Re: [v1 1/1] dinput: Sort virtual joysticks by name on the Mac

[Ken Thomases]

On Jul 16, 2016, at 3:15 AM, David Lawrie  wrote:
> Tested on OS X 10.10.5.
> Signed-off-by: David Lawrie
>
> dlls/dinput/joystick_osx.c | 35 ++++++++++++++++++++++++++++++++---
> 1 file changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/dlls/dinput/joystick_osx.c b/dlls/dinput/joystick_osx.c
> index 637692b..22bdc4f 100644
> --- a/dlls/dinput/joystick_osx.c
> +++ b/dlls/dinput/joystick_osx.c
> @@ -193,6 +193,26 @@ static long get_device_property_long(IOHIDDeviceRef device, CFStringRef key)
>     return result;
> }
>
> +static CFStringRef get_device_name(IOHIDDeviceRef device)
> +{
> - CFTypeRef ref;
> - CFStringRef name = CFSTR("Default Name");

You can probably do better for a fallback.  For example, you can format the vendor ID and product ID into a string.  For an extreme take on this, see the Copy_DeviceName() function in Apple's HID Calibrator sample code:
https://developer.apple.com/library/mac/samplecode/HID_Calibrator/Listings/H...
> -
> - if(device)
> - {
> -
>    assert(IOHIDDeviceGetTypeID() == CFGetTypeID(device));
> -
> -
>    ref = IOHIDDeviceGetProperty(device, CFSTR(kIOHIDProductKey));
> -
> -
>    if (ref && CFStringGetTypeID() == CFGetTypeID(ref))
> -
>        name = ref;
> -
>    else if (ref)
> -
>        name = CFCopyDescription(ref);

This introduces a memory-management problem, a.k.a. a leak.  This copy is never released.

If you follow my suggestion above for formatting a string as a fallback if the product name isn't available, you'd also have to release that.

So, you would change this function's name to copy_device_name() and make sure all code paths return an owned reference to the caller, which the caller has to release.  Basically, in the case where IOHIDDeviceGetProperty() gives you a string, you'd have to copy it to match the other code paths.  Of course, you'd have to make sure the callers do, in fact, release the references.
> - }
> -
> - return name;
>
> +}
> -
>
> static long get_device_location_ID(IOHIDDeviceRef device)
> {
>     return get_device_property_long(device, CFSTR(kIOHIDLocationIDKey));
> @@ -203,7 +223,15 @@ static void copy_set_to_array(const void *value, void *context)
>     CFArrayAppendValue(context, value);
> }
>
> -static CFComparisonResult device_location_comparator(const void *val1, const void *val2, void *context)
> +static CFComparisonResult device_name_comparator(IOHIDDeviceRef device1, IOHIDDeviceRef device2)
> +{
> - CFStringRef name1 = get_device_name(device1), name2 = get_device_name(device2);
> - CFStringCompareFlags compareOptions = kCFCompareForcedOrdering | kCFCompareNumerically;

Any reason you've added this separate variable instead of just inlining the options in the call?
> -
> - return CFStringCompare(name1, name2, compareOptions);
>
> +}

-Ken