package systemd
import (
"errors"
"math/big"
"strconv"
"strings"
)
// RangeToBits converts a text representation of a CPU mask (as written to
// or read from cgroups' cpuset.* files, e.g. "1,3-5") to a slice of bytes
// with the corresponding bits set (as consumed by systemd over dbus as
// AllowedCPUs/AllowedMemoryNodes unit property value).
func RangeToBits(str string) ([]byte, error) {
bits := new(big.Int)
for _, r := range strings.Split(str, ",") {
// allow extra spaces around
r = strings.TrimSpace(r)
// allow empty elements (extra commas)
if r == "" {
continue
}
ranges := strings.SplitN(r, "-", 2)
if len(ranges) > 1 {
start, err := strconv.ParseUint(ranges[0], 10, 32)
if err != nil {
return nil, err
}
end, err := strconv.ParseUint(ranges[1], 10, 32)
if err != nil {
return nil, err
}
if start > end {
return nil, errors.New("invalid range: " + r)
}
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.SetBit(bits, int(val), 1)
}
}
ret := bits.Bytes()
if len(ret) == 0 {
// do not allow empty values
return nil, errors.New("empty value")
}
// fit cpuset parsing order in systemd
for l, r := 0, len(ret)-1; l < r; l, r = l+1, r-1 {
ret[l], ret[r] = ret[r], ret[l]
}
return ret, nil
}