");
- $u2 = URI->new("foo/bar", "file");
-
- $u3 = URI::file->new($path);
- $u4 = URI::file->new("c:\\windows\\", "win32");
-
- $u1->file;
- $u1->file("mac");
-
- =head1 DESCRIPTION
-
- The C<URI::file> class supports C<URI> objects belonging to the I<file>
- URI scheme. This scheme allows us to map the conventional file names
- found on various computer systems to the URI name space. An old
- specification of the I<file> URI scheme is found in RFC 1738. Some
- older background information is also in RFC 1630. There are no newer
- specifications as far as I know.
-
- If you simply want to construct I<file> URI objects from URI strings,
- use the normal C<URI> constructor. If you want to construct I<file>
- URI objects from the actual file names used by various systems, then
- use one of the following C<URI::file> constructors:
-
- =over 4
-
- =item $u = URI::file->new( $filename, [$os] )
-
- Maps a file name to the I<file:> URI name space, creates a URI object
- and returns it. The $filename is interpreted as belonging to the
- indicated operating system ($os), which defaults to the value of the
- $^O variable. The $filename can be either absolute or relative, and
- the corresponding type of URI object for $os is returned.
-
- =item $u = URI::file->new_abs( $filename, [$os] )
-
- Same as URI::file->new, but makes sure that the URI returned
- represents an absolute file name. If the $filename argument is
- relative, then the name is resolved relative to the current directory,
- i.e. this constructor is really the same as:
-
- URI::file->new($filename)->abs(URI::file->cwd);
-
- =item $u = URI::file->cwd
-
- Returns a I<file> URI that represents the current working directory.
- See L<Cwd>.
-
- =back
-
- The following methods are supported for I<file> URI (in addition to
- the common and generic methods described in L<URI>):
-
- =over 4
-
- =item $u->file( [$os] )
-
- Returns a file name. It maps from the URI name space
- to the file name space of the indicated operating system.
-
- It might return C<undef> if the name can not be represented in the
- indicated file system.
-
- =item $u->dir( [$os] )
-
- Some systems use a different form for names of directories than for plain
- files. Use this method if you know you want to use the name for
- a directory.
-
- =back
-
- The C<URI::file> module can be used to map generic file names to names
- suitable for the current system. As such, it can work as a nice
- replacement for the C<File::Spec> module. For instance, the following
- code translates the UNIX-style file name F<Foo/Bar.pm> to a name
- suitable for the local system:
-
- $file = URI::file->new("Foo/Bar.pm", "unix")->file;
- die "Can't map filename Foo/Bar.pm for $^O" unless defined $file;
- open(FILE, $file) || die "Can't open '$file': $!";
- # do something with FILE
-
- =head1 MAPPING NOTES
-
- Most computer systems today have hierarchically organized file systems.
- Mapping the names used in these systems to the generic URI syntax
- allows us to work with relative file URIs that behave as they should
- when resolved using the generic algorithm for URIs (specified in RFC
- 2396). Mapping a file name to the generic URI syntax involves mapping
- the path separator character to "/" and encoding any reserved
- characters that appear in the path segments of the file name. If
- path segments consisting of the strings "." or ".." have a
- different meaning than what is specified for generic URIs, then these
- must be encoded as well.
-
- If the file system has device, volume or drive specifications as
- the root of the name space, then it makes sense to map them to the
- authority field of the generic URI syntax. This makes sure that
- relative URIs can not be resolved "above" them, i.e. generally how
- relative file names work in those systems.
-
- Another common use of the authority field is to encode the host on which
- this file name is valid. The host name "localhost" is special and
- generally has the same meaning as a missing or empty authority
- field. This use is in conflict with using it as a device
- specification, but can often be resolved for device specifications
- having characters not legal in plain host names.
-
- File name to URI mapping in normally not one-to-one. There are
- usually many URIs that map to any given file name. For instance, an
- authority of "localhost" maps the same as a URI with a missing or empty
- authority.
-
- Example 1: The Mac uses ":" as path separator, but not in the same way
- as a generic URI. ":foo" is a relative name. "foo:bar" is an absolute
- name. Also, path segments can contain the "/" character as well as the
- literal "." or "..". So the mapping looks like this:
-
- Mac URI
- ---------- -------------------
- :foo:bar <==> foo/bar
- : <==> ./
- ::foo:bar <==> ../foo/bar
- ::: <==> ../../
- foo:bar <==> file:/foo/bar
- foo:bar: <==> file:/foo/bar/
- .. <==> %2E%2E
- <undef> <== /
- foo/ <== file:/foo%2F
- ./foo.txt <== file:/.%2Ffoo.txt
-
- Note that if you want a relative URL, you *must* begin the path with a :. Any
- path that begins with [^:] is treated as absolute.
-
- Example 2: The UNIX file system is easy to map, as it uses the same path
- separator as URIs, has a single root, and segments of "." and ".."
- have the same meaning. URIs that have the character "\0" or "/" as
- part of any path segment can not be turned into valid UNIX file names.
-
- UNIX URI
- ---------- ------------------
- foo/bar <==> foo/bar
- /foo/bar <==> file:/foo/bar
- /foo/bar <== file://localhost/foo/bar
- file: ==> ./file:
- <undef> <== file:/fo%00/bar
- / <==> file:/
-
- =cut
-
-
- 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 mechanism 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".
-
- =head1 SEE ALSO
-
- L<URI>, L<File::Spec>, L<perlport>
-
- =head1 COPYRIGHT
-
- Copyright 1995-1998 Gisle Aas.
-
- This library is free software; you can redistribute it and/or
- modify it under the same terms as Perl itself.
-
- =cut
-