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AK: NonnullRefPtr should allow assigning owner to ownee

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Given the following situation:

    struct Object : public RefCounted<Object> {
        RefPtr<Object> parent;
    }

    NonnullRefPtr<Object> object = get_some_object();
    object = *object->parent;

We would previously crash if 'object' was the only strongly referencing
pointer to 'parent'. This happened because NonnullRefPtr would unref
the outgoing pointee before reffing the incoming pointee.

This patch fixes that by implementing NonnullRefPtr assignments using
pointer swaps, just like RefPtr already did.
This commit is contained in:
Andreas Kling 2020-01-18 13:33:44 +01:00
parent 4e6fe3c14b
commit 7ea264a660
2 changed files with 40 additions and 27 deletions
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14
AK/Tests/TestNonnullRefPtr.cpp
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@ -59,4 +59,18 @@ TEST_CASE(assign_reference)
EXPECT_EQ(object->ref_count(), 1);
}
TEST_CASE(assign_owner_of_self)
{
struct Object : public RefCounted<Object> {
RefPtr<Object> parent;
};
auto parent = adopt(*new Object);
auto child = adopt(*new Object);
child->parent = move(parent);
child = *child->parent;
EXPECT_EQ(child->ref_count(), 1);
}
TEST_MAIN(String)