WP_Upgrader::unpack_package( string $package, bool $delete_package = true ): string|WP_Error

356	public function unpack_package( $package, $delete_package = true ) {357		global $wp_filesystem;358 359		$this->skin->feedback( 'unpack_package' );360 361		if ( ! $wp_filesystem->wp_content_dir() ) {362			return new WP_Error( 'fs_no_content_dir', $this->strings['fs_no_content_dir'] );363		}364 365		$upgrade_folder = $wp_filesystem->wp_content_dir() . 'upgrade/';366 367		// Clean up contents of upgrade directory beforehand.368		$upgrade_files = $wp_filesystem->dirlist( $upgrade_folder );369		if ( ! empty( $upgrade_files ) ) {370			foreach ( $upgrade_files as $file ) {371				$wp_filesystem->delete( $upgrade_folder . $file['name'], true );372			}373		}374 375		// We need a working directory - strip off any .tmp or .zip suffixes.376		$working_dir = $upgrade_folder . basename( basename( $package, '.tmp' ), '.zip' );377 378		// Clean up working directory.379		if ( $wp_filesystem->is_dir( $working_dir ) ) {380			$wp_filesystem->delete( $working_dir, true );381		}382 383		// Unzip package to working directory.384		$result = unzip_file( $package, $working_dir );385 386		// Once extracted, delete the package if required.387		if ( $delete_package ) {388			unlink( $package );389		}390 391		if ( is_wp_error( $result ) ) {392			$wp_filesystem->delete( $working_dir, true );393			if ( 'incompatible_archive' === $result->get_error_code() ) {394				return new WP_Error( 'incompatible_archive', $this->strings['incompatible_archive'], $result->get_error_data() );395			}396			return $result;397		}398 399		return $working_dir;400	}