wp_upload_dir()

wp_upload_dir( string|null $time = null, bool $create_dir = true, bool $refresh_cache = false ): array

function wp_upload_dir( $time = null, $create_dir = true, $refresh_cache = false ) {
	static $cache = array(), $tested_paths = array();

	$key = sprintf( '%d-%s', get_current_blog_id(), (string) $time );

	if ( $refresh_cache || empty( $cache[ $key ] ) ) {
		$cache[ $key ] = _wp_upload_dir( $time );
	}

	/**
	 * Filters the uploads directory data.
	 *
	 * @since 2.0.0
	 *
	 * @param array $uploads {
	 *     Array of information about the upload directory.
	 *
	 *     @type string       $path    Base directory and subdirectory or full path to upload directory.
	 *     @type string       $url     Base URL and subdirectory or absolute URL to upload directory.
	 *     @type string       $subdir  Subdirectory if uploads use year/month folders option is on.
	 *     @type string       $basedir Path without subdir.
	 *     @type string       $baseurl URL path without subdir.
	 *     @type string|false $error   False or error message.
	 * }
	 */
	$uploads = apply_filters( 'upload_dir', $cache[ $key ] );

	if ( $create_dir ) {
		$path = $uploads['path'];

		if ( array_key_exists( $path, $tested_paths ) ) {
			$uploads['error'] = $tested_paths[ $path ];
		} else {
			if ( ! wp_mkdir_p( $path ) ) {
				if ( str_starts_with( $uploads['basedir'], ABSPATH ) ) {
					$error_path = str_replace( ABSPATH, '', $uploads['basedir'] ) . $uploads['subdir'];
				} else {
					$error_path = wp_basename( $uploads['basedir'] ) . $uploads['subdir'];
				}

				$uploads['error'] = sprintf(
					/* translators: %s: Directory path. */
					__( 'Unable to create directory %s. Is its parent directory writable by the server?' ),
					esc_html( $error_path )
				);
			}

			$tested_paths[ $path ] = $uploads['error'];
		}
	}

	return $uploads;
}