Bug in String.lastIndexOf with NULL character in Semeru 11.0.21 and 11.0.22

[SgtSilvio]

We discovered a bug affecting Semeru 11.0.21+9 and 11.0.22+7. (I hope that OpenJ9 is the right place for this issue. If not, please point me to the right place.)

The bug happens in the String.lastIndexOf(String) method which always returns-1 when passing a String with the NULL character ("\u0000").

The following code can be used to reproduce the issue:

import java.util.stream.Collectors;

class Main {
    public static void main(String... args) {
        String s = args[0] + "\u0000" + args[1];
        int index = s.lastIndexOf("\u0000");
        System.out.println("string code points: " + s.codePoints().boxed().collect(Collectors.toList()));
        System.out.println("last index of NULL character (0): " + index + ", should be: " + args[0].length());
        if (index == -1) {
            throw new AssertionError();
        }
    }
}

Just run

• javac Main.java
• <path to affected java> -cp . Main string1 string2

The following versions of Semeru were found to be not affected:

• 11.0.20.1+1
• 17.0.10+7
• 21.0.2+13

[pshipton]

This is the correct place to report the issue.

You can work around the problem by using the -XX:-CompactStrings option.

[SgtSilvio]

Thank you for the quick response. We recommended our customer to try out 17.0.10 moving forward.

[pshipton]

Internal details. It's failing because "\u0000" isn't LATIN1 encoded and the code reasonably assumes a UTF16 string can't be found in a LATIN1 string.