[patch] memory leak in read builtin

[Tim Waugh]

There is at least one memory leak in the read builtin in bash-3.0.  To
demonstrate it, try this test case:

  https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=173283#c10

There is a link to a file, nonblock.c, which you should compile like
'make nonblock'.  Then run the short script to see the problem.

The problem comes about when stdin has O_NONBLOCK set.  Here is the
fix:

--- bash-3.0/builtins/read.def.read-memleak     2005-12-07 17:45:38.000000000 
+0000
+++ bash-3.0/builtins/read.def  2005-12-07 17:45:39.000000000 +0000
@@ -461,6 +461,7 @@
   if (retval < 0)
     {
       builtin_error (_("read error: %d: %s"), fd, strerror (errno));
+      run_unwind_frame ("read_builtin");
       return (EXECUTION_FAILURE);
     }
 #endif

There is another suspicious place in that function where an xfree is
notable by its absence:

--- bash-3.0/builtins/read.def.read-memleak     2005-12-07 17:45:38.000000000 
+0000
+++ bash-3.0/builtins/read.def  2005-12-07 18:00:26.000000000 +0000
@@ -508,7 +508,10 @@
 
       var = find_or_make_array_variable (arrayname, 1);
       if (var == 0)
-       return EXECUTION_FAILURE;       /* readonly or noassign */
+       {
+         xfree (input_string);
+         return EXECUTION_FAILURE;     /* readonly or noassign */
+       }
       array_flush (array_cell (var));
 
       alist = list_string (input_string, ifs_chars, 0);

..but I couldn't work out how to demonstrate this particular leak, if
that's what it is.

Tim.
*/