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Filename : class-tar-archiver.php
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<?php
/**
 * MainWP Tar Archiver
 *
 * This file handles the Tar archiver actions.
 *
 * @package MainWP\Child
 */

namespace MainWP\Child;

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

// phpcs:disable WordPress.WP.AlternativeFunctions, Generic.Metrics.CyclomaticComplexity -- to custom read/write files, complex tar archiver library.

/**
 * Class Tar_Archiver
 *
 * Handle the Tar archiver actions.
 */
class Tar_Archiver {
    const IDLE   = 0;
    const APPEND = 1;
    const CREATE = 2;

    /**
     * Whether to exclude zip archives.
     *
     * @var bool Set true to exclude ZIP archives from the backup.
     */
    protected $excludeZip;

    /**
     * Backup archive file.
     *
     * @var resource Backup file.
     */
    protected $archive;

    /**
     * Backup archive file path.
     *
     * @var string Backup file path.
     */
    protected $archivePath;

    /**
     * Backup archive file size.
     *
     * @var float Backup file size.
     */
    protected $archiveSize;

    /**
     * Last time a backup has been run.
     *
     * @var string Last backup run.
     */
    protected $lastRun = 0;

    /**
     * Enable debug mode.
     *
     * @var bool Set try to enable debugging.
     */
    protected $debug;

    /**
     * Chunk of the backup.
     *
     * @var string Backup chunk.
     */
    protected $chunk = '';

    /**
     * Backup chunk size.
     *
     * @var int Backup chunk size.
     */
    protected $chunkSize = 4194304;

    /**
     * MainWP_Backup class instance.
     *
     * @var object MainWP_Backup class
     */
    protected $backup;

    /**
     * Backup archive type.
     *
     * @var string Archive type.
     */
    protected $type;

    /**
     * Backup PID file.
     *
     * @var resource PID file.
     */
    protected $pidFile;

    /**
     * Backup PID file content.
     *
     * @var string PID file content.
     */
    protected $pidContent;

    /**
     * Time of the last PID file update.
     *
     * @var string Last PID file update.
     */
    protected $pidUpdated;

    /**
     * Arvive mode, IDLE, APPEND or CREATE.
     *
     * @var int Arvive mode.
     */
    protected $mode = self::IDLE;

    /**
     * Enable logging.
     *
     * @var bool Set true to log records.
     */
    protected $logHandle = false;

    /**
     * Tar_Archiver constructor.
     *
     * Run any time class is called.
     *
     * @param object $backup  MainWP_Backup class instance.
     * @param string $type    Backup arvhive type.
     * @param bool   $pidFile Request PID file or not.
     */
    public function __construct( $backup, $type = 'tar', $pidFile = false ) {
        $this->debug = false;

        $this->pidFile = $pidFile;
        $this->backup  = $backup;

        $this->type = $type;
        if ( 'tar.bz2' === $this->type ) {
            if ( ! function_exists( 'bzopen' ) ) {
                $this->type = 'tar.gz';
            }
        }

        if ( 'tar.gz' === $this->type ) {
            if ( ! function_exists( 'gzopen' ) ) {
                $this->type = 'tar';
            }
        }
    }

    /**
     * Get backup archive file extension, .tar.bz2, .tar.gz or .tar.
     *
     * @return string Aarchive file extension, .tar.bz2, .tar.gz or .tar.
     */
    public function get_extension() {
        if ( 'tar.bz2' === $this->type ) {
            return '.tar.bz2';
        }
        if ( 'tar.gz' === $this->type ) {
            return '.tar.gz';
        }

        return '.tar';
    }

    /**
     * Create ZIP file.
     *
     * @param array  $files Files to zip.
     * @param string $archive Type of archive to create.
     *
     * @uses Tar_Archiver::create() Create archive file.
     * @uses Tar_Archiver::add_file() Add file to the archive file.
     * @uses Tar_Archiver::add_data() Add data to the archive file.
     * @uses Tar_Archiver::close() Close archive file.
     *
     * @return bool Return false on failure, true on success.
     */
    public function zip_file( $files, $archive ) {
        $this->create( $archive );
        if ( $this->archive ) {
            $this->init_log_handle( $archive . '.log' );
            foreach ( $files as $filepath ) {
                $this->add_file( $filepath, basename( $filepath ) );
            }

            $this->add_data( pack( 'a1024', '' ) );
            $this->close();

            return true;
        }

        return false;
    }

    /**
     * Create backup archive PID file.
     *
     * @param resource $file Backup archive PID file.
     *
     * @uses WP_Filesystem_Direct::put_contents() Writes a string to a file.
     * @see https://developer.wordpress.org/reference/classes/wp_filesystem_direct/put_contents/
     *
     * @used-by Tar_Archiver::create_full_backup() Create full backup.
     *
     * @return bool Return false on failure, true on success.
     */
    private function create_pid_file( $file ) {
        if ( false === $this->pidFile ) {
            return false;
        }
        $this->pidContent = $file;

        /**
         * Global variable containing the instance of the (auto-)configured filesystem object after the filesystem "factory" has been run.
         *
         * @global object $wp_filesystem Filesystem object.
         */
        global $wp_filesystem;

        $wp_filesystem->put_contents( $this->pidFile, $this->pidContent );

        $this->pidUpdated = time();

        return true;
    }

    /**
     * Update backup archive PID file.
     *
     * @uses WP_Filesystem_Direct::put_contents() Writes a string to a file.
     * @see https://developer.wordpress.org/reference/classes/wp_filesystem_direct/put_contents/
     *
     * @used-by Tar_Archiver::add_empty_dir() Add empty directory.
     *
     * @return bool Return false on failure, true on success.
     */
    public function update_pid_file() {
        if ( false === $this->pidFile ) {
            return false;
        }
        if ( time() - $this->pidUpdated < 40 ) {
            return false;
        }

        /**
         * Global variable containing the instance of the (auto-)configured filesystem object after the filesystem "factory" has been run.
         *
         * @global object $wp_filesystem Filesystem object.
         */
        global $wp_filesystem;

        $wp_filesystem->put_contents( $this->pidFile, $this->pidContent );
        $this->pidUpdated = time();

        return true;
    }

    /**
     * Complete backup archive PID file.
     *
     * @uses WP_Filesystem_Direct::move() Moves a file.
     * @see https://developer.wordpress.org/reference/classes/wp_filesystem_direct/move/
     *
     * @used-by Tar_Archiver::create_full_backup() Create full backup.
     *
     * @return bool Return false on failure, true on success.
     */
    private function complete_pid_file() {
        if ( false === $this->pidFile ) {
            return false;
        }

        /**
         * Global variable containing the instance of the (auto-)configured filesystem object after the filesystem "factory" has been run.
         *
         * @global object $wp_filesystem Filesystem object.
         */
        global $wp_filesystem;

        $filename = basename( $this->pidFile );
        $wp_filesystem->move( $this->pidFile, trailingslashit( dirname( $this->pidFile ) ) . substr( $filename, 0, strlen( $filename ) - 4 ) . '.done' );
        $this->pidFile = false;

        return true;
    }

    /**
     * Init log file handle.
     *
     * @param string $file_log         Log file path.
     */
    public function init_log_handle( $file_log ) {
        //phpcs:ignore -- for debug.
        // $this->logHandle = fopen( $file_log, 'a+' );
    }

    /**
     * Create full backup.
     *
     * @param string $filepath         Backup file path.
     * @param array  $excludes         Files to exclude from the backup.
     * @param bool   $addConfig        Add config file to backup.
     * @param bool   $includeCoreFiles Include WordPress core files.
     * @param bool   $excludezip       Exclude zip files from the backup.
     * @param bool   $excludenonwp     Exclude non-WordPress directories in site root.
     * @param bool   $append           Append to backup file name.
     *
     * @return bool Return false on failure, true on success.
     * @throws \Exception Error message.
     *
     * @uses Tar_Archiver::create_pid_file() Create PID file.
     * @uses Tar_Archiver::prepare_append() Prepare to append.
     * @uses Tar_Archiver::create() Create backup archive file.
     * @uses Tar_Archiver::include_core_files() Include WordPress core files.
     * @uses Tar_Archiver::create_backup_db() Create database backup.
     * @uses Tar_Archiver::add_file() Add file to backup archive file.
     * @uses Tar_Archiver::add_dir() Add directory to backup archive file.
     * @uses Tar_Archiver::add_config() Add config file to backup archive file.
     * @uses Tar_Archiver::add_empty_directory() Add empty 'clone' directory to backup archive file.
     * @uses Tar_Archiver::add_file_from_string() Add file from a string.
     * @uses Tar_Archiver::add_data() Add data to the backup archive file.
     * @uses Tar_Archiver::close() Close the bacukup archive file.
     * @uses Tar_Archiver::complete_pid_file() Complete the PID file.
     * @uses \MainWP\Child\MainWP_Helper::starts_with()
     * @uses \MainWP\Child\MainWP_Helper::in_excludes()
     */
    public function create_full_backup( $filepath, $excludes, $addConfig, $includeCoreFiles, $excludezip, $excludenonwp, $append = false ) {

        $this->init_log_handle( $filepath . '.log' );

        $this->create_pid_file( $filepath );

        $this->excludeZip = $excludezip;

        $this->archivePath = $filepath;

        if ( $append && file_exists( $filepath ) ) {
            $this->mode = self::APPEND;
            $this->prepare_append( $filepath );
        } else {
            $this->mode = self::CREATE;
            $this->create( $filepath );
        }

        if ( $this->archive ) {
            $nodes = glob( ABSPATH . '*' );
            if ( ! $includeCoreFiles ) {
                $this->include_core_files( $nodes );
            }

            $db_files = $this->backup->create_backup_db( dirname( $filepath ) . DIRECTORY_SEPARATOR . 'dbBackup', false, $this );

            foreach ( $db_files as $db_file ) {
                $this->add_file( $db_file, basename( WP_CONTENT_DIR ) . '/' . basename( $db_file ) );
            }

            if ( file_exists( ABSPATH . '.htaccess' ) ) {
                $this->add_file( ABSPATH . '.htaccess', 'mainwp-htaccess' );
            }

            foreach ( $nodes as $node ) {
                if ( $excludenonwp && is_dir( $node ) ) {
                    if ( ! MainWP_Helper::starts_with( $node, WP_CONTENT_DIR ) && ! MainWP_Helper::starts_with( $node, ABSPATH . 'wp-admin' ) && ! MainWP_Helper::starts_with( $node, ABSPATH . WPINC ) ) {
                        continue;
                    }
                }

                if ( ! MainWP_Helper::in_excludes( $excludes, str_replace( ABSPATH, '', $node ) ) ) {
                    if ( is_dir( $node ) ) {
                        $this->add_dir( $node, $excludes );
                    } elseif ( is_file( $node ) ) {
                        $this->add_file( $node, str_replace( ABSPATH, '', $node ) );
                    }
                }
            }

            if ( $addConfig ) {
                $string = $this->add_config();
                $this->add_empty_directory( 'clone', 0, 0, 0, time() );
                $this->add_file_from_string( 'clone/config.txt', $string );
            }

            $this->add_data( pack( 'a1024', '' ) );
            $this->close();
            foreach ( $db_files as $db_file ) {
                wp_delete_file( $db_file );
            }

            $this->complete_pid_file();

            return true;
        }

        return false;
    }

    /**
     * Include WordPress core file.
     *
     * @param array $nodes Default nodes.
     *
     * @used-by  \MainWP\Child\Tar_Archiver::create_full_backup() Create full backup.
     * @uses    \MainWP\Child\MainWP_Helper::starts_with()
     */
    private function include_core_files( &$nodes ) {
        $coreFiles = array(
            'favicon.ico',
            'index.php',
            'license.txt',
            'readme.html',
            'wp-activate.php',
            'wp-app.php',
            'wp-blog-header.php',
            'wp-comments-post.php',
            'wp-config.php',
            'wp-config-sample.php',
            'wp-cron.php',
            'wp-links-opml.php',
            'wp-load.php',
            'wp-login.php',
            'wp-mail.php',
            'wp-pass.php',
            'wp-register.php',
            'wp-settings.php',
            'wp-signup.php',
            'wp-trackback.php',
            'xmlrpc.php',
        );
        foreach ( $nodes as $key => $node ) {
            if ( MainWP_Helper::starts_with( $node, ABSPATH . WPINC ) ) {
                unset( $nodes[ $key ] );
            } elseif ( MainWP_Helper::starts_with( $node, ABSPATH . basename( admin_url( '' ) ) ) ) {
                unset( $nodes[ $key ] );
            } else {
                foreach ( $coreFiles as $coreFile ) {
                    if ( ABSPATH . $coreFile === $node ) {
                        unset( $nodes[ $key ] );
                    }
                }
            }
        }
        unset( $coreFiles );
    }

    /**
     * Add config file to the backup archive file.
     *
     * @uses wp_json_encode() Encode a variable into JSON, with some sanity checks.
     * @see https://developer.wordpress.org/reference/functions/wp_json_encode/
     *
     * @uses get_option() Retrieves an option value based on an option name.
     * @see https://developer.wordpress.org/reference/functions/get_option/
     *
     * @uses get_bloginfo() Retrieves information about the current site.
     * @see https://developer.wordpress.org/reference/functions/get_bloginfo/
     *
     * @used-by Tar_Archiver::create_full_backup() Create full backup.
     */
    private function add_config() {

        /**
         * Object, providing access to the WordPress database.
         *
         * @global $wpdb WordPress Database instance.
         */
        global $wpdb;

        $plugins = array();
        $dir     = WP_CONTENT_DIR . '/plugins/';
        $fh      = opendir( $dir );
        while ( $entry = readdir( $fh ) ) {
            if ( ! is_dir( $dir . $entry ) ) {
                continue;
            }
            if ( ( '.' === $entry ) || ( '..' === $entry ) ) {
                continue;
            }
            $plugins[] = $entry;
        }
        closedir( $fh );

        $themes = array();
        $dir    = WP_CONTENT_DIR . '/themes/';
        $fh     = opendir( $dir );
        while ( $entry = readdir( $fh ) ) {
            if ( ! is_dir( $dir . $entry ) ) {
                continue;
            }
            if ( ( '.' === $entry ) || ( '..' === $entry ) ) {
                continue;
            }
            $themes[] = $entry;
        }
        closedir( $fh );

        $string = wp_json_encode(
            array(
                'siteurl' => get_option( 'siteurl' ),
                'home'    => get_option( 'home' ),
                'abspath' => ABSPATH,
                'prefix'  => $wpdb->prefix,
                'lang'    => get_bloginfo( 'language' ),
                'plugins' => $plugins,
                'themes'  => $themes,
            )
        );

        return $string;
    }

    /**
     * Add directory to the backup archive file.
     *
     * @param string $path     File path.
     * @param array  $excludes List of file to exclude from the backup.
     *
     * @uses \MainWP\Child\Tar_Archiver::add_empty_dir() Add empty directory to the backup archive file.
     * @uses \MainWP\Child\Tar_Archiver::add_file() Add file to the backup archive file.
     * @uses \MainWP\Child\MainWP_Helper::in_excludes()
     *
     * @used-by \MainWP\Child\Tar_Archiver::create_full_backup() Create full backup.
     */
    public function add_dir( $path, $excludes ) {
        if ( ( '.' === basename( $path ) ) || ( '..' === basename( $path ) ) ) {
            return;
        }

        $this->add_empty_dir( $path, str_replace( ABSPATH, '', $path ) );

        if ( file_exists( rtrim( $path, '/' ) . '/.htaccess' ) ) {
            $this->add_file( rtrim( $path, '/' ) . '/.htaccess', rtrim( str_replace( ABSPATH, '', $path ), '/' ) . '/mainwp-htaccess' );
        }

        $iterator = new \RecursiveIteratorIterator( new \RecursiveDirectoryIterator( $path ), \RecursiveIteratorIterator::SELF_FIRST, \RecursiveIteratorIterator::CATCH_GET_CHILD );

        foreach ( $iterator as $path ) {
            $name = $path->__toString();
            if ( ( '.' === basename( $name ) ) || ( '..' === basename( $name ) ) ) {
                continue;
            }

            if ( ! MainWP_Helper::in_excludes( $excludes, str_replace( ABSPATH, '', $name ) ) ) {
                if ( $path->isDir() ) {
                    $this->add_empty_dir( $name, str_replace( ABSPATH, '', $name ) );
                } else {
                    $this->add_file( $name, str_replace( ABSPATH, '', $name ) );
                }
            }
            $name = null;
            unset( $name );
        }

        $iterator = null;
        unset( $iterator );
    }

    /**
     * Add data to the backup archive file.
     *
     * @param arary $data Data to add to the backup archive file.
     *
     * @uses Tar_Archiver::add_empty_dir() Add empty directory to the backup archive file.
     * @uses Tar_Archiver::add_file() Add file to the backup archive file.
     *
     * @used-by Tar_Archiver::create_full_backup() Create full backup.
     *
     * @throws \Exception Error message.
     */
    private function add_data( $data ) {
        if ( $this->debug ) {
            $this->chunk .= $data;

            if ( strlen( $this->chunk ) > $this->chunkSize ) {
                $this->write_chunk();
            }

            return;
        }

        if ( 'tar.gz' === $this->type ) {
            if ( false === gzwrite( $this->archive, $data, strlen( $data ) ) ) {
                throw new \Exception( 'Could not write to archive' );
            }
        } elseif ( 'tar.bz2' === $this->type ) {
            if ( false === bzwrite( $this->archive, $data, strlen( $data ) ) ) {
                throw new \Exception( 'Could not write to archive' );
            }
        } else {
            if ( false === fwrite( $this->archive, $data, strlen( $data ) ) ) {
                throw new \Exception( 'Could not write to archive' );
            }
            fflush( $this->archive );
        }
    }

    /**
     * Write backup chunk.
     *
     * @throws \Exception Error message.
     */
    private function write_chunk() {
        $len = strlen( $this->chunk );
        if ( 0 === $len ) {
            return;
        }

        if ( 'tar.gz' === $this->type ) {
            $this->log( 'writing & flushing ' . $len );
            $this->chunk = gzencode( $this->chunk );
            if ( false === fwrite( $this->archive, $this->chunk, strlen( $this->chunk ) ) ) {
                throw new \Exception( 'Could not write to archive' );
            }
            fflush( $this->archive );
        } elseif ( 'tar.bz2' === $this->type ) {
            if ( false === bzwrite( $this->archive, $this->chunk, strlen( $len ) ) ) {
                throw new \Exception( 'Could not write to archive' );
            }
        } else {
            if ( false === fwrite( $this->archive, $len, strlen( $len ) ) ) {
                throw new \Exception( 'Could not write to archive' );
            }
            fflush( $this->archive );
        }

        $this->chunk = '';
    }

    /**
     * Fire off the add_empty_directory() function.
     *
     * @param string $path      File path.
     * @param string $entryName Entry name.
     *
     * @uses Tar_Archiver::add_empty_directory() Add empty directory to the backup archive file.
     *
     * @used-by Tar_Archiver::create_full_backup() Create full backup.
     */
    private function add_empty_dir( $path, $entryName ) {
        $stat = stat( $path );

        $this->add_empty_directory( $entryName, $stat['mode'], $stat['uid'], $stat['gid'], $stat['mtime'] );
    }

    /**
     * Add empty directory to the backup archive file.
     *
     * @param string $entryName Entry name.
     * @param int    $mode      Inode protection mode.
     * @param int    $uid       Userid of the file owner.
     * @param int    $gid       Groupid of the file owner .
     * @param string $mtime     Time of last modification of the file.
     *
     * @uses Tar_Archiver::check_before_append() Check before append.
     * @uses Tar_Archiver::add_data() Add data to the backup archive file.
     *
     * @used-by Tar_Archiver::add_empty_dir() Fire off the add_empty_directory() function.
     */
    private function add_empty_directory( $entryName, $mode, $uid, $gid, $mtime ) {
        if ( self::APPEND === $this->mode ) {
            if ( true === $this->check_before_append( $entryName ) ) {
                return true;
            }
        }

        $prefix = '';
        if ( strlen( $entryName ) > 99 ) {
            $prefix    = substr( $entryName, 0, strpos( $entryName, '/', strlen( $entryName ) - 100 ) + 1 );
            $entryName = substr( $entryName, strlen( $prefix ) );
            if ( strlen( $prefix ) > 154 || strlen( $entryName ) > 99 ) {
                $entryName = $prefix . $entryName;
                $prefix    = '';

                $block = pack(
                    'a100a8a8a8a12a12a8a1a100a6a2a32a32a8a8a155a12',
                    '././@LongLink',
                    sprintf( '%07o', 0 ),
                    sprintf( '%07o', 0 ),
                    sprintf( '%07o', 0 ),
                    sprintf( '%011o', strlen( $entryName ) ),
                    sprintf( '%011o', 0 ),
                    '        ',
                    'L',
                    '',
                    'ustar',
                    ' ',
                    '',
                    '',
                    '',
                    '',
                    '',
                    ''
                );

                $checksum = 0;
                for ( $i = 0; $i < 512; $i++ ) {
                    $checksum += ord( substr( $block, $i, 1 ) );
                }
                $checksum = pack( 'a8', sprintf( '%07o', $checksum ) );
                $block    = substr_replace( $block, $checksum, 148, 8 );

                $this->add_data( $block );
                $this->add_data( pack( 'a512', $entryName ) );
                $entryName = substr( $entryName, 0, 100 );
            }
        }

        $block = pack(
            'a100a8a8a8a12a12a8a1a100a6a2a32a32a8a8a155a12',
            $entryName,
            sprintf( '%07o', $mode ),
            sprintf( '%07o', $uid ),
            sprintf( '%07o', $gid ),
            sprintf( '%011o', 0 ),
            sprintf( '%011o', $mtime ),
            '        ',
            5,
            '',
            'ustar',
            ' ',
            'Unknown',
            'Unknown',
            '',
            '',
            $prefix,
            ''
        );

        $checksum = 0;
        for ( $i = 0; $i < 512; $i++ ) {
            $checksum += ord( substr( $block, $i, 1 ) );
        }
        $checksum = pack( 'a8', sprintf( '%07o', $checksum ) );
        $block    = substr_replace( $block, $checksum, 148, 8 );

        $this->add_data( $block );

        return true;
    }

    /**
     * Block of the backup content.
     *
     * @var array Block of content.
     */
    protected $block;

    /**
     * Temprary backup content.
     *
     * @var string Temprary content.
     */
    protected $tempContent;

    /**
     * Garbage collection count.
     *
     * @var int Garbage collection count.
     */
    protected $gcCnt = 0;

    /**
     * Count number.
     *
     * @var int Count number.
     */
    protected $cnt = 0;

    /**
     * Add file to the backup archive file.
     *
     * @param string $path      File path.
     * @param string $entryName Entry name.
     *
     * @return bool Return false on failure, true on success.
     * @throws \Exception Error message.
     *
     * @used-by \MainWP\Child\Tar_Archiver::create_full_backup() Create full backup.
     * @uses    \MainWP\Child\Tar_Archiver::add_data() Add data to the backup archive file.
     * @uses    \MainWP\Child\Tar_Archiver::update_pid_file() Update the PID file.
     * @uses    \MainWP\Child\MainWP_Helper::ends_with()
     */
    private function add_file( $path, $entryName ) { // phpcs:ignore -- Current complexity is the only way to achieve desired results, pull request solutions appreciated.
        if ( ( '.' === basename( $path ) ) || ( '..' === basename( $path ) ) ) {
            return false;
        }

        if ( $this->excludeZip && MainWP_Helper::ends_with( $path, '.zip' ) ) {
            $this->log( 'Skipping ' . $path );

            return false;
        }

        $this->log( 'Adding ' . $path );

        $this->update_pid_file();

        $rslt = false;
        if ( self::APPEND === $this->mode ) {
            $rslt = $this->check_before_append( $entryName );
            if ( true === $rslt ) {
                return true;
            }
        }

        if ( time() - $this->lastRun > 60 ) {
            set_time_limit( 20 * 60 * 60 );
            $this->lastRun = time();
        }

        ++$this->gcCnt;
        if ( $this->gcCnt > 20 ) {
            if ( function_exists( 'gc_enable' ) ) {
                gc_enable();
            }
            if ( function_exists( 'gc_collect_cycles' ) ) {
                gc_collect_cycles();
            }
            $this->gcCnt = 0;
        }

        $stat = stat( $path ); // NOSONAR .
        $fp   = fopen( $path, 'rb' ); // NOSONAR .
        if ( ! $fp ) {
            return;
        }

        $prefix = '';
        if ( strlen( $entryName ) > 99 ) {
            $prefix    = substr( $entryName, 0, strpos( $entryName, '/', strlen( $entryName ) - 100 ) + 1 );
            $entryName = substr( $entryName, strlen( $prefix ) );
            if ( strlen( $prefix ) > 154 || strlen( $entryName ) > 99 ) {
                $entryName = $prefix . $entryName;
                $prefix    = '';

                $block = pack(
                    'a100a8a8a8a12a12a8a1a100a6a2a32a32a8a8a155a12',
                    '././@LongLink',
                    sprintf( '%07o', 0 ),
                    sprintf( '%07o', 0 ),
                    sprintf( '%07o', 0 ),
                    sprintf( '%011o', strlen( $entryName ) ),
                    sprintf( '%011o', 0 ),
                    '        ',
                    'L',
                    '',
                    'ustar',
                    ' ',
                    '',
                    '',
                    '',
                    '',
                    '',
                    ''
                );

                $checksum = 0;
                for ( $i = 0; $i < 512; $i++ ) {
                    $checksum += ord( substr( $block, $i, 1 ) );
                }
                $checksum = pack( 'a8', sprintf( '%07o', $checksum ) );
                $block    = substr_replace( $block, $checksum, 148, 8 );

                if ( ! isset( $rslt['bytesRead'] ) ) {
                    $this->add_data( $block );
                }
                if ( ! isset( $rslt['bytesRead'] ) ) {
                    $this->add_data( pack( 'a512', $entryName ) );
                }
                $entryName = substr( $entryName, 0, 100 );
            }
        }

        $this->block = pack(
            'a100a8a8a8a12a12a8a1a100a6a2a32a32a8a8a155a12',
            $entryName,
            sprintf( '%07o', $stat['mode'] ),
            sprintf( '%07o', $stat['uid'] ),
            sprintf( '%07o', $stat['gid'] ),
            sprintf( '%011o', $stat['size'] ),
            sprintf( '%011o', $stat['mtime'] ),
            '        ',
            0,
            '',
            'ustar',
            ' ',
            'Unknown',
            'Unknown',
            '',
            '',
            $prefix,
            ''
        );

        $checksum = 0;
        for ( $i = 0; $i < 512; $i++ ) {
            $checksum += ord( substr( $this->block, $i, 1 ) );
        }
        $checksum    = pack( 'a8', sprintf( '%07o', $checksum ) );
        $this->block = substr_replace( $this->block, $checksum, 148, 8 );

        if ( ! isset( $rslt['bytesRead'] ) ) {
            $this->add_data( $this->block );
        }

        if ( isset( $rslt['bytesRead'] ) ) {
            fseek( $fp, $rslt['bytesRead'] );

            $alreadyRead = ( $rslt['bytesRead'] % 512 );
            $toRead      = 512 - $alreadyRead;
            if ( $toRead > 0 ) {
                $this->tempContent = fread( $fp, $toRead );

                $this->add_data( $this->tempContent );

                $remainder = 512 - ( strlen( $this->tempContent ) + $alreadyRead );
                $this->log( 'DEBUG-Added ' . strlen( $this->tempContent ) . '(before: ' . $alreadyRead . ') will pack: ' . $remainder . ' (packed: ' . strlen( pack( 'a' . $remainder, '' ) ) );
                if ( $remainder > 0 ) {
                    $this->add_data( pack( 'a' . $remainder ), '' );
                }
            }
        }

        while ( ! feof( $fp ) ) {
            $this->tempContent = fread( $fp, 1024000 * 5 );

            $read   = strlen( $this->tempContent );
            $divide = $read % 512;

            $this->add_data( substr( $this->tempContent, 0, $read - $divide ) );

            if ( $divide > 0 ) {
                $this->add_data( pack( 'a512', substr( $this->tempContent, - 1 * $divide ) ) );
            }

            $this->update_pid_file();
        }

        fclose( $fp );

        return true;
    }

    /**
     * Add file from a string.
     *
     * @param string $entryName Entry name.
     * @param string $content   Entry content.
     *
     * @uses Tar_Archiver::add_data() Add data to the backup archive file.
     *
     * @return bool Return false on failure, true on success.
     */
    private function add_file_from_string( $entryName, $content ) {
        $this->log( 'Add from string ' . $entryName );

        if ( self::APPEND === $this->mode ) {
            if ( true === $this->check_before_append( $entryName ) ) {
                return true;
            }
        }

        $prefix = '';
        if ( strlen( $entryName ) > 99 ) {
            $prefix    = substr( $entryName, 0, strpos( $entryName, '/', strlen( $entryName ) - 100 ) + 1 );
            $entryName = substr( $entryName, strlen( $prefix ) );
            if ( strlen( $prefix ) > 154 || strlen( $entryName ) > 99 ) {
                $entryName = $prefix . $entryName;
                $prefix    = '';

                $block = pack(
                    'a100a8a8a8a12a12a8a1a100a6a2a32a32a8a8a155a12',
                    '././@LongLink',
                    sprintf( '%07o', 0 ),
                    sprintf( '%07o', 0 ),
                    sprintf( '%07o', 0 ),
                    sprintf( '%011o', strlen( $entryName ) ),
                    sprintf( '%011o', 0 ),
                    '        ',
                    'L',
                    '',
                    'ustar',
                    ' ',
                    '',
                    '',
                    '',
                    '',
                    '',
                    ''
                );

                $checksum = 0;
                for ( $i = 0; $i < 512; $i++ ) {
                    $checksum += ord( substr( $block, $i, 1 ) );
                }
                $checksum = pack( 'a8', sprintf( '%07o', $checksum ) );
                $block    = substr_replace( $block, $checksum, 148, 8 );

                $this->add_data( $block );
                $this->add_data( pack( 'a512', $entryName ) );
                $entryName = substr( $entryName, 0, 100 );
            }
        }

        $block = pack(
            'a100a8a8a8a12a12a8a1a100a6a2a32a32a8a8a155a12',
            $entryName,
            sprintf( '%07o', 0 ),
            sprintf( '%07o', 0 ),
            sprintf( '%07o', 0 ),
            sprintf( '%011o', strlen( $content ) ),
            sprintf( '%011o', time() ),
            '        ',
            0,
            '',
            'ustar',
            ' ',
            'Unknown',
            'Unknown',
            '',
            '',
            $prefix,
            ''
        );

        $checksum = 0;
        for ( $i = 0; $i < 512; $i++ ) {
            $checksum += ord( substr( $block, $i, 1 ) );
        }
        $checksum = pack( 'a8', sprintf( '%07o', $checksum ) );
        $block    = substr_replace( $block, $checksum, 148, 8 );

        $this->add_data( $block );
        $i = 0;
        while ( ( $line = substr( $content, $i * 512, 512 ) ) !== '' ) {
            ++$i;
            $this->add_data( pack( 'a512', $line ) );
        }

        return true;
    }

    /**
     * Check before append.
     *
     * @param string $entryName Entry name.
     *
     * @uses Tar_Archiver::close() Close the backup archive file.
     * @uses Tar_Archiver::append() Append to the backup archive file.
     *
     * @return array Return function output.
     */
    private function check_before_append( $entryName ) {
        $rslt = $this->is_next_file( $entryName );

        if ( true === $rslt ) {
            return true;
        }

        $out = false;

        $this->close( false );
        $this->log( 'Reopen archive to append from here' );
        $this->append( $this->archivePath );
        if ( is_array( $rslt ) ) {
            if ( 'tar' === $this->type ) {
                $startOffset = $rslt['startOffset'];
                fseek( $this->archive, $startOffset );
                ftruncate( $this->archive, $startOffset );
            } elseif ( 'tar.gz' === $this->type ) {
                $readOffset = $rslt['readOffset'];
                $bytesRead  = $rslt['bytesRead'];

                $out = array( 'bytesRead' => $bytesRead );
            }
        } elseif ( false === $rslt ) {
            if ( 'tar' === $this->type ) {
                fseek( $this->archive, 0, SEEK_END );
            }
        } else {
            fseek( $this->archive, $rslt );
            ftruncate( $this->archive, $rslt );
        }
        $this->mode = self::CREATE;

        return $out;
    }

    /**
     * Is next file.
     *
     * @param string $entryName Entry name.
     *
     * @throws \Exception Error message.
     *
     * @return array|bool If true,skip file, if false or number, nothing to read, will continue with current file.
     */
    private function is_next_file( $entryName ) {
        $currentOffset = ftell( $this->archive );
        $rslt          = array( 'startOffset' => $currentOffset );
        try {
            $block = fread( $this->archive, 512 );

            if ( false === $block || 0 === strlen( $block ) ) {
                return $rslt;
            }

            if ( 512 !== strlen( $block ) ) {
                throw new \Exception( 'Invalid block found' );
            }

            $temp = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
            if ( 'L' === $temp['type'] ) {
                $fname          = trim( fread( $this->archive, 512 ) );
                $block          = fread( $this->archive, 512 );
                $temp           = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
                $temp['prefix'] = '';
                $temp['name']   = $fname;
            }
            $file = array(
                'name'     => trim( $temp['prefix'] ) . trim( $temp['name'] ),
                'stat'     => array(
                    2 => $temp['mode'],
                    4 => octdec( $temp['uid'] ),
                    5 => octdec( $temp['gid'] ),
                    7 => octdec( $temp['size'] ),
                    9 => octdec( $temp['mtime'] ),
                ),
                'checksum' => octdec( $temp['checksum'] ),
                'type'     => $temp['type'],
                'magic'    => $temp['magic'],
            );

            if ( 5 === (int) $file['type'] ) {
                if ( 0 === strcmp( trim( $file['name'] ), trim( $entryName ) ) ) {
                    $this->log( 'Skipping directory [' . $file['name'] . ']' );

                    return true;
                } else {
                    throw new \Exception( 'Unexpected directory [' . $file['name'] . ']' );
                }
            } elseif ( 0 === (int) $file['type'] ) {
                if ( 0 === strcmp( trim( $file['name'] ), trim( $entryName ) ) ) {
                    return $this->read_next_bytes( $file );
                } else {
                    $this->log( 'Unexpected file [' . $file['name'] . ']' );
                    throw new \Exception( 'Unexpected file' );
                }
            }

            $this->log( 'ERROR' );
            throw new \Exception( 'Should never get here?' );
        } catch ( \Exception $e ) {
            $this->log( $e->getMessage() );
            throw $e;
        }
    }

    /**
     * Read next bytes.
     *
     * @param resource $file File to process.
     *
     * @return array|bool Number of bytes or false on failure.
     */
    private function read_next_bytes( $file ) {
        $previousFtell = ftell( $this->archive );
        $bytes         = $file['stat'][7] + ( 512 === ( 512 - $file['stat'][7] % 512 ) ? 0 : ( 512 - $file['stat'][7] % 512 ) );
        fseek( $this->archive, ftell( $this->archive ) + $bytes );
        $ftell = ftell( $this->archive );
        if ( 'tar.gz' === $this->type ) {
            if ( ( false === $ftell ) || ( -1 === $ftell ) ) {
                fseek( $this->archive, $previousFtell );

                $bytesRead   = 0;
                $bytesToRead = $file['stat'][7];

                while ( $bytesToRead > 0 ) {
                    $readNow            = $bytesToRead > 1024 ? 1024 : $bytesToRead;
                    $bytesCurrentlyRead = strlen( fread( $this->archive, $readNow ) );

                    if ( 0 === $bytesCurrentlyRead ) {
                        break;
                    }

                    $bytesRead   += $bytesCurrentlyRead;
                    $bytesToRead -= $bytesCurrentlyRead;
                }

                if ( 0 === $bytesToRead ) {
                    $toRead = ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 );
                    if ( $toRead > 0 ) {
                        $read       = strlen( fread( $this->archive, $toRead ) );
                        $bytesRead += $read;
                    }
                }

                $rslt['bytesRead']  = $bytesRead;
                $rslt['readOffset'] = $previousFtell;

                $this->log( 'Will append this: ' . print_r( $rslt, 1 ) ); // phpcs:ignore -- debug feature.

                return $rslt;
            }
        } elseif ( ( 'tar' === $this->type ) && ( ( false === $ftell ) || ( -1 === $ftell ) ) ) {
            $this->log( 'Will append this: ' . print_r( $rslt, 1 ) ); // phpcs:ignore -- debug feature.

            return $rslt;
        }
        $this->log( 'Skipping file [' . $file['name'] . ']' );
        return true;
    }

    /**
     * Log messages to the backup error log.
     *
     * @param string $text Log message.
     */
    public function log( $text ) {
        if ( $this->logHandle ) {
            fwrite( $this->logHandle, $text . "\n" );
        }
    }

    /**
     * Create backup archive file.
     *
     * @param string $filepath File location path.
     */
    public function create( $filepath ) {
        $this->log( 'Creating ' . $filepath );
        if ( $this->debug ) {
            if ( 'tar.bz2' === $this->type ) {
                $this->archive = bzopen( $filepath, 'w' );
            } else {
                $this->archive = fopen( $filepath, 'wb+' ); // NOSONAR .
            }

            return;
        }

        if ( 'tar.gz' === $this->type ) {
            $this->archive = gzopen( $filepath, 'wb' );
        } elseif ( 'tar.bz2' === $this->type ) {
            $this->archive = bzopen( $filepath, 'w' );
        } else {
            $this->archive = fopen( $filepath, 'wb+' ); // NOSONAR .
        }
    }

    /**
     * Append to the backup archive file.
     *
     * @param string $filepath File location path.
     */
    public function append( $filepath ) {
        $this->log( 'Appending to ' . $filepath );
        if ( $this->debug ) {
            if ( 'tar.bz2' === $this->type ) {
                $this->archive = bzopen( $filepath, 'a' );
            } else {
                $this->archive = fopen( $filepath, 'ab+' ); // NOSONAR .
            }

            return;
        }

        if ( 'tar.gz' === $this->type ) {
            $this->archive = gzopen( $filepath, 'ab' );
        } elseif ( 'tar.bz2' === $this->type ) {
            $this->archive = bzopen( $filepath, 'a' );
        } else {
            $this->archive = fopen( $filepath, 'ab+' ); // NOSONAR .
        }
    }

    /**
     * Verify if the backup archive file is open.
     *
     * @return bool True if open, if not, false.
     */
    public function is_open() {
        return ! empty( $this->archive );
    }

    /**
     * Prepare the append process.
     *
     * @param string $filepath File location path.
     *
     * @throws \Exception Error message.
     */
    public function prepare_append( $filepath ) {
        if ( $this->debug ) {
            if ( 'tar.gz' === substr( $filepath, - 6 ) ) {
                $text        = chr( 31 ) . chr( 139 ) . chr( 8 ) . chr( 0 ) . chr( 0 ) . chr( 0 ) . chr( 0 ) . chr( 0 ) . chr( 0 );
                $fh          = fopen( $filepath, 'rb' ); // NOSONAR .
                $read        = '';
                $lastCorrect = 0;
                try {
                    while ( ! feof( $fh ) ) {
                        $read .= fread( $fh, 1000 );
                        while ( ( $pos = strpos( $read, $text, 2 ) ) !== false ) {
                            for ( $i = 0; $i < 10; $i++ ) {
                                echo ord( $read[ $i ] ) . "\n"; // phpcs:ignore WordPress.Security.EscapeOutput
                            }

                            if ( ! $this->is_valid_block( substr( $read, 10, $pos - 10 ) ) ) {
                                throw new \Exception( 'invalid!' );
                            }

                            $lastCorrect += $pos;
                            $read         = substr( $read, $pos );
                        }
                    }

                    if ( ! $this->is_valid_block( substr( $read, 10 ) ) ) {
                        throw new \Exception( 'invalid!' );
                    }

                    fclose( $fh );
                } catch ( \Exception $e ) {
                    fclose( $fh );
                    $fh = fopen( $filepath, 'ab+' ); // NOSONAR .
                    fseek( $fh, $lastCorrect );
                    ftruncate( $fh, $lastCorrect );
                    fclose( $fh );
                }
            }
        }

        $this->read( $filepath );
    }

    /**
     * Read the backup archive file.
     *
     * @param string $filepath File location path.
     */
    public function read( $filepath ) {
        $this->log( 'Reading ' . $filepath );
        $this->archiveSize = false;

        if ( 'tar.gz' === substr( $filepath, - 6 ) ) {
            $this->type    = 'tar.gz';
            $this->archive = gzopen( $filepath, 'r' );
        } elseif ( 'tar.bz2' === substr( $filepath, - 7 ) ) {
            $this->type    = 'tar.bz2';
            $this->archive = bzopen( $filepath, 'r' );
        } else {
            $currentPos = ftell( $this->archive );
            fseek( $this->archive, 0, SEEK_END );
            $lastPos = ftell( $this->archive );
            fseek( $this->archive, $currentPos );

            $this->archiveSize = $lastPos;

            $this->type    = 'tar';
            $this->archive = fopen( $filepath, 'rb' ); // NOSONAR .
        }
    }

    /**
     * Close the backup archive file.
     *
     * @param bool $closeLog Log this action if set true.
     */
    public function close( $closeLog = true ) {
        $this->write_chunk();
        $this->log( 'Closing archive' );

        if ( $closeLog && $this->logHandle ) {
            fclose( $this->logHandle );
        }

        if ( $this->archive ) {
            if ( 'tar.gz' === $this->type ) {
                gzclose( $this->archive );
            } elseif ( 'tar.bz2' === $this->type ) {
                bzclose( $this->archive );
            } else {
                fclose( $this->archive );
            }
        }
    }

    /**
     * Get File content retrived by name.
     *
     * @param string $entryName Entry name.
     *
     * @return string File content.
     */
    public function get_from_name( $entryName ) {
        if ( ! $this->archive ) {
            return false;
        }
        if ( empty( $entryName ) ) {
            return false;
        }
        $content = false;
        fseek( $this->archive, 0 );
        while ( $block = fread( $this->archive, 512 ) ) {
            $temp = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
            if ( 'L' === $temp['type'] ) {
                $fname          = trim( fread( $this->archive, 512 ) );
                $block          = fread( $this->archive, 512 );
                $temp           = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
                $temp['prefix'] = '';
                $temp['name']   = $fname;
            }
            $file = array(
                'name'     => trim( $temp['prefix'] ) . trim( $temp['name'] ),
                'stat'     => array(
                    2 => $temp['mode'],
                    4 => octdec( $temp['uid'] ),
                    5 => octdec( $temp['gid'] ),
                    7 => octdec( $temp['size'] ),
                    9 => octdec( $temp['mtime'] ),
                ),
                'checksum' => octdec( $temp['checksum'] ),
                'type'     => $temp['type'],
                'magic'    => $temp['magic'],
            );

            if ( 0x00000000 === $file['checksum'] ) {
                break;
            } elseif ( 'ustar' !== substr( $file['magic'], 0, 5 ) ) {
                break;
            }

            $block    = substr_replace( $block, '        ', 148, 8 );
            $checksum = 0;
            for ( $i = 0; $i < 512; $i++ ) {
                $checksum += ord( substr( $block, $i, 1 ) );
            }

            if ( 0 === (int) $file['type'] ) {
                if ( 0 === strcmp( trim( $file['name'] ), trim( $entryName ) ) ) {
                    if ( $file['stat'][7] > 0 ) {
                        $content = fread( $this->archive, $file['stat'][7] );
                    } else {
                        $content = '';
                    }
                    break;
                } else {
                    $bytes = $file['stat'][7] + ( ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 ) );
                    fseek( $this->archive, ftell( $this->archive ) + $bytes );
                }
            }

            unset( $file );
        }

        return $content;
    }

    /**
     * Check if the file exists.
     *
     * @param string $entryName Entry name.
     *
     * @return bool Return tru if the file exists, false if it doesn't.
     */
    public function file_exists( $entryName ) {
        if ( ! $this->archive ) {
            return false;
        }
        $entryName = untrailingslashit( $entryName );
        if ( empty( $entryName ) ) {
            return false;
        }
        fseek( $this->archive, 0 );
        while ( $block = fread( $this->archive, 512 ) ) {
            $temp = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
            if ( 'L' === $temp['type'] ) {
                $fname          = trim( fread( $this->archive, 512 ) );
                $block          = fread( $this->archive, 512 );
                $temp           = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
                $temp['prefix'] = '';
                $temp['name']   = $fname;
            }
            $file = array(
                'name'     => trim( $temp['prefix'] ) . trim( $temp['name'] ),
                'stat'     => array(
                    2 => $temp['mode'],
                    4 => octdec( $temp['uid'] ),
                    5 => octdec( $temp['gid'] ),
                    7 => octdec( $temp['size'] ),
                    9 => octdec( $temp['mtime'] ),
                ),
                'checksum' => octdec( $temp['checksum'] ),
                'type'     => $temp['type'],
                'magic'    => $temp['magic'],
            );

            if ( 0x00000000 === $file['checksum'] ) {
                break;
            } elseif ( 'ustar' !== substr( $file['magic'], 0, 5 ) ) {
                break;
            }

            $block    = substr_replace( $block, '        ', 148, 8 );
            $checksum = 0;
            for ( $i = 0; $i < 512; $i++ ) {
                $checksum += ord( substr( $block, $i, 1 ) );
            }

            if ( 5 === (int) $file['type'] ) {
                if ( 0 === strcmp( trim( $file['name'] ), trim( $entryName ) ) ) {
                    return true;
                }
            } elseif ( 0 === $file['type'] ) {
                if ( 0 === strcmp( trim( $file['name'] ), trim( $entryName ) ) ) {
                    return true;
                } else {
                    $bytes = $file['stat'][7] + ( ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 ) );
                    fseek( $this->archive, ftell( $this->archive ) + $bytes );
                }
            }

            unset( $file );
        }

        return false;
    }

    /**
     * Extract backup archive file to a location.
     *
     * @param string $to Desired location to extract file.
     *
     * @return null
     */
    public function extract_to( $to ) { // phpcs:ignore -- Current complexity is the only way to achieve desired results, pull request solutions appreciated.

        /**
         * Global variable containing the instance of the (auto-)configured filesystem object after the filesystem "factory" has been run.
         *
         * @global object $wp_filesystem Filesystem object.
         */
        global $wp_filesystem;

        $to = trailingslashit( $to );
        fseek( $this->archive, 0 );
        while ( $block = fread( $this->archive, 512 ) ) {
            $temp = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
            if ( 'L' === $temp['type'] ) {
                $fname          = trim( fread( $this->archive, 512 ) );
                $block          = fread( $this->archive, 512 );
                $temp           = unpack( 'a100name/a8mode/a8uid/a8gid/a12size/a12mtime/a8checksum/a1type/a100symlink/a6magic/a2temp/a32temp/a32temp/a8temp/a8temp/a155prefix/a12temp', $block );
                $temp['prefix'] = '';
                $temp['name']   = $fname;
            }
            $file = array(
                'name'     => trim( $temp['prefix'] ) . trim( $temp['name'] ),
                'stat'     => array(
                    2 => $temp['mode'],
                    4 => octdec( $temp['uid'] ),
                    5 => octdec( $temp['gid'] ),
                    7 => octdec( $temp['size'] ),
                    9 => octdec( $temp['mtime'] ),
                ),
                'checksum' => octdec( $temp['checksum'] ),
                'type'     => $temp['type'],
                'magic'    => $temp['magic'],
            );

            if ( 0x00000000 === $file['checksum'] ) {
                break;
            } elseif ( 'ustar' !== substr( $file['magic'], 0, 5 ) ) {
                break;
            }
            $block    = substr_replace( $block, '        ', 148, 8 );
            $checksum = 0;
            for ( $i = 0; $i < 512; $i++ ) {
                $checksum += ord( substr( $block, $i, 1 ) );
            }
            if ( 5 === (int) $file['type'] ) {
                if ( ! is_dir( $to . $file['name'] ) ) {
                    if ( ! empty( $wp_filesystem ) ) {
                        $wp_filesystem->mkdir( $to . $file['name'], FS_CHMOD_DIR );
                    } else {
                        mkdir( $to . $file['name'], 0777, true );
                    }
                }
            } elseif ( 0 === (int) $file['type'] ) {
                if ( ! is_dir( dirname( $to . $file['name'] ) ) ) {
                    if ( ! empty( $wp_filesystem ) ) {
                        $wp_filesystem->mkdir( dirname( $to . $file['name'] ), FS_CHMOD_DIR );
                    } else {
                        mkdir( dirname( $to . $file['name'] ), 0777, true );
                    }
                }

                if ( ! empty( $wp_filesystem ) && ( $file['stat'][7] < 2000000 ) ) {
                    $contents    = '';
                    $bytesToRead = $file['stat'][7];
                    while ( $bytesToRead > 0 ) {
                        $readNow      = $bytesToRead > 1024 ? 1024 : $bytesToRead;
                        $contents    .= fread( $this->archive, $readNow );
                        $bytesToRead -= $readNow;
                    }

                    $toRead = ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 );
                    if ( $toRead > 0 ) {
                        fread( $this->archive, ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 ) );
                    }

                    if ( 'wp-config.php' !== $file['name'] ) {
                        $wp_filesystem->put_contents( $to . $file['name'], $contents, FS_CHMOD_FILE );
                    }
                } else {
                    if ( 'wp-config.php' !== $file['name'] ) {
                        $new = fopen( $to . $file['name'], 'wb+' );
                    } else {
                        $new = false;
                    }
                    $bytesToRead = $file['stat'][7];
                    while ( $bytesToRead > 0 ) {
                        $readNow = $bytesToRead > 1024 ? 1024 : $bytesToRead;
                        if ( false !== $new ) {
                            fwrite( $new, fread( $this->archive, $readNow ) );
                        } else {
                            fread( $this->archive, $readNow );
                        }
                        $bytesToRead -= $readNow;
                    }

                    $toRead = ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 );
                    if ( $toRead > 0 ) {
                        fread( $this->archive, ( 512 - $file['stat'][7] % 512 ) === 512 ? 0 : ( 512 - $file['stat'][7] % 512 ) );
                    }
                    if ( false !== $new ) {
                        fclose( $new );
                    }
                }
            }
            unset( $file );
        }

        return null;
    }

    /**
     * Check if block is valid.
     *
     * @param array $block Block of the backup file content.
     *
     * @return bool Return true if it's valid block, false if not.
     */
    public function is_valid_block( $block ) {
        $test = gzinflate( $block );
        if ( false === $test ) {
            return false;
        }
        $crc      = crc32( $test );
        $crcFound = substr( $block, strlen( $block ) - 8, 4 );
        $crcFound = ( ord( $crcFound[3] ) << 24 ) + ( ord( $crcFound[2] ) << 16 ) + ( ord( $crcFound[1] ) << 8 ) + ( ord( $crcFound[0] ) );

        return $crcFound === $crc;
    }
}