RobotPy 2021 issue with rev module on roborio

[thomas302]

Whenever I try to run a program that imports the rev library on the roborio I get an error message like this one:

    Traceback (most recent call last):
      File "/home/lvuser/test.py", line 1, in <module>
        import rev
      File "/usr/local/lib/python3.9/site-packages/rev/__init__.py", line 3, in <module>
        from . import _init_rev
      File "/usr/local/lib/python3.9/site-packages/rev/_init_rev.py", line 12, in <module>
        import rev._sparkmaxdriver._init_rev_spark_driver
      File "/usr/local/lib/python3.9/site-packages/rev/_sparkmaxdriver/__init__.py", line 1, in <module>
        from . import _init_rev_spark_driver
      File "/usr/local/lib/python3.9/site-packages/rev/_sparkmaxdriver/_init_rev_spark_driver.py", line 14, in <module>
        _lib = cdll.LoadLibrary(join(_root, "lib", "libSparkMaxDriver.so"))
      File "/usr/local/lib/python3.9/ctypes/__init__.py", line 452, in LoadLibrary
        return self._dlltype(name)
      File "/usr/local/lib/python3.9/ctypes/__init__.py", line 374, in __init__
        self._handle = _dlopen(self._name, mode)
    OSError: libwpimathjni.so: cannot open shared object file: No such file or directory

Does anyone know how I can fix this?

(You may notice that it is not running the main program and is instead running a file called test.py, this file contains only a single line with import rev)

[auscompgeek]

Well, we knew this affected the macOS libraries, but didn’t notice this was also a problem on the roboRIO. That’s awkward.

[Thad_House]

There is a workaround solution. Download the following file, and inside in the linux\athena\shared folder there is a libwpimathjni.so file. if you ftp that into /usr/local/frc/third-party/lib on the roborio, it should then run. You might also have to ssh in and run ldconfig

https://frcmaven.wpi.edu/artifactory/release/edu/wpi/first/wpimath/wpimath-cpp/2021.2.1/wpimath-cpp-2021.2.1-linuxathena.zip

[thomas302]

This worked, thanks. I did not have to run ldconfig (though its probably because I reset the roborio before I tested if the program was now running).

[auscompgeek]

I’ve found a workaround at build time. robotpy-rev 2021.0.2 should fix this for good (and has the bonus of macOS support too).