[PATCH] ShellPkg: print only valid characters for file overwrite prompt

[Tapan Shah <tapandshah@hpe.com>]

When copy command prompts to overwrite an existing file, pressing
backspace continuously removes everything including the shell prompt.
So print only valid characters for file overwrite prompt.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Tapan Shah <tapandshah@hpe.com>
---
 ShellPkg/Library/UefiShellLib/UefiShellLib.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/ShellPkg/Library/UefiShellLib/UefiShellLib.c b/ShellPkg/Library/UefiShellLib/UefiShellLib.c
index 2389207..536db3c 100644
--- a/ShellPkg/Library/UefiShellLib/UefiShellLib.c
+++ b/ShellPkg/Library/UefiShellLib/UefiShellLib.c
@@ -3403,7 +3403,8 @@ ShellPromptForResponse (
             break;
         }
       }
-      break;    case ShellPromptResponseTypeYesNoAllCancel:
+      break;
+      case ShellPromptResponseTypeYesNoAllCancel:
        if (Prompt != NULL) {
         ShellPrintEx(-1, -1, L"%s", Prompt);
       }
@@ -3421,7 +3422,11 @@ ShellPromptForResponse (
         if (EFI_ERROR(Status)) {
           break;
         }
-        ShellPrintEx(-1, -1, L"%c", Key.UnicodeChar);
+
+        if (Key.UnicodeChar <= 127 && Key.UnicodeChar >= 32) {
+          ShellPrintEx (-1, -1, L"%c", Key.UnicodeChar);
+        }
+
         switch (Key.UnicodeChar) {
           case L'Y':
           case L'y':
-- 
1.9.5.msysgit.0