System libraries are not used when running in a venv

[C0rn3j]

0.9.8b3

Downstream report - Taiko2k/Tauon#1625

I can reproduce this 100% by running Tauon's clean venv script, which does this https://github.com/Taiko2k/Tauon/blob/d09209bd117d6b1d52842a45e06063def2e1051e/run.sh#L55-L84

If I define SDL_BINARY_PATH as /usr/lib, it works.

Forcing SDL_FIND_BINARIES to 1 makes no difference.

The app works just fine outside of the venv.

Tauon additionally sets these:

os.environ["SDL_DISABLE_METADATA"]         = "1" # Disable metadata method,                     "0"        by default.
os.environ["SDL_CHECK_VERSION"]            = "0" # Disable version checking,                    "1"        by default.
os.environ["SDL_CHECK_BINARY_VERSION"]     = "0" # Disable binary version checking,             "1"        by default.
os.environ["SDL_IGNORE_MISSING_FUNCTIONS"] = "1" # Disable missing function warnings,           "0"        by default.

[C0rn3j]

This actually does not seem to work even outside of a venv on a system install.

[Samueru-sama]

This is a bigger issue related to cpython: python/cpython#142020

They ended up deprecating find_library because it is very flawed.

Right now this issue is preventing us from making an appimage of tauon, because setting SDL_BINARY_PATH=$APPDIR/lib only prevents a crash, but the bloody thing still ends up loading the libSDL3 of the host, what is funny is that if the host does not have libSDL3 installed it loads the bundled library without issue lol

[C0rn3j]

the bloody thing still ends up loading the libSDL3 of the host, what is funny is that if the host does not have libSDL3 installed it loads the bundled library without issue lol

This is why the portable Tauon version has libSDL3.so.0 copied next to the executable, since that's where it checks first, see Taiko2k/Tauon@f623e01 and Taiko2k/Tauon#2052

You can verify the load order via strace

[Samueru-sama]

This is why the portable Tauon version has libSDL3.so.0 copied next to the executable, since that's where it checks first, see Taiko2k/Tauon@f623e01 and Taiko2k/Tauon#2052

You can verify the load order via strace

I ended up fixing it by patching pysdl here.

This is a more universal solution for other python apps that use this library as well.

For what is worth, before doing this I tested preloading libSDL and that did not work, I also tested using pathmap and redirecting all /usr/lib/libSDL* calls to $APPDIR/lib/libSDL* and even that did not work somehow.