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Problem

CGO breaks SetUnhandledExceptionFilter API on Windows x64. Automated crash reporting tools, such as Sentry, use the aforementioned API to capture SEH exceptions and send them to backend for processing. The reports are converted into stacktraces and aggregated. This allows the developer of an application to monitor stability of their product and fix crashes as their appear on the dashboard.

Because of this CGO issue, Go becomes very unnatractive for any serious client application development on Windows. Fixing this issue would make Go much more suited for client application development.

Architecture of this sample

This program is broken down into 3 binaries: main.exe, wrapgo.dll and crashc.dll. main.exe calls into wrapgo.dll, which in turn forwards the call to crashc.dll. crashc.dll crashes the program. In this setup, Go is the middle man between the main program, and another library that is crashing.

Steps to reproduce

  • Get a Windows installation. Since this is a Windows issue, you must have a Windows installation to be able to test it. Its possible to build on Linux, but since testing must be done on Windows, the provided build script is written using Windows Batch.

  • Clone the source.

      git clone [email protected]:arg0d/sentryProblem.git

  • Get MinGW compilers. Download prebuilt compilers from [here] (https://sourceforge.net/projects/mingw-w64/files/). Get the latest version MinGW-W64 GCC-8.1.0. For Windows x64, get x86_64-win32-seh. For Windows x86, get i686-win32-sjlj. Extract the contents of archives into sentryProblem/mingw64 and sentryProblem/mingw32

  • Build.

      build.bat

  • Run.

      run.bat

  • Check the output. After running the program, observe that string OnUnhandledException is missing.

      C:\workspace\sentryBugReport\build>main.exe
  WrapGo_Start()
  CrashC_Start()

Works on Windows x86

SetUnhandledExceptionFilter seems to be working fine when using x86. To test that, do the following:

  • Comment out the contents of function initExceptionHandler at sentryProblem/go/src/runtime/signal_windows.go. The exception handling implementation is overriding the previously set unhandled exception filter.

  • Build.

      build.bat x86

  • Run.

      run.bat

  • Check the output. After running the program, observe that OnUnhandledException is present.

      C:\workspace\sentryBugReport\build>main.exe
  WrapGo_Start()
  CrashC_Start()
  OnUnhandledException()