Unbreak support for OpenBSD.

OpenBSD does not have procfs and tere's no canonical way to get an executable
path so this implementation is a best effort.

osext_procfs.go

@@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build linux netbsd openbsd solaris dragonfly
// +build linux netbsd solaris dragonfly

package osext

@@ -27,7 +27,7 @@ func executable() (string, error) {
		return execpath, nil
	case "netbsd":
		return os.Readlink("/proc/curproc/exe")
	case "openbsd", "dragonfly":
	case "dragonfly":
		return os.Readlink("/proc/curproc/file")
	case "solaris":
		return os.Readlink(fmt.Sprintf("/proc/%d/path/a.out", os.Getpid()))

osext_sysctl.go

@@ -2,12 +2,13 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build darwin freebsd
// +build darwin freebsd openbsd

package osext

import (
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"syscall"
@@ -23,6 +24,8 @@ func executable() (string, error) {
		mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
	case "darwin":
		mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
	case "openbsd":
		mib = [4]int32{1 /* CTL_KERN */, 55 /* KERN_PROC_ARGS */, int32(os.Getpid()), 1 /* KERN_PROC_ARGV */}
	}

	n := uintptr(0)
@@ -42,14 +45,58 @@ func executable() (string, error) {
	if n == 0 { // This shouldn't happen.
		return "", nil
	}
	for i, v := range buf {
		if v == 0 {
			buf = buf[:i]
			break

	var execPath string
	switch runtime.GOOS {
	case "openbsd":
		// buf now contains **argv, with pointers to each of the C-style
		// NULL terminated arguments.
		var args []string
		argv := uintptr(unsafe.Pointer(&buf[0]))
		Loop:
			for {
				argp := *(**[1<<20]byte)(unsafe.Pointer(argv))
				if argp == nil {
					break
				}
				for i := 0; uintptr(i) < n; i++ {
					// we don't want the full arguments list
					if string(argp[i]) == " " {
						break Loop
					}
					if argp[i] != 0 {
						continue
					}
					args = append(args, string(argp[:i]))
					n -= uintptr(i)
					break
				}
				if n < unsafe.Sizeof(argv) {
					break
				}
				argv += unsafe.Sizeof(argv)
				n -= unsafe.Sizeof(argv)
			}
		execPath = args[0]
		// There is no canonical way to get an executable path on
		// OpenBSD, so check PATH in case we are called directly
		if execPath[0] != '/' && execPath[0] != '.' {
			execIsInPath, err := exec.LookPath(execPath)
			if err == nil {
				execPath = execIsInPath
			}
		}
	default:
		for i, v := range buf {
			if v == 0 {
				buf = buf[:i]
				break
			}
		}
		execPath = string(buf)
	}

	var err error
	execPath := string(buf)
	// execPath will not be empty due to above checks.
	// Try to get the absolute path if the execPath is not rooted.
	if execPath[0] != '/' {

osext_test.go

@@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build darwin linux freebsd netbsd windows
// +build darwin linux freebsd netbsd windows openbsd

package osext