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+package Cwd;
+require 5.000;
+
+=head1 NAME
+
+getcwd - get pathname of current working directory
+
+=head1 SYNOPSIS
+
+ use Cwd;
+ $dir = cwd;
+
+ use Cwd;
+ $dir = getcwd;
+
+ use Cwd;
+ $dir = fastgetcwd;
+
+ use Cwd 'chdir';
+ chdir "/tmp";
+ print $ENV{'PWD'};
+
+ use Cwd 'abs_path';
+ print abs_path($ENV{'PWD'});
+
+ use Cwd 'fast_abs_path';
+ print fast_abs_path($ENV{'PWD'});
+
+=head1 DESCRIPTION
+
+The getcwd() function re-implements the getcwd(3) (or getwd(3)) functions
+in Perl.
+
+The abs_path() function takes a single argument and returns the
+absolute pathname for that argument. It uses the same algoritm as
+getcwd(). (actually getcwd() is abs_path("."))
+
+The fastcwd() function looks the same as getcwd(), but runs faster.
+It's also more dangerous because it might conceivably chdir() you out
+of a directory that it can't chdir() you back into. If fastcwd
+encounters a problem it will return undef but will probably leave you
+in a different directory. For a measure of extra security, if
+everything appears to have worked, the fastcwd() function will check
+that it leaves you in the same directory that it started in. If it has
+changed it will C<die> with the message "Unstable directory path,
+current directory changed unexpectedly". That should never happen.
+
+The fast_abs_path() function looks the same as abs_path(), but runs faster.
+And like fastcwd() is more dangerous.
+
+The cwd() function looks the same as getcwd and fastgetcwd but is
+implemented using the most natural and safe form for the current
+architecture. For most systems it is identical to `pwd` (but without
+the trailing line terminator).
+
+It is recommended that cwd (or another *cwd() function) is used in
+I<all> code to ensure portability.
+
+If you ask to override your chdir() built-in function, then your PWD
+environment variable will be kept up to date. (See
+L<perlsub/Overriding Builtin Functions>.) Note that it will only be
+kept up to date if all packages which use chdir import it from Cwd.
+
+=cut
+
+## use strict;
+
+use Carp;
+
+$VERSION = '2.01';
+
+require Exporter;
+@ISA = qw(Exporter);
+@EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
+@EXPORT_OK = qw(chdir abs_path fast_abs_path);
+
+
+# The 'natural and safe form' for UNIX (pwd may be setuid root)
+
+sub _backtick_pwd {
+ my $cwd;
+ chop($cwd = `pwd`);
+ $cwd;
+}
+
+# Since some ports may predefine cwd internally (e.g., NT)
+# we take care not to override an existing definition for cwd().
+
+*cwd = \&_backtick_pwd unless defined &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.
+
+# List of metachars taken from do_exec() in doio.c
+my $quoted_shell_meta = quotemeta('$&*(){}[]";\\|?<>~`'."'\n");
+
+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);
+ # At this point $path may be tainted (if tainting) and chdir would fail.
+ # To be more useful we untaint it then check that we landed where we started.
+ $path = $1 if $path =~ /^(.*)$/; # untaint
+ CORE::chdir($path) || return undef;
+ ($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 $^O ne 'dos') {
+ my($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 {
+ $ENV{'PWD'} = cwd();
+ }
+ # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
+ if ($ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|) {
+ 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;
+ chdir_init() unless $chdir_init;
+ return 0 unless CORE::chdir $newdir;
+ if ($^O eq 'VMS') { return $ENV{'PWD'} = $ENV{'DEFAULT'} }
+
+ if ($newdir =~ m#^/#) {
+ $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;
+}
+
+# Taken from Cwd.pm It is really getcwd with an optional
+# parameter instead of '.'
+#
+
+sub 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;
+}
+
+sub fast_abs_path {
+ my $cwd = getcwd();
+ my $path = shift || '.';
+ CORE::chdir($path) || croak "Cannot chdir to $path:$!";
+ my $realpath = getcwd();
+ CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
+ $realpath;
+}
+
+
+# --- PORTING SECTION ---
+
+# VMS: $ENV{'DEFAULT'} points to default directory at all times
+# 06-Mar-1996 Charles Bailey bailey@genetics.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;
+}
+
+{
+ local $^W = 0; # assignments trigger 'subroutine redefined' warning
+
+ if ($^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 eq 'qnx') {
+ *cwd = \&_qnx_cwd;
+ *getcwd = \&_qnx_cwd;
+ *fastgetcwd = \&_qnx_cwd;
+ *fastcwd = \&_qnx_cwd;
+ *abs_path = \&_qnx_abs_path;
+ *fast_abs_path = \&_qnx_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";
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