RFR: 8367859: Remove shell script from nio exception gensrc

[Magnus Ihse Bursie]

On Wed, 17 Sep 2025 10:17:33 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> The only remaining shell script that is being used in the gensrc phase to generate Java code is for the nio exceptions. This should be removed as well, and replaced with a standard solution (Java buildtool or makefile API calls).

Some implementation notes:

I considered writing a Java buildtool to read the existing `exceptions` files, but that seemed like a lot of work to keep up with a format that was not really ideal anyway, but was in fact a shell script snippet, disguised as a data file.

The `*.java.template` method aligns better with most other gensrc solutions. This also makes it easier to get a better understanding of how the resulting file will look. As a matter of fact, the generated file with the old solution did not match up with how our files should look. I modified the template to follow this pattern. As an effect of this, all generated files has a diff (in whitespace or comments only) with this code compared to the old, like this:


--- ReadOnlyBufferException.java        2025-09-11 11:55:45
+++ NEW/ReadOnlyBufferException.java    2025-09-12 17:40:57
@@ -1,6 +1,5 @@
 /*
- * Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
- *
+ * Copyright (c) 2000, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,14 +21,10 @@
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
- *
  */

-// -- This file was mechanically generated: Do not edit! -- //
-
 package java.nio;

-
 /**
  * Unchecked exception thrown when a content-mutation method such as
  * <code>put</code> or <code>compact</code> is invoked upon a read-only buffer.
@@ -48,5 +43,4 @@
      * Constructs an instance of this class.
      */
     public ReadOnlyBufferException() { }
-
 }


I consider this an improvement, not a bug.

I also discovered a real bug. Due to how the old `exceptions` files were actually shell script snippets that were included and executed, proper care needed to be taken in how to handle quotes. This was not done for `IllegalCharsetNameException.java`. The `"` were eaten by the shell, so the generated Java code was:

 * <a href=Charset.html#names>legal charset name</a> is used as such.

instead of (the intended, and correct)

 * <a href="Charset.html#names">legal charset name</a> is used as such.


That is fixed with this PR. 

Apart from these changes, the generated files are identical before and after this PR.

I don't understand what is going on with GHA. It works perfectly well on my local computer and Oracle's internal CI system.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/27338#issuecomment-3302348906
PR Comment: https://git.openjdk.org/jdk/pull/27338#issuecomment-3302581306