bzip2_file_compression.pl

#!/usr/bin/perl

# Compress files using Bzip2.

use 5.036;
use Getopt::Std    qw(getopts);
use File::Basename qw(basename);

use IO::Compress::Bzip2     qw(bzip2);
use IO::Uncompress::Bunzip2 qw(bunzip2);

use constant {
              PKGNAME => 'BZIP2',
              VERSION => '0.01',
              FORMAT  => 'bz2',
             };

sub usage {
    my ($code) = @_;
    print <<"EOH";
usage: $0 [options] [input file] [output file]

options:
        -e            : extract
        -i <filename> : input filename
        -o <filename> : output filename
        -r            : rewrite output

        -v            : version number
        -h            : this message

examples:
         $0 document.txt
         $0 document.txt archive.${\FORMAT}
         $0 archive.${\FORMAT} document.txt
         $0 -e -i archive.${\FORMAT} -o document.txt

EOH

    exit($code // 0);
}

sub version {
    printf("%s %s\n", PKGNAME, VERSION);
    exit;
}

sub main {
    my %opt;
    getopts('ei:o:vhr', \%opt);

    $opt{h} && usage(0);
    $opt{v} && version();

    my ($input, $output) = @ARGV;
    $input  //= $opt{i} // usage(2);
    $output //= $opt{o};

    my $ext = qr{\.${\FORMAT}\z}io;
    if ($opt{e} || $input =~ $ext) {

        if (not defined $output) {
            ($output = basename($input)) =~ s{$ext}{}
              || die "$0: no output file specified!\n";
        }

        if (not $opt{r} and -e $output) {
            print "'$output' already exists! -- Replace? [y/N] ";
            <STDIN> =~ /^y/i || exit 17;
        }

        decompress_file($input, $output)
          || die "$0: error: decompression failed!\n";
    }
    elsif ($input !~ $ext || (defined($output) && $output =~ $ext)) {
        $output //= basename($input) . '.' . FORMAT;
        compress_file($input, $output)
          || die "$0: error: compression failed!\n";
    }
    else {
        warn "$0: don't know what to do...\n";
        usage(1);
    }
}

# Compress file
sub compress_file ($input, $output) {

    open my $fh, '<:raw', $input
      or die "Can't open file <<$input>> for reading: $!";

    # Open the output file for writing
    open my $out_fh, '>:raw', $output
      or die "Can't open file <<$output>> for write: $!";

    # Compress data
    bzip2($fh, $out_fh) or die "compression error";

    # Close the file
    close $out_fh;
}

# Decompress file
sub decompress_file ($input, $output) {

    # Open and validate the input file
    open my $fh, '<:raw', $input
      or die "Can't open file <<$input>> for reading: $!";

    # Open the output file
    open my $out_fh, '>:raw', $output
      or die "Can't open file <<$output>> for writing: $!";

    bunzip2($fh, $out_fh) or die "decompression error";

    # Close the file
    close $fh;
    close $out_fh;
}

main();
exit(0);