[ID 20010301.004] Technically speaking in perldata

[perl5.git] / lib / File / Copy.pm

# File/Copy.pm. Written in 1994 by Aaron Sherman <ajs@ajs.com>. This
# source code has been placed in the public domain by the author.
# Please be kind and preserve the documentation.
#
# Additions copyright 1996 by Charles Bailey.  Permission is granted
# to distribute the revised code under the same terms as Perl itself.

package File::Copy;

use 5.005_64;
use strict;
use Carp;
our(@ISA, @EXPORT, @EXPORT_OK, $VERSION, $Too_Big, $Syscopy_is_copy);
sub copy;
sub syscopy;
sub cp;
sub mv;

# Note that this module implements only *part* of the API defined by
# the File/Copy.pm module of the File-Tools-2.0 package.  However, that
# package has not yet been updated to work with Perl 5.004, and so it
# would be a Bad Thing for the CPAN module to grab it and replace this
# module.  Therefore, we set this module's version higher than 2.0.
$VERSION = '2.03';

require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(copy move);
@EXPORT_OK = qw(cp mv);

$Too_Big = 1024 * 1024 * 2;

sub _catname { #  Will be replaced by File::Spec when it arrives
    my($from, $to) = @_;
    if (not defined &basename) {
	require File::Basename;
	import  File::Basename 'basename';
    }
    if ($^O eq 'VMS')  { $to = VMS::Filespec::vmspath($to) . basename($from); }
    elsif ($^O eq 'MacOS') { $to .= ':' . basename($from); }
    elsif ($to =~ m|\\|)   { $to .= '\\' . basename($from); }
    else                   { $to .= '/' . basename($from); }
}

sub copy {
    croak("Usage: copy(FROM, TO [, BUFFERSIZE]) ")
      unless(@_ == 2 || @_ == 3);

    my $from = shift;
    my $to = shift;

    my $from_a_handle = (ref($from)
			 ? (ref($from) eq 'GLOB'
			    || UNIVERSAL::isa($from, 'GLOB')
                            || UNIVERSAL::isa($from, 'IO::Handle'))
			 : (ref(\$from) eq 'GLOB'));
    my $to_a_handle =   (ref($to)
			 ? (ref($to) eq 'GLOB'
			    || UNIVERSAL::isa($to, 'GLOB')
                            || UNIVERSAL::isa($to, 'IO::Handle'))
			 : (ref(\$to) eq 'GLOB'));

    if (!$from_a_handle && !$to_a_handle && -d $to && ! -d $from) {
	$to = _catname($from, $to);
    }

    if (defined &syscopy && !$Syscopy_is_copy
	&& !$to_a_handle
	&& !($from_a_handle && $^O eq 'os2' )	# OS/2 cannot handle handles
	&& !($from_a_handle && $^O eq 'mpeix')	# and neither can MPE/iX.
	&& !($from_a_handle && $^O eq 'MSWin32')
       )
    {
	return syscopy($from, $to);
    }

    my $closefrom = 0;
    my $closeto = 0;
    my ($size, $status, $r, $buf);
    local(*FROM, *TO);
    local($\) = '';

    if ($from_a_handle) {
	*FROM = *$from{FILEHANDLE};
    } else {
	$from = "./$from" if $from =~ /^\s/s;
	open(FROM, "< $from\0") or goto fail_open1;
	binmode FROM or die "($!,$^E)";
	$closefrom = 1;
    }

    if ($to_a_handle) {
	*TO = *$to{FILEHANDLE};
    } else {
	$to = "./$to" if $to =~ /^\s/s;
	open(TO,"> $to\0") or goto fail_open2;
	binmode TO or die "($!,$^E)";
	$closeto = 1;
    }

    if (@_) {
	$size = shift(@_) + 0;
	croak("Bad buffer size for copy: $size\n") unless ($size > 0);
    } else {
	$size = -s FROM;
	$size = 1024 if ($size < 512);
	$size = $Too_Big if ($size > $Too_Big);
    }

    $! = 0;
    for (;;) {
	my ($r, $w, $t);
	defined($r = sysread(FROM, $buf, $size))
	    or goto fail_inner;
	last unless $r;
	for ($w = 0; $w < $r; $w += $t) {
	    $t = syswrite(TO, $buf, $r - $w, $w)
		or goto fail_inner;
	}
    }

    close(TO) || goto fail_open2 if $closeto;
    close(FROM) || goto fail_open1 if $closefrom;

    # Use this idiom to avoid uninitialized value warning.
    return 1;

    # All of these contortions try to preserve error messages...
  fail_inner:
    if ($closeto) {
	$status = $!;
	$! = 0;
	close TO;
	$! = $status unless $!;
    }
  fail_open2:
    if ($closefrom) {
	$status = $!;
	$! = 0;
	close FROM;
	$! = $status unless $!;
    }
  fail_open1:
    return 0;
}

sub move {
    my($from,$to) = @_;
    my($copied,$fromsz,$tosz1,$tomt1,$tosz2,$tomt2,$sts,$ossts);

    if (-d $to && ! -d $from) {
	$to = _catname($from, $to);
    }

    ($tosz1,$tomt1) = (stat($to))[7,9];
    $fromsz = -s $from;
    if ($^O eq 'os2' and defined $tosz1 and defined $fromsz) {
      # will not rename with overwrite
      unlink $to;
    }
    return 1 if rename $from, $to;

    ($sts,$ossts) = ($! + 0, $^E + 0);
    # Did rename return an error even though it succeeded, because $to
    # is on a remote NFS file system, and NFS lost the server's ack?
    return 1 if defined($fromsz) && !-e $from &&           # $from disappeared
                (($tosz2,$tomt2) = (stat($to))[7,9]) &&    # $to's there
                ($tosz1 != $tosz2 or $tomt1 != $tomt2) &&  #   and changed
                $tosz2 == $fromsz;                         # it's all there

    ($tosz1,$tomt1) = (stat($to))[7,9];  # just in case rename did something
    return 1 if ($copied = copy($from,$to)) && unlink($from);

    ($tosz2,$tomt2) = ((stat($to))[7,9],0,0) if defined $tomt1;
    unlink($to) if !defined($tomt1) or $tomt1 != $tomt2 or $tosz1 != $tosz2;
    ($!,$^E) = ($sts,$ossts);
    return 0;
}

*cp = \&copy;
*mv = \&move;

# &syscopy is an XSUB under OS/2
unless (defined &syscopy) {
    if ($^O eq 'VMS') {
	*syscopy = \&rmscopy;
    } elsif ($^O eq 'mpeix') {
	*syscopy = sub {
	    return 0 unless @_ == 2;
	    # Use the MPE cp program in order to
	    # preserve MPE file attributes.
	    return system('/bin/cp', '-f', $_[0], $_[1]) == 0;
	};
    } elsif ($^O eq 'MSWin32') {
	*syscopy = sub {
	    return 0 unless @_ == 2;
	    return Win32::CopyFile(@_, 1);
	};
    } else {
	$Syscopy_is_copy = 1;
	*syscopy = \&copy;
    }
}

1;

__END__

=head1 NAME

File::Copy - Copy files or filehandles

=head1 SYNOPSIS

  	use File::Copy;

	copy("file1","file2");
  	copy("Copy.pm",\*STDOUT);'
	move("/dev1/fileA","/dev2/fileB");

  	use POSIX;
	use File::Copy cp;

	$n = FileHandle->new("/a/file","r");
	cp($n,"x");'

=head1 DESCRIPTION

The File::Copy module provides two basic functions, C<copy> and
C<move>, which are useful for getting the contents of a file from
one place to another.

=over 4

=item *

The C<copy> function takes two
parameters: a file to copy from and a file to copy to. Either
argument may be a string, a FileHandle reference or a FileHandle
glob. Obviously, if the first argument is a filehandle of some
sort, it will be read from, and if it is a file I<name> it will
be opened for reading. Likewise, the second argument will be
written to (and created if need be).

B<Note that passing in
files as handles instead of names may lead to loss of information
on some operating systems; it is recommended that you use file
names whenever possible.>  Files are opened in binary mode where
applicable.  To get a consistent behaviour when copying from a
filehandle to a file, use C<binmode> on the filehandle.

An optional third parameter can be used to specify the buffer
size used for copying. This is the number of bytes from the
first file, that wil be held in memory at any given time, before
being written to the second file. The default buffer size depends
upon the file, but will generally be the whole file (up to 2Mb), or
1k for filehandles that do not reference files (eg. sockets).

You may use the syntax C<use File::Copy "cp"> to get at the
"cp" alias for this function. The syntax is I<exactly> the same.

=item *

The C<move> function also takes two parameters: the current name
and the intended name of the file to be moved.  If the destination
already exists and is a directory, and the source is not a
directory, then the source file will be renamed into the directory
specified by the destination.

If possible, move() will simply rename the file.  Otherwise, it copies
the file to the new location and deletes the original.  If an error occurs
during this copy-and-delete process, you may be left with a (possibly partial)
copy of the file under the destination name.

You may use the "mv" alias for this function in the same way that
you may use the "cp" alias for C<copy>.

=back

File::Copy also provides the C<syscopy> routine, which copies the
file specified in the first parameter to the file specified in the
second parameter, preserving OS-specific attributes and file
structure.  For Unix systems, this is equivalent to the simple
C<copy> routine.  For VMS systems, this calls the C<rmscopy>
routine (see below).  For OS/2 systems, this calls the C<syscopy>
XSUB directly. For Win32 systems, this calls C<Win32::CopyFile>.

=head2 Special behaviour if C<syscopy> is defined (OS/2, VMS and Win32)

If both arguments to C<copy> are not file handles,
then C<copy> will perform a "system copy" of
the input file to a new output file, in order to preserve file
attributes, indexed file structure, I<etc.>  The buffer size
parameter is ignored.  If either argument to C<copy> is a
handle to an opened file, then data is copied using Perl
operators, and no effort is made to preserve file attributes
or record structure.

The system copy routine may also be called directly under VMS and OS/2
as C<File::Copy::syscopy> (or under VMS as C<File::Copy::rmscopy>, which
is the routine that does the actual work for syscopy).

=over 4

=item rmscopy($from,$to[,$date_flag])

The first and second arguments may be strings, typeglobs, typeglob
references, or objects inheriting from IO::Handle;
they are used in all cases to obtain the
I<filespec> of the input and output files, respectively.  The
name and type of the input file are used as defaults for the
output file, if necessary.

A new version of the output file is always created, which
inherits the structure and RMS attributes of the input file,
except for owner and protections (and possibly timestamps;
see below).  All data from the input file is copied to the
output file; if either of the first two parameters to C<rmscopy>
is a file handle, its position is unchanged.  (Note that this
means a file handle pointing to the output file will be
associated with an old version of that file after C<rmscopy>
returns, not the newly created version.)

The third parameter is an integer flag, which tells C<rmscopy>
how to handle timestamps.  If it is E<lt> 0, none of the input file's
timestamps are propagated to the output file.  If it is E<gt> 0, then
it is interpreted as a bitmask: if bit 0 (the LSB) is set, then
timestamps other than the revision date are propagated; if bit 1
is set, the revision date is propagated.  If the third parameter
to C<rmscopy> is 0, then it behaves much like the DCL COPY command:
if the name or type of the output file was explicitly specified,
then no timestamps are propagated, but if they were taken implicitly
from the input filespec, then all timestamps other than the
revision date are propagated.  If this parameter is not supplied,
it defaults to 0.

Like C<copy>, C<rmscopy> returns 1 on success.  If an error occurs,
it sets C<$!>, deletes the output file, and returns 0.

=back

=head1 RETURN

All functions return 1 on success, 0 on failure.
$! will be set if an error was encountered.

=head1 AUTHOR

File::Copy was written by Aaron Sherman I<E<lt>ajs@ajs.comE<gt>> in 1995,
and updated by Charles Bailey I<E<lt>bailey@newman.upenn.eduE<gt>> in 1996.

=cut