Dangerzone help message printed when we open the Dangerzone app via the CLI in macOS

[apyrgio]

While testing the 0.7.0 release on macOS, we were sometimes opening the Dangerzone application via the CLI. When we were doing so and were converting a document, we were surprised to see that the help message of Dangerzone was printed to the terminal, and a -B argument was provided.

This does not affect the conversion, but it may be a sign of a larger problem. Also this is something that most of our users will never encounter, so it's a low priority issue.

[almet]

This seem to be a common pitfall of pyinstaller, when using multiprocessing. This is why we see it only with macOS, as pyinstaller is only used there.

In our case, the reason is that the spawned processes is passed the -B option, thinking it's python (but it's dangerzone).

   -B     Don't write .pyc files on import. See also PYTHONDONTWRITEBYTECODE.

As a result, dangerzone is spawned with the -B option, which doesn't mean anything for it.

In the frozen application, sys.executable points to your application executable. So when the multiprocessing module in your main process attempts to spawn a subprocess (a worker or the resource tracker), it runs another instance of your program, with the following arguments for resource tracker:

my_program -B -S -I -c "from multiprocessing.resource_tracker import main;main(5)"

The fix seem to be to add this code before actually spawning the new thread:

import multiprocessing
multiprocessing.freeze_support()