(CCL_WRITE_CHAR): Check if CH is valid or not. If

invalid, execute CCL_INVALID_CMD.
(ccl_driver): If the CCL program is terminated because of
CCL_STAT_INVALID_CMD, copy the remaining source data to the
destination instead of throwing them away.

src/ccl.c

@@ -721,8 +721,10 @@ else
 		 multibyte form later.  */				\
 	      extra_bytes++;						\
 	  }								\
-	else								\
+	else if (CHAR_VALID_P (ch, 0))					\
 	  dst += CHAR_STRING (ch, dst);					\
+	else								\
+	  CCL_INVALID_CMD;						\
       }									\
     else								\
       CCL_SUSPEND (CCL_STAT_SUSPEND_BY_DST);				\
@@ -1781,6 +1783,16 @@ ccl_driver (ccl, source, destination, src_bytes, dst_bytes, consumed)
 	  bcopy (msg, dst, msglen);
 	  dst += msglen;
 	}
+      if (ccl->status == CCL_STAT_INVALID_CMD)
+	{
+	  /* Copy the remaining source data.  */
+	  int i = src_end - src;
+	  if (dst_bytes && (dst_end - dst) < i)
+	    i = dst_end - dst;
+	  bcopy (src, dst, i);
+	  src += i;
+	  dst += i;
+	}
     }
 
  ccl_finish: