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[patch] Fix #1: use SDL_GetNextJoystickInstanceID() for alloc'ing joystick-ids in Emscripten joystick backend

SDL_Bug_5097-Fix_1.patch (text/plain), 2.55 KB, created by David Ludwig on 2020-04-18 16:13:38 UTC

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Creator: David Ludwig

Created: 2020-04-18 16:13:38 UTC

Size: 2.55 KB

patch

obsolete

># HG changeset patch
># User David Ludwig <dludwig@pobox.com>
># Date 1587226196 14400
>#      Sat Apr 18 12:09:56 2020 -0400
># Node ID ea04d691126200b6b18960cd679a06ff7466e3bc
># Parent  671d8b2548b340faa50ef47e9f902a0978e53dd8
>Fix for Bug 5097, Emscripten: connecting and disconnecting real-joysticks can close virtual joysticks
>
>Emscripten was using its own, private integer in order to allocate
>new SDL_JoystickIDs.  SDL keeps a similar integer for allocating
>joystick-ids, one which is shared across multiple joystick backends.
>
>SDL 2.0.13 introduces a new joystick-backend, a Virtual joystick
>backend, which allows for software-driven joysticks, and which is
>designed to sit alongside joystick-backends that provide access to
>physical joysticks.
>
>The Emscripten and the Virtual backends were, at times, getting
>allocated the same SDL_JoystickIDs, if and when both backends were used
>simultaneously.  This could happen if, for example, an application
>was using a virtual joystick in order to drive a touch-screen
>based joystick, while also supporting physical joysticks through the
>Emscripten backend.
>
>When two joysticks end up with the same SDL_JoystickID, conflicts
>can occur.  For example, disconnecting a physical joystick with
>the same SDL_JoystickID as a virtual one, can lead to the virtual
>joystick being closed, inadvertently.
>
>This fix makes the Emscripten backend use SDL's cross-joystick-backend
>integer counter, which is shared among joystick backends, for allocating
>new SDL_JoystickIDs, rather than a private, Emscripten-specific
>counter.
>
>diff -r 671d8b2548b3 -r ea04d6911262 src/joystick/emscripten/SDL_sysjoystick.c
>--- a/src/joystick/emscripten/SDL_sysjoystick.c	Fri Apr 17 21:30:58 2020 -0700
>+++ b/src/joystick/emscripten/SDL_sysjoystick.c	Sat Apr 18 12:09:56 2020 -0400
>@@ -38,7 +38,6 @@
> static SDL_joylist_item *SDL_joylist = NULL;
> static SDL_joylist_item *SDL_joylist_tail = NULL;
> static int numjoysticks = 0;
>-static int instance_counter = 0;
> 
> static EM_BOOL
> Emscripten_JoyStickConnected(int eventType, const EmscriptenGamepadEvent *gamepadEvent, void *userData)
>@@ -74,7 +73,7 @@
> 
>     item->naxes = gamepadEvent->numAxes;
>     item->nbuttons = gamepadEvent->numButtons;
>-    item->device_instance = instance_counter++;
>+    item->device_instance = SDL_GetNextJoystickInstanceID();
> 
>     item->timestamp = gamepadEvent->timestamp;
> 
>@@ -172,7 +171,6 @@
>     SDL_joylist = SDL_joylist_tail = NULL;
> 
>     numjoysticks = 0;
>-    instance_counter = 0;
> 
>     emscripten_set_gamepadconnected_callback(NULL, 0, NULL);
>     emscripten_set_gamepaddisconnected_callback(NULL, 0, NULL);

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Attachments on bug 5097: 4310

We are currently migrating Bugzilla to GitHub issues.Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.