libgo: update to Go 1.11

    
    Reviewed-on: https://go-review.googlesource.com/136435

gotools/:
	* Makefile.am (mostlyclean-local): Run chmod on check-go-dir to
	make sure it is writable.
	(check-go-tools): Likewise.
	(check-vet): Copy internal/objabi to check-vet-dir.
	* Makefile.in: Rebuild.

From-SVN: r264546

1 files changed, 32 insertions, 5 deletions

diff --git a/libgo/go/os/sys_linux.go b/libgo/go/os/sys_linux.go
index 76cdf504323..36a8a244555 100644
--- a/libgo/go/os/sys_linux.go
+++ b/libgo/go/os/sys_linux.go
@@ -2,19 +2,46 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Linux-specific
-
 package os
 
+import (
+	"runtime"
+	"syscall"
+)
+
 func hostname() (name string, err error) {
+	// Try uname first, as it's only one system call and reading
+	// from /proc is not allowed on Android.
+	var un syscall.Utsname
+	err = syscall.Uname(&un)
+
+	var buf [512]byte // Enough for a DNS name.
+	for i, b := range un.Nodename[:] {
+		buf[i] = uint8(b)
+		if b == 0 {
+			name = string(buf[:i])
+			break
+		}
+	}
+	// If we got a name and it's not potentially truncated
+	// (Nodename is 65 bytes), return it.
+	if err == nil && len(name) > 0 && len(name) < 64 {
+		return name, nil
+	}
+	if runtime.GOOS == "android" {
+		if name != "" {
+			return name, nil
+		}
+		return "localhost", nil
+	}
+
 	f, err := Open("/proc/sys/kernel/hostname")
 	if err != nil {
 		return "", err
 	}
 	defer f.Close()
 
-	var buf [512]byte // Enough for a DNS name.
-	n, err := f.Read(buf[0:])
+	n, err := f.Read(buf[:])
 	if err != nil {
 		return "", err
 	}
@@ -22,5 +49,5 @@ func hostname() (name string, err error) {
 	if n > 0 && buf[n-1] == '\n' {
 		n--
 	}
-	return string(buf[0:n]), nil
+	return string(buf[:n]), nil
 }