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Bug 3869

Summary: [udev] SDL_UDEV_DYNAMIC only checks for one libudev version
Product: SDL Reporter: Ethan Lee <flibitijibibo>
Component: joystickAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: sezeroz
Version: 2.0.6   
Hardware: All   
OS: Linux   
Attachments: Fix for SDL_UDEV_DYNAMIC/SDL_UDEV_LIBS

Description Ethan Lee 2017-10-10 15:53:19 UTC 
This commit appears to have introduced a bug where SDL will forcibly depend on a single udev version, rather than prioritizing one or the other:

https://hg.libsdl.org/SDL/rev/1ae4e8001b73

For example, if the build system has libudev.so.1 and the user has libudev.so.0, even if the game does not link to libudev at all the game will fail to detect devices for the user:

http://steamcommunity.com/app/543260/discussions/0/1471966894869753969/?ctp=2#c1489987634012244580

I don't know the full context for this commit so I'm not sure about this, but would it make more sense to have SDL_UDEV_DYNAMIC be a separate thing entirely and _then_ check for the list if SDL_UDEV_DYNAMIC isn't found? For example:



static const char *SDL_UDEV_LIBS[] = { "libudev.so.1", "libudev.so.0" };

#ifdef SDL_UDEV_DYNAMIC
_this->udev_handle = SDL_LoadObject(SDL_UDEV_DYNAMIC);
if (_this->udev_handle != NULL) {
    /* blah... */
    return retval; /* ...? */
}
#endif

for( i = 0 ; i < SDL_arraysize(SDL_UDEV_LIBS); i++) {
    /* You get the idea... */
}



Again, this is entirely a guess, but it does seem like we should at the very least have the full list of udev libs for the case where the executable doesn't directly link to udev.
Comment 1 Sam Lantinga 2017-10-10 22:45:10 UTC 
Not a bad idea, do you want to provide a tested patch?

Thanks!
Comment 2 Ethan Lee 2017-10-11 00:24:07 UTC 
Created attachment 2972 [details]
Fix for SDL_UDEV_DYNAMIC/SDL_UDEV_LIBS

Attached is the patch implementing my idea, will send a patched binary to the user with this issue and report back (if someone else doesn't test this first).
Comment 3 Ethan Lee 2017-10-11 03:33:15 UTC 
Looks like the patch worked! This should be good to merge provided we haven’t missed a case other than so.0 and so.1...
Comment 4 Sam Lantinga 2017-10-11 20:33:09 UTC 
Added, thanks!
https://hg.libsdl.org/SDL/rev/0f2de8f6c959