Replace bitset with stdlib math/big

Sync changes in runc https://github.com/opencontainers/runc/pull/3219

WORKSPACE

@@ -1896,10 +1896,3 @@ go_repository(
     sum = "h1:LhYJRs+L4fBtjZUfuSZIKGeVu0QRy8e5Xi7D17UxZ74=",
     version = "v1.2.0",
 )
-
-go_repository(
-    name = "com_github_bits_and_blooms_bitset",
-    importpath = "github.com/bits-and-blooms/bitset",
-    sum = "h1:M+/hrU9xlMp7t4TyTDQW97d3tRPVuKFC6zBEK16QnXY=",
-    version = "v1.2.1",
-)

go.mod

@@ -5,7 +5,6 @@ go 1.17
 require (
 	github.com/BurntSushi/toml v0.3.1
 	github.com/bazelbuild/rules_go v0.30.0
-	github.com/bits-and-blooms/bitset v1.2.0
 	github.com/cenkalti/backoff v1.1.1-0.20190506075156-2146c9339422
 	github.com/containerd/cgroups v1.0.1
 	github.com/containerd/console v1.0.1

go.sum

@@ -61,8 +61,6 @@ github.com/bazelbuild/rules_go v0.30.0 h1:kX4jVcstqrsRqKPJSn2mq2o+TI21edRzEJSrEO
 github.com/bazelbuild/rules_go v0.30.0/go.mod h1:MC23Dc/wkXEyk3Wpq6lCqz0ZAYOZDw2DR5y3N1q2i7M=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
 github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
-github.com/bits-and-blooms/bitset v1.2.0 h1:Kn4yilvwNtMACtf1eYDlG8H77R07mZSPbMjLyS07ChA=
-github.com/bits-and-blooms/bitset v1.2.0/go.mod h1:gIdJ4wp64HaoK2YrL1Q5/N7Y16edYb8uY+O0FJTyyDA=
 github.com/cenkalti/backoff v1.1.1-0.20190506075156-2146c9339422 h1:8eZxmY1yvxGHzdzTEhI09npjMVGzNAdrqzruTX6jcK4=
 github.com/cenkalti/backoff v1.1.1-0.20190506075156-2146c9339422/go.mod h1:b6Nc7NRH5C4aCISLry0tLnTjcuTEvoiqcWDdsU0sOGM=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=

runsc/cgroup/BUILD

@@ -13,7 +13,6 @@ go_library(
     deps = [
         "//pkg/cleanup",
         "//pkg/log",
-        "@com_github_bits_and_blooms_bitset//:go_default_library",
         "@com_github_cenkalti_backoff//:go_default_library",
         "@com_github_coreos_go_systemd_v22//dbus:go_default_library",
         "@com_github_godbus_dbus_v5//:go_default_library",

runsc/cgroup/cgroup_v2.go

@@ -20,18 +20,17 @@ import (
 	"bufio"
 	"bytes"
 	"context"
-	"encoding/binary"
 	"errors"
 	"fmt"
 	"io/ioutil"
 	"math"
+	"math/big"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/bits-and-blooms/bitset"
 	"github.com/cenkalti/backoff"
 	"github.com/coreos/go-systemd/v22/dbus"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
@@ -834,7 +833,8 @@ func parseUint(s string, base, bitSize int) (uint64, error) {
 // AllowedCPUs/AllowedMemoryNodes unit property value).
 // Copied from runc.
 func RangeToBits(str string) ([]byte, error) {
-	bits := &bitset.BitSet{}
+	bits := &big.Int{}
+
 	for _, r := range strings.Split(str, ",") {
 		// allow extra spaces around
 		r = strings.TrimSpace(r)
@@ -855,31 +855,22 @@ func RangeToBits(str string) ([]byte, error) {
 			if start > end {
 				return nil, errors.New("invalid range: " + r)
 			}
-			for i := uint(start); i <= uint(end); i++ {
-				bits.Set(i)
+			for i := start; i <= end; i++ {
+				bits.SetBit(bits, int(i), 1)
 			}
 		} else {
 			val, err := strconv.ParseUint(ranges[0], 10, 32)
 			if err != nil {
 				return nil, err
 			}
-			bits.Set(uint(val))
+			bits.SetBit(bits, int(val), 1)
 		}
 	}
 
-	val := bits.Bytes()
-	if len(val) == 0 {
+	ret := bits.Bytes()
+	if len(ret) == 0 {
 		// do not allow empty values
 		return nil, errors.New("empty value")
 	}
-	ret := make([]byte, len(val)*8)
-	for i := range val {
-		// bitset uses BigEndian internally
-		binary.BigEndian.PutUint64(ret[i*8:], val[len(val)-1-i])
-	}
-	// remove upper all-zero bytes
-	for ret[0] == 0 {
-		ret = ret[1:]
-	}
 	return ret, nil
 }