Small fixes

include/zinnia/ident.h

@@ -11,3 +11,5 @@ struct ident {
 };
 
 const struct ident* ident_kernel(void);
+
+bool ident_in_group(const struct ident* identity, gid_t gid, bool use_real);

include/zinnia/list.h

@@ -10,7 +10,7 @@
         type _sl_link; \
     }
 
-#define list_is_empty(head)   ((head)->_sl_head == NULL)
+#define list_is_empty(head)   ((head)->_sl_head == nullptr)
 #define list_first(head)      ((head)->_sl_head)
 #define list_next(elm, field) ((elm)->field._sl_link)
 

include/zinnia/refcount.h

@@ -16,6 +16,15 @@ static inline void refcount_inc(struct refcount* rc) {
     atomic_fetch_add(&rc->count, 1, ATOMIC_RELAXED);
 }
 
+static inline bool refcount_inc_not_zero(struct refcount* rc) {
+    size_t count = atomic_load(&rc->count, ATOMIC_RELAXED);
+    do {
+        if (count == 0)
+            return false;
+    } while (!atomic_compare_exchange_weak(&rc->count, &count, count + 1, ATOMIC_ACQUIRE, ATOMIC_RELAXED));
+    return true;
+}
+
 static inline bool refcount_dec(struct refcount* rc) {
     if (atomic_fetch_sub(&rc->count, 1, ATOMIC_RELEASE) != 1)
         return false;

include/zinnia/spin.h

@@ -14,5 +14,7 @@ void spin_init(struct spinlock* spin);
 // Attempts to lock a spinlock. If it's already locked, waits until it's freed.
 void spin_lock(struct spinlock* spin);
 
+bool spin_trylock(struct spinlock* spin);
+
 // Unlocks a spinlock.
 void spin_unlock(struct spinlock* spin);