PO::read_line( resource $f, string $action = 'read' ): bool

457		public function read_line( $f, $action = 'read' ) {458			static $last_line     = '';459			static $use_last_line = false;460			if ( 'clear' === $action ) {461				$last_line = '';462				return true;463			}464			if ( 'put-back' === $action ) {465				$use_last_line = true;466				return true;467			}468 469			if ( $use_last_line ) {470				$line = $last_line;471			} else {472				$line = fgets( $f );473				if ( false === $line ) {474					return $line;475				}476 477				// Handle \r-only terminated lines after the deprecation of auto_detect_line_endings in PHP 8.1.478				$r = strpos( $line, "\r" );479				if ( false !== $r ) {480					if ( strlen( $line ) === $r + 1481						&& "\r\n" === substr( $line, $r )482					) {483						$line = rtrim( $line, "\r\n" ) . "\n";484					} else {485						// The lines are terminated by just \r, so we end the line there and rewind.486						$rewind = strlen( $line ) - $r - 1;487						$line   = substr( $line, 0, $r ) . "\n";488						fseek( $f, - $rewind, SEEK_CUR );489					}490				}491			}492 493			$last_line     = $line;494			$use_last_line = false;495			return $line;496		}