[perl5.git] / lib / Cwd.pm

package Cwd;
require 5.6.0;

=head1 NAME

Cwd - get pathname of current working directory

=head1 SYNOPSIS

    use Cwd;
    my $dir = getcwd;

    use Cwd 'abs_path';
    my $abs_path = abs_path($file);

=head1 DESCRIPTION

This module provides functions for determining the pathname of the
current working directory.  It is recommended that getcwd (or another
*cwd() function) be used in I<all> code to ensure portability.

By default, it exports the functions cwd(), getcwd(), fastcwd(), and
fastgetcwd() into the caller's namespace.  


=head2 getcwd and friends

Each of these functions are called without arguments and return the
absolute path of the current working directory.

=over 4

=item getcwd

    my $cwd = getcwd();

Returns the current working directory.

Re-implements the getcwd(3) (or getwd(3)) functions in Perl.

=item cwd

    my $cwd = cwd();

The cwd() is the most natural form for the current architecture. For
most systems it is identical to `pwd` (but without the trailing line
terminator).

Unfortunately, cwd() tends to break if called under taint mode.

=item fastcwd

    my $cwd = fastcwd();

A more dangerous version of getcwd(), but potentially faster.

It might conceivably chdir() you out of a directory that it can't
chdir() you back into.  If fastcwd encounters a problem it will return
undef but will probably leave you in a different directory.  For a
measure of extra security, if everything appears to have worked, the
fastcwd() function will check that it leaves you in the same directory
that it started in. If it has changed it will C<die> with the message
"Unstable directory path, current directory changed
unexpectedly". That should never happen.

=item fastgetcwd

  my $cwd = fastgetcwd();

The fastgetcwd() function is provided as a synonym for cwd().

=back


=head2 abs_path and friends

These functions are exported only on request.  They each take a single
argument and return the absolute pathname for it.

=over 4

=item abs_path

  my $abs_path = abs_path($file);

Uses the same algorithm as getcwd().  Symbolic links and relative-path
components ("." and "..") are resolved to return the canonical
pathname, just like realpath(3).

=item realpath

  my $abs_path = realpath($file);

A synonym for abs_path().

=item fast_abs_path

  my $abs_path = abs_path($file);

A more dangerous, but potentially faster version of abs_path.

=back

=head2 $ENV{PWD}

If you ask to override your chdir() built-in function, 

  use Cwd qw(chdir);

then your PWD environment variable will be kept up to date.  Note that
it will only be kept up to date if all packages which use chdir import
it from Cwd.


=head1 NOTES

=over 4

=item *

Since the path seperators are different on some operating systems ('/'
on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
modules wherever portability is a concern.

=item *

Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
functions  are all aliases for the C<cwd()> function, which, on Mac OS,
calls `pwd`. Likewise, the C<abs_path()> function is an alias for
C<fast_abs_path()>.

=back

=head1 SEE ALSO

L<File::chdir>

=cut

use strict;

use Carp;

our $VERSION = '2.06';

use base qw/ Exporter /;
our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);

# sys_cwd may keep the builtin command

# All the functionality of this module may provided by builtins,
# there is no sense to process the rest of the file.
# The best choice may be to have this in BEGIN, but how to return from BEGIN?

if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
    local $^W = 0;
    *cwd		= \&sys_cwd;
    *getcwd		= \&cwd;
    *fastgetcwd		= \&cwd;
    *fastcwd		= \&cwd;
    *abs_path		= \&sys_abspath;
    *fast_abs_path	= \&abs_path;
    *realpath		= \&abs_path;
    *fast_realpath	= \&abs_path;
    return 1;
}

eval {
    require XSLoader;
    XSLoader::load('Cwd');
};


# Find the pwd command in the expected locations.  We assume these
# are safe.  This prevents _backtick_pwd() consulting $ENV{PATH}
# so everything works under taint mode.
my $pwd_cmd;
foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
    if( -x $try ) {
        $pwd_cmd = $try;
        last;
    }
}
$pwd_cmd ||= 'pwd';

# The 'natural and safe form' for UNIX (pwd may be setuid root)
sub _backtick_pwd {
    my $cwd = `$pwd_cmd`;
    # `pwd` may fail e.g. if the disk is full
    chomp($cwd) if defined $cwd;
    $cwd;
}

# Since some ports may predefine cwd internally (e.g., NT)
# we take care not to override an existing definition for cwd().

unless(defined &cwd) {
    # The pwd command is not available in some chroot(2)'ed environments
    if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
	*cwd = \&_backtick_pwd;
    }
    else {
	*cwd = \&getcwd;
    }
}

# set a reasonable (and very safe) default for fastgetcwd, in case it
# isn't redefined later (20001212 rspier)
*fastgetcwd = \&cwd;

# By Brandon S. Allbery
#
# Usage: $cwd = getcwd();

sub getcwd
{
    abs_path('.');
}

# Keeps track of current working directory in PWD environment var
# Usage:
#	use Cwd 'chdir';
#	chdir $newdir;

my $chdir_init = 0;

sub chdir_init {
    if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
	my($dd,$di) = stat('.');
	my($pd,$pi) = stat($ENV{'PWD'});
	if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
	    $ENV{'PWD'} = cwd();
	}
    }
    else {
	my $wd = cwd();
	$wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
	$ENV{'PWD'} = $wd;
    }
    # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
    if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
	my($pd,$pi) = stat($2);
	my($dd,$di) = stat($1);
	if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
	    $ENV{'PWD'}="$2$3";
	}
    }
    $chdir_init = 1;
}

sub chdir {
    my $newdir = @_ ? shift : '';	# allow for no arg (chdir to HOME dir)
    $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
    chdir_init() unless $chdir_init;
    my $newpwd;
    if ($^O eq 'MSWin32') {
	# get the full path name *before* the chdir()
	$newpwd = Win32::GetFullPathName($newdir);
    }

    return 0 unless CORE::chdir $newdir;

    if ($^O eq 'VMS') {
	return $ENV{'PWD'} = $ENV{'DEFAULT'}
    }
    elsif ($^O eq 'MacOS') {
	return $ENV{'PWD'} = cwd();
    }
    elsif ($^O eq 'MSWin32') {
	$ENV{'PWD'} = $newpwd;
	return 1;
    }

    if ($newdir =~ m#^/#s) {
	$ENV{'PWD'} = $newdir;
    } else {
	my @curdir = split(m#/#,$ENV{'PWD'});
	@curdir = ('') unless @curdir;
	my $component;
	foreach $component (split(m#/#, $newdir)) {
	    next if $component eq '.';
	    pop(@curdir),next if $component eq '..';
	    push(@curdir,$component);
	}
	$ENV{'PWD'} = join('/',@curdir) || '/';
    }
    1;
}

# added function alias for those of us more
# used to the libc function.  --tchrist 27-Jan-00
*realpath = \&abs_path;

sub fast_abs_path {
    my $cwd = getcwd();
    require File::Spec;
    my $path = @_ ? shift : File::Spec->curdir;
    CORE::chdir($path) || croak "Cannot chdir to $path:$!";
    my $realpath = getcwd();
    CORE::chdir($cwd)  || croak "Cannot chdir back to $cwd:$!";
    $realpath;
}

# added function alias to follow principle of least surprise
# based on previous aliasing.  --tchrist 27-Jan-00
*fast_realpath = \&fast_abs_path;


# --- PORTING SECTION ---

# VMS: $ENV{'DEFAULT'} points to default directory at all times
# 06-Mar-1996  Charles Bailey  bailey@newman.upenn.edu
# Note: Use of Cwd::chdir() causes the logical name PWD to be defined
#   in the process logical name table as the default device and directory
#   seen by Perl. This may not be the same as the default device
#   and directory seen by DCL after Perl exits, since the effects
#   the CRTL chdir() function persist only until Perl exits.

sub _vms_cwd {
    return $ENV{'DEFAULT'};
}

sub _vms_abs_path {
    return $ENV{'DEFAULT'} unless @_;
    my $path = VMS::Filespec::pathify($_[0]);
    croak("Invalid path name $_[0]") unless defined $path;
    return VMS::Filespec::rmsexpand($path);
}

sub _os2_cwd {
    $ENV{'PWD'} = `cmd /c cd`;
    chop $ENV{'PWD'};
    $ENV{'PWD'} =~ s:\\:/:g ;
    return $ENV{'PWD'};
}

sub _win32_cwd {
    $ENV{'PWD'} = Win32::GetCwd();
    $ENV{'PWD'} =~ s:\\:/:g ;
    return $ENV{'PWD'};
}

*_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd && 
                            defined &Win32::GetCwd);

*_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;

sub _dos_cwd {
    if (!defined &Dos::GetCwd) {
        $ENV{'PWD'} = `command /c cd`;
        chop $ENV{'PWD'};
        $ENV{'PWD'} =~ s:\\:/:g ;
    } else {
        $ENV{'PWD'} = Dos::GetCwd();
    }
    return $ENV{'PWD'};
}

sub _qnx_cwd {
    $ENV{'PWD'} = `/usr/bin/fullpath -t`;
    chop $ENV{'PWD'};
    return $ENV{'PWD'};
}

sub _qnx_abs_path {
    my $path = @_ ? shift : '.';
    my $realpath=`/usr/bin/fullpath -t $path`;
    chop $realpath;
    return $realpath;
}

sub _epoc_cwd {
    $ENV{'PWD'} = EPOC::getcwd();
    return $ENV{'PWD'};
}

{
    no warnings;	# assignments trigger 'subroutine redefined' warning

    if ($^O eq 'VMS') {
        *cwd		= \&_vms_cwd;
        *getcwd		= \&_vms_cwd;
        *fastcwd	= \&_vms_cwd;
        *fastgetcwd	= \&_vms_cwd;
        *abs_path	= \&_vms_abs_path;
        *fast_abs_path	= \&_vms_abs_path;
    }
    elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
        # We assume that &_NT_cwd is defined as an XSUB or in the core.
        *cwd		= \&_NT_cwd;
        *getcwd		= \&_NT_cwd;
        *fastcwd	= \&_NT_cwd;
        *fastgetcwd	= \&_NT_cwd;
        *abs_path	= \&fast_abs_path;
    }
    elsif ($^O eq 'os2') {
        # sys_cwd may keep the builtin command
        *cwd		= defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
        *getcwd		= \&cwd;
        *fastgetcwd	= \&cwd;
        *fastcwd	= \&cwd;
        *abs_path	= \&fast_abs_path;
    }
    elsif ($^O eq 'dos') {
        *cwd		= \&_dos_cwd;
        *getcwd		= \&_dos_cwd;
        *fastgetcwd	= \&_dos_cwd;
        *fastcwd	= \&_dos_cwd;
        *abs_path	= \&fast_abs_path;
    }
    elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
        *cwd		= \&_qnx_cwd;
        *getcwd		= \&_qnx_cwd;
        *fastgetcwd	= \&_qnx_cwd;
        *fastcwd	= \&_qnx_cwd;
        *abs_path	= \&_qnx_abs_path;
        *fast_abs_path	= \&_qnx_abs_path;
    }
    elsif ($^O eq 'cygwin') {
        *getcwd	= \&cwd;
        *fastgetcwd	= \&cwd;
        *fastcwd	= \&cwd;
        *abs_path	= \&fast_abs_path;
    }
    elsif ($^O eq 'epoc') {
        *cwd            = \&_epoc_cwd;
        *getcwd	        = \&_epoc_cwd;
        *fastgetcwd	= \&_epoc_cwd;
        *fastcwd	= \&_epoc_cwd;
        *abs_path	= \&fast_abs_path;
    }
    elsif ($^O eq 'MacOS') {
    	*getcwd     = \&cwd;
    	*fastgetcwd = \&cwd;
    	*fastcwd    = \&cwd;
    	*abs_path   = \&fast_abs_path;
    }
}

# package main; eval join('',<DATA>) || die $@;	# quick test

1;

__END__
BEGIN { import Cwd qw(:DEFAULT chdir); }
print join("\n", cwd, getcwd, fastcwd, "");
chdir('..');
print join("\n", cwd, getcwd, fastcwd, "");
print "$ENV{PWD}\n";
Commit	Line	Data
a0d0e21e	1	package Cwd;
4d6b4052	2	require 5.6.0;
a0d0e21e	3
f06db76b AD	4	=head1 NAME
f06db76b AD	5
902bacac	6	Cwd - get pathname of current working directory
f06db76b AD	7
	8	=head1 SYNOPSIS
	9
4633a7c4	10	use Cwd;
04929354	11	my $dir = getcwd;
4633a7c4	12
04929354 MS	13	use Cwd 'abs_path';
04929354 MS	14	my $abs_path = abs_path($file);
f06db76b	15
04929354	16	=head1 DESCRIPTION
902bacac	17
04929354 MS	18	This module provides functions for determining the pathname of the
	19	current working directory. It is recommended that getcwd (or another
	20	*cwd() function) be used in I<all> code to ensure portability.
f06db76b	21
04929354 MS	22	By default, it exports the functions cwd(), getcwd(), fastcwd(), and
04929354 MS	23	fastgetcwd() into the caller's namespace.
f06db76b	24
20408e3c	25
04929354	26	=head2 getcwd and friends
20408e3c	27
04929354 MS	28	Each of these functions are called without arguments and return the
04929354 MS	29	absolute path of the current working directory.
f06db76b	30
04929354 MS	31	=over 4
	32
	33	=item getcwd
	34
	35	my $cwd = getcwd();
	36
	37	Returns the current working directory.
	38
	39	Re-implements the getcwd(3) (or getwd(3)) functions in Perl.
	40
	41	=item cwd
	42
	43	my $cwd = cwd();
	44
	45	The cwd() is the most natural form for the current architecture. For
	46	most systems it is identical to `pwd` (but without the trailing line
	47	terminator).
	48
	49	Unfortunately, cwd() tends to break if called under taint mode.
	50
	51	=item fastcwd
	52
	53	my $cwd = fastcwd();
	54
	55	A more dangerous version of getcwd(), but potentially faster.
	56
	57	It might conceivably chdir() you out of a directory that it can't
	58	chdir() you back into. If fastcwd encounters a problem it will return
	59	undef but will probably leave you in a different directory. For a
	60	measure of extra security, if everything appears to have worked, the
	61	fastcwd() function will check that it leaves you in the same directory
	62	that it started in. If it has changed it will C<die> with the message
	63	"Unstable directory path, current directory changed
	64	unexpectedly". That should never happen.
	65
	66	=item fastgetcwd
	67
	68	my $cwd = fastgetcwd();
f06db76b	69
902bacac	70	The fastgetcwd() function is provided as a synonym for cwd().
fb73857a	71
04929354 MS	72	=back
04929354 MS	73
902bacac	74
04929354 MS	75	=head2 abs_path and friends
	76
	77	These functions are exported only on request. They each take a single
	78	argument and return the absolute pathname for it.
	79
	80	=over 4
	81
	82	=item abs_path
	83
	84	my $abs_path = abs_path($file);
	85
	86	Uses the same algorithm as getcwd(). Symbolic links and relative-path
	87	components ("." and "..") are resolved to return the canonical
	88	pathname, just like realpath(3).
	89
	90	=item realpath
	91
	92	my $abs_path = realpath($file);
	93
	94	A synonym for abs_path().
	95
	96	=item fast_abs_path
	97
	98	my $abs_path = abs_path($file);
	99
	100	A more dangerous, but potentially faster version of abs_path.
	101
	102	=back
	103
	104	=head2 $ENV{PWD}
	105
	106	If you ask to override your chdir() built-in function,
	107
	108	use Cwd qw(chdir);
	109
	110	then your PWD environment variable will be kept up to date. Note that
	111	it will only be kept up to date if all packages which use chdir import
	112	it from Cwd.
4633a7c4	113
4633a7c4	114
4d6b4052 JH	115	=head1 NOTES
	116
	117	=over 4
	118
	119	=item *
	120
04929354 MS	121	Since the path seperators are different on some operating systems ('/'
	122	on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
	123	modules wherever portability is a concern.
	124
04929354	125	=item *
4d6b4052 JH	126
	127	Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
	128	functions are all aliases for the C<cwd()> function, which, on Mac OS,
	129	calls `pwd`. Likewise, the C<abs_path()> function is an alias for
	130	C<fast_abs_path()>.
	131
	132	=back
	133
04929354 MS	134	=head1 SEE ALSO
	135
	136	L<File::chdir>
	137
f06db76b AD	138	=cut
f06db76b AD	139
b060a406	140	use strict;
96e4d5b1 PP	141
	142	use Carp;
	143
04929354	144	our $VERSION = '2.06';
96e4d5b1	145
b060a406 TJ	146	use base qw/ Exporter /;
	147	our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
	148	our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
a0d0e21e	149
f5f423e4 IZ	150	# sys_cwd may keep the builtin command
	151
	152	# All the functionality of this module may provided by builtins,
	153	# there is no sense to process the rest of the file.
	154	# The best choice may be to have this in BEGIN, but how to return from BEGIN?
	155
	156	if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
	157	local $^W = 0;
	158	*cwd = \&sys_cwd;
	159	*getcwd = \&cwd;
	160	*fastgetcwd = \&cwd;
	161	*fastcwd = \&cwd;
	162	*abs_path = \&sys_abspath;
	163	*fast_abs_path = \&abs_path;
	164	*realpath = \&abs_path;
	165	*fast_realpath = \&abs_path;
	166	return 1;
	167	}
	168
f22d8e4b DM	169	eval {
	170	require XSLoader;
	171	XSLoader::load('Cwd');
	172	};
4633a7c4	173
96e4d5b1	174
3547aa9a MS	175	# Find the pwd command in the expected locations. We assume these
	176	# are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
	177	# so everything works under taint mode.
	178	my $pwd_cmd;
	179	foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
	180	if( -x $try ) {
	181	$pwd_cmd = $try;
	182	last;
	183	}
	184	}
	185	$pwd_cmd \|\|= 'pwd';
	186
	187	# The 'natural and safe form' for UNIX (pwd may be setuid root)
8b88ae92	188	sub _backtick_pwd {
3547aa9a	189	my $cwd = `$pwd_cmd`;
7e03f963 TJ	190	# `pwd` may fail e.g. if the disk is full
7e03f963 TJ	191	chomp($cwd) if defined $cwd;
4633a7c4	192	$cwd;
8b88ae92	193	}
4633a7c4 LW	194
	195	# Since some ports may predefine cwd internally (e.g., NT)
	196	# we take care not to override an existing definition for cwd().
	197
ea54c8bd EC	198	unless(defined &cwd) {
ea54c8bd EC	199	# The pwd command is not available in some chroot(2)'ed environments
4aecb5b5	200	if($^O eq 'MacOS' \|\| grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
ea54c8bd EC	201	*cwd = \&_backtick_pwd;
	202	}
	203	else {
	204	*cwd = \&getcwd;
	205	}
	206	}
a0d0e21e	207
1f4f94f5 RS	208	# set a reasonable (and very safe) default for fastgetcwd, in case it
	209	# isn't redefined later (20001212 rspier)
	210	*fastgetcwd = \&cwd;
748a9306	211
a0d0e21e LW	212	# By Brandon S. Allbery
	213	#
	214	# Usage: $cwd = getcwd();
	215
	216	sub getcwd
	217	{
07569ed3	218	abs_path('.');
a0d0e21e LW	219	}
a0d0e21e LW	220
4633a7c4	221	# Keeps track of current working directory in PWD environment var
a0d0e21e LW	222	# Usage:
	223	# use Cwd 'chdir';
	224	# chdir $newdir;
	225
4633a7c4	226	my $chdir_init = 0;
a0d0e21e	227
4633a7c4	228	sub chdir_init {
3b8e3443	229	if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
a0d0e21e LW	230	my($dd,$di) = stat('.');
	231	my($pd,$pi) = stat($ENV{'PWD'});
	232	if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
4633a7c4	233	$ENV{'PWD'} = cwd();
a0d0e21e LW	234	}
	235	}
	236	else {
3b8e3443 GS	237	my $wd = cwd();
	238	$wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
	239	$ENV{'PWD'} = $wd;
a0d0e21e	240	}
4633a7c4	241	# Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
3b8e3443	242	if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m\|(/[^/]+(/[^/]+/[^/]+))(.*)\|s) {
a0d0e21e LW	243	my($pd,$pi) = stat($2);
	244	my($dd,$di) = stat($1);
	245	if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
	246	$ENV{'PWD'}="$2$3";
	247	}
	248	}
	249	$chdir_init = 1;
	250	}
	251
	252	sub chdir {
22978713	253	my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
3b8e3443	254	$newdir =~ s\|///*\|/\|g unless $^O eq 'MSWin32';
a0d0e21e	255	chdir_init() unless $chdir_init;
4ffa1610 JH	256	my $newpwd;
	257	if ($^O eq 'MSWin32') {
	258	# get the full path name before the chdir()
	259	$newpwd = Win32::GetFullPathName($newdir);
	260	}
	261
4633a7c4	262	return 0 unless CORE::chdir $newdir;
4ffa1610	263
3b8e3443 GS	264	if ($^O eq 'VMS') {
	265	return $ENV{'PWD'} = $ENV{'DEFAULT'}
	266	}
4aecb5b5 JH	267	elsif ($^O eq 'MacOS') {
	268	return $ENV{'PWD'} = cwd();
	269	}
3b8e3443	270	elsif ($^O eq 'MSWin32') {
4ffa1610	271	$ENV{'PWD'} = $newpwd;
3b8e3443 GS	272	return 1;
3b8e3443 GS	273	}
748a9306	274
392d8ab8	275	if ($newdir =~ m#^/#s) {
a0d0e21e	276	$ENV{'PWD'} = $newdir;
4633a7c4 LW	277	} else {
	278	my @curdir = split(m#/#,$ENV{'PWD'});
	279	@curdir = ('') unless @curdir;
	280	my $component;
a0d0e21e LW	281	foreach $component (split(m#/#, $newdir)) {
	282	next if $component eq '.';
	283	pop(@curdir),next if $component eq '..';
	284	push(@curdir,$component);
	285	}
	286	$ENV{'PWD'} = join('/',@curdir) \|\| '/';
	287	}
4633a7c4	288	1;
a0d0e21e LW	289	}
a0d0e21e LW	290
e4c51978 GS	291	# added function alias for those of us more
	292	# used to the libc function. --tchrist 27-Jan-00
	293	*realpath = \&abs_path;
	294
96e4d5b1 PP	295	sub fast_abs_path {
96e4d5b1 PP	296	my $cwd = getcwd();
4d6b4052 JH	297	require File::Spec;
4d6b4052 JH	298	my $path = @_ ? shift : File::Spec->curdir;
e79e61e4	299	CORE::chdir($path) \|\| croak "Cannot chdir to $path:$!";
96e4d5b1	300	my $realpath = getcwd();
e79e61e4	301	CORE::chdir($cwd) \|\| croak "Cannot chdir back to $cwd:$!";
96e4d5b1	302	$realpath;
8b88ae92 NIS	303	}
8b88ae92 NIS	304
e4c51978 GS	305	# added function alias to follow principle of least surprise
	306	# based on previous aliasing. --tchrist 27-Jan-00
	307	*fast_realpath = \&fast_abs_path;
	308
4633a7c4 LW	309
	310	# --- PORTING SECTION ---
	311
	312	# VMS: $ENV{'DEFAULT'} points to default directory at all times
bd3fa61c	313	# 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
c6538b72	314	# Note: Use of Cwd::chdir() causes the logical name PWD to be defined
8b88ae92 NIS	315	# in the process logical name table as the default device and directory
8b88ae92 NIS	316	# seen by Perl. This may not be the same as the default device
4633a7c4 LW	317	# and directory seen by DCL after Perl exits, since the effects
4633a7c4 LW	318	# the CRTL chdir() function persist only until Perl exits.
4633a7c4 LW	319
4633a7c4 LW	320	sub _vms_cwd {
96e4d5b1 PP	321	return $ENV{'DEFAULT'};
	322	}
	323
	324	sub _vms_abs_path {
	325	return $ENV{'DEFAULT'} unless @_;
	326	my $path = VMS::Filespec::pathify($_[0]);
	327	croak("Invalid path name $_[0]") unless defined $path;
	328	return VMS::Filespec::rmsexpand($path);
4633a7c4	329	}
68dc0745	330
4633a7c4 LW	331	sub _os2_cwd {
	332	$ENV{'PWD'} = `cmd /c cd`;
	333	chop $ENV{'PWD'};
	334	$ENV{'PWD'} =~ s:\\:/:g ;
	335	return $ENV{'PWD'};
	336	}
	337
96e4d5b1	338	sub _win32_cwd {
2d7a9237	339	$ENV{'PWD'} = Win32::GetCwd();
96e4d5b1 PP	340	$ENV{'PWD'} =~ s:\\:/:g ;
	341	return $ENV{'PWD'};
	342	}
	343
	344	*_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
2d7a9237	345	defined &Win32::GetCwd);
96e4d5b1 PP	346
96e4d5b1 PP	347	*_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
68dc0745	348
39e571d4 ML	349	sub _dos_cwd {
	350	if (!defined &Dos::GetCwd) {
	351	$ENV{'PWD'} = `command /c cd`;
	352	chop $ENV{'PWD'};
	353	$ENV{'PWD'} =~ s:\\:/:g ;
	354	} else {
	355	$ENV{'PWD'} = Dos::GetCwd();
	356	}
55497cff PP	357	return $ENV{'PWD'};
	358	}
	359
7fbf1995 NA	360	sub _qnx_cwd {
	361	$ENV{'PWD'} = `/usr/bin/fullpath -t`;
	362	chop $ENV{'PWD'};
	363	return $ENV{'PWD'};
	364	}
	365
	366	sub _qnx_abs_path {
fa921dc6	367	my $path = @_ ? shift : '.';
7fbf1995 NA	368	my $realpath=`/usr/bin/fullpath -t $path`;
	369	chop $realpath;
	370	return $realpath;
	371	}
	372
ed79a026 OF	373	sub _epoc_cwd {
	374	$ENV{'PWD'} = EPOC::getcwd();
	375	return $ENV{'PWD'};
	376	}
	377
ac1ad7f0	378	{
db376a24	379	no warnings; # assignments trigger 'subroutine redefined' warning
4633a7c4	380
ac1ad7f0	381	if ($^O eq 'VMS') {
96e4d5b1 PP	382	*cwd = \&_vms_cwd;
	383	*getcwd = \&_vms_cwd;
	384	*fastcwd = \&_vms_cwd;
	385	*fastgetcwd = \&_vms_cwd;
	386	*abs_path = \&_vms_abs_path;
	387	*fast_abs_path = \&_vms_abs_path;
ac1ad7f0 PM	388	}
	389	elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
	390	# We assume that &_NT_cwd is defined as an XSUB or in the core.
96e4d5b1 PP	391	*cwd = \&_NT_cwd;
	392	*getcwd = \&_NT_cwd;
	393	*fastcwd = \&_NT_cwd;
	394	*fastgetcwd = \&_NT_cwd;
	395	*abs_path = \&fast_abs_path;
ac1ad7f0 PM	396	}
	397	elsif ($^O eq 'os2') {
	398	# sys_cwd may keep the builtin command
96e4d5b1 PP	399	*cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
	400	*getcwd = \&cwd;
	401	*fastgetcwd = \&cwd;
	402	*fastcwd = \&cwd;
	403	*abs_path = \&fast_abs_path;
ac1ad7f0	404	}
39e571d4 ML	405	elsif ($^O eq 'dos') {
	406	*cwd = \&_dos_cwd;
	407	*getcwd = \&_dos_cwd;
	408	*fastgetcwd = \&_dos_cwd;
	409	*fastcwd = \&_dos_cwd;
96e4d5b1	410	*abs_path = \&fast_abs_path;
ac1ad7f0	411	}
7438b6ad	412	elsif ($^O =~ m/^(?:qnx\|nto)$/ ) {
7fbf1995 NA	413	*cwd = \&_qnx_cwd;
	414	*getcwd = \&_qnx_cwd;
	415	*fastgetcwd = \&_qnx_cwd;
	416	*fastcwd = \&_qnx_cwd;
	417	*abs_path = \&_qnx_abs_path;
	418	*fast_abs_path = \&_qnx_abs_path;
	419	}
4fabb596	420	elsif ($^O eq 'cygwin') {
1cab015a FE	421	*getcwd = \&cwd;
	422	*fastgetcwd = \&cwd;
	423	*fastcwd = \&cwd;
	424	*abs_path = \&fast_abs_path;
	425	}
ed79a026	426	elsif ($^O eq 'epoc') {
fa6a1c44 OF	427	*cwd = \&_epoc_cwd;
fa6a1c44 OF	428	*getcwd = \&_epoc_cwd;
ed79a026 OF	429	*fastgetcwd = \&_epoc_cwd;
	430	*fastcwd = \&_epoc_cwd;
	431	*abs_path = \&fast_abs_path;
	432	}
4aecb5b5 JH	433	elsif ($^O eq 'MacOS') {
	434	*getcwd = \&cwd;
	435	*fastgetcwd = \&cwd;
	436	*fastcwd = \&cwd;
	437	*abs_path = \&fast_abs_path;
	438	}
55497cff	439	}
4633a7c4 LW	440
	441	# package main; eval join('',<DATA>) \|\| die $@; # quick test
	442
a0d0e21e LW	443	1;
a0d0e21e LW	444
4633a7c4 LW	445	__END__
	446	BEGIN { import Cwd qw(:DEFAULT chdir); }
	447	print join("\n", cwd, getcwd, fastcwd, "");
	448	chdir('..');
	449	print join("\n", cwd, getcwd, fastcwd, "");
	450	print "$ENV{PWD}\n";