subsys.go (2882B)
1 // Copyright (c) 2017 Uber Technologies, Inc. 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a copy 4 // of this software and associated documentation files (the "Software"), to deal 5 // in the Software without restriction, including without limitation the rights 6 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 7 // copies of the Software, and to permit persons to whom the Software is 8 // furnished to do so, subject to the following conditions: 9 // 10 // The above copyright notice and this permission notice shall be included in 11 // all copies or substantial portions of the Software. 12 // 13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 18 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 19 // THE SOFTWARE. 20 21 //go:build linux 22 // +build linux 23 24 package cgroups 25 26 import ( 27 "bufio" 28 "os" 29 "strconv" 30 "strings" 31 ) 32 33 const ( 34 _cgroupSep = ":" 35 _cgroupSubsysSep = "," 36 ) 37 38 const ( 39 _csFieldIDID = iota 40 _csFieldIDSubsystems 41 _csFieldIDName 42 _csFieldCount 43 ) 44 45 // CGroupSubsys represents the data structure for entities in 46 // `/proc/$PID/cgroup`. See also proc(5) for more information. 47 type CGroupSubsys struct { 48 ID int 49 Subsystems []string 50 Name string 51 } 52 53 // NewCGroupSubsysFromLine returns a new *CGroupSubsys by parsing a string in 54 // the format of `/proc/$PID/cgroup` 55 func NewCGroupSubsysFromLine(line string) (*CGroupSubsys, error) { 56 fields := strings.SplitN(line, _cgroupSep, _csFieldCount) 57 58 if len(fields) != _csFieldCount { 59 return nil, cgroupSubsysFormatInvalidError{line} 60 } 61 62 id, err := strconv.Atoi(fields[_csFieldIDID]) 63 if err != nil { 64 return nil, err 65 } 66 67 cgroup := &CGroupSubsys{ 68 ID: id, 69 Subsystems: strings.Split(fields[_csFieldIDSubsystems], _cgroupSubsysSep), 70 Name: fields[_csFieldIDName], 71 } 72 73 return cgroup, nil 74 } 75 76 // parseCGroupSubsystems parses procPathCGroup (usually at `/proc/$PID/cgroup`) 77 // and returns a new map[string]*CGroupSubsys. 78 func parseCGroupSubsystems(procPathCGroup string) (map[string]*CGroupSubsys, error) { 79 cgroupFile, err := os.Open(procPathCGroup) 80 if err != nil { 81 return nil, err 82 } 83 defer cgroupFile.Close() 84 85 scanner := bufio.NewScanner(cgroupFile) 86 subsystems := make(map[string]*CGroupSubsys) 87 88 for scanner.Scan() { 89 cgroup, err := NewCGroupSubsysFromLine(scanner.Text()) 90 if err != nil { 91 return nil, err 92 } 93 for _, subsys := range cgroup.Subsystems { 94 subsystems[subsys] = cgroup 95 } 96 } 97 98 if err := scanner.Err(); err != nil { 99 return nil, err 100 } 101 102 return subsystems, nil 103 }