RFR: 8284910: Buffer clean in PasswordCallback

[Roger Riggs]

On Sat, 16 Apr 2022 15:45:21 GMT, Xue-Lei Andrew Fan <xuelei at openjdk.org> wrote:

> Please review this password cleanup enhancement in the PasswordCallback implementation.  This is one of the effort to clean up the buffered passwords.
> 
> The PasswordCallback.setPassword() clones the password, but is not registered for cleanup. An application could call clearPassword() for the purpose, but it would be nice to cleanup the buffer as well if clearPassword() was not called in an application. And, if the setPassword() get called multiple times, the clearPassword() should also be called the same times if not relying on finalization. It could be fragile in practice.

Please combine these closely related cases into a single test, preferably with TestNG or JUnit.

test/jdk/javax/security/auth/callback/ClearPasswordMethod.java line 53:

> 51:             System.gc();
> 52:             Thread.sleep(100);
> 53:         }

The test could complete more quickly if the loop was exited when whm.size() == 0.
And in the other test.

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PR: https://git.openjdk.java.net/jdk/pull/8272