initial commit [141.14.140.180,mike]

util.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+)
+
+func readJSON(path string, v any) error {
+	body, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(body, v)
+}
+
+// writeJSON replaces the file atomically: a half-written state file would look
+// like a corrupt install on the next run.
+func writeJSON(path string, v any) error {
+	body, err := json.MarshalIndent(v, "", "   ")
+	if err != nil {
+		return err
+	}
+	tmp := fmt.Sprintf("%s.%d", path, os.Getpid())
+	addTemp(tmp)
+	defer dropTemp(tmp)
+
+	if err := os.WriteFile(tmp, append(body, '\n'), 0o644); err != nil {
+		return fmt.Errorf("cannot write %s: %w", tmp, err)
+	}
+	if err := os.Rename(tmp, path); err != nil {
+		os.Remove(tmp)
+		return fmt.Errorf("cannot update %s: %w", path, err)
+	}
+	return nil
+}
+
+func humanSize(n int64) string {
+	switch {
+	case n >= 1024*1024:
+		return fmt.Sprintf("%.1f MB", float64(n)/1024/1024)
+	case n >= 1024:
+		return fmt.Sprintf("%.1f kB", float64(n)/1024)
+	}
+	return fmt.Sprintf("%d B", n)
+}