container: move scheduler policy constants to std

This avoids depending on cgo.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/syscall.go

@@ -1,9 +1,6 @@
 package container
 
 import (
-	"encoding"
-	"strconv"
-	"sync"
 	. "syscall"
 	"unsafe"
 
@@ -46,132 +43,6 @@ func Isatty(fd int) bool {
 	return r == 0
 }
 
-// SchedPolicy denotes a scheduling policy defined in include/uapi/linux/sched.h.
-type SchedPolicy int
-
-// include/uapi/linux/sched.h
-const (
-	SCHED_NORMAL SchedPolicy = iota
-	SCHED_FIFO
-	SCHED_RR
-	SCHED_BATCH
-	_SCHED_ISO // SCHED_ISO: reserved but not implemented yet
-	SCHED_IDLE
-	SCHED_DEADLINE
-	SCHED_EXT
-
-	_SCHED_LAST SchedPolicy = iota - 1
-)
-
-var _ encoding.TextMarshaler = _SCHED_LAST
-var _ encoding.TextUnmarshaler = new(_SCHED_LAST)
-
-// String returns a unique representation of policy, also used in encoding.
-func (policy SchedPolicy) String() string {
-	switch policy {
-	case SCHED_NORMAL:
-		return ""
-	case SCHED_FIFO:
-		return "fifo"
-	case SCHED_RR:
-		return "rr"
-	case SCHED_BATCH:
-		return "batch"
-	case SCHED_IDLE:
-		return "idle"
-	case SCHED_DEADLINE:
-		return "deadline"
-	case SCHED_EXT:
-		return "ext"
-
-	default:
-		return "invalid policy " + strconv.Itoa(int(policy))
-	}
-}
-
-// MarshalText performs bounds checking and returns the result of String.
-func (policy SchedPolicy) MarshalText() ([]byte, error) {
-	if policy == _SCHED_ISO || policy < 0 || policy > _SCHED_LAST {
-		return nil, EINVAL
-	}
-	return []byte(policy.String()), nil
-}
-
-// InvalidSchedPolicyError is an invalid string representation of a [SchedPolicy].
-type InvalidSchedPolicyError string
-
-func (InvalidSchedPolicyError) Unwrap() error { return EINVAL }
-func (e InvalidSchedPolicyError) Error() string {
-	return "invalid scheduling policy " + strconv.Quote(string(e))
-}
-
-// UnmarshalText is the inverse of MarshalText.
-func (policy *SchedPolicy) UnmarshalText(text []byte) error {
-	switch string(text) {
-	case "fifo":
-		*policy = SCHED_FIFO
-	case "rr":
-		*policy = SCHED_RR
-	case "batch":
-		*policy = SCHED_BATCH
-	case "idle":
-		*policy = SCHED_IDLE
-	case "deadline":
-		*policy = SCHED_DEADLINE
-	case "ext":
-		*policy = SCHED_EXT
-
-	case "":
-		*policy = 0
-		return nil
-	default:
-		return InvalidSchedPolicyError(text)
-	}
-	return nil
-}
-
-// for sched_get_priority_max and sched_get_priority_min
-var (
-	schedPriority     [_SCHED_LAST + 1][2]std.Int
-	schedPriorityErr  [_SCHED_LAST + 1][2]error
-	schedPriorityOnce [_SCHED_LAST + 1][2]sync.Once
-)
-
-// GetPriorityMax returns the maximum priority value that can be used with the
-// scheduling algorithm identified by policy.
-func (policy SchedPolicy) GetPriorityMax() (std.Int, error) {
-	schedPriorityOnce[policy][0].Do(func() {
-		priority, _, errno := Syscall(
-			SYS_SCHED_GET_PRIORITY_MAX,
-			uintptr(policy),
-			0, 0,
-		)
-		schedPriority[policy][0] = std.Int(priority)
-		if schedPriority[policy][0] < 0 {
-			schedPriorityErr[policy][0] = errno
-		}
-	})
-	return schedPriority[policy][0], schedPriorityErr[policy][0]
-}
-
-// GetPriorityMin returns the minimum priority value that can be used with the
-// scheduling algorithm identified by policy.
-func (policy SchedPolicy) GetPriorityMin() (std.Int, error) {
-	schedPriorityOnce[policy][1].Do(func() {
-		priority, _, errno := Syscall(
-			SYS_SCHED_GET_PRIORITY_MIN,
-			uintptr(policy),
-			0, 0,
-		)
-		schedPriority[policy][1] = std.Int(priority)
-		if schedPriority[policy][1] < 0 {
-			schedPriorityErr[policy][1] = errno
-		}
-	})
-	return schedPriority[policy][1], schedPriorityErr[policy][1]
-
-}
-
 // schedParam is equivalent to struct sched_param from include/linux/sched.h.
 type schedParam struct {
 	// sched_priority
@@ -191,7 +62,7 @@ type schedParam struct {
 // this if you do not have something similar in place!
 //
 // [very subtle to use correctly]: https://www.openwall.com/lists/musl/2016/03/01/4
-func schedSetscheduler(tid int, policy SchedPolicy, param *schedParam) error {
+func schedSetscheduler(tid int, policy std.SchedPolicy, param *schedParam) error {
 	if r, _, errno := Syscall(
 		SYS_SCHED_SETSCHEDULER,
 		uintptr(tid),