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Protect against localizing an %ENV slice.
[perl5.git] / lib / Cwd.pm
CommitLineData
a0d0e21e 1package Cwd;
3b825e41 2use 5.006;
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
4633a7c4 10 use Cwd;
04929354 11 my $dir = getcwd;
4633a7c4 12
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13 use Cwd 'abs_path';
14 my $abs_path = abs_path($file);
f06db76b 15
04929354 16=head1 DESCRIPTION
902bacac 17
04929354
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18This module provides functions for determining the pathname of the
19current working directory. It is recommended that getcwd (or another
20*cwd() function) be used in I<all> code to ensure portability.
f06db76b 21
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22By default, it exports the functions cwd(), getcwd(), fastcwd(), and
23fastgetcwd() into the caller's namespace.
f06db76b 24
20408e3c 25
04929354 26=head2 getcwd and friends
20408e3c 27
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28Each of these functions are called without arguments and return the
29absolute path of the current working directory.
f06db76b 30
04929354
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31=over 4
32
33=item getcwd
34
35 my $cwd = getcwd();
36
37Returns the current working directory.
38
39Re-implements the getcwd(3) (or getwd(3)) functions in Perl.
40
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41Taint-safe.
42
04929354
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43=item cwd
44
45 my $cwd = cwd();
46
47The cwd() is the most natural form for the current architecture. For
48most systems it is identical to `pwd` (but without the trailing line
49terminator).
50
248785eb 51Taint-safe.
04929354
MS
52
53=item fastcwd
54
55 my $cwd = fastcwd();
56
57A more dangerous version of getcwd(), but potentially faster.
58
59It might conceivably chdir() you out of a directory that it can't
60chdir() you back into. If fastcwd encounters a problem it will return
61undef but will probably leave you in a different directory. For a
62measure of extra security, if everything appears to have worked, the
63fastcwd() function will check that it leaves you in the same directory
64that it started in. If it has changed it will C<die> with the message
65"Unstable directory path, current directory changed
66unexpectedly". That should never happen.
67
68=item fastgetcwd
69
70 my $cwd = fastgetcwd();
f06db76b 71
902bacac 72The fastgetcwd() function is provided as a synonym for cwd().
fb73857a 73
04929354
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74=back
75
902bacac 76
04929354
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77=head2 abs_path and friends
78
79These functions are exported only on request. They each take a single
80argument 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
88Uses the same algorithm as getcwd(). Symbolic links and relative-path
89components ("." and "..") are resolved to return the canonical
90pathname, just like realpath(3).
91
bde417e1
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92Taint-safe.
93
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94=item realpath
95
96 my $abs_path = realpath($file);
97
98A synonym for abs_path().
99
bde417e1
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100Taint-safe.
101
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102=item fast_abs_path
103
510179aa 104 my $abs_path = fast_abs_path($file);
04929354
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105
106A more dangerous, but potentially faster version of abs_path.
107
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RGS
108This function is B<Not> taint-safe : you can't use it in programs
109that work under taint mode.
bde417e1 110
04929354
MS
111=back
112
113=head2 $ENV{PWD}
114
115If you ask to override your chdir() built-in function,
116
117 use Cwd qw(chdir);
118
119then your PWD environment variable will be kept up to date. Note that
120it will only be kept up to date if all packages which use chdir import
121it from Cwd.
4633a7c4 122
4633a7c4 123
4d6b4052
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124=head1 NOTES
125
126=over 4
127
128=item *
129
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130Since the path seperators are different on some operating systems ('/'
131on Unix, ':' on MacPerl, etc...) we recommend you use the File::Spec
132modules wherever portability is a concern.
133
04929354 134=item *
4d6b4052
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135
136Actually, on Mac OS, the C<getcwd()>, C<fastgetcwd()> and C<fastcwd()>
137functions are all aliases for the C<cwd()> function, which, on Mac OS,
138calls `pwd`. Likewise, the C<abs_path()> function is an alias for
139C<fast_abs_path()>.
140
141=back
142
04929354
MS
143=head1 SEE ALSO
144
145L<File::chdir>
146
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147=cut
148
b060a406 149use strict;
96e4d5b1 150
151use Carp;
152
04929354 153our $VERSION = '2.06';
96e4d5b1 154
b060a406
TJ
155use base qw/ Exporter /;
156our @EXPORT = qw(cwd getcwd fastcwd fastgetcwd);
157our @EXPORT_OK = qw(chdir abs_path fast_abs_path realpath fast_realpath);
a0d0e21e 158
f5f423e4
IZ
159# sys_cwd may keep the builtin command
160
161# All the functionality of this module may provided by builtins,
162# there is no sense to process the rest of the file.
163# The best choice may be to have this in BEGIN, but how to return from BEGIN?
164
165if ($^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
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178eval {
179 require XSLoader;
716e3b8c 180 undef *Cwd::fastcwd; # avoid redefinition warning
f22d8e4b
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181 XSLoader::load('Cwd');
182};
4633a7c4 183
96e4d5b1 184
3547aa9a
MS
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.
188my $pwd_cmd;
189foreach 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 198sub _backtick_pwd {
680d0beb
RGS
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
LW
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
EC
215unless(defined &cwd) {
216 # The pwd command is not available in some chroot(2)'ed environments
73b801a6
MS
217 if( $^O eq 'MacOS' || (defined $ENV{PATH} &&
218 grep { -x "$_/pwd" } split(':', $ENV{PATH})) )
219 {
ea54c8bd
EC
220 *cwd = \&_backtick_pwd;
221 }
222 else {
223 *cwd = \&getcwd;
224 }
225}
a0d0e21e 226
1f4f94f5
RS
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
LW
231# By Brandon S. Allbery
232#
233# Usage: $cwd = getcwd();
234
235sub getcwd
236{
07569ed3 237 abs_path('.');
a0d0e21e
LW
238}
239
a0c9c202
JH
240
241# By John Bazik
242#
243# Usage: $cwd = &fastcwd;
244#
245# This is a faster version of getcwd. It's also more dangerous because
246# you might chdir out of a directory that you can't chdir back into.
247
248sub fastcwd {
249 my($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
RGS
278 # Untaint it then check that we landed where we started.
279 $path =~ /^(.*)\z/s # untaint
280 && CORE::chdir($1) or return undef;
a0c9c202
JH
281 ($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
LW
289# Usage:
290# use Cwd 'chdir';
291# chdir $newdir;
292
4633a7c4 293my $chdir_init = 0;
a0d0e21e 294
4633a7c4 295sub chdir_init {
3b8e3443 296 if ($ENV{'PWD'} and $^O ne 'os2' and $^O ne 'dos' and $^O ne 'MSWin32') {
a0d0e21e
LW
297 my($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
LW
301 }
302 }
303 else {
3b8e3443
GS
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 $ENV{'PWD'} =~ m|(/[^/]+(/[^/]+/[^/]+))(.*)|s) {
a0d0e21e
LW
310 my($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
319sub 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
JH
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 $newdir;
4ffa1610 330
3b8e3443
GS
331 if ($^O eq 'VMS') {
332 return $ENV{'PWD'} = $ENV{'DEFAULT'}
333 }
4aecb5b5
JH
334 elsif ($^O eq 'MacOS') {
335 return $ENV{'PWD'} = cwd();
336 }
3b8e3443 337 elsif ($^O eq 'MSWin32') {
4ffa1610 338 $ENV{'PWD'} = $newpwd;
3b8e3443
GS
339 return 1;
340 }
748a9306 341
392d8ab8 342 if ($newdir =~ m#^/#s) {
a0d0e21e 343 $ENV{'PWD'} = $newdir;
4633a7c4
LW
344 } else {
345 my @curdir = split(m#/#,$ENV{'PWD'});
346 @curdir = ('') unless @curdir;
347 my $component;
a0d0e21e
LW
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
LW
356}
357
a0c9c202
JH
358
359# In case the XS version doesn't load.
360*abs_path = \&_perl_abs_path unless defined &abs_path;
361sub _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
GS
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 419sub fast_abs_path {
420 my $cwd = getcwd();
4d6b4052
JH
421 require File::Spec;
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
NIS
428}
429
e4c51978
GS
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
LW
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
NIS
440# in the process logical name table as the default device and directory
441# seen by Perl. This may not be the same as the default device
4633a7c4
LW
442# and directory seen by DCL after Perl exits, since the effects
443# the CRTL chdir() function persist only until Perl exits.
4633a7c4
LW
444
445sub _vms_cwd {
96e4d5b1 446 return $ENV{'DEFAULT'};
447}
448
449sub _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
LW
456sub _os2_cwd {
457 $ENV{'PWD'} = `cmd /c cd`;
458 chop $ENV{'PWD'};
aa6b7957 459 $ENV{'PWD'} =~ s:\\:/:g ;
4633a7c4
LW
460 return $ENV{'PWD'};
461}
462
96e4d5b1 463sub _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
472*_NT_cwd = \&_os2_cwd unless defined &_NT_cwd;
68dc0745 473
39e571d4
LM
474sub _dos_cwd {
475 if (!defined &Dos::GetCwd) {
476 $ENV{'PWD'} = `command /c cd`;
477 chop $ENV{'PWD'};
aa6b7957 478 $ENV{'PWD'} =~ s:\\:/:g ;
39e571d4
LM
479 } else {
480 $ENV{'PWD'} = Dos::GetCwd();
481 }
55497cff 482 return $ENV{'PWD'};
483}
484
7fbf1995 485sub _qnx_cwd {
35b807ef
NA
486 local $ENV{PATH} = '';
487 local $ENV{CDPATH} = '';
488 local $ENV{ENV} = '';
7fbf1995
NA
489 $ENV{'PWD'} = `/usr/bin/fullpath -t`;
490 chop $ENV{'PWD'};
491 return $ENV{'PWD'};
492}
493
494sub _qnx_abs_path {
35b807ef
NA
495 local $ENV{PATH} = '';
496 local $ENV{CDPATH} = '';
497 local $ENV{ENV} = '';
fa921dc6 498 my $path = @_ ? shift : '.';
7fbf1995
NA
499 my $realpath=`/usr/bin/fullpath -t $path`;
500 chop $realpath;
501 return $realpath;
502}
503
ed79a026
OF
504sub _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
PM
519 }
520 elsif ($^O eq 'NT' or $^O eq 'MSWin32') {
521 # We assume that &_NT_cwd is defined as an XSUB or in the core.
96e4d5b1 522 *cwd = \&_NT_cwd;
523 *getcwd = \&_NT_cwd;
524 *fastcwd = \&_NT_cwd;
525 *fastgetcwd = \&_NT_cwd;
526 *abs_path = \&fast_abs_path;
cade0c02 527 *realpath = \&fast_abs_path;
ac1ad7f0
PM
528 }
529 elsif ($^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
LM
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)$/ ) {
7fbf1995
NA
545 *cwd = \&_qnx_cwd;
546 *getcwd = \&_qnx_cwd;
547 *fastgetcwd = \&_qnx_cwd;
548 *fastcwd = \&_qnx_cwd;
549 *abs_path = \&_qnx_abs_path;
550 *fast_abs_path = \&_qnx_abs_path;
551 }
4fabb596 552 elsif ($^O eq 'cygwin') {
1cab015a
EF
553 *getcwd = \&cwd;
554 *fastgetcwd = \&cwd;
555 *fastcwd = \&cwd;
556 *abs_path = \&fast_abs_path;
557 }
ed79a026 558 elsif ($^O eq 'epoc') {
fa6a1c44
OF
559 *cwd = \&_epoc_cwd;
560 *getcwd = \&_epoc_cwd;
ed79a026
OF
561 *fastgetcwd = \&_epoc_cwd;
562 *fastcwd = \&_epoc_cwd;
563 *abs_path = \&fast_abs_path;
564 }
4aecb5b5
JH
565 elsif ($^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 5741;