read header.gmi and set header variable to that or to the default

core/core.go

@@ -28,9 +28,14 @@ var Data = FullData{
 	// Maps are created in init()
 }
 
+// the header of feeds.gmi.
+// set in Init, either to the contents of header.gmi or to the default string
+var Header string
+
 // have to do this instead of the automatically called init() because
 // initialization stuff requires parsing of command line args first
 func Init(dataPath string) error {
+	// initialize comitium.json & data maps
 	f, err := os.Open(filepath.Join(dataPath, "comitium.json"))
 	if err == nil {
 		// File exists and could be opened
@@ -59,6 +64,30 @@ func Init(dataPath string) error {
 	if Data.Pages == nil {
 		Data.Pages = make(map[string]*Page)
 	}
+
+	// initialize header.gmi
+	f, err = os.Open(filepath.Join(dataPath, "header.gmi"))
+	if err == nil {
+		fi, err := f.Stat()
+		if err == nil && fi.Size() > 0 {
+			headerBytes, err := ioutil.ReadAll(f)
+			f.Close()
+			if err != nil {
+				return fmt.Errorf("read header.gmi error: %w", err)
+			}
+			Header = string(headerBytes)
+		}
+		f.Close()
+	} else if !os.IsNotExist(err) {
+		return fmt.Errorf("open header.gmi error: %w", err)
+	}
+
+	if Header == "" {
+		Header = `# comitium subscriptions
+
+`
+	}
+
 	return nil
 }