[p5sagit/p5-mst-13.2.git] / lib / Cwd.pm

package Cwd;
use 5.006;

=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.

Taint-safe.

=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).

Taint-safe.

=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).

Taint-safe.

=item realpath

  my $abs_path = realpath($file);

A synonym for abs_path().

Taint-safe.

=item fast_abs_path

  my $abs_path = fast_abs_path($file);

A more dangerous, but potentially faster version of abs_path.

This function is B<Not> taint-safe : you can't use it in programs
that work under taint mode.

=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;
    undef *Cwd::fastcwd; # avoid redefinition warning
    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 {
    local $ENV{PATH};
    local $ENV{IFS};
    local $ENV{CDPATH};
    local $ENV{ENV};
    local $ENV{BASH_ENV};
    my $cwd = `$pwd_cmd`;
    # Belt-and-suspenders in case someone said "undef $/".
    local $/ = "\n";
    # `pwd` may fail e.g. if the disk is full
    chomp($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' || (defined $ENV{PATH} && 
                           grep { -x "$_/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('.');
}


# By John Bazik
#
# Usage: $cwd = &fastcwd;
#
# This is a faster version of getcwd.  It's also more dangerous because
# you might chdir out of a directory that you can't chdir back into.
    
sub fastcwd {
    my($odev, $oino, $cdev, $cino, $tdev, $tino);
    my(@path, $path);
    local(*DIR);

    my($orig_cdev, $orig_cino) = stat('.');
    ($cdev, $cino) = ($orig_cdev, $orig_cino);
    for (;;) {
	my $direntry;
	($odev, $oino) = ($cdev, $cino);
	CORE::chdir('..') || return undef;
	($cdev, $cino) = stat('.');
	last if $odev == $cdev && $oino == $cino;
	opendir(DIR, '.') || return undef;
	for (;;) {
	    $direntry = readdir(DIR);
	    last unless defined $direntry;
	    next if $direntry eq '.';
	    next if $direntry eq '..';

	    ($tdev, $tino) = lstat($direntry);
	    last unless $tdev != $odev || $tino != $oino;
	}
	closedir(DIR);
	return undef unless defined $direntry; # should never happen
	unshift(@path, $direntry);
    }
    $path = '/' . join('/', @path);
    if ($^O eq 'apollo') { $path = "/".$path; }
    # At this point $path may be tainted (if tainting) and chdir would fail.
    # Untaint it then check that we landed where we started.
    $path =~ /^(.*)\z/s		# untaint
	&& CORE::chdir($1) or return undef;
    ($cdev, $cino) = stat('.');
    die "Unstable directory path, current directory changed unexpectedly"
	if $cdev != $orig_cdev || $cino != $orig_cino;
    $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;
}


# In case the XS version doesn't load.
*abs_path = \&_perl_abs_path unless defined &abs_path;
sub _perl_abs_path
{
    my $start = @_ ? shift : '.';
    my($dotdots, $cwd, @pst, @cst, $dir, @tst);

    unless (@cst = stat( $start ))
    {
	carp "stat($start): $!";
	return '';
    }
    $cwd = '';
    $dotdots = $start;
    do
    {
	$dotdots .= '/..';
	@pst = @cst;
	unless (opendir(PARENT, $dotdots))
	{
	    carp "opendir($dotdots): $!";
	    return '';
	}
	unless (@cst = stat($dotdots))
	{
	    carp "stat($dotdots): $!";
	    closedir(PARENT);
	    return '';
	}
	if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
	{
	    $dir = undef;
	}
	else
	{
	    do
	    {
		unless (defined ($dir = readdir(PARENT)))
	        {
		    carp "readdir($dotdots): $!";
		    closedir(PARENT);
		    return '';
		}
		$tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
	    }
	    while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
		   $tst[1] != $pst[1]);
	}
	$cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
	closedir(PARENT);
    } while (defined $dir);
    chop($cwd) unless $cwd eq '/'; # drop the trailing /
    $cwd;
}


# 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();
    -d $cwd && CORE::chdir($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 {
	local $ENV{PATH} = '';
	local $ENV{CDPATH} = '';
	local $ENV{ENV} = '';
    $ENV{'PWD'} = `/usr/bin/fullpath -t`;
    chop $ENV{'PWD'};
    return $ENV{'PWD'};
}

sub _qnx_abs_path {
	local $ENV{PATH} = '';
	local $ENV{CDPATH} = '';
	local $ENV{ENV} = '';
    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 $^O eq 'MSWin32') {
        # We assume that &_NT_cwd is defined as an XSUB or in the core.
        *cwd		= \&_NT_cwd;
        *getcwd		= \&_NT_cwd;
        *fastcwd	= \&_NT_cwd;
        *fastgetcwd	= \&_NT_cwd;
        *abs_path	= \&fast_abs_path;
        *realpath   = \&fast_abs_path;
    }
    elsif ($^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;
    }
}


1;
Commit	Line	Data
a0d0e21e	1	package Cwd;
3b825e41	2	use 5.006;
a0d0e21e	3
f06db76b	4	=head1 NAME
f06db76b	5
902bacac	6	Cwd - get pathname of current working directory
f06db76b	7
	8	=head1 SYNOPSIS
	9
4633a7c4	10	use Cwd;
04929354	11	my $dir = getcwd;
4633a7c4	12
04929354	13	use Cwd 'abs_path';
04929354	14	my $abs_path = abs_path($file);
f06db76b	15
04929354	16	=head1 DESCRIPTION
902bacac	17
04929354	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	22	By default, it exports the functions cwd(), getcwd(), fastcwd(), and
04929354	23	fastgetcwd() into the caller's namespace.
f06db76b	24
20408e3c	25
04929354	26	=head2 getcwd and friends
20408e3c	27
04929354	28	Each of these functions are called without arguments and return the
04929354	29	absolute path of the current working directory.
f06db76b	30
04929354	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
bde417e1	41	Taint-safe.
bde417e1	42
04929354	43	=item cwd
	44
	45	my $cwd = cwd();
	46
	47	The cwd() is the most natural form for the current architecture. For
	48	most systems it is identical to `pwd` (but without the trailing line
	49	terminator).
	50
248785eb	51	Taint-safe.
04929354	52
	53	=item fastcwd
	54
	55	my $cwd = fastcwd();
	56
	57	A more dangerous version of getcwd(), but potentially faster.
	58
	59	It might conceivably chdir() you out of a directory that it can't
	60	chdir() you back into. If fastcwd encounters a problem it will return
	61	undef but will probably leave you in a different directory. For a
	62	measure of extra security, if everything appears to have worked, the
	63	fastcwd() function will check that it leaves you in the same directory
	64	that it started in. If it has changed it will C<die> with the message
	65	"Unstable directory path, current directory changed
	66	unexpectedly". That should never happen.
	67
	68	=item fastgetcwd
	69
	70	my $cwd = fastgetcwd();
f06db76b	71
902bacac	72	The fastgetcwd() function is provided as a synonym for cwd().
fb73857a	73
04929354	74	=back
04929354	75
902bacac	76
04929354	77	=head2 abs_path and friends
	78
	79	These functions are exported only on request. They each take a single
	80	argument and return the absolute pathname for it.
	81
	82	=over 4
	83
	84	=item abs_path
	85
	86	my $abs_path = abs_path($file);
	87
	88	Uses the same algorithm as getcwd(). Symbolic links and relative-path
	89	components ("." and "..") are resolved to return the canonical
	90	pathname, just like realpath(3).
	91
bde417e1	92	Taint-safe.
bde417e1	93
04929354	94	=item realpath
	95
	96	my $abs_path = realpath($file);
	97
	98	A synonym for abs_path().
	99
bde417e1	100	Taint-safe.
bde417e1	101
04929354	102	=item fast_abs_path
04929354	103
510179aa	104	my $abs_path = fast_abs_path($file);
04929354	105
	106	A more dangerous, but potentially faster version of abs_path.
	107
248785eb	108	This function is B<Not> taint-safe : you can't use it in programs
248785eb	109	that work under taint mode.
bde417e1	110
04929354	111	=back
	112
	113	=head2 $ENV{PWD}
	114
	115	If you ask to override your chdir() built-in function,
	116
	117	use Cwd qw(chdir);
	118
	119	then your PWD environment variable will be kept up to date. Note that
	120	it will only be kept up to date if all packages which use chdir import
	121	it from Cwd.
4633a7c4	122
4633a7c4	123
4d6b4052	124	=head1 NOTES
	125
	126	=over 4
	127
	128	=item *
	129
04929354	130	Since the path seperators are different on some operating systems ('/'
	131	on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
	132	modules wherever portability is a concern.
	133
04929354	134	=item *
4d6b4052	135
	136	Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
	137	functions are all aliases for the C<cwd()> function, which, on Mac OS,
	138	calls `pwd`. Likewise, the C<abs_path()> function is an alias for
	139	C<fast_abs_path()>.
	140
	141	=back
	142
04929354	143	=head1 SEE ALSO
	144
	145	L<File::chdir>
	146
f06db76b	147	=cut
f06db76b	148
b060a406	149	use strict;
96e4d5b1	150
	151	use Carp;
	152
04929354	153	our $VERSION = '2.06';
96e4d5b1	154
b060a406	155	use base qw/ Exporter /;
	156	our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
	157	our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
a0d0e21e	158
f5f423e4	159	# sys_cwd may keep the builtin command
	160
	161	# All the functionality of this module may provided by builtins,
	162	# there is no sense to process the rest of the file.
	163	# The best choice may be to have this in BEGIN, but how to return from BEGIN?
	164
	165	if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
	166	local $^W = 0;
	167	*cwd = \&sys_cwd;
	168	*getcwd = \&cwd;
	169	*fastgetcwd = \&cwd;
	170	*fastcwd = \&cwd;
	171	*abs_path = \&sys_abspath;
	172	*fast_abs_path = \&abs_path;
	173	*realpath = \&abs_path;
	174	*fast_realpath = \&abs_path;
	175	return 1;
	176	}
	177
f22d8e4b	178	eval {
f22d8e4b	179	require XSLoader;
716e3b8c	180	undef *Cwd::fastcwd; # avoid redefinition warning
f22d8e4b	181	XSLoader::load('Cwd');
f22d8e4b	182	};
4633a7c4	183
96e4d5b1	184
3547aa9a	185	# Find the pwd command in the expected locations. We assume these
	186	# are safe. This prevents _backtick_pwd() consulting $ENV{PATH}
	187	# so everything works under taint mode.
	188	my $pwd_cmd;
	189	foreach my $try (qw(/bin/pwd /usr/bin/pwd)) {
	190	if( -x $try ) {
	191	$pwd_cmd = $try;
	192	last;
	193	}
	194	}
	195	$pwd_cmd \|\|= 'pwd';
	196
	197	# The 'natural and safe form' for UNIX (pwd may be setuid root)
8b88ae92	198	sub _backtick_pwd {
680d0beb	199	local $ENV{PATH};
	200	local $ENV{IFS};
	201	local $ENV{CDPATH};
	202	local $ENV{ENV};
	203	local $ENV{BASH_ENV};
3547aa9a	204	my $cwd = `$pwd_cmd`;
ac3b20cb	205	# Belt-and-suspenders in case someone said "undef $/".
5cf6da5f	206	local $/ = "\n";
ac3b20cb	207	# `pwd` may fail e.g. if the disk is full
7e03f963	208	chomp($cwd) if defined $cwd;
4633a7c4	209	$cwd;
8b88ae92	210	}
4633a7c4	211
	212	# Since some ports may predefine cwd internally (e.g., NT)
	213	# we take care not to override an existing definition for cwd().
	214
ea54c8bd	215	unless(defined &cwd) {
ea54c8bd	216	# The pwd command is not available in some chroot(2)'ed environments
73b801a6	217	if( $^O eq 'MacOS' \|\| (defined $ENV{PATH} &&
	218	grep { -x "$_/pwd" } split(':', $ENV{PATH})) )
	219	{
ea54c8bd	220	*cwd = \&_backtick_pwd;
	221	}
	222	else {
	223	*cwd = \&getcwd;
	224	}
	225	}
a0d0e21e	226
1f4f94f5	227	# set a reasonable (and very safe) default for fastgetcwd, in case it
	228	# isn't redefined later (20001212 rspier)
	229	*fastgetcwd = \&cwd;
748a9306	230
a0d0e21e	231	# By Brandon S. Allbery
	232	#
	233	# Usage: $cwd = getcwd();
	234
	235	sub getcwd
	236	{
07569ed3	237	abs_path('.');
a0d0e21e	238	}
a0d0e21e	239
a0c9c202	240
	241	# By John Bazik
	242	#
	243	# Usage: $cwd = &fastcwd;
	244	#
	245	# This is a faster version of getcwd. It's also more dangerous because
	246	# you might chdir out of a directory that you can't chdir back into.
	247
	248	sub fastcwd {
	249	my($odev, $oino, $cdev, $cino, $tdev, $tino);
	250	my(@path, $path);
	251	local(*DIR);
	252
	253	my($orig_cdev, $orig_cino) = stat('.');
	254	($cdev, $cino) = ($orig_cdev, $orig_cino);
	255	for (;;) {
	256	my $direntry;
	257	($odev, $oino) = ($cdev, $cino);
	258	CORE::chdir('..') \|\| return undef;
	259	($cdev, $cino) = stat('.');
	260	last if $odev == $cdev && $oino == $cino;
	261	opendir(DIR, '.') \|\| return undef;
	262	for (;;) {
	263	$direntry = readdir(DIR);
	264	last unless defined $direntry;
	265	next if $direntry eq '.';
	266	next if $direntry eq '..';
	267
	268	($tdev, $tino) = lstat($direntry);
	269	last unless $tdev != $odev \|\| $tino != $oino;
	270	}
	271	closedir(DIR);
	272	return undef unless defined $direntry; # should never happen
	273	unshift(@path, $direntry);
	274	}
	275	$path = '/' . join('/', @path);
	276	if ($^O eq 'apollo') { $path = "/".$path; }
	277	# At this point $path may be tainted (if tainting) and chdir would fail.
248785eb	278	# Untaint it then check that we landed where we started.
	279	$path =~ /^(.*)\z/s # untaint
	280	&& CORE::chdir($1) or return undef;
a0c9c202	281	($cdev, $cino) = stat('.');
	282	die "Unstable directory path, current directory changed unexpectedly"
	283	if $cdev != $orig_cdev \|\| $cino != $orig_cino;
	284	$path;
	285	}
	286
	287
4633a7c4	288	# Keeps track of current working directory in PWD environment var
a0d0e21e	289	# Usage:
	290	# use Cwd 'chdir';
	291	# chdir $newdir;
	292
4633a7c4	293	my $chdir_init = 0;
a0d0e21e	294
4633a7c4	295	sub chdir_init {
3b8e3443	296	if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
a0d0e21e	297	my($dd,$di) = stat('.');
	298	my($pd,$pi) = stat($ENV{'PWD'});
	299	if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
4633a7c4	300	$ENV{'PWD'} = cwd();
a0d0e21e	301	}
	302	}
	303	else {
3b8e3443	304	my $wd = cwd();
	305	$wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
	306	$ENV{'PWD'} = $wd;
a0d0e21e	307	}
4633a7c4	308	# Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
3b8e3443	309	if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m\|(/[^/]+(/[^/]+/[^/]+))(.*)\|s) {
a0d0e21e	310	my($pd,$pi) = stat($2);
	311	my($dd,$di) = stat($1);
	312	if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
	313	$ENV{'PWD'}="$2$3";
	314	}
	315	}
	316	$chdir_init = 1;
	317	}
	318
	319	sub chdir {
22978713	320	my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
3b8e3443	321	$newdir =~ s\|///*\|/\|g unless $^O eq 'MSWin32';
a0d0e21e	322	chdir_init() unless $chdir_init;
4ffa1610	323	my $newpwd;
	324	if ($^O eq 'MSWin32') {
	325	# get the full path name before the chdir()
	326	$newpwd = Win32::GetFullPathName($newdir);
	327	}
	328
4633a7c4	329	return 0 unless CORE::chdir $newdir;
4ffa1610	330
3b8e3443	331	if ($^O eq 'VMS') {
	332	return $ENV{'PWD'} = $ENV{'DEFAULT'}
	333	}
4aecb5b5	334	elsif ($^O eq 'MacOS') {
	335	return $ENV{'PWD'} = cwd();
	336	}
3b8e3443	337	elsif ($^O eq 'MSWin32') {
4ffa1610	338	$ENV{'PWD'} = $newpwd;
3b8e3443	339	return 1;
3b8e3443	340	}
748a9306	341
392d8ab8	342	if ($newdir =~ m#^/#s) {
a0d0e21e	343	$ENV{'PWD'} = $newdir;
4633a7c4	344	} else {
	345	my @curdir = split(m#/#,$ENV{'PWD'});
	346	@curdir = ('') unless @curdir;
	347	my $component;
a0d0e21e	348	foreach $component (split(m#/#, $newdir)) {
	349	next if $component eq '.';
	350	pop(@curdir),next if $component eq '..';
	351	push(@curdir,$component);
	352	}
	353	$ENV{'PWD'} = join('/',@curdir) \|\| '/';
	354	}
4633a7c4	355	1;
a0d0e21e	356	}
a0d0e21e	357
a0c9c202	358
	359	# In case the XS version doesn't load.
	360	*abs_path = \&_perl_abs_path unless defined &abs_path;
	361	sub _perl_abs_path
	362	{
	363	my $start = @_ ? shift : '.';
	364	my($dotdots, $cwd, @pst, @cst, $dir, @tst);
	365
	366	unless (@cst = stat( $start ))
	367	{
	368	carp "stat($start): $!";
	369	return '';
	370	}
	371	$cwd = '';
	372	$dotdots = $start;
	373	do
	374	{
	375	$dotdots .= '/..';
	376	@pst = @cst;
	377	unless (opendir(PARENT, $dotdots))
	378	{
	379	carp "opendir($dotdots): $!";
	380	return '';
	381	}
	382	unless (@cst = stat($dotdots))
	383	{
	384	carp "stat($dotdots): $!";
	385	closedir(PARENT);
	386	return '';
	387	}
	388	if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
	389	{
	390	$dir = undef;
	391	}
	392	else
	393	{
	394	do
	395	{
	396	unless (defined ($dir = readdir(PARENT)))
	397	{
	398	carp "readdir($dotdots): $!";
	399	closedir(PARENT);
	400	return '';
	401	}
	402	$tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
	403	}
	404	while ($dir eq '.' \|\| $dir eq '..' \|\| $tst[0] != $pst[0] \|\|
	405	$tst[1] != $pst[1]);
	406	}
	407	$cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
	408	closedir(PARENT);
	409	} while (defined $dir);
	410	chop($cwd) unless $cwd eq '/'; # drop the trailing /
	411	$cwd;
	412	}
	413
	414
e4c51978	415	# added function alias for those of us more
	416	# used to the libc function. --tchrist 27-Jan-00
	417	*realpath = \&abs_path;
	418
96e4d5b1	419	sub fast_abs_path {
96e4d5b1	420	my $cwd = getcwd();
4d6b4052	421	require File::Spec;
4d6b4052	422	my $path = @_ ? shift : File::Spec->curdir;
926cbafe	423	CORE::chdir($path) \|\| croak "Cannot chdir to $path: $!";
96e4d5b1	424	my $realpath = getcwd();
bde417e1	425	-d $cwd && CORE::chdir($cwd) \|\|
926cbafe	426	croak "Cannot chdir back to $cwd: $!";
96e4d5b1	427	$realpath;
8b88ae92	428	}
8b88ae92	429
e4c51978	430	# added function alias to follow principle of least surprise
	431	# based on previous aliasing. --tchrist 27-Jan-00
	432	*fast_realpath = \&fast_abs_path;
	433
4633a7c4	434
	435	# --- PORTING SECTION ---
	436
	437	# VMS: $ENV{'DEFAULT'} points to default directory at all times
bd3fa61c	438	# 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
c6538b72	439	# Note: Use of Cwd::chdir() causes the logical name PWD to be defined
8b88ae92	440	# in the process logical name table as the default device and directory
8b88ae92	441	# seen by Perl. This may not be the same as the default device
4633a7c4	442	# and directory seen by DCL after Perl exits, since the effects
4633a7c4	443	# the CRTL chdir() function persist only until Perl exits.
4633a7c4	444
4633a7c4	445	sub _vms_cwd {
96e4d5b1	446	return $ENV{'DEFAULT'};
	447	}
	448
	449	sub _vms_abs_path {
	450	return $ENV{'DEFAULT'} unless @_;
	451	my $path = VMS::Filespec::pathify($_[0]);
	452	croak("Invalid path name $_[0]") unless defined $path;
	453	return VMS::Filespec::rmsexpand($path);
4633a7c4	454	}
68dc0745	455
4633a7c4	456	sub _os2_cwd {
	457	$ENV{'PWD'} = `cmd /c cd`;
	458	chop $ENV{'PWD'};
aa6b7957	459	$ENV{'PWD'} =~ s:\\:/:g ;
4633a7c4	460	return $ENV{'PWD'};
	461	}
	462
96e4d5b1	463	sub _win32_cwd {
2d7a9237	464	$ENV{'PWD'} = Win32::GetCwd();
aa6b7957	465	$ENV{'PWD'} =~ s:\\:/:g ;
96e4d5b1	466	return $ENV{'PWD'};
	467	}
	468
	469	*_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
2d7a9237	470	defined &Win32::GetCwd);
96e4d5b1	471
96e4d5b1	472	*_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
68dc0745	473
39e571d4	474	sub _dos_cwd {
	475	if (!defined &Dos::GetCwd) {
	476	$ENV{'PWD'} = `command /c cd`;
	477	chop $ENV{'PWD'};
aa6b7957	478	$ENV{'PWD'} =~ s:\\:/:g ;
39e571d4	479	} else {
	480	$ENV{'PWD'} = Dos::GetCwd();
	481	}
55497cff	482	return $ENV{'PWD'};
	483	}
	484
7fbf1995	485	sub _qnx_cwd {
35b807ef	486	local $ENV{PATH} = '';
	487	local $ENV{CDPATH} = '';
	488	local $ENV{ENV} = '';
7fbf1995	489	$ENV{'PWD'} = `/usr/bin/fullpath -t`;
	490	chop $ENV{'PWD'};
	491	return $ENV{'PWD'};
	492	}
	493
	494	sub _qnx_abs_path {
35b807ef	495	local $ENV{PATH} = '';
	496	local $ENV{CDPATH} = '';
	497	local $ENV{ENV} = '';
fa921dc6	498	my $path = @_ ? shift : '.';
7fbf1995	499	my $realpath=`/usr/bin/fullpath -t $path`;
	500	chop $realpath;
	501	return $realpath;
	502	}
	503
ed79a026	504	sub _epoc_cwd {
	505	$ENV{'PWD'} = EPOC::getcwd();
	506	return $ENV{'PWD'};
	507	}
	508
ac1ad7f0	509	{
db376a24	510	no warnings; # assignments trigger 'subroutine redefined' warning
4633a7c4	511
ac1ad7f0	512	if ($^O eq 'VMS') {
96e4d5b1	513	*cwd = \&_vms_cwd;
	514	*getcwd = \&_vms_cwd;
	515	*fastcwd = \&_vms_cwd;
	516	*fastgetcwd = \&_vms_cwd;
	517	*abs_path = \&_vms_abs_path;
	518	*fast_abs_path = \&_vms_abs_path;
ac1ad7f0	519	}
	520	elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
	521	# We assume that &_NT_cwd is defined as an XSUB or in the core.
96e4d5b1	522	*cwd = \&_NT_cwd;
	523	*getcwd = \&_NT_cwd;
	524	*fastcwd = \&_NT_cwd;
	525	*fastgetcwd = \&_NT_cwd;
	526	*abs_path = \&fast_abs_path;
cade0c02	527	*realpath = \&fast_abs_path;
ac1ad7f0	528	}
	529	elsif ($^O eq 'os2') {
	530	# sys_cwd may keep the builtin command
96e4d5b1	531	*cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
	532	*getcwd = \&cwd;
	533	*fastgetcwd = \&cwd;
	534	*fastcwd = \&cwd;
	535	*abs_path = \&fast_abs_path;
ac1ad7f0	536	}
39e571d4	537	elsif ($^O eq 'dos') {
	538	*cwd = \&_dos_cwd;
	539	*getcwd = \&_dos_cwd;
	540	*fastgetcwd = \&_dos_cwd;
	541	*fastcwd = \&_dos_cwd;
96e4d5b1	542	*abs_path = \&fast_abs_path;
ac1ad7f0	543	}
7438b6ad	544	elsif ($^O =~ m/^(?:qnx\|nto)$/ ) {
7fbf1995	545	*cwd = \&_qnx_cwd;
	546	*getcwd = \&_qnx_cwd;
	547	*fastgetcwd = \&_qnx_cwd;
	548	*fastcwd = \&_qnx_cwd;
	549	*abs_path = \&_qnx_abs_path;
	550	*fast_abs_path = \&_qnx_abs_path;
	551	}
4fabb596	552	elsif ($^O eq 'cygwin') {
1cab015a	553	*getcwd = \&cwd;
	554	*fastgetcwd = \&cwd;
	555	*fastcwd = \&cwd;
	556	*abs_path = \&fast_abs_path;
	557	}
ed79a026	558	elsif ($^O eq 'epoc') {
fa6a1c44	559	*cwd = \&_epoc_cwd;
fa6a1c44	560	*getcwd = \&_epoc_cwd;
ed79a026	561	*fastgetcwd = \&_epoc_cwd;
	562	*fastcwd = \&_epoc_cwd;
	563	*abs_path = \&fast_abs_path;
	564	}
4aecb5b5	565	elsif ($^O eq 'MacOS') {
	566	*getcwd = \&cwd;
	567	*fastgetcwd = \&cwd;
	568	*fastcwd = \&cwd;
	569	*abs_path = \&fast_abs_path;
	570	}
55497cff	571	}
4633a7c4	572
4633a7c4	573
a0d0e21e	574	1;