1 // Copyright 2023 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 darwin || freebsd || linux || netbsd || openbsd 6 7 package toolchain 8 9 import ( 10 "io/fs" 11 "syscall" 12 ) 13 14 // sysWriteBits determines which bits to OR into the mode to make a directory writable. 15 // It must be called when there are no other file system operations happening. 16 func sysWriteBits() fs.FileMode { 17 // Read current umask. There's no way to read it without also setting it, 18 // so set it conservatively and then restore the original one. 19 m := syscall.Umask(0o777) 20 syscall.Umask(m) // restore bits 21 if m&0o22 == 0o22 { // group and world are unwritable by default 22 return 0o700 23 } 24 if m&0o2 == 0o2 { // group is writable by default, but not world 25 return 0o770 26 } 27 return 0o777 // everything is writable by default 28 } 29