Source

File: wp-admin/includes/file.php

function _unzip_file_ziparchive( $file, $to, $needed_dirs = array() ) {
	global $wp_filesystem;

	$z = new ZipArchive();

	$zopen = $z->open( $file, ZIPARCHIVE::CHECKCONS );
	if ( true !== $zopen ) {
		return new WP_Error( 'incompatible_archive', __( 'Incompatible Archive.' ), array( 'ziparchive_error' => $zopen ) );
	}

	$uncompressed_size = 0;

	for ( $i = 0; $i < $z->numFiles; $i++ ) {
		$info = $z->statIndex( $i );
		if ( ! $info ) {
			return new WP_Error( 'stat_failed_ziparchive', __( 'Could not retrieve file from archive.' ) );
		}

		if ( '__MACOSX/' === substr( $info['name'], 0, 9 ) ) { // Skip the OS X-created __MACOSX directory.
			continue;
		}

		// Don't extract invalid files:
		if ( 0 !== validate_file( $info['name'] ) ) {
			continue;
		}

		$uncompressed_size += $info['size'];

		$dirname = dirname( $info['name'] );

		if ( '/' === substr( $info['name'], -1 ) ) {
			// Directory.
			$needed_dirs[] = $to . untrailingslashit( $info['name'] );
		} elseif ( '.' !== $dirname ) {
			// Path to a file.
			$needed_dirs[] = $to . untrailingslashit( $dirname );
		}
	}

	/*
	 * disk_free_space() could return false. Assume that any falsey value is an error.
	 * A disk that has zero free bytes has bigger problems.
	 * Require we have enough space to unzip the file and copy its contents, with a 10% buffer.
	 */
	if ( wp_doing_cron() ) {
		$available_space = @disk_free_space( WP_CONTENT_DIR );
		if ( $available_space && ( $uncompressed_size * 2.1 ) > $available_space ) {
			return new WP_Error( 'disk_full_unzip_file', __( 'Could not copy files. You may have run out of disk space.' ), compact( 'uncompressed_size', 'available_space' ) );
		}
	}

	$needed_dirs = array_unique( $needed_dirs );
	foreach ( $needed_dirs as $dir ) {
		// Check the parent folders of the folders all exist within the creation array.
		if ( untrailingslashit( $to ) == $dir ) { // Skip over the working directory, we know this exists (or will exist).
			continue;
		}
		if ( strpos( $dir, $to ) === false ) { // If the directory is not within the working directory, skip it.
			continue;
		}

		$parent_folder = dirname( $dir );
		while ( ! empty( $parent_folder ) && untrailingslashit( $to ) != $parent_folder && ! in_array( $parent_folder, $needed_dirs, true ) ) {
			$needed_dirs[] = $parent_folder;
			$parent_folder = dirname( $parent_folder );
		}
	}
	asort( $needed_dirs );

	// Create those directories if need be:
	foreach ( $needed_dirs as $_dir ) {
		// Only check to see if the Dir exists upon creation failure. Less I/O this way.
		if ( ! $wp_filesystem->mkdir( $_dir, FS_CHMOD_DIR ) && ! $wp_filesystem->is_dir( $_dir ) ) {
			return new WP_Error( 'mkdir_failed_ziparchive', __( 'Could not create directory.' ), substr( $_dir, strlen( $to ) ) );
		}
	}
	unset( $needed_dirs );

	for ( $i = 0; $i < $z->numFiles; $i++ ) {
		$info = $z->statIndex( $i );
		if ( ! $info ) {
			return new WP_Error( 'stat_failed_ziparchive', __( 'Could not retrieve file from archive.' ) );
		}

		if ( '/' === substr( $info['name'], -1 ) ) { // Directory.
			continue;
		}

		if ( '__MACOSX/' === substr( $info['name'], 0, 9 ) ) { // Don't extract the OS X-created __MACOSX directory files.
			continue;
		}

		// Don't extract invalid files:
		if ( 0 !== validate_file( $info['name'] ) ) {
			continue;
		}

		$contents = $z->getFromIndex( $i );
		if ( false === $contents ) {
			return new WP_Error( 'extract_failed_ziparchive', __( 'Could not extract file from archive.' ), $info['name'] );
		}

		if ( ! $wp_filesystem->put_contents( $to . $info['name'], $contents, FS_CHMOD_FILE ) ) {
			return new WP_Error( 'copy_failed_ziparchive', __( 'Could not copy file.' ), $info['name'] );
		}
	}

	$z->close();

	return true;
}