8361613: System.console() should only be available for interactive terminal #26273

naotoj · 2025-07-11T18:46:14Z

In prior JDK releases, System.console() could return a Console instance even when the JVM was not attached to an interactive terminal. This could lead to confusion, particularly when input was not from a keyboard or output was redirected, such as to or from a file or pipe, especially when using methods like readPassword(). Starting with JDK 25, the default behavior has changed: System.console() now returns null if standard input and/or output is redirected. However, if a JLine-based Console implementation is explicitly specified via the system property -Djdk.console=jdk.internal.le, the previous behavior may still occur.
This PR aims to align the behavior of the JLine-based Console implementation with the default System.console() behavior. The actual code change is a one-liner in JdkConsoleProviderImpl.java; the rest of the changes are adjustments to test cases to reflect the updated behavior. A corresponding CSR has also been drafted.

Progress

Change must be properly reviewed (1 review required, with at least 1 Reviewer)
Change must not contain extraneous whitespace
Change requires CSR request JDK-8361911 to be approved
Commit message must refer to an issue

Issues

JDK-8361613: System.console() should only be available for interactive terminal (Bug - P4)
JDK-8361911: System.console() should only be available for interactive terminal (CSR)

Reviewers

Jan Lahoda (@lahodaj - Reviewer)

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$ git pull https://git.openjdk.org/jdk.git pull/26273/head

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bridgekeeper · 2025-07-11T18:46:40Z

👋 Welcome back naoto! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2025-07-11T18:47:12Z

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

openjdk · 2025-07-11T18:47:52Z

@naotoj The following labels will be automatically applied to this pull request:

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mlbridge · 2025-07-11T18:54:46Z

Webrevs

test/jdk/java/io/Console/LocaleTest.java

Co-authored-by: Andrey Turbanov <[email protected]>

justin-curtis-lu · 2025-07-14T17:57:22Z

test/jdk/java/io/Console/DefaultCharsetTest.java

+    @ValueSource(strings = {"UTF-8", "ISO-8859-1", "US-ASCII", "foo", ""})
+    void testDefaultCharset(String stdoutEncoding) throws Exception {
+        // check "expect" command availability
+        var expect = Paths.get("/usr/bin/expect");


We only need to check "expect" availability once, so we should move this check to a @BeforeAll static method. It's also more clear that this check is a precondition, and not part of the actual test. Applies to the other locations, but primarily the other parameterized tests.

Good point. Modified to use @BeforeAll. For ModuleSelectionTest, one of the test is not using expect, so I left it as it is. In addition to that, I removed the @requires condition to allow that test to run on windows.

justin-curtis-lu · 2025-07-14T18:29:43Z

test/jdk/java/io/Console/ModuleSelectionTest.java

+
+    @ParameterizedTest
+    @MethodSource("options")
+    void testWithoutExpect(String opts, String expected) throws Exception {


expected param looks unused.

justin-curtis-lu · 2025-07-14T18:37:56Z

test/jdk/java/io/Console/ModuleSelectionTest.java

+
+    @ParameterizedTest
+    @MethodSource("options")
+    void testWithExpect(String opts, String expected) throws Exception {


I think it would be more clear if these tests were renamed to expectConsoleTest and noConsoleTest or something along those lines.

Yeah, using expect command with junit's expect is confusing 🙂. Just renamed those methods using TTY/NonTTY, as"expect/noConsoleTest" reads somewhat odd as it includes the expected results in the test name.

justin-curtis-lu · 2025-07-14T18:40:04Z

test/jdk/java/io/Console/ModuleSelectionTest.java

+ * @requires (os.family == "linux") | (os.family == "mac")
+ * @library /test/lib
+ * @build jdk.test.lib.Utils
+ *        jdk.test.lib.JDKToolFinder


Is jdk.test.lib.JDKToolFinder needed?

lahodaj

Looks good to me, although additional review from core libs might be desirable. Thanks!

AlanBateman · 2025-07-15T13:25:16Z

src/java.base/share/classes/java/lang/System.java

     * with the current Java virtual machine, if any.
     *
     * @return  The system console, if any, otherwise {@code null}.
+     * @see Console


The method declaration already links to Console so I don't think we need another link in the "See also" section.

Maybe I missed it, but do we have anything to make it clear that it returns null if either stdin or stdout are redirected?

we do have wordings like " If the virtual machine is started from an interactive command line without redirecting the standard input AND output streams then its console will exist ..." and "If no console device is
available then an invocation of that method will return null" from the very beginning. not very "straightforward" but i think it's clear enough?

I think adding @see tag would be more helpful.

As to the spec wording wrt stdin/out, there is another issue filed to make it clearer: JDK-8361972. This PR addresses the implementation part only so that it can be backported to prior LTSes without spec change.

initial commit

ea72f44

openjdk bot added csr Pull request needs approved CSR before integration rfr Pull request is ready for review labels Jul 11, 2025

openjdk bot added core-libs [email protected] compiler [email protected] labels Jul 11, 2025

turbanoff reviewed Jul 11, 2025

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test/jdk/java/io/Console/LocaleTest.java Outdated Show resolved Hide resolved

Update test/jdk/java/io/Console/LocaleTest.java

8277308

Co-authored-by: Andrey Turbanov <[email protected]>

justin-curtis-lu reviewed Jul 14, 2025

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lahodaj approved these changes Jul 15, 2025

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8361613: System.console() should only be available for interactive terminal #26273

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