Function SchedGetaffinity

pkg/sentry/syscalls/linux/sys_thread.go:543–577

SchedGetaffinity implements linux syscall sched_getaffinity(2).

(t *kernel.Task, sysno uintptr, args arch.SyscallArguments)

// SchedGetaffinity implements linux syscall sched_getaffinity(2).
func SchedGetaffinity(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
	tid := args[0].Int()
	size := args[1].SizeT()
	maskAddr := args[2].Pointer()

	// This limitation is because linux stores the cpumask
	// in an array of "unsigned long" so the buffer needs to
	// be a multiple of the word size.
	if size&(t.Arch().Width()-1) > 0 {
		return 0, nil, linuxerr.EINVAL
	}

	var task *kernel.Task
	if tid == 0 {
		task = t
	} else {
		task = t.PIDNamespace().TaskWithID(kernel.ThreadID(tid))
		if task == nil {
			return 0, nil, linuxerr.ESRCH
		}
	}

	mask := task.CPUMask()
	// The buffer needs to be big enough to hold a cpumask with
	// all possible cpus.
	if size < mask.Size() {
		return 0, nil, linuxerr.EINVAL
	}
	_, err := t.CopyOutBytes(maskAddr, mask)

	// NOTE: The syscall interface is slightly different than the glibc
	// interface. The raw sched_getaffinity syscall returns the number of
	// bytes used to represent a cpu mask.
	return uintptr(mask.Size()), nil, err
}

// Getcpu implements linux syscall getcpu(2).
func Getcpu(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {