RFR: 8335610: DiagnosticFramework: CmdLine::is_executable() correction

[David Holmes]

On Sun, 28 Jul 2024 09:48:21 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> CmdLine::is_executable() looks wrong, surely an empty line is not executable.
>> 
>> With this change, in DCmd::parse_and_execute() we will avoid needlessly entering the code block to try and execute the command.
>> 
>> DCmd tests all good:
>> make images test TEST="test/hotspot/jtreg/serviceability/dcmd test/jdk/sun/tools/jcmd"
>
> Oh, and also, the output of my Python running:
> 
> 
> Connect
> None
> Sending payload
> None
> Sent
> Received response: -1
> java.lang.IllegalArgumentException: Unknown diagnostic command

@jdksjolen - thank you! IIUC from your report, our own code may never have an empty CmdLine but you can directly inject one using the communication protocol. In that case we the fix is good as-is. A test case would be nice but not if we need to use python.

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PR Comment: https://git.openjdk.org/jdk/pull/20006#issuecomment-2254763896