RFR: 8307478: Implementation of Prepare to Restrict The Dynamic Loading of Agents [v4]

[Chris Plummer]

On Fri, 19 May 2023 17:11:36 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> This is the implementation for JEP 451. There are two parts to this:
>> 
>> 1. A multi-line warning is printed when a JVM TI or Java agent is loaded into a running VM. For JVM TI, the message is printed to stderr from JvmtiAgent::load. For Java agents, it is printed to System.err (as that may be redirected) in the JPLIS (j.l.instrumentation) implementation. This part includes an update to the JVM TI spec and API docs to require the warning.
>> 
>> 2. If running with -Djdk.instrument.traceUsage or -Djdk.instrument.traceUsage=true, the calls to the Instrumentation API print a trace message and stack trace.
>
> Alan Bateman has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:
> 
>  - Merge
>  - Refresh package description
>  - Merge
>  - Tweak docs
>  - Merge
>  - Draft docs changes
>  - Merge
>  - Rename/cleanup
>  - Merge
>  - Initial commit

test/jdk/com/sun/tools/attach/warnings/DynamicLoadWarningTest.java line 90:

> 88:         } else {
> 89:             libname = "lib" + JVMTI_AGENT_LIB + ".so";
> 90:         }

We have some test library support for this with Platform.sharedLibraryExt(). Unfortunately there is no "prefix" API, or better yet, one that builds out the whole file name, but the following is a bit shorter:

`libname = (Platform.isWindows() ? "" : "lib") + JVMTI_AGENT_LIB + "." + Platform.sharedLibraryExt();`

Up to you if you want to make this change

test/jdk/com/sun/tools/attach/warnings/DynamicLoadWarningTest.java line 108:

> 106:         // no warning should be printed
> 107:         test((pid, vm) -> vm.loadAgentLibrary(JVMTI_AGENT_LIB), "-XX:+EnableDynamicAgentLoading")
> 108:                 .shouldNotContain(message);

How about adding a test case for `-XX:-EnableDynamicAgentLoading`. Same thing in `testJCmdJvmtiAgentLoad()` and `testLoadJavaAgent()` below.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13899#discussion_r1201475362
PR Review Comment: https://git.openjdk.org/jdk/pull/13899#discussion_r1201485800