79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
// Copyright 2016 CNI authors
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package sysctl
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import (
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"fmt"
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"io/ioutil"
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"path/filepath"
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"strings"
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)
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// Sysctl provides a method to set/get values from /proc/sys - in linux systems
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// new interface to set/get values of variables formerly handled by sysctl syscall
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// If optional `params` have only one string value - this function will
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// set this value into corresponding sysctl variable
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func Sysctl(name string, params ...string) (string, error) {
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if len(params) > 1 {
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return "", fmt.Errorf("unexcepted additional parameters")
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} else if len(params) == 1 {
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return setSysctl(name, params[0])
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}
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return getSysctl(name)
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}
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func getSysctl(name string) (string, error) {
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fullName := filepath.Join("/proc/sys", toNormalName(name))
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data, err := ioutil.ReadFile(fullName)
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if err != nil {
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return "", err
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}
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return string(data[:len(data)-1]), nil
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}
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func setSysctl(name, value string) (string, error) {
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fullName := filepath.Join("/proc/sys", toNormalName(name))
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if err := ioutil.WriteFile(fullName, []byte(value), 0644); err != nil {
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return "", err
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}
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return getSysctl(name)
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}
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// Normalize names by using slash as separator
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// Sysctl names can use dots or slashes as separator:
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// - if dots are used, dots and slashes are interchanged.
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// - if slashes are used, slashes and dots are left intact.
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// Separator in use is determined by first occurrence.
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func toNormalName(name string) string {
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interchange := false
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for _, c := range name {
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if c == '.' {
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interchange = true
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break
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}
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if c == '/' {
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break
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}
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}
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if interchange {
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r := strings.NewReplacer(".", "/", "/", ".")
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return r.Replace(name)
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}
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return name
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}
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