Fix a potential infinite loop in the Windows resource parser.

PR 26082
	* mclex.c (yylex): Add test for an empty input stream.

binutils/ChangeLog

@@ -1,3 +1,8 @@
+2020-06-05  Joel Anderson  <joelanderson333@gmail.com>
+
+	PR 26082
+	* mclex.c (yylex): Add test for an empty input stream.
+
 2020-06-04  Stephen Casner  <casner@acm.org>
 
 	* testsuite/binutils-all/pr25662-pdp11.s: Alternate source file

binutils/mclex.c

@@ -337,17 +337,19 @@ yylex (void)
   if (mclex_want_line)
     {
       start_token = input_stream_pos;
+      if (input_stream_pos[0] == 0)
+	return -1;
       if (input_stream_pos[0] == '.'
 	  && (input_stream_pos[1] == '\n'
 	      || (input_stream_pos[1] == '\r' && input_stream_pos[2] == '\n')))
-      {
-	mclex_want_line = FALSE;
-	while (input_stream_pos[0] != 0 && input_stream_pos[0] != '\n')
-	  ++input_stream_pos;
-	if (input_stream_pos[0] == '\n')
-	  ++input_stream_pos;
-	return MCENDLINE;
-      }
+	{
+	  mclex_want_line = FALSE;
+	  while (input_stream_pos[0] != 0 && input_stream_pos[0] != '\n')
+	    ++input_stream_pos;
+	  if (input_stream_pos[0] == '\n')
+	    ++input_stream_pos;
+	  return MCENDLINE;
+	}
       while (input_stream_pos[0] != 0 && input_stream_pos[0] != '\n')
 	++input_stream_pos;
       if (input_stream_pos[0] == '\n')