RFR: 8362116: System.in.read() etc. don't accept input once immediate Ctrl+D pressed in JShell

[Christian Stein]

On Mon, 14 Jul 2025 12:48:27 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> When in JShell, doing:
> 
> jshell> IO.readln();
> //Ctrl-D
> $1 ==> null
> 
> jshell> IO.readln()
> $2 ==> null //no input allowed
> 
> 
> Where relying input from the main process to the remote/agent process, need to propagate `-1` as `-1` without close, which is what this PR is attempting to do.

`\u0004` can now be declared as a constant in `UITesting.java`, right next to:
https://github.com/openjdk/jdk/blob/bcd86d575fe0682a234228c18b0c2e817d3816da/test/langtools/jdk/jshell/UITesting.java#L48

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PR Comment: https://git.openjdk.org/jdk/pull/26292#issuecomment-3069580222