[R-pkg-devel] RFC: C backtraces for R CMD check via just-in-time debugging

[Vladimir Dergachev]

I use libunwind in my programs, works quite well, and simple to use.

Happy to share the code if there is interest..

best

Vladimir Dergachev

On Mon, 4 Mar 2024, Ivan Krylov via R-package-devel wrote:

> On Sun, 3 Mar 2024 19:19:43 -0800
> Kevin Ushey <kevinushey using gmail.com> wrote:
>
>> Would libSegFault be useful here?
>
> Glad to know it has been moved to
> <https://github.com/zatrazz/glibc-tools/tree/main/libSegFault> and not
> just removed altogether after the upstream commit
> <https://sourceware.org/git/?p=glibc.git;a=commit;h=65ccd641bacea33be23d51da737c2de7543d0f5e>.
>
> libSegFault is safer than, say, libsegfault [*] because it both
> supports SA_ONSTACK (for when a SIGSEGV is caused by stack overflow)
> and avoids functions like snprintf() (which depend on the locale code,
> which may have been the source of the crash). The only correctness
> problem that may still be unaddressed is potential memory allocations
> in backtrace() when it loads libgcc on first use. That should be easy
> to fix by calling backtrace() once in segfault_init(). Unfortunately,
> libSegFault is limited to glibc systems, so a different solution will
> be needed on Windows, macOS and Linux systems with the musl libc.
>
> Google-owned "backward" [**] tries to do most of this right, but (1) is
> designed to be compiled together with C++ programs, not injected into
> unrelated processes and (2) will exit the process if it survives
> raise(signum), which will interfere with both rJava (judging by the
> number of Java-related SIGSEGVs I saw while running R CMD check) and R's
> own stack overflow survival attempts.
>
> -- 
> Best regards,
> Ivan
>
> [*] https://github.com/stass/libsegfault
> (Which doesn't compile out of the box on GNU/Linux due to missing
> pthread_np.h, although that should be easy to patch.)
>
> [**] https://github.com/bombela/backward-cpp
>
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