RFR: 8291917: Windows - Dump error diagnostics when runtime libraries fail to load [v3]

[Thomas Stuefe]

On Thu, 4 Aug 2022 17:42:45 GMT, Julian Waters <jwaters at openjdk.org> wrote:

>> Please review a small patch for dumping the failure reason when the MSVCRT libraries or the Java Virtual Machine fails to load on Windows, which can provide invaluable insight when debugging related launcher issues. This also fixes a small bug in the Windows implementation of JLI_ErrorMessageSys where C runtime errors are never written to stderr.
>
> Julian Waters has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Missing spacing between errors

Hi Julian,

I don't get it.

AFAICS the existing version displays the failure reason for win32 API just fine, appending it to the message. Where is the bug? I see that the message was omitted for CRT errors, so that is okay to fix, but that could have been fixed with a simple freeit=1 in the CRT error path (although my taste would be to just append errtxt if errtxt!=NULL, which is less circumvent).

I also do not understand the changes to the call sites, where you add "%s". What is the point? If you want to separate error message and detail error message with " - ", you can just do an additional conditional strcat in the error message function.

Cheers, Thomas

src/java.base/share/native/libjli/emessages.h line 111:

> 109: #define DLL_ERROR2      "Error: failed %s, because %s"
> 110: #define DLL_ERROR3      "Error: could not find executable %s"
> 111: #define DLL_ERROR4      "Error: Failed to load %s"

Have you looked into all usages of this macro, also non-windows/shared code? Please make sure the replacement text makes sense in all those cases.

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PR: https://git.openjdk.org/jdk/pull/9749