[PATCH] ShellPkg:‘cd \’ command fails to go back to the root directory of a file system

[Tapan Shah <tapandshah@hpe.com>]

Allows cd command to go back to the root directory when 'cd \' executed in system.

This change prevents last PathRemoveLastItem() call which truncates '\' from 'fs0:\'
in desired root path which is required to set CWD to the root directory.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Tapan Shah <tapandshah@hpe.com>
---
 ShellPkg/Library/UefiShellLevel2CommandsLib/Cd.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/ShellPkg/Library/UefiShellLevel2CommandsLib/Cd.c b/ShellPkg/Library/UefiShellLevel2CommandsLib/Cd.c
index 2e51b4c..0967bc7 100644
--- a/ShellPkg/Library/UefiShellLevel2CommandsLib/Cd.c
+++ b/ShellPkg/Library/UefiShellLevel2CommandsLib/Cd.c
@@ -1,6 +1,7 @@
 /** @file
   Main file for attrib shell level 2 function.
 
+  (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
   (C) Copyright 2015 Hewlett-Packard Development Company, L.P.<BR>
   Copyright (c) 2009 - 2016, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
@@ -164,7 +165,16 @@ ShellCommandRunCd (
               StrCpyS (Cwd, StrSize (Directory) / sizeof (CHAR16) + 1, Directory);
               StrCatS (Cwd, StrSize (Directory) / sizeof (CHAR16) + 1, L"\\");
               Drive = GetFullyQualifiedPath (Cwd);
-              while (PathRemoveLastItem (Drive));
+              while (PathRemoveLastItem (Drive)) {
+                //
+                // Check if Drive contains 'fsx:\' only or still points to a sub-directory.
+                // Don't remove trailing '\' from Drive if it points to the root directory.
+                //
+                Path = StrStr (Drive, L":\\");
+                if ((Path != NULL) && (*(Path + 2) == CHAR_NULL)) {
+                  break;
+                }
+              }
               FreePool (Cwd);
             }
           }
-- 
1.9.5.msysgit.0