386 lines
9.7 KiB
Perl
386 lines
9.7 KiB
Perl
package Cwd;
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require 5.000;
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=head1 NAME
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getcwd - get pathname of current working directory
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=head1 SYNOPSIS
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use Cwd;
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$dir = cwd;
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use Cwd;
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$dir = getcwd;
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use Cwd;
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$dir = fastgetcwd;
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use Cwd 'chdir';
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chdir "/tmp";
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print $ENV{'PWD'};
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use Cwd 'abs_path';
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print abs_path($ENV{'PWD'});
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use Cwd 'fast_abs_path';
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print fast_abs_path($ENV{'PWD'});
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=head1 DESCRIPTION
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The getcwd() function re-implements the getcwd(3) (or getwd(3)) functions
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in Perl.
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The abs_path() function takes a single argument and returns the
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absolute pathname for that argument. It uses the same algoritm as
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getcwd(). (actually getcwd() is abs_path("."))
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The fastcwd() function looks the same as getcwd(), but runs faster.
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It's also more dangerous because it might conceivably chdir() you out
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of a directory that it can't chdir() you back into. If fastcwd
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encounters a problem it will return undef but will probably leave you
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in a different directory. For a measure of extra security, if
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everything appears to have worked, the fastcwd() function will check
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that it leaves you in the same directory that it started in. If it has
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changed it will C<die> with the message "Unstable directory path,
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current directory changed unexpectedly". That should never happen.
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The fast_abs_path() function looks the same as abs_path(), but runs faster.
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And like fastcwd() is more dangerous.
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The cwd() function looks the same as getcwd and fastgetcwd but is
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implemented using the most natural and safe form for the current
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architecture. For most systems it is identical to `pwd` (but without
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the trailing line terminator).
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It is recommended that cwd (or another *cwd() function) is used in
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I<all> code to ensure portability.
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If you ask to override your chdir() built-in function, then your PWD
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environment variable will be kept up to date. (See
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L<perlsub/Overriding Builtin Functions>.) Note that it will only be
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kept up to date if all packages which use chdir import it from Cwd.
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=cut
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## use strict;
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use Carp;
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$VERSION = '2.01';
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require Exporter;
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@ISA = qw(Exporter);
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@EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
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@EXPORT_OK = qw(chdir abs_path fast_abs_path);
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# The 'natural and safe form' for UNIX (pwd may be setuid root)
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sub _backtick_pwd {
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my $cwd;
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chop($cwd = `/bin/pwd`);
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$cwd;
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}
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# Since some ports may predefine cwd internally (e.g., NT)
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# we take care not to override an existing definition for cwd().
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*cwd = \&_backtick_pwd unless defined &cwd;
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# By Brandon S. Allbery
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#
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# Usage: $cwd = getcwd();
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sub getcwd
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{
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abs_path('.');
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}
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# By John Bazik
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#
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# Usage: $cwd = &fastcwd;
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#
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# This is a faster version of getcwd. It's also more dangerous because
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# you might chdir out of a directory that you can't chdir back into.
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# List of metachars taken from do_exec() in doio.c
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my $quoted_shell_meta = quotemeta('$&*(){}[]";\\|?<>~`'."'\n");
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sub fastcwd {
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my($odev, $oino, $cdev, $cino, $tdev, $tino);
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my(@path, $path);
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local(*DIR);
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my($orig_cdev, $orig_cino) = stat('.');
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($cdev, $cino) = ($orig_cdev, $orig_cino);
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for (;;) {
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my $direntry;
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($odev, $oino) = ($cdev, $cino);
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CORE::chdir('..') || return undef;
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($cdev, $cino) = stat('.');
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last if $odev == $cdev && $oino == $cino;
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opendir(DIR, '.') || return undef;
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for (;;) {
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$direntry = readdir(DIR);
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last unless defined $direntry;
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next if $direntry eq '.';
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next if $direntry eq '..';
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($tdev, $tino) = lstat($direntry);
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last unless $tdev != $odev || $tino != $oino;
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}
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closedir(DIR);
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return undef unless defined $direntry; # should never happen
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unshift(@path, $direntry);
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}
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$path = '/' . join('/', @path);
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# At this point $path may be tainted (if tainting) and chdir would fail.
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# To be more useful we untaint it then check that we landed where we started.
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$path = $1 if $path =~ /^(.*)$/; # untaint
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CORE::chdir($path) || return undef;
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($cdev, $cino) = stat('.');
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die "Unstable directory path, current directory changed unexpectedly"
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if $cdev != $orig_cdev || $cino != $orig_cino;
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$path;
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}
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# Keeps track of current working directory in PWD environment var
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# Usage:
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# use Cwd 'chdir';
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# chdir $newdir;
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my $chdir_init = 0;
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sub chdir_init {
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if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos') {
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my($dd,$di) = stat('.');
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my($pd,$pi) = stat($ENV{'PWD'});
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if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
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$ENV{'PWD'} = cwd();
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}
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}
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else {
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$ENV{'PWD'} = cwd();
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}
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# Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
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if ($ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|) {
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my($pd,$pi) = stat($2);
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my($dd,$di) = stat($1);
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if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
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$ENV{'PWD'}="$2$3";
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}
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}
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$chdir_init = 1;
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}
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sub chdir {
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my $newdir = shift || ''; # allow for no arg (chdir to HOME dir)
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$newdir =~ s|///*|/|g;
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chdir_init() unless $chdir_init;
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return 0 unless CORE::chdir $newdir;
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if ($^O eq 'VMS') { return $ENV{'PWD'} = $ENV{'DEFAULT'} }
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if ($newdir =~ m#^/#) {
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$ENV{'PWD'} = $newdir;
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} else {
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my @curdir = split(m#/#,$ENV{'PWD'});
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@curdir = ('') unless @curdir;
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my $component;
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foreach $component (split(m#/#, $newdir)) {
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next if $component eq '.';
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pop(@curdir),next if $component eq '..';
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push(@curdir,$component);
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}
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$ENV{'PWD'} = join('/',@curdir) || '/';
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}
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1;
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}
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# Taken from Cwd.pm It is really getcwd with an optional
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# parameter instead of '.'
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#
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sub abs_path
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{
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my $start = @_ ? shift : '.';
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my($dotdots, $cwd, @pst, @cst, $dir, @tst);
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unless (@cst = stat( $start ))
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{
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carp "stat($start): $!";
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return '';
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}
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$cwd = '';
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$dotdots = $start;
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do
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{
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$dotdots .= '/..';
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@pst = @cst;
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unless (opendir(PARENT, $dotdots))
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{
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carp "opendir($dotdots): $!";
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return '';
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}
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unless (@cst = stat($dotdots))
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{
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carp "stat($dotdots): $!";
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closedir(PARENT);
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return '';
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}
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if ($pst[0] == $cst[0] && $pst[1] == $cst[1])
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{
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$dir = undef;
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}
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else
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{
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do
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{
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unless (defined ($dir = readdir(PARENT)))
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{
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carp "readdir($dotdots): $!";
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closedir(PARENT);
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return '';
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}
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$tst[0] = $pst[0]+1 unless (@tst = lstat("$dotdots/$dir"))
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}
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while ($dir eq '.' || $dir eq '..' || $tst[0] != $pst[0] ||
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$tst[1] != $pst[1]);
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}
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$cwd = (defined $dir ? "$dir" : "" ) . "/$cwd" ;
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closedir(PARENT);
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} while (defined $dir);
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chop($cwd) unless $cwd eq '/'; # drop the trailing /
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$cwd;
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}
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sub fast_abs_path {
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my $cwd = getcwd();
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my $path = shift || '.';
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CORE::chdir($path) || croak "Cannot chdir to $path:$!";
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my $realpath = getcwd();
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CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
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$realpath;
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}
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# --- PORTING SECTION ---
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# VMS: $ENV{'DEFAULT'} points to default directory at all times
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# 06-Mar-1996 Charles Bailey bailey@genetics.upenn.edu
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# Note: Use of Cwd::chdir() causes the logical name PWD to be defined
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# in the process logical name table as the default device and directory
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# seen by Perl. This may not be the same as the default device
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# and directory seen by DCL after Perl exits, since the effects
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# the CRTL chdir() function persist only until Perl exits.
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sub _vms_cwd {
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return $ENV{'DEFAULT'};
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}
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sub _vms_abs_path {
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return $ENV{'DEFAULT'} unless @_;
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my $path = VMS::Filespec::pathify($_[0]);
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croak("Invalid path name $_[0]") unless defined $path;
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return VMS::Filespec::rmsexpand($path);
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}
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sub _os2_cwd {
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$ENV{'PWD'} = `cmd /c cd`;
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chop $ENV{'PWD'};
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$ENV{'PWD'} =~ s:\\:/:g ;
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return $ENV{'PWD'};
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}
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sub _win32_cwd {
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$ENV{'PWD'} = Win32::GetCwd();
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$ENV{'PWD'} =~ s:\\:/:g ;
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return $ENV{'PWD'};
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}
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*_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
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defined &Win32::GetCwd);
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*_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
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sub _dos_cwd {
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if (!defined &Dos::GetCwd) {
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$ENV{'PWD'} = `command /c cd`;
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chop $ENV{'PWD'};
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$ENV{'PWD'} =~ s:\\:/:g ;
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} else {
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$ENV{'PWD'} = Dos::GetCwd();
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}
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return $ENV{'PWD'};
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}
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sub _qnx_cwd {
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$ENV{'PWD'} = `/usr/bin/fullpath -t`;
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chop $ENV{'PWD'};
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return $ENV{'PWD'};
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}
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sub _qnx_abs_path {
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my $path = shift || '.';
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my $realpath=`/usr/bin/fullpath -t $path`;
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chop $realpath;
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return $realpath;
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}
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{
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local $^W = 0; # assignments trigger 'subroutine redefined' warning
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if ($^O eq 'VMS') {
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*cwd = \&_vms_cwd;
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*getcwd = \&_vms_cwd;
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*fastcwd = \&_vms_cwd;
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*fastgetcwd = \&_vms_cwd;
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*abs_path = \&_vms_abs_path;
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*fast_abs_path = \&_vms_abs_path;
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}
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elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
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# We assume that &_NT_cwd is defined as an XSUB or in the core.
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*cwd = \&_NT_cwd;
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*getcwd = \&_NT_cwd;
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*fastcwd = \&_NT_cwd;
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*fastgetcwd = \&_NT_cwd;
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*abs_path = \&fast_abs_path;
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}
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elsif ($^O eq 'os2') {
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# sys_cwd may keep the builtin command
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*cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
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*getcwd = \&cwd;
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*fastgetcwd = \&cwd;
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*fastcwd = \&cwd;
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*abs_path = \&fast_abs_path;
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}
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elsif ($^O eq 'dos') {
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*cwd = \&_dos_cwd;
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*getcwd = \&_dos_cwd;
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*fastgetcwd = \&_dos_cwd;
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*fastcwd = \&_dos_cwd;
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*abs_path = \&fast_abs_path;
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}
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elsif ($^O eq 'qnx') {
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*cwd = \&_qnx_cwd;
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*getcwd = \&_qnx_cwd;
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*fastgetcwd = \&_qnx_cwd;
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*fastcwd = \&_qnx_cwd;
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*abs_path = \&_qnx_abs_path;
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*fast_abs_path = \&_qnx_abs_path;
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}
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}
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# package main; eval join('',<DATA>) || die $@; # quick test
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1;
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__END__
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BEGIN { import Cwd qw(:DEFAULT chdir); }
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print join("\n", cwd, getcwd, fastcwd, "");
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chdir('..');
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print join("\n", cwd, getcwd, fastcwd, "");
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print "$ENV{PWD}\n";
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