feat: add more PDF formats, drastically improve LibreOffice long-running instance management

pkg/modules/libreoffice/uno/freeport.go

@@ -0,0 +1,31 @@
+package uno
+
+import (
+	"fmt"
+	"net"
+	"strconv"
+
+	"go.uber.org/zap"
+)
+
+func freePort(logger *zap.Logger) (int, error) {
+	netListener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return 0, fmt.Errorf("listen on the local network address: %w", err)
+	}
+	defer func() {
+		err := netListener.Close()
+		if err != nil {
+			logger.Error(fmt.Sprintf("close network listener: %s", err.Error()))
+		}
+	}()
+
+	addr := netListener.Addr().String()
+
+	_, portStr, err := net.SplitHostPort(addr)
+	if err != nil {
+		return 0, fmt.Errorf("get free port from host: %w", err)
+	}
+
+	return strconv.Atoi(portStr)
+}