On Tue, 19 Aug 2025 15:20:52 GMT, Guanqiang Han <[email protected]> wrote:
>> Validate class name length immediately after GetStringUTFLength() in
>> Class.forName0. This prevents potential issues caused by overly long class
>> names before they reach later code that would reject them, throwing
>> ClassNotFoundException early.
>
> Guanqiang Han has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Update Class.java
>
> correct length of class name
src/java.base/share/classes/java/lang/Class.java line 4160:
> 4158: private static boolean classNameLengthIsValid(String name) {
> 4159: Objects.requireNonNull(name);
> 4160: return getUtf8Length(name) <= JAVA_CLASSNAME_MAX_LEN;
An exact UTF-8 length is not needed to know that the length is valid.
The worst case expansion is *4 for an encoding of a pair of surrogate chars.
A quick approximation would be: `name.length() <= JAVA_CLASSNAME_MAX_LEN / 4`.
Most class names are much shorter and almost never need to compute the exact
UTF-8 length.
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PR Review Comment: https://git.openjdk.org/jdk/pull/26802#discussion_r2286624874
