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[perl5.git] / lib / Cwd.pm
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1package Cwd;
2require 5.000;
a0d0e21e 3
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4=head1 NAME
5
902bacac 6Cwd - get pathname of current working directory
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7
8=head1 SYNOPSIS
9
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10 use Cwd;
11 $dir = cwd;
12
13 use Cwd;
14 $dir = getcwd;
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15
16 use Cwd;
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17 $dir = fastcwd;
18
19 use Cwd;
4633a7c4 20 $dir = fastgetcwd;
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21
22 use Cwd 'chdir';
23 chdir "/tmp";
24 print $ENV{'PWD'};
25
e4c51978 26 use Cwd 'abs_path'; # aka realpath()
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27 print abs_path($ENV{'PWD'});
28
29 use Cwd 'fast_abs_path';
30 print fast_abs_path($ENV{'PWD'});
31
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32=head1 DESCRIPTION
33
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34This module provides functions for determining the pathname of the
35current working directory. By default, it exports the functions
36cwd(), getcwd(), fastcwd(), and fastgetcwd() into the caller's
37namespace. Each of these functions are called without arguments and
38return the absolute path of the current working directory. It is
39recommended that cwd (or another *cwd() function) be used in I<all>
40code to ensure portability.
41
42The cwd() is the most natural and safe form for the current
43architecture. For most systems it is identical to `pwd` (but without
44the trailing line terminator).
45
f06db76b 46The getcwd() function re-implements the getcwd(3) (or getwd(3)) functions
4633a7c4 47in Perl.
f06db76b 48
cb1a09d0 49The fastcwd() function looks the same as getcwd(), but runs faster.
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50It's also more dangerous because it might conceivably chdir() you out
51of a directory that it can't chdir() you back into. If fastcwd
52encounters a problem it will return undef but will probably leave you
53in a different directory. For a measure of extra security, if
54everything appears to have worked, the fastcwd() function will check
55that it leaves you in the same directory that it started in. If it has
56changed it will C<die> with the message "Unstable directory path,
57current directory changed unexpectedly". That should never happen.
f06db76b 58
902bacac 59The fastgetcwd() function is provided as a synonym for cwd().
fb73857a 60
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61The abs_path() function takes a single argument and returns the
62absolute pathname for that argument. It uses the same algorithm as
63getcwd(). (Actually, getcwd() is abs_path(".")) Symbolic links and
64relative-path components ("." and "..") are resolved to return the
65canonical pathname, just like realpath(3). This function is also
66callable as realpath().
67
68The fast_abs_path() function looks the same as abs_path() but runs
69faster and, like fastcwd(), is more dangerous.
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70
71If you ask to override your chdir() built-in function, then your PWD
72environment variable will be kept up to date. (See
55497cff 73L<perlsub/Overriding Builtin Functions>.) Note that it will only be
1fef88e7 74kept up to date if all packages which use chdir import it from Cwd.
4633a7c4 75
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76=cut
77
b060a406 78use strict;
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79
80use Carp;
81
1f4f94f5 82our $VERSION = '2.04';
96e4d5b1 83
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84use base qw/ Exporter /;
85our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
86our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
a0d0e21e 87
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88# sys_cwd may keep the builtin command
89
90# All the functionality of this module may provided by builtins,
91# there is no sense to process the rest of the file.
92# The best choice may be to have this in BEGIN, but how to return from BEGIN?
93
94if ($^O eq 'os2' && defined &sys_cwd && defined &sys_abspath) {
95 local $^W = 0;
96 *cwd = \&sys_cwd;
97 *getcwd = \&cwd;
98 *fastgetcwd = \&cwd;
99 *fastcwd = \&cwd;
100 *abs_path = \&sys_abspath;
101 *fast_abs_path = \&abs_path;
102 *realpath = \&abs_path;
103 *fast_realpath = \&abs_path;
104 return 1;
105}
106
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107eval {
108 require XSLoader;
109 XSLoader::load('Cwd');
110};
4633a7c4 111
8b88ae92 112# The 'natural and safe form' for UNIX (pwd may be setuid root)
96e4d5b1 113
8b88ae92 114sub _backtick_pwd {
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115 my $cwd = `pwd`;
116 # `pwd` may fail e.g. if the disk is full
117 chomp($cwd) if defined $cwd;
4633a7c4 118 $cwd;
8b88ae92 119}
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120
121# Since some ports may predefine cwd internally (e.g., NT)
122# we take care not to override an existing definition for cwd().
123
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124unless(defined &cwd) {
125 # The pwd command is not available in some chroot(2)'ed environments
4aecb5b5 126 if($^O eq 'MacOS' || grep { -x "$_/pwd" } split(':', $ENV{PATH})) {
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127 *cwd = \&_backtick_pwd;
128 }
129 else {
130 *cwd = \&getcwd;
131 }
132}
a0d0e21e 133
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134# set a reasonable (and very safe) default for fastgetcwd, in case it
135# isn't redefined later (20001212 rspier)
136*fastgetcwd = \&cwd;
748a9306 137
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138# By Brandon S. Allbery
139#
140# Usage: $cwd = getcwd();
141
142sub getcwd
143{
07569ed3 144 abs_path('.');
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145}
146
4633a7c4 147# Keeps track of current working directory in PWD environment var
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148# Usage:
149# use Cwd 'chdir';
150# chdir $newdir;
151
4633a7c4 152my $chdir_init = 0;
a0d0e21e 153
4633a7c4 154sub chdir_init {
3b8e3443 155 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
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156 my($dd,$di) = stat('.');
157 my($pd,$pi) = stat($ENV{'PWD'});
158 if (!defined $dd or !defined $pd or $di != $pi or $dd != $pd) {
4633a7c4 159 $ENV{'PWD'} = cwd();
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160 }
161 }
162 else {
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163 my $wd = cwd();
164 $wd = Win32::GetFullPathName($wd) if $^O eq 'MSWin32';
165 $ENV{'PWD'} = $wd;
a0d0e21e 166 }
4633a7c4 167 # Strip an automounter prefix (where /tmp_mnt/foo/bar == /foo/bar)
3b8e3443 168 if ($^O ne 'MSWin32' and $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
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169 my($pd,$pi) = stat($2);
170 my($dd,$di) = stat($1);
171 if (defined $pd and defined $dd and $di == $pi and $dd == $pd) {
172 $ENV{'PWD'}="$2$3";
173 }
174 }
175 $chdir_init = 1;
176}
177
178sub chdir {
22978713 179 my $newdir = @_ ? shift : ''; # allow for no arg (chdir to HOME dir)
3b8e3443 180 $newdir =~ s|///*|/|g unless $^O eq 'MSWin32';
a0d0e21e 181 chdir_init() unless $chdir_init;
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182 my $newpwd;
183 if ($^O eq 'MSWin32') {
184 # get the full path name *before* the chdir()
185 $newpwd = Win32::GetFullPathName($newdir);
186 }
187
4633a7c4 188 return 0 unless CORE::chdir $newdir;
4ffa1610 189
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190 if ($^O eq 'VMS') {
191 return $ENV{'PWD'} = $ENV{'DEFAULT'}
192 }
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193 elsif ($^O eq 'MacOS') {
194 return $ENV{'PWD'} = cwd();
195 }
3b8e3443 196 elsif ($^O eq 'MSWin32') {
4ffa1610 197 $ENV{'PWD'} = $newpwd;
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198 return 1;
199 }
748a9306 200
392d8ab8 201 if ($newdir =~ m#^/#s) {
a0d0e21e 202 $ENV{'PWD'} = $newdir;
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203 } else {
204 my @curdir = split(m#/#,$ENV{'PWD'});
205 @curdir = ('') unless @curdir;
206 my $component;
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207 foreach $component (split(m#/#, $newdir)) {
208 next if $component eq '.';
209 pop(@curdir),next if $component eq '..';
210 push(@curdir,$component);
211 }
212 $ENV{'PWD'} = join('/',@curdir) || '/';
213 }
4633a7c4 214 1;
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215}
216
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217# added function alias for those of us more
218# used to the libc function. --tchrist 27-Jan-00
219*realpath = \&abs_path;
220
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221sub fast_abs_path {
222 my $cwd = getcwd();
3c65c14b 223 my $path = @_ ? shift : '.';
e79e61e4 224 CORE::chdir($path) || croak "Cannot chdir to $path:$!";
96e4d5b1 225 my $realpath = getcwd();
e79e61e4 226 CORE::chdir($cwd) || croak "Cannot chdir back to $cwd:$!";
96e4d5b1 227 $realpath;
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228}
229
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230# added function alias to follow principle of least surprise
231# based on previous aliasing. --tchrist 27-Jan-00
232*fast_realpath = \&fast_abs_path;
233
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234
235# --- PORTING SECTION ---
236
237# VMS: $ENV{'DEFAULT'} points to default directory at all times
bd3fa61c 238# 06-Mar-1996 Charles Bailey bailey@newman.upenn.edu
c6538b72 239# Note: Use of Cwd::chdir() causes the logical name PWD to be defined
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240# in the process logical name table as the default device and directory
241# seen by Perl. This may not be the same as the default device
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242# and directory seen by DCL after Perl exits, since the effects
243# the CRTL chdir() function persist only until Perl exits.
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244
245sub _vms_cwd {
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246 return $ENV{'DEFAULT'};
247}
248
249sub _vms_abs_path {
250 return $ENV{'DEFAULT'} unless @_;
251 my $path = VMS::Filespec::pathify($_[0]);
252 croak("Invalid path name $_[0]") unless defined $path;
253 return VMS::Filespec::rmsexpand($path);
4633a7c4 254}
68dc0745 255
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256sub _os2_cwd {
257 $ENV{'PWD'} = `cmd /c cd`;
258 chop $ENV{'PWD'};
259 $ENV{'PWD'} =~ s:\\:/:g ;
260 return $ENV{'PWD'};
261}
262
96e4d5b1 263sub _win32_cwd {
2d7a9237 264 $ENV{'PWD'} = Win32::GetCwd();
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265 $ENV{'PWD'} =~ s:\\:/:g ;
266 return $ENV{'PWD'};
267}
268
269*_NT_cwd = \&_win32_cwd if (!defined &_NT_cwd &&
2d7a9237 270 defined &Win32::GetCwd);
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271
272*_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
68dc0745 273
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274sub _dos_cwd {
275 if (!defined &Dos::GetCwd) {
276 $ENV{'PWD'} = `command /c cd`;
277 chop $ENV{'PWD'};
278 $ENV{'PWD'} =~ s:\\:/:g ;
279 } else {
280 $ENV{'PWD'} = Dos::GetCwd();
281 }
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282 return $ENV{'PWD'};
283}
284
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285sub _qnx_cwd {
286 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
287 chop $ENV{'PWD'};
288 return $ENV{'PWD'};
289}
290
291sub _qnx_abs_path {
fa921dc6 292 my $path = @_ ? shift : '.';
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293 my $realpath=`/usr/bin/fullpath -t $path`;
294 chop $realpath;
295 return $realpath;
296}
297
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298sub _epoc_cwd {
299 $ENV{'PWD'} = EPOC::getcwd();
300 return $ENV{'PWD'};
301}
302
ac1ad7f0 303{
db376a24 304 no warnings; # assignments trigger 'subroutine redefined' warning
4633a7c4 305
ac1ad7f0 306 if ($^O eq 'VMS') {
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307 *cwd = \&_vms_cwd;
308 *getcwd = \&_vms_cwd;
309 *fastcwd = \&_vms_cwd;
310 *fastgetcwd = \&_vms_cwd;
311 *abs_path = \&_vms_abs_path;
312 *fast_abs_path = \&_vms_abs_path;
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313 }
314 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
315 # We assume that &_NT_cwd is defined as an XSUB or in the core.
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316 *cwd = \&_NT_cwd;
317 *getcwd = \&_NT_cwd;
318 *fastcwd = \&_NT_cwd;
319 *fastgetcwd = \&_NT_cwd;
320 *abs_path = \&fast_abs_path;
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321 }
322 elsif ($^O eq 'os2') {
323 # sys_cwd may keep the builtin command
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324 *cwd = defined &sys_cwd ? \&sys_cwd : \&_os2_cwd;
325 *getcwd = \&cwd;
326 *fastgetcwd = \&cwd;
327 *fastcwd = \&cwd;
328 *abs_path = \&fast_abs_path;
ac1ad7f0 329 }
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330 elsif ($^O eq 'dos') {
331 *cwd = \&_dos_cwd;
332 *getcwd = \&_dos_cwd;
333 *fastgetcwd = \&_dos_cwd;
334 *fastcwd = \&_dos_cwd;
96e4d5b1 335 *abs_path = \&fast_abs_path;
ac1ad7f0 336 }
7438b6ad 337 elsif ($^O =~ m/^(?:qnx|nto)$/ ) {
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338 *cwd = \&_qnx_cwd;
339 *getcwd = \&_qnx_cwd;
340 *fastgetcwd = \&_qnx_cwd;
341 *fastcwd = \&_qnx_cwd;
342 *abs_path = \&_qnx_abs_path;
343 *fast_abs_path = \&_qnx_abs_path;
344 }
4fabb596 345 elsif ($^O eq 'cygwin') {
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346 *getcwd = \&cwd;
347 *fastgetcwd = \&cwd;
348 *fastcwd = \&cwd;
349 *abs_path = \&fast_abs_path;
350 }
ed79a026 351 elsif ($^O eq 'epoc') {
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352 *cwd = \&_epoc_cwd;
353 *getcwd = \&_epoc_cwd;
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354 *fastgetcwd = \&_epoc_cwd;
355 *fastcwd = \&_epoc_cwd;
356 *abs_path = \&fast_abs_path;
357 }
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358 elsif ($^O eq 'MacOS') {
359 *getcwd = \&cwd;
360 *fastgetcwd = \&cwd;
361 *fastcwd = \&cwd;
362 *abs_path = \&fast_abs_path;
363 }
55497cff 364}
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365
366# package main; eval join('',<DATA>) || die $@; # quick test
367
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3681;
369
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370__END__
371BEGIN { import Cwd qw(:DEFAULT chdir); }
372print join("\n", cwd, getcwd, fastcwd, "");
373chdir('..');
374print join("\n", cwd, getcwd, fastcwd, "");
375print "$ENV{PWD}\n";