127 lines
3.2 KiB
Go
127 lines
3.2 KiB
Go
// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !go1.8,darwin !go1.8,freebsd openbsd
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package osext
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import (
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"os"
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"os/exec"
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"path/filepath"
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"runtime"
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"syscall"
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"unsafe"
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)
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var initCwd, initCwdErr = os.Getwd()
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func executable() (string, error) {
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var mib [4]int32
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switch runtime.GOOS {
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case "freebsd":
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mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
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case "darwin":
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mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
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case "openbsd":
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mib = [4]int32{1 /* CTL_KERN */, 55 /* KERN_PROC_ARGS */, int32(os.Getpid()), 1 /* KERN_PROC_ARGV */}
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}
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n := uintptr(0)
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// Get length.
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_, _, errNum := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
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if errNum != 0 {
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return "", errNum
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}
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if n == 0 { // This shouldn't happen.
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return "", nil
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}
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buf := make([]byte, n)
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_, _, errNum = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
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if errNum != 0 {
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return "", errNum
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}
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if n == 0 { // This shouldn't happen.
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return "", nil
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}
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var execPath string
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switch runtime.GOOS {
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case "openbsd":
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// buf now contains **argv, with pointers to each of the C-style
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// NULL terminated arguments.
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var args []string
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argv := uintptr(unsafe.Pointer(&buf[0]))
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Loop:
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for {
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argp := *(**[1 << 20]byte)(unsafe.Pointer(argv))
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if argp == nil {
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break
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}
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for i := 0; uintptr(i) < n; i++ {
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// we don't want the full arguments list
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if string(argp[i]) == " " {
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break Loop
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}
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if argp[i] != 0 {
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continue
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}
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args = append(args, string(argp[:i]))
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n -= uintptr(i)
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break
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}
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if n < unsafe.Sizeof(argv) {
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break
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}
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argv += unsafe.Sizeof(argv)
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n -= unsafe.Sizeof(argv)
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}
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execPath = args[0]
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// There is no canonical way to get an executable path on
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// OpenBSD, so check PATH in case we are called directly
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if execPath[0] != '/' && execPath[0] != '.' {
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execIsInPath, err := exec.LookPath(execPath)
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if err == nil {
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execPath = execIsInPath
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}
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}
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default:
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for i, v := range buf {
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if v == 0 {
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buf = buf[:i]
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break
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}
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}
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execPath = string(buf)
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}
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var err error
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// execPath will not be empty due to above checks.
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// Try to get the absolute path if the execPath is not rooted.
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if execPath[0] != '/' {
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execPath, err = getAbs(execPath)
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if err != nil {
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return execPath, err
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}
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}
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// For darwin KERN_PROCARGS may return the path to a symlink rather than the
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// actual executable.
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if runtime.GOOS == "darwin" {
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if execPath, err = filepath.EvalSymlinks(execPath); err != nil {
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return execPath, err
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}
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}
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return execPath, nil
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}
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func getAbs(execPath string) (string, error) {
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if initCwdErr != nil {
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return execPath, initCwdErr
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}
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// The execPath may begin with a "../" or a "./" so clean it first.
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// Join the two paths, trailing and starting slashes undetermined, so use
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// the generic Join function.
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return filepath.Join(initCwd, filepath.Clean(execPath)), nil
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}
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