Function Getpriority

pkg/sentry/syscalls/linux/sys_thread.go:716–747

Getpriority pretends to implement the linux syscall getpriority(2). This is a stub; real priorities require a full scheduler.

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

//
// This is a stub; real priorities require a full scheduler.
func Getpriority(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
	which := args[0].Int()
	who := kernel.ThreadID(args[1].Int())

	switch which {
	case linux.PRIO_PROCESS:
		// Look for who, return ESRCH if not found.
		var task *kernel.Task
		if who == 0 {
			task = t
		} else {
			task = t.PIDNamespace().TaskWithID(who)
		}

		if task == nil {
			return 0, nil, linuxerr.ESRCH
		}

		// From kernel/sys.c:getpriority:
		// "To avoid negative return values, 'getpriority()'
		// will not return the normal nice-value, but a negated
		// value that has been offset by 20"
		return uintptr(20 - task.Niceness()), nil, nil
	case linux.PRIO_USER:
		fallthrough
	case linux.PRIO_PGRP:
		// PRIO_USER and PRIO_PGRP have no further implementation yet.
		return 0, nil, nil
	default:
		return 0, nil, linuxerr.EINVAL
	}
}

// Setpriority pretends to implement the linux syscall setpriority(2).
//