input/InputStream: add method Skip()

src/input/InputStream.cxx

@@ -100,6 +100,13 @@ InputStream::LockSeek(offset_type _offset, Error &error)
 	return Seek(_offset, error);
 }
 
+bool
+InputStream::LockSkip(offset_type _offset, Error &error)
+{
+	const ScopeLock protect(mutex);
+	return Skip(_offset, error);
+}
+
 Tag *
 InputStream::ReadTag()
 {

src/input/InputStream.hxx

@@ -295,6 +295,15 @@ public:
 	}
 
 	/**
+	 * Skip input bytes.
+	 */
+	bool Skip(offset_type _offset, Error &error) {
+		return Seek(GetOffset() + _offset, error);
+	}
+
+	bool LockSkip(offset_type _offset, Error &error);
+
+	/**
 	 * Returns true if the stream has reached end-of-file.
 	 *
 	 * The caller must lock the mutex.