8368165: (fs) Path.toRealPath does not perform correctly for symbolic links in a mapped drive (win)

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

@@ -260,8 +260,54 @@ static String getRealPath(WindowsPath input, boolean resolveLinks)
                 if (resolveLinks &&
                     WindowsFileAttributes.isReparsePoint(fileData.attributes()))
                 {
-                    String result = getFinalPath(input);
-                    if (result == null) {
+                    long handle = INVALID_HANDLE_VALUE;
+                    boolean reparsePointOpened = false;
+                    try {
+                        // first try opening while following links
+                        handle = input.openForReadAttributeAccess(true);
+                    } catch (WindowsException x) {
+                        try {
+                            // fall back to opening the reparse point itself
+                            handle = input.openForReadAttributeAccess(false);
+                            CloseHandle(handle);
+                            handle = INVALID_HANDLE_VALUE;
+
+                            // set flag to suppress the IOException below
+                            reparsePointOpened = true;
+                        } catch (WindowsException y) {
+                            // suppress exception from opening reparse point
+                            x.addSuppressed(y);
+                        }
+                        // fail if opening failed, following or not following
+                        if (!reparsePointOpened)
+                            x.rethrowAsIOException(input);
+                    }
+
+                    // attempt to get the final path if the handle is valid
+                    String result = null;
+                    if (handle != INVALID_HANDLE_VALUE) {
+                        try {
+                            result = stripPrefix(GetFinalPathNameByHandle(handle));
+                        } catch (WindowsException x) {
+                            // ERROR_INVALID_LEVEL is the error returned when
+                            // not supported (a symlink to file on FAT32 or
+                            // Samba server for example)
+                            if (x.lastError() != ERROR_INVALID_LEVEL)
+                                x.rethrowAsIOException(input);
+                        } finally {
+                            CloseHandle(handle);
+                        }
+                    }
+
+                    // if the final path is null or is the UNC version of
+                    // a drive path, then derive the final path by stepping
+                    // through the elements of the path
+                    if (result == null ||
+                        (Character.isLetter(input.toString().charAt(0)) &&
+                        result.charAt(0) == '\\' &&
+                        input.toString().charAt(1) == ':' &&
+                        result.charAt(1) == '\\' &&
+                        input.toString().charAt(2) == '\\')) {
                         // Fallback to slow path, usually because there is a sym
                         // link to a file system that doesn't support sym links.
                         WindowsPath resolved = resolveAllLinks(