+/* Like WrapperOutputStream, but additionally computes a checksum of data as it
+ * is written. */
+class ChecksumOutputStream : public OutputStream {
+public:
+ explicit ChecksumOutputStream(OutputStream &o);
+ virtual ~ChecksumOutputStream() { }
+
+ /* Once a checksum is computed, no further data should be written to the
+ * stream. */
+ const uint8_t *finish_and_checksum();
+ size_t checksum_size() const { return csum.checksum_size(); }
+
+protected:
+ virtual void write_internal(const void *data, size_t len);
+
+private:
+ OutputStream ℜ
+ SHA1Checksum csum;
+};
+