Wayland video subsystem uses a mix of libc and SDL function.
This patch switches libc functions to SDL ones and fixes a mismatch in memory
allocation/dealoccation of SDL_Cursor in SDL_waylandmouse.c (calloc on line 201
and SDL_free on line 313) which caused memory corruption if custom memory
allocator where provided to SDL.
If you hide a window on Mutter, for example, the compositor never requests
new frames, which will cause Mesa to block forever in eglSwapBuffers to
satisfy the swap interval.
We now always set the swap interval to 0 and manage this ourselves, handing
the frame to Wayland when it requests a new one, and timing out at 10fps just
to keep apps moving if the compositor wants no frames at all.
My understanding is that other protocols are coming that might improve upon
this solution, but for now it solves the total hang.
Fixes#4335.
Previous version used 'popen' which required to sanitize user provided text. Not
sanitizing text could cause failure if user provided text included a " or command
injection with `cmd`.
This unearthed an unspeakably large amount of bugs in the wl_output enumerator,
notably the fact that the wl_output user pointer was to temporary memory!
This was "fixed" in e862856, and was then pointed out as a leak in 4183211,
which was undone in d9ba204. The busted fix was correct that the malloc was an
issue, but wrong about _why_; SDL_AddVideoDisplay copies by value and does not
reuse the pointer, so generally you want your VideoDisplay to be on the stack,
but of course the callbacks don't allow that, so a malloc was a workaround. But
we can do better and just host our temporary display inside WaylandOutputData
because that will be persistent while also not leaking.
Wait, wasn't I talking about move events? Right, that: wl_surface_listener does
at least give us the ability to know what monitor we're on, even though we have
no idea where we are on the monitor. All we need to do is check the wl_output
against the display list and then push a move event that both indicates the
correct display while also not being _too_ much of a lie (but enough of a lie
to where our event doesn't get discarded as "undefined" or whatever). The index
check for the video display is what spawned the great nightmare you see before
you; aside from the bugfix this is actually a really basic patch.
