1 // Copyright 2019 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 //go:build unix 6 7 package modload 8 9 import ( 10 "io/fs" 11 "os" 12 "syscall" 13 ) 14 15 // hasWritePerm reports whether the current user has permission to write to the 16 // file with the given info. 17 // 18 // Although the root user on most Unix systems can write to files even without 19 // permission, hasWritePerm reports false if no appropriate permission bit is 20 // set even if the current user is root. 21 func hasWritePerm(path string, fi fs.FileInfo) bool { 22 if os.Getuid() == 0 { 23 // The root user can access any file, but we still want to default to 24 // read-only mode if the go.mod file is marked as globally non-writable. 25 // (If the user really intends not to be in readonly mode, they can 26 // pass -mod=mod explicitly.) 27 return fi.Mode()&0222 != 0 28 } 29 30 const W_OK = 0x2 31 return syscall.Access(path, W_OK) == nil 32 } 33