初版功能完成

internal/config/load.go

@@ -0,0 +1,37 @@
+// Package config loads only non-sensitive RemLink YAML configuration.
+package config
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+func decodeStrict(path string, target any) error {
+	file, err := os.Open(path)
+	if err != nil {
+		return fmt.Errorf("open config %q: %w", path, err)
+	}
+	defer file.Close()
+
+	decoder := yaml.NewDecoder(file)
+	decoder.KnownFields(true)
+	if err := decoder.Decode(target); err != nil {
+		if errors.Is(err, io.EOF) {
+			return fmt.Errorf("config %q is empty", path)
+		}
+		return fmt.Errorf("decode config %q: %w", path, err)
+	}
+
+	var extra any
+	if err := decoder.Decode(&extra); !errors.Is(err, io.EOF) {
+		if err != nil {
+			return fmt.Errorf("decode trailing YAML document in %q: %w", path, err)
+		}
+		return fmt.Errorf("config %q must contain exactly one YAML document", path)
+	}
+	return nil
+}