On Wed, 12 Jan 2022 06:08:29 GMT, Xue-Lei Andrew Fan <[email protected]> wrote:
>> Change the order so parent class is at the left.
>
> src/java.base/share/classes/com/sun/crypto/provider/BlockCipherParamsCore.java
> line 111:
>
>> 109: <T extends AlgorithmParameterSpec> T getParameterSpec(Class<T>
>> paramSpec)
>> 110: throws InvalidParameterSpecException {
>> 111: if (paramSpec.isAssignableFrom(IvParameterSpec.class)) {
>
> The call to cast() is confusing. But if the paramSpec is
> AlgorithmParameterSpec.class or Object.class, what's the expected behavior?
> There are potential casting exception, I guess. Maybe, a exactly class
> matching could be better.
If so, then the `if` block will be true and the spec object is casted to your
specified class (`AlgorithmParameterSpec.class` or `Object.class`) and it
always succeeds.
This is exactly what I want to achieve. In fact, this bug and the other
`getInstance(oid)` bug have the same root. I was trying to decode an algorithm
identifier from its encoding. First, the encoding of the algorithm is in OID so
`AlgorithmParameters.getInstance()` must support OID. Second, I want to get the
spec from the parameters without knowing the algorithm name and the child
`AlgorithmParametersSpec` class type, so
`AlgorithmParameters::getParameterSpec` must support
`AlgorithmParameterSpec.class` as the argument.
Otherwise, the program needs to know name and parameter spec type on all
supported algorithms.
-------------
PR: https://git.openjdk.java.net/jdk/pull/7037
