github.com/tych0/umoci@v0.4.2/third_party/shared/util.go (about) 1 /* 2 * lxd: daemon based on liblxd with a REST API 3 * Copyright (C) 2015-2017 LXD Authors 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 // This code was copied from https://github.com/lxc/lxd, which is available 19 // under the the Apache 2.0 license (as noted above). The version of this code 20 // comes from the tag lxd-2.21 at /shared/util.go. 21 22 package shared 23 24 import ( 25 "bufio" 26 "fmt" 27 "os" 28 ) 29 30 // RunningInUserNS returns whether the current process is (likely) inside a 31 // user namespace. This has a possible false-negative (where it will return 32 // false while inside a user namespace if it was intentionally configured to be 33 // confusing to programs like this). 34 func RunningInUserNS() bool { 35 file, err := os.Open("/proc/self/uid_map") 36 if err != nil { 37 return false 38 } 39 defer file.Close() 40 41 buf := bufio.NewReader(file) 42 l, _, err := buf.ReadLine() 43 if err != nil { 44 return false 45 } 46 47 line := string(l) 48 var a, b, c int64 49 fmt.Sscanf(line, "%d %d %d", &a, &b, &c) 50 if a == 0 && b == 0 && c == 4294967295 { 51 return false 52 } 53 return true 54 }