tangetools/rrm/rrm

#!/usr/bin/perl

=encoding utf8

=head1 NAME

rrm - record and remove file


=head1 SYNOPSIS

B<rrm> I<file>


=head1 DESCRIPTION

B<rrm> records a file's MD5sum before removing it. It makes it
possible to automatically remove the file again should it ever
reappear.

This is useful for cleaning up photos where other partial backups of
the photos are later added: Photos removed once can easily be
identified and removed automatically if added by the backup.


=head1 EXAMPLE

B<rrm> IMG_2035.JPG

Restore a backup containing I<IMG_2035.JPG>.

B<rclean>

B<rclean> will find B<IMG_2035.JPG> as it has the same size and SHA256sum
as an already removed file.


=head1 FILES

The file B<.rrm> contains the database of size, sha256sum, and names of
the files. It is created in current directory if it cannot be found in
any of the (grand*)parent directories.


=head1 SEE ALSO

B<rclean>(1), B<rm>(1), B<sha256sum>(1)


=cut


use Digest::SHA;

my %size;
my %hashval;
my @remove;
for my $file (@ARGV) {
    if(-s $file > 0) {
	$size{$file} = -s $file;
	my $sha = Digest::SHA->new(256);
	$sha->addfile($file);
	$hashval{$file} = "SHA256:".$sha->b64digest;
	push @remove, $file;
    }
    if(not -e $file) {
	warn("File does not exist: $file");
    }
}

$rrmfile = find_rrm_file(".") || ".rrm";

open(RRM,">>",$rrmfile) || die("Cannot write to $rrmfile.");
print RRM map { $size{$_}."\t".$hashval{$_}."\t".$_."\0\n" } @remove;
close RRM;
unlink @remove;

sub find_rrm_file {
    my $dir = shift;
    if(-r "$dir/.rrm") {
	return "$dir/.rrm";
    }
    if(join(" ",stat $dir) eq join(" ",stat "../$dir")) {
	# We have reached root dir (.. = .)
	return undef;
    } else {
	return find_rrm_file("../$dir");
    } 
}