[PATCH] Windows 32-bit DLL name decoration (original) (raw)

Alexey Ivanov alexey.ivanov at oracle.com
Wed Dec 12 16:02:33 UTC 2018

Hi Simon,

I'd like to clarify some points… Please see my comments inline:

On 11/12/2018 17:16, Alexey Ivanov wrote:

Hi Simon,

Thank you for your comments. The updated webrev: http://cr.openjdk.java.net/~aivanov/8214122/webrev.01/ Indeed, it looks much cleaner. Regards, Alexey On 11/12/2018 16:43, Simon Tooke wrote: On 2018-12-11 10:05 a.m., Alexey Ivanov wrote:

Hi everyone,

I came up with the following patch: http://cr.openjdk.java.net/~aivanov/8214122/webrev.00/ It specifically addresses the problem in JDK-8214122 where on 32 bit Windows jdwpTransportOnLoad can exported with its plain and _stdcall-mangled name. I used conditional compilation so that for other platforms the code remains as it is now. jshell starts successfully with this fix; an IDE debugger works as well. I am not a reviewer, but this patch only works for the specific case under discussion; the '@16' refers to the reserved stack size in the Pascal calling convention.  So, the patch only works for 16 bytes of parameters.  To be generic, the routine needs to have the stack size passed in by the caller.  If a generic fix isn't desired (and I hope it is), I'd prefer to see the caller simply pass the decorated or undecorated name depending on the Win32/64 defines.

At this time, it's only one function. So the current approach works well enough, although it will not scale.

If other similar functions are added in the future, _OnUnload for example, we should implement approach used in Hotspot as suggested by Bob: http://mail.openjdk.java.net/pipermail/build-dev/2018-December/024373.html

#if defined(WIN32) && !defined(WIN64) onLoad = (jdwpTransportOnLoadt) dbgsysFindLibraryEntry(handle, "jdwpTransportOnLoad at 16"); #else onLoad = (jdwpTransportOnLoadt) dbgsysFindLibraryEntry(handle, "jdwpTransportOnLoad"); #endif

I believe falling back to undecorated name is the right thing in the case where the decorated name isn't found. Only the undecorated name has been looked up before. If a (third-party) JDWP transport DLL exports the undecorated name only, it will fail to load. With fallback in place, it will load successfully.

Does it sound reasonable?

Regards, Alexey

Thanks, -Simon Regards, Alexey https://bugs.openjdk.java.net/browse/JDK-8214122 On 10/12/2018 15:11, Magnus Ihse Bursie wrote: Since removing JNICALL is not an option, there are only two options:

1. Add |/export| option to the Makefile or pragma-comment to the source file; 2. Lookup the decorated name |jdwpTransportOnLoad at 16| for Win32 with fallback to undecorated one. Yes. I think the correct solution here is 2.

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