75 lines
1.6 KiB
Go
75 lines
1.6 KiB
Go
/*
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Copyright 2025 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package securitycontext
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import (
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"os"
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"runtime"
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"strconv"
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"strings"
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"sync"
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)
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// possibleCPUs returns the number of possible CPUs on this host.
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func possibleCPUs() (cpus []int) {
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if ncpu := possibleCPUsParsed(); ncpu != nil {
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return ncpu
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}
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for i := range runtime.NumCPU() {
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cpus = append(cpus, i)
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}
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return cpus
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}
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// possibleCPUsParsed is parsing the amount of possible CPUs on this host from
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// /sys/devices.
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var possibleCPUsParsed = sync.OnceValue(func() (cpus []int) {
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data, err := os.ReadFile("/sys/devices/system/cpu/possible")
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if err != nil {
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return nil
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}
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ranges := strings.SplitSeq(strings.TrimSpace(string(data)), ",")
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for r := range ranges {
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if rStart, rEnd, ok := strings.Cut(r, "-"); !ok {
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cpu, err := strconv.Atoi(rStart)
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if err != nil {
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return nil
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}
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cpus = append(cpus, cpu)
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} else {
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var start, end int
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start, err := strconv.Atoi(rStart)
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if err != nil {
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return nil
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}
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end, err = strconv.Atoi(rEnd)
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if err != nil {
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return nil
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}
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for i := start; i <= end; i++ {
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cpus = append(cpus, i)
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}
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}
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}
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return cpus
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})
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