RFR: 8338596: Clarify handling of restricted and caller-sensitive methods [v2]

Thu Sep 19 14:08:36 UTC 2024

On Thu, 19 Sep 2024 13:59:30 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> This PR moves the section on restricted methods from the the javadoc of `java.lang.foreign` package into a standalone static [javadoc page](https://cr.openjdk.org/~mcimadamore/jdk/restricted_javadoc_section/docs/api/java.base/java/lang/foreign/doc-files/RestrictedMethods.html).
>> 
>> This is because, after [JEP 472](https://openjdk.org/jeps/472), we now have restricted methods *outside* the foreign package, namely `System::loadLibrary`, `Runtime::loadLibrary` (and related methods). And, even before, we also had a restricted method in `ModuleLayer.Controller`.
>> 
>> The new static page contains some guidance of what happens when a restricted method is called when there's no Java frame on the stack (this can happen e.g. when upcalling into a restricted method from a native thread not known to the JVM) - that is, the call is treated as originating from an unnamed module.
>> 
>> The static page is linked from the restricted method banner in a restricted method javadoc. Here's an [example](https://cr.openjdk.org/~mcimadamore/jdk/restricted_javadoc_section/docs/api/java.base/java/lang/foreign/Linker.html#downcallHandle(java.lang.foreign.MemorySegment,java.lang.foreign.FunctionDescriptor,java.lang.foreign.Linker.Option...)).
>
> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move restricted method page to `java.lang`
>   Update restricted method page

src/java.base/share/classes/java/lang/doc-files/RestrictedMethods.html line 31:

> 29: </head>
> 30: <body>
> 31: <h1 id="restricted">Restricted methods</h1>

I've kept the text more general. I took the liberty to use (and tweak) some text in here:
https://cr.openjdk.org/~iris/se/23/spec/fr/java-se-23-fr-spec/

The example is now gone - while we could still provide some example, I believe it's hard not to get too drawn into specifics. I think stating that these methods can violate integrity is probably enough.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21067#discussion_r1766904504