vendor: Update github.com/calmh/du (ref #4079)

vendor/github.com/calmh/du/README.md

@@ -1,14 +0,0 @@
-du
-==
-
-Get total and available disk space on a given volume.
-
-Documentation
--------------
-
-http://godoc.org/github.com/calmh/du
-
-License
--------
-
-Public Domain

vendor/github.com/calmh/du/diskusage_windows.go

@@ -1,6 +1,7 @@
 package du
 
 import (
+	"runtime"
 	"syscall"
 	"unsafe"
 )
@@ -13,14 +14,20 @@ func Get(path string) (Usage, error) {
 
 	var u Usage
 
+	pathw, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return Usage{}, err
+	}
+
 	ret, _, err := c.Call(
-		uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(path))),
+		uintptr(unsafe.Pointer(pathw)),
 		uintptr(unsafe.Pointer(&u.FreeBytes)),
 		uintptr(unsafe.Pointer(&u.TotalBytes)),
 		uintptr(unsafe.Pointer(&u.AvailBytes)))
+	runtime.KeepAlive(pathw)
 
 	if ret == 0 {
-		return u, err
+		return Usage{}, err
 	}
 
 	return u, nil

vendor/github.com/calmh/du/diskusage_windows_test.go

@@ -0,0 +1,27 @@
+package du
+
+import "testing"
+
+func TestDiskUsage(t *testing.T) {
+	cases := []struct {
+		path string
+		ok   bool
+	}{
+		{"c:\\", true},
+		{"c:\\windows", true},
+		{"c:\\aux", false},
+		{"c:\\does-not-exist-09sadkjhdsa98234bj23hgasd98", false},
+	}
+	for _, tc := range cases {
+		res, err := Get(tc.path)
+		if tc.ok {
+			if err != nil {
+				t.Errorf("Unexpected error Get(%q) => %v", tc.path, err)
+			} else if res.TotalBytes == 0 || res.AvailBytes == 0 || res.FreeBytes == 0 {
+				t.Errorf("Suspicious result Get(%q) => %v", tc.path, res)
+			}
+		} else if err == nil {
+			t.Errorf("Unexpected nil error in Get(%q)", tc.path)
+		}
+	}
+}

vendor/manifest

@@ -34,8 +34,8 @@
 		{
 			"importpath": "github.com/calmh/du",
 			"repository": "https://github.com/calmh/du",
-			"vcs": "",
-			"revision": "3c0690cca16228b97741327b1b6781397afbdb24",
+			"vcs": "git",
+			"revision": "dd9dc2043353249b2910b29dcfd6f6d4e64f39be",
 			"branch": "master"
 		},
 		{