Facedancer --suggest mode doesn't print suggestions, as Ctrl-C is no longer caught

[miek]

When running facedancer examples with the --suggest argument, pressing Ctrl-C to end the script just prints a backtrace instead of printing the aggregated suggestions. It used to catch the exception, but that got removed in #92

[mossmann]

@kauwua Do you have any objection to reverting ea8c2a6?

[kauwua]

I don't think this commit should be reverted : if Facedancer catches the exception without rethrowing it, it prevents Facedancer users from catching Ctrl-C. I personnaly needed to catch Ctrl-C in a script that was creating devices in a loop and Facedancer was catching the KeyboardInterrupt without rethrowing it so I had no way to get a KeyboardInterrupt event (to print my own results before the script ends). If I remember correctly it also interfered with the way Ctrl-C is used by the Python interpreter to stop the script.

The emulation of the device (https://github.com/greatscottgadgets/facedancer/blob/cfb3d5899463b58b097ed6860099dd0320df8a20/facedancer/devices/__init__.py#L40C1-L44C43) could be wrapped like this to ensure suggestions will always be printed (finally will always be executed : it will run after any except handler and before any uncaught exception)

try:
    # Run the relevant code, along with any added coroutines.
    device.emulate(*coroutines)
finally:
    if args.suggest:
        device.print_suggested_additions()

[antoinevg]

How about: #119

[kauwua]

catching KeyboardInterrupt would be ok in default_main since it's a convenience function (the main issue was Facedancer catching Ctrl-C directly in the core library and not exiting). this way you could print the suggestions, exit cleanly (with exit probably) to remove the ugly backtrace and users could create their own main if they want.

#119 PR works for me as well

[miek]

I'm reluctant to introduce a new keyboard shortcut if we don't need to, I like the suggestion of catching KeyboardInterrupt in default_main instead.

[mossmann]

@antoinevg plans to rework #119 so that the interrupt is caught in default_main and the ctrl-e solution is moved to an example.

[antoinevg]

PR updated, feedback appreciated plz! #119