github.com/camlistore/go4@v0.0.0-20200104003542-c7e774b10ea0/osutil/exec_sysctl.go (about) 1 // Copyright 2015 The go4 Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 // +build freebsd darwin 16 17 package osutil 18 19 import ( 20 "os" 21 "path/filepath" 22 "runtime" 23 "syscall" 24 "unsafe" 25 ) 26 27 var cacheWD, cacheWDErr = os.Getwd() 28 29 func executable() (string, error) { 30 var mib [4]int32 31 switch runtime.GOOS { 32 case "freebsd": 33 mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1} 34 case "darwin": 35 mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1} 36 } 37 38 n := uintptr(0) 39 // get length 40 _, _, err := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0) 41 if err != 0 { 42 return "", err 43 } 44 if n == 0 { // shouldn't happen 45 return "", nil 46 } 47 buf := make([]byte, n) 48 _, _, err = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0) 49 if err != 0 { 50 return "", err 51 } 52 if n == 0 { // shouldn't happen 53 return "", nil 54 } 55 p := string(buf[:n-1]) 56 if !filepath.IsAbs(p) { 57 if cacheWDErr != nil { 58 return p, cacheWDErr 59 } 60 p = filepath.Join(cacheWD, filepath.Clean(p)) 61 } 62 return filepath.EvalSymlinks(p) 63 }