CFRuntime.__CFDoExternRefOperation

gistfile1.c

// we disguise pointers so that programs like 'leaks' forget about these references
#define DISGUISE(O) (~(uintptr_t)(O))

#if DEPLOYMENT_TARGET_MACOSX
#define NUM_EXTERN_TABLES 8
#define EXTERN_TABLE_IDX(O) (((uintptr_t)(O) >> 8) & 0x7)
#elif DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI || DEPLOYMENT_TARGET_WINDOWS || DEPLOYMENT_TARGET_LINUX
#define NUM_EXTERN_TABLES 1
#define EXTERN_TABLE_IDX(O) 0
#else
#error
#endif

static struct {
    CFSpinLock_t lock;
    CFBasicHashRef table;
    uint8_t padding[64 - sizeof(CFBasicHashRef) - sizeof(CFSpinLock_t)];
} __NSRetainCounters[NUM_EXTERN_TABLES];

CF_EXPORT uintptr_t __CFDoExternRefOperation(uintptr_t op, id obj) {
    if (nil == obj) HALT;
    uintptr_t idx = EXTERN_TABLE_IDX(obj);
    uintptr_t disguised = DISGUISE(obj);
    CFSpinLock_t *lock = &__NSRetainCounters[idx].lock;
    CFBasicHashRef table = __NSRetainCounters[idx].table;
    uintptr_t count;
    switch (op) {
    case 300:   // increment
    case 350:   // increment, no event
        __CFSpinLock(lock);
	CFBasicHashAddValue(table, disguised, disguised);
        __CFSpinUnlock(lock);
        if (__CFOASafe && op != 350) __CFRecordAllocationEvent(__kCFObjectRetainedEvent, obj, 0, 0, NULL);
        return (uintptr_t)obj;
    case 400:   // decrement
        if (__CFOASafe) __CFRecordAllocationEvent(__kCFObjectReleasedEvent, obj, 0, 0, NULL);
    case 450:   // decrement, no event
        __CFSpinLock(lock);
        count = (uintptr_t)CFBasicHashRemoveValue(table, disguised);
        __CFSpinUnlock(lock);
        return 0 == count;
    case 500:
        __CFSpinLock(lock);
        count = (uintptr_t)CFBasicHashGetCountOfKey(table, disguised);
        __CFSpinUnlock(lock);
        return count;
    }
    return 0;
}