unix: add Uname on openbsd

Change-Id: I40f99aab912c7002d113f82ccc60c9f68b9bc496
Reviewed-on: https://go-review.googlesource.com/82855
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/syscall_openbsd.go

@@ -135,6 +135,52 @@ func IoctlGetTermios(fd int, req uint) (*Termios, error) {
 	return &value, err
 }
 
+func Uname(uname *Utsname) error {
+	mib := []_C_int{CTL_KERN, KERN_OSTYPE}
+	n := unsafe.Sizeof(uname.Sysname)
+	if err := sysctl(mib, &uname.Sysname[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	mib = []_C_int{CTL_KERN, KERN_HOSTNAME}
+	n = unsafe.Sizeof(uname.Nodename)
+	if err := sysctl(mib, &uname.Nodename[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	mib = []_C_int{CTL_KERN, KERN_OSRELEASE}
+	n = unsafe.Sizeof(uname.Release)
+	if err := sysctl(mib, &uname.Release[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	mib = []_C_int{CTL_KERN, KERN_VERSION}
+	n = unsafe.Sizeof(uname.Version)
+	if err := sysctl(mib, &uname.Version[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	// The version might have newlines or tabs in it, convert them to
+	// spaces.
+	for i, b := range uname.Version {
+		if b == '\n' || b == '\t' {
+			if i == len(uname.Version)-1 {
+				uname.Version[i] = 0
+			} else {
+				uname.Version[i] = ' '
+			}
+		}
+	}
+
+	mib = []_C_int{CTL_HW, HW_MACHINE}
+	n = unsafe.Sizeof(uname.Machine)
+	if err := sysctl(mib, &uname.Machine[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 /*
  * Exposed directly
  */