Change gamepad state logic to fix crash #445
Conversation
The problem with this solution is that it must be mirrored across platforms, which feels like it could run into some issues since the code already exhibits unique behavior for each platform and comments describe inconsistencies.
2. Moving the state change into the constructor, rather than in start()
This I think is the better solution, as it ensures that the state is not changed until the object has been fully initialized, making the state atomic more properly act as the gate which stops any calls to uninitialized objects.
I've also added an additional check where the error from #5 comes from:
// src/sources/input_source.cpp:67
if (m_settings.use_local_input() && gamepad_hook::state && gamepad_hook::local_gamepads) {
m_settings.gamepad = gamepad_hook::local_gamepads->get_controller_from_index(m_settings.gamepad_index);This is entirely redundant, but makes me feel a bit better since it confirms that this if statement won't do anything wonky from where it might be called elsewhere.
Extras
I haven't tested this on Windows yet, but the fix works properly on my Gentoo machine. I expect that the logic will also work on other platforms, since I haven't changed anything about the order of operations regarding the other init functions that run, so they should be still functional.
Moves the state change logic into the constructor to ensure that it will not be changed until the object is finished being constructed, as well as adding an additional check in the if statement that requires it to be constructed so that we don't call methods on an uninitialized object.
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thanks for the pr |
Summary
This change fixes #426 by moving the gamepad state change logic into the constructor, which ensures it will not be updated until the object is finished being constructed, and therefore not be attempted to be accessed until it is initialized.
Context
Sometime late last year, I started getting a bug where OBS would crash on boot if not in safe mode. My OBS and input-display were both up to date, OBS would run normally without input-display active (or in safe mode), and I had no other plugins installed, so I knew the issue must be with input-display. In addition, the issue persisted across platforms (Flatpak, as well as Portage; and it seems like the issue is also present on Windows, as the linked issue shows). I did some digging and found the above-linked issue, which had the exact same error, log, callstack/backtrace, and also a workaround (unplugging the controller before booting OBS).
When troubleshooting, this is the full backtrace I got with debugging symbols:
The problem lies in
#5:What ends up happening is
local_gamepads::get_controller_from_indexis getting called on agamepadthat has not been initialized, which crashes because of something regarding the SDL2 init function that gets run.Fix
The issue can be fixed one of two ways:
gamepads so that the SDL init doesn't fail: