Fetch the koid current owner of a futex, if any.
#include <zircon/syscalls.h> zx_status_t zx_futex_get_owner(const zx_futex_t* value_ptr, zx_koid_t* koid);
Fetch the koid of the current owner of the futex identified by value_ptr, or ZX_KOID_INVALID if there is no current owner. Knowledge of the ownership of a futex typically serves no purpose when building synchronization primitives from futexes. This syscall is used primarily for testing.
See Ownership and Priority Inheritance in futex for details.
zx_futex_get_owner() returns ZX_OK on success, and koids hold the owner of
the futex at the time of the syscall, or ZX_KOID_INVALID if there was no
ZX_ERR_INVALID_ARGS One of the following is true:
- value_ptr is not a valid userspace pointer.
- value_ptr is not aligned to a
- koid is not a valid userspace pointer.