Adding support for ChangeTime in Windows, adding HasChangeTime() and …

…HasBirthTime() to timespec

README.md

@@ -30,11 +30,11 @@ func main() {
   log.Println(t.AccessTime())
   log.Println(t.ModTime())
 
-  if times.HasChangeTime {
+  if t.HasChangeTime() {
     log.Println(t.ChangeTime())
   }
 
-  if times.HasBirthTime {
+  if t.HasBirthTime() {
     log.Println(t.BirthTime())
   }
 }
@@ -46,9 +46,13 @@ Supported Times
 |:-----:|:-------:|:-----:|:-------:|:---------:|:------:|:-------:|:----:|:------:|:-------:|:-----:|
 | atime | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | mtime | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| ctime |  | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |  |
+| ctime | ✓* | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |  |
 | btime | ✓ |  |  |  |  | ✓ |  ✓| ✓ |  
 
+* Windows XP does not have ChangeTime so HasChangeTime = false, 
+however Vista onward does have ChangeTime so Timespec.HasChangeTime() will 
+only return false on those platforms when the syscall used to obtain them fails.
+
 Installation
 ------------
 ```sh

ctime_windows.go

@@ -0,0 +1,90 @@
+package times
+
+import (
+	"os"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+type timespecEx struct {
+	atime
+	mtime
+	ctime
+	btime
+}
+
+// StatFile finds a Windows Timespec with ChangeTime.
+func StatFile(file *os.File) (Timespec, error) {
+	var fileInfo fileBasicInfo
+	if err := getFileInformationByHandleEx(syscall.Handle(file.Fd()), &fileInfo); err != nil {
+		return nil, err
+	}
+
+	var t timespecEx
+	t.atime.v = time.Unix(0, fileInfo.LastAccessTime.Nanoseconds())
+	t.mtime.v = time.Unix(0, fileInfo.LastWriteTime.Nanoseconds())
+	t.ctime.v = time.Unix(0, fileInfo.ChangeTime.Nanoseconds())
+	t.btime.v = time.Unix(0, fileInfo.CreationTime.Nanoseconds())
+	return t, nil
+}
+
+func statEx(file string) (Timespec, error) {
+	if findProcErr != nil {
+		// fail fast, don't bother opening the file
+		return nil, findProcErr
+	}
+
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return StatFile(f)
+}
+
+var (
+	findProcErr                      error
+	procGetFileInformationByHandleEx *syscall.Proc
+)
+
+func init() {
+	var modkernel32 *syscall.DLL
+	if modkernel32, findProcErr = syscall.LoadDLL("kernel32.dll"); findProcErr == nil {
+		procGetFileInformationByHandleEx, findProcErr = modkernel32.FindProc("GetFileInformationByHandleEx")
+	}
+}
+
+// fileBasicInfo holds the C++ data for FileTimes.
+//
+// https://msdn.microsoft.com/en-us/library/windows/desktop/aa364217(v=vs.85).aspx
+type fileBasicInfo struct {
+	CreationTime   syscall.Filetime
+	LastAccessTime syscall.Filetime
+	LastWriteTime  syscall.Filetime
+	ChangeTime     syscall.Filetime
+	FileAttributes uint32
+	_              uint32 // padding
+}
+
+type fileInformationClass int
+
+const (
+	fileBasicInfoClass fileInformationClass = iota
+)
+
+func getFileInformationByHandleEx(handle syscall.Handle, data *fileBasicInfo) (err error) {
+	if findProcErr != nil {
+		return findProcErr
+	}
+
+	r1, _, e1 := syscall.Syscall6(procGetFileInformationByHandleEx.Addr(), 4, uintptr(handle), uintptr(fileBasicInfoClass), uintptr(unsafe.Pointer(data)), unsafe.Sizeof(*data), 0, 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = error(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}

stat.go

@@ -21,13 +21,15 @@ func Stat(name string) (Timespec, error) {
 }
 
 // Timespec provides access to file times.
-// ChangeTime() panics unless times.HasChangeTime is true and
-// BirthTime() panics unless times.HasBirthTime is true
+// ChangeTime() panics unless HasChangeTime() is true and
+// BirthTime() panics unless HasBirthTime() is true.
 type Timespec interface {
 	ModTime() time.Time
 	AccessTime() time.Time
 	ChangeTime() time.Time
 	BirthTime() time.Time
+	HasChangeTime() bool
+	HasBirthTime() bool
 }
 
 type atime struct {
@@ -40,6 +42,8 @@ type ctime struct {
 	v time.Time
 }
 
+func (ctime) HasChangeTime() bool { return true }
+
 func (c ctime) ChangeTime() time.Time { return c.v }
 
 type mtime struct {
@@ -52,12 +56,18 @@ type btime struct {
 	v time.Time
 }
 
+func (btime) HasBirthTime() bool { return true }
+
 func (b btime) BirthTime() time.Time { return b.v }
 
 type noctime struct{}
 
+func (noctime) HasChangeTime() bool { return false }
+
 func (noctime) ChangeTime() time.Time { panic("ctime not available") }
 
 type nobtime struct{}
 
+func (nobtime) HasBirthTime() bool { return false }
+
 func (nobtime) BirthTime() time.Time { panic("birthtime not available") }

times_test.go

@@ -54,10 +54,10 @@ func TestGet(t *testing.T) {
 	if at.ModTime().Before(et) {
 		t.Errorf("expected mtime to be recent: got %v instead of ~%v", at.ModTime(), et)
 	}
-	if HasChangeTime && at.ChangeTime().Before(et) {
+	if at.HasChangeTime() && at.ChangeTime().Before(et) {
 		t.Errorf("expected ctime to be recent: got %v instead of ~%v", at.ChangeTime(), et)
 	}
-	if HasBirthTime && at.BirthTime().Before(et) {
+	if at.HasBirthTime() && at.BirthTime().Before(et) {
 		t.Errorf("expected btime to be recent: got %v instead of ~%v", at.BirthTime(), et)
 	}
 }

times_windows.go

@@ -26,7 +26,12 @@ type timespec struct {
 	btime
 }
 
-func getTimespec(fi os.FileInfo) (t timespec) {
+func getTimespec(fi os.FileInfo) Timespec {
+	if ts, err := statEx(fi.Name()); err == nil {
+		return ts
+	}
+
+	var t timespec
 	stat := fi.Sys().(*syscall.Win32FileAttributeData)
 	t.atime.v = time.Unix(0, stat.LastAccessTime.Nanoseconds())
 	t.mtime.v = time.Unix(0, stat.LastWriteTime.Nanoseconds())