8231174: (fs) FileTime should have 100ns resolution (win)

Reviewed-by: alanb

Author: Brian Burkhalter

src/java.base/windows/classes/sun/nio/fs/WindowsFileAttributes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -108,8 +108,9 @@ class WindowsFileAttributes
     private static final short OFFSETOF_FIND_DATA_SIZELOW = 32;
     private static final short OFFSETOF_FIND_DATA_RESERVED0 = 36;
 
-    // used to adjust values between Windows and java epoch
-    private static final long WINDOWS_EPOCH_IN_MICROSECONDS = -11644473600000000L;
+    // used to adjust values between Windows and java epochs
+    private static final long WINDOWS_EPOCH_IN_MICROS = -11644473600000000L;
+    private static final long WINDOWS_EPOCH_IN_100NS  = -116444736000000000L;
 
     // indicates if accurate metadata is required (interesting on NTFS only)
     private static final boolean ensureAccurateMetadata;
@@ -137,24 +138,23 @@ class WindowsFileAttributes
      * since January 1, 1601 to a FileTime.
      */
     static FileTime toFileTime(long time) {
-        // 100ns -> us
-        time /= 10L;
-        // adjust to java epoch
-        time += WINDOWS_EPOCH_IN_MICROSECONDS;
-        return FileTime.from(time, TimeUnit.MICROSECONDS);
+        try {
+            long adjusted = Math.addExact(time, WINDOWS_EPOCH_IN_100NS);
+            long nanos = Math.multiplyExact(adjusted, 100L);
+            return FileTime.from(nanos, TimeUnit.NANOSECONDS);
+        } catch (ArithmeticException e) {
+            long micros = Math.addExact(time/10L, WINDOWS_EPOCH_IN_MICROS);
+            return FileTime.from(micros, TimeUnit.MICROSECONDS);
+        }
     }
 
     /**
-     * Convert FileTime to 64-bit value representing the number of 100-nanosecond
-     * intervals since January 1, 1601.
+     * Convert FileTime to 64-bit value representing the number of
+     * 100-nanosecond intervals since January 1, 1601.
      */
     static long toWindowsTime(FileTime time) {
-        long value = time.to(TimeUnit.MICROSECONDS);
-        // adjust to Windows epoch+= 11644473600000000L;
-        value -= WINDOWS_EPOCH_IN_MICROSECONDS;
-        // us -> 100ns
-        value *= 10L;
-        return value;
+        long adjusted = time.to(TimeUnit.NANOSECONDS)/100L;
+        return adjusted - WINDOWS_EPOCH_IN_100NS;
     }
 
     /**

test/jdk/java/nio/file/attribute/BasicFileAttributeView/SetTimesNanos.java

@@ -22,9 +22,9 @@
  */
 
 /* @test
- * @bug 8181493
+ * @bug 8181493 8231174
  * @summary Verify that nanosecond precision is maintained for file timestamps
- * @requires (os.family == "linux") | (os.family == "mac") | (os.family == "solaris")
+ * @requires (os.family == "linux") | (os.family == "mac") | (os.family == "solaris") | (os.family == "windows")
  * @modules java.base/sun.nio.fs:+open
  */
 
@@ -40,14 +40,21 @@
 import java.util.concurrent.TimeUnit;
 
 public class SetTimesNanos {
+    private static final boolean IS_WINDOWS =
+        System.getProperty("os.name").startsWith("Windows");
+
     public static void main(String[] args) throws Exception {
-        // Check whether futimens() system call is supported
-        Class unixNativeDispatcherClass = Class.forName("sun.nio.fs.UnixNativeDispatcher");
-        Method futimensSupported = unixNativeDispatcherClass.getDeclaredMethod("futimensSupported");
-        futimensSupported.setAccessible(true);
-        if (!(boolean)futimensSupported.invoke(null)) {
-            System.err.println("futimens() system call not supported; skipping test");
-            return;
+        if (!IS_WINDOWS) {
+            // Check whether futimens() system call is supported
+            Class unixNativeDispatcherClass =
+                Class.forName("sun.nio.fs.UnixNativeDispatcher");
+            Method futimensSupported =
+                unixNativeDispatcherClass.getDeclaredMethod("futimensSupported");
+            futimensSupported.setAccessible(true);
+            if (!(boolean)futimensSupported.invoke(null)) {
+                System.err.println("futimens() not supported; skipping test");
+                return;
+            }
         }
 
         Path dirPath = Path.of("test");
@@ -56,7 +63,8 @@ public static void main(String[] args) throws Exception {
         System.out.format("FileStore: \"%s\" on %s (%s)%n",
             dir, store.name(), store.type());
 
-        Set<String> testedTypes = Set.of("apfs", "ext4", "xfs", "zfs");
+        Set<String> testedTypes = IS_WINDOWS ?
+            Set.of("NTFS") : Set.of("apfs", "ext4", "xfs", "zfs");
         if (!testedTypes.contains(store.type())) {
             System.err.format("%s not in %s; skipping test", store.type(), testedTypes);
             return;
@@ -77,6 +85,11 @@ private static void testNanos(Path path) throws IOException {
             Files.getFileAttributeView(path, BasicFileAttributeView.class);
         view.setTimes(pathTime, pathTime, null);
 
+        // Windows file time resolution is 100ns so truncate
+        if (IS_WINDOWS) {
+            timeNanos = 100L*(timeNanos/100L);
+        }
+
         // Read attributes
         BasicFileAttributes attrs =
             Files.readAttributes(path, BasicFileAttributes.class);