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Perl POD Document | 2006-04-25 | 7.8 KB | 311 lines

package File::Path;

=head1 NAME

File::Path - create or remove directory trees

=head1 SYNOPSIS

    use File::Path;

    mkpath(['/foo/bar/baz', 'blurfl/quux'], 1, 0711);
    rmtree(['foo/bar/baz', 'blurfl/quux'], 1, 1);

=head1 DESCRIPTION

The C<mkpath> function provides a convenient way to create directories, even
if your C<mkdir> kernel call won't create more than one level of directory at
a time.  C<mkpath> takes three arguments:

=over 4

=item *

the name of the path to create, or a reference
to a list of paths to create,

=item *

a boolean value, which if FALSE (the default for non-root users) will
cause C<rmtree> to adjust the mode of directories (if required) prior
to attempting to remove the contents.  Note that on interruption or
failure of C<rmtree>, directories may be left with more permissi
modes for the owner.

=item *

the numeric mode to use when creating the directories
(defaults to 0777), to be modified by the current umask.

=back

It returns a list of all directories (including intermediates, determined
using the Unix '/' separator) created.

If a system error prevents a directory from being created, then the
C<mkpath> function throws a fatal error with C<Carp::croak>. This error
can be trapped with an C<eval> block:

  eval { mkpath($dir) };
  if ($@) {
    print "Couldn't create $dir: $@";
  }

Similarly, the C<rmtree> function provides a convenient way to delete a
subtree from the directory structure, much like the Unix command C<rm -r>.
C<rmtree> takes three arguments:

=over 4

=item *

the root of the subtree to delete, or a reference to
a list of roots.  All of the files and directories
below each root, as well as the roots themselves,
will be deleted.

=item *

a boolean value, which if TRUE will cause C<rmtree> to
print a message each time it examines a file, giving the
name of the file, and indicating whether it's using C<rmdir>
or C<unlink> to remove it, or that it's skipping it.
(defaults to FALSE)

=item *

a boolean value, which if TRUE will cause C<rmtree> to
skip any files to which you do not have delete access
(if running under VMS) or write access (if running
under another OS).  This will change in the future when
a criterion for 'delete permission' under OSs other
than VMS is settled.  (defaults to FALSE)

=back

It returns the number of files successfully deleted.  Symlinks are
simply deleted and not followed.

B<NOTE:> There are race conditions internal to the implementation of
C<rmtree> making it unsafe to use on directory trees which may be
altered or moved while C<rmtree> is running, and in particular on any
directory trees with any path components or subdirectories potentially
writable by untrusted users.

Additionally, if the third parameter is not TRUE and C<rmtree> is
interrupted, it may leave files and directories with permissions altered
to allow deletion (and older versions of this module would even set
files and directories to world-read/writable!)

Note also that the occurrence of errors in C<rmtree> can be determined I<only>
by trapping diagnostic messages using C<$SIG{__WARN__}>; it is not apparent
from the return value.

=head1 DIAGNOSTICS

=over 4

=item *

On Windows, if C<mkpath> gives you the warning: B<No such file or
directory>, this may mean that you've exceeded your filesystem's
maximum path length.

=back

=head1 AUTHORS

Tim Bunce <F<[e-mail]>> and
Charles Bailey <F<[e-mail]>>

=cut

use 5.006;
use Carp;
use File::Basename ();
use Exporter ();
use strict;
use warnings;
use Cwd 'getcwd';

our $VERSION = "1.07";
our @ISA = qw( Exporter );
our @EXPORT = qw( mkpath rmtree );

my $Is_VMS = $^O eq 'VMS';
my $Is_MacOS = $^O eq 'MacOS';

# These OSes complain if you want to remove a file that you have no
# write permission to:
my $force_writeable = ($^O eq 'os2' || $^O eq 'dos' || $^O eq 'MSWin32' ||
               $^O eq 'amigaos' || $^O eq 'MacOS' || $^O eq 'epoc');

sub mkpath {
    my($paths, $verbose, $mode) = @_;
    # $paths   -- either a path string or ref to list of paths
    # $verbose -- optional print "mkdir $path" for each directory created
    # $mode    -- optional permissions, defaults to 0777
    local($")=$Is_MacOS ? ":" : "/";
    $mode = 0777 unless defined($mode);
    $paths = [$paths] unless ref $paths;
    my(@created,$path);
    foreach $path (@$paths) {
    $path .= '/' if $^O eq 'os2' and $path =~ /^\w:\z/s; # feature of CRT
    # Logic wants Unix paths, so go with the flow.
    if ($Is_VMS) {
        next if $path eq '/';
        $path = VMS::Filespec::unixify($path);
        if ($path =~ m:^(/[^/]+)/?\z:) {
            $path = $1.'/000000';
        }
    }
    next if -d $path;
    my $parent = File::Basename::dirname($path);
    unless (-d $parent or $path eq $parent) {
        push(@created,mkpath($parent, $verbose, $mode));
     }
    print "mkdir $path\n" if $verbose;
    unless (mkdir($path,$mode)) {
        my $e = $!;
        # allow for another process to have created it meanwhile
        croak "mkdir $path: $e" unless -d $path;
    }
    push(@created, $path);
    }
    @created;
}

sub _rmtree;
sub _rmtree
{

    my ($path, $prefix, $up, $up_dev, $up_ino, $verbose, $safe) = @_;

    my ($dev, $ino) = lstat $path or do {
        carp "Can't stat $prefix$path ($!)" unless $!{ENOENT};
    return 0;
    };

    unless (-d _)
    {
    print "unlink $prefix$path\n" if $verbose;
    unless (unlink $path)
    {
        carp "Can't remove file $prefix$path ($!)";
        return 0;
     }
    return 1;
    }

    unless (chdir $path)
    {
    carp "Can't chdir to $prefix$path ($!)";
    return 0;
    }

    # avoid a race condition where a directory may be replaced by a
    # symlink between the lstat and the chdir
    my ($new_dev, $new_ino, $perm) = stat '.';
    unless ("$new_dev:$new_ino" eq "$dev:$ino")
    {
    croak "Directory $prefix$path changed before chdir, aborting";
    }

    $perm &= 07777;
    my $nperm = $perm | 0700;
    unless ($safe or $nperm == $perm or chmod $nperm, '.')
    {
    carp "Can't make directory $prefix$path read+writeable ($!)";
    $nperm = $perm;
    }

    my $count = 0;
    if (opendir my $dir, '.')
    {
    my $entry;
    while (defined ($entry = readdir $dir))
    {
        next if $entry =~ /^\.\.?$/;
        $entry =~ /^(.*)$/s; $entry = $1; # untaint
        $count += _rmtree $entry, "$prefix$path/", '..', $dev, $ino,
        $verbose, $safe;
     }

    closedir $dir;
    }

    # restore directory permissions if required (in case the rmdir
    # below fails) now, while we're still in the directory and may do
    # so without a race via '.'
    unless ($nperm == $perm or chmod $perm, '.')
    {
    carp "Can't restore permissions on directory $prefix$path ($!)";
    }

    # don't leave the caller in an unexpected directory
    unless (chdir $up)
    {
    croak "Can't return to $up from $prefix$path ($!)";
    }

    # ensure that a chdir ..  didn't take us somewhere other than
    # where we expected (see CVE-2002-0435)
    unless (($new_dev, $new_ino) = stat '.'
    and "$new_dev:$new_ino" eq "$up_dev:$up_ino")
    {
    croak "Previous directory $up changed since entering $prefix$path";
    }

    print "rmdir $prefix$path\n" if $verbose;
    if (rmdir $path)
    {
    $count++;
    }
    else
    {
    carp "Can't remove directory $prefix$path ($!)";
    }

    return $count;
}

sub rmtree
{
    my ($p, $verbose, $safe) = @_;
    $p = [] unless defined $p and length $p;
    $p = [ $p ] unless ref $p;
    my @paths = grep defined && length, @$p;

    # default to "unsafe" for non-root (will chmod dirs)
    $safe = $> ? 0 : 1 unless defined $safe;

    unless (@paths)
    {
    carp "No root path(s) specified";
    return;
    }

    my $oldpwd = getcwd or do {
    carp "Can't fetch initial working directory";
    return;
    };

    my ($dev, $ino) = stat '.' or do {
    carp "Can't stat initial working directory";
    return;
    };

    # untaint
    for ($oldpwd) { /^(.*)$/s; $_ = $1 }

    my $count = 0;
    for my $path (@paths)
    {
    $count += _rmtree $path, '', $oldpwd, $dev, $ino, $verbose, $safe;
    }

    $count;
}

1;