Incompatible with JNI on Windows: use unique handle for SymInitialize

[Kyuuhachi]

When trying to use cpptrace in a JNI library, it only gives empty traces, or with absorb_trace_exceptions(false), it gives an exception Cpptrace internal error: SymInitialize failed 87 (87 is ERROR_INVALID_PARAMETER). This appears to be caused by doing SymInitialize on the same handle twice, since openjdk also does that.

This can be solved by duplicating the handle, so that cpptrace initializes its own unique copy. The following diff (in {unwind,symbols}_with_dbghelp.cpp), in conjunction with cpptrace::experimental::set_cache_mode(cpptrace::cache_mode::prioritize_memory), allows capturing traces when GetCurrentProcess() is already initialized.

-         HANDLE proc = GetCurrentProcess();`
+         HANDLE proc0 = GetCurrentProcess(), proc;
+         DuplicateHandle(proc0, proc0, proc0, &proc, 0, FALSE, DUPLICATE_SAME_ACCESS);

This is only a sketch for a fix: a real one would need to close the handle and to support other cache modes. I don't currently have the time nor expertise to make a PR for a real fix, so a bug report will have to suffice.

[jeremy-rifkin]

Hi,
Thanks for the report and suggested fix. I don’t have enough windows api expertise to understand the full implications of duplicating the process handle for this purpose. I see in documentation that a process requires specific permissions in order to use this so it’s probably not something cpptrace should try to unconditionally use. It might be sufficient to use it only in the case of SymInitialize failure but I’m not immediately sure. I’ll have to investigate this more.

[firesgc]

Hi!

I am running into the same issue because Tracy does the same as JNI.

In the official Microsoft example, the handle is duplicated as well (https://learn.microsoft.com/en-us/windows/win32/debug/initializing-the-symbol-handler).

Perhaps it is the best practice?

[jeremy-rifkin]

Thanks for the link, if microsoft shows this as an example that helps give me confidence in the approach. I can take a look at making changes in cpptrace here or I'd welcome a PR

[firesgc]

I have created a PR, and in my own project, it works as intended, but the integration tests are failing. In Windows, CMake doesn't create the integration tests (at least I dont see them in the VS solution), so I don't know how to debug it.

[jeremy-rifkin]

Thanks so much for taking the time to make a PR. I'm looking now and I'll give it a test locally.

[firesgc]

I have edited most of the comments and also added that the duplicate handles will be closed at the end now.

[jeremy-rifkin]

Resolved on dev, will do a release some time in the near future