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lzbws_file_compression.pl
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lzbws_file_compression.pl
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#!/usr/bin/perl
# Author: Trizen
# Date: 15 December 2022
# Edit: 25 July 2024
# https://github.com/trizen
# Compress/decompress files using LZ77 compression + symbolic Bzip2 (MRL variant).
use 5.036;
use Getopt::Std qw(getopts);
use File::Basename qw(basename);
use Compression::Util qw(:all);
use constant {
PKGNAME => 'LZBWS',
VERSION => '0.01',
FORMAT => 'lzbws',
CHUNK_SIZE => 1 << 18, # higher value = better compression
};
# Container signature
use constant SIGNATURE => uc(FORMAT) . chr(1);
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($code // 0);
}
sub version {
printf("%s %s\n", PKGNAME, VERSION);
exit;
}
sub valid_archive {
my ($fh) = @_;
if (read($fh, (my $sig), length(SIGNATURE), 0) == length(SIGNATURE)) {
$sig eq SIGNATURE || return;
}
return 1;
}
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: $!";
my $header = SIGNATURE;
# Open the output file for writing
open my $out_fh, '>:raw', $output
or die "Can't open file <<$output>> for write: $!";
# Print the header
print $out_fh $header;
# Compress data
while (read($fh, (my $chunk), CHUNK_SIZE)) {
print $out_fh lz77_compress($chunk, \&mrl_compress_symbolic);
}
# 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: $!";
valid_archive($fh) || die "$0: file `$input' is not a \U${\FORMAT}\E v${\VERSION} archive!\n";
# Open the output file
open my $out_fh, '>:raw', $output
or die "Can't open file <<$output>> for writing: $!";
while (!eof($fh)) {
print $out_fh lz77_decompress($fh, \&mrl_decompress_symbolic);
}
# Close the file
close $fh;
close $out_fh;
}
main();
exit(0);