URI::file - URI that map to local file names
$u1 = URI->new("file:/foo/bar"); $u2 = URI->new("foo/bar", "file");
$u3 = URI::file->new($path); $u4 = URI::file->new("c:\\windows\\", "win32");
If you want simply to construct file URI objects from URI strings,
use the normal
The following methods are supported for file URI (in addition to the common and generic methods described in the URI manpage):
$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
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 of any reserved characters that appear in the path segments of the file names. 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 URI 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 that this file name is valid on. The host name ``localhost'' is special and generally have the same meaning as an missing or empty authority field. This use will be 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 URI that map to the same file name. For instance an authority of ``localhost'' maps the same as a URI with a missing or empty authority.
Example 1: The Mac use ``:'' as path separator, but not in the same way as generic URI. ``:foo'' is a relative name. ``foo:bar'' is an absolute name. Also path segments can contain the ``/'' character as well as be literal ``.'' or ``..''. It means that we will map 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 [^:] will be treated as absolute.
Example 2: The Unix file system is easy to map as it use the same path separator as URIs, have 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:/
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.