RFR: 8331535: Incorrect prompt for Console.readLine

[Pavel Rappo]

On Fri, 3 May 2024 10:11:02 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> When JLine reads a line, there may be a prompt provided. However, JLine will not interpret the prompt literally, it will handle `%` specially. As a consequence, doing:
> 
> System.console().readLine("%%s");
> 
> 
> will not print `%s`, as first `String.format` is used, which will convert `%%s` to `%s`, and then JLine will interpret the `%`. The proposed solution is to duplicate the `%`, so that JLine will print it.

src/jdk.internal.le/share/classes/jdk/internal/org/jline/JdkConsoleProviderImpl.java line 101:

> 99:             try {
> 100:                 initJLineIfNeeded();
> 101:                 return jline.readLine(fmt.formatted(args).replace("%", "%%"));

I understand that [JLine interprets `%` in a prompt](https://github.com/openjdk/jdk/blob/4ed38f5ad5f822ab948257ed39717ea919fd32ed/src/jdk.internal.le/share/classes/jdk/internal/org/jline/reader/impl/LineReaderImpl.java#L4050), but are the interpretation rules documented on JLine GitHub page or elsewhere?

src/jdk.internal.le/share/classes/jdk/internal/org/jline/JdkConsoleProviderImpl.java line 116:

> 114:             try {
> 115:                 initJLineIfNeeded();
> 116:                 return jline.readLine(fmt.formatted(args).replace("%", "%%"), '\0')

I find `'\0'` more cryptic and confusing than `(char) 0`, but okay. (Had to re-read https://docs.oracle.com/javase/specs/jls/se22/html/jls-3.html#jls-EscapeSequence)

test/jdk/jdk/internal/jline/JLineConsoleProviderTest.java line 27:

> 25:  * @test
> 26:  * @bug 8331535
> 27:  * @summary Verify the jdk.internal.le's console provider works properly.

There's a hidden assumption in this test below that the _default_ console is `jdk.internal.le`. Is there any way to assert that?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19081#discussion_r1589074603
PR Review Comment: https://git.openjdk.org/jdk/pull/19081#discussion_r1589065719
PR Review Comment: https://git.openjdk.org/jdk/pull/19081#discussion_r1589067927