Fail gracefully when failed to parse serial input (#255)

# Preface

Please ensure you have read the [contribution
docs](https://github.com/microsoft/mu/blob/master/CONTRIBUTING.md) prior
to submitting the pull request. In particular,
[pull request
guidelines](https://github.com/microsoft/mu/blob/master/CONTRIBUTING.md#pull-request-best-practices).

## Description

Current behavior of ConfApp will either assert or reboot the system
depending on the build configuration. However, uninterruptable incoming
data could actually occur during normal usage, due to user error, bad
serial traffic, etc. The application should handle such errors more
gracefully.

This change modifies the error handling, when the incoming XML cannot be
parsed, to prompt a user message, indicating the user to re-enter the
XML file.


![image](https://github.com/microsoft/mu_feature_config/assets/42554914/c0021f64-9fbd-4bfc-84a5-0a1921cd21c2)

For each item, place an "x" in between `[` and `]` if true. Example:
`[x]`.
_(you can also check items in the GitHub UI)_

- [x] Impacts functionality?
- **Functionality** - Does the change ultimately impact how firmware
functions?
- Examples: Add a new library, publish a new PPI, update an algorithm,
...
- [ ] Impacts security?
- **Security** - Does the change have a direct security impact on an
application,
    flow, or firmware?
  - Examples: Crypto algorithm change, buffer overflow fix, parameter
    validation improvement, ...
- [ ] Breaking change?
- **Breaking change** - Will anyone consuming this change experience a
break
    in build or boot behavior?
- Examples: Add a new library class, move a module to a different repo,
call
    a function in a new library class in a pre-existing module, ...
- [ ] Includes tests?
  - **Tests** - Does the change include any explicit test code?
  - Examples: Unit tests, integration tests, robot tests, ...
- [ ] Includes documentation?
- **Documentation** - Does the change contain explicit documentation
additions
    outside direct code modifications (and comments)?
- Examples: Update readme file, add feature readme file, link to
documentation
    on an a separate Web page, ...

## How This Was Tested

This was tested on QEMU Q35 ConfApp.

## Integration Instructions

N/A.

SetupDataPkg/ConfApp/SetupConf.c

@@ -417,7 +417,8 @@ ApplySettings (
     Status = Base64Decode (Value, b64Size, ByteArray, &ValueSize);
     if (EFI_ERROR (Status)) {
       FreePool (ByteArray);
-      DEBUG ((DEBUG_ERROR, "Cannot set binary data. Code=%r\n", Status));
+      DEBUG ((DEBUG_ERROR, "Cannot decode binary data. Code=%r\n", Status));
+      Status = EFI_NO_MAPPING;
       goto EXIT;
     }
 
@@ -586,7 +587,14 @@ ProcessSvdSerialInput (
     }
 
     Status = ApplySettings (TempAsciiStr, mConfDataOffset - 1);
-    if (EFI_ERROR (Status)) {
+    if (Status == EFI_NO_MAPPING) {
+      // When failing to parse incoming buffer, we give users another chance, after cleaning up the buffer.
+      DEBUG ((DEBUG_ERROR, "%a Failed to parse SVD file.\n", __FUNCTION__));
+      FreePool (mConfDataBuffer);
+      mConfDataBuffer = NULL;
+      goto Exit;
+    } else if (EFI_ERROR (Status)) {
+      // For other failures, we either assert or reboot.
       DEBUG ((DEBUG_ERROR, "%a Failed to apply received settings - %r\n", __FUNCTION__, Status));
       ASSERT_EFI_ERROR (Status);
       goto Exit;
@@ -948,7 +956,15 @@ SetupConfMgr (
         mSetupConfState = SetupConfExit;
       } else {
         Status = ProcessSvdSerialInput (KeyData.Key.UnicodeChar);
-        if (EFI_ERROR (Status)) {
+        if (Status == EFI_NO_MAPPING) {
+          // Do not fail completely if we just cannot find the file...
+          gST->ConOut->SetAttribute (gST->ConOut, EFI_TEXT_ATTR (EFI_YELLOW, EFI_BLACK));
+          Print (L"\nFailed to parse input SVD data, please check the input and try again.\n");
+          gST->ConOut->SetAttribute (gST->ConOut, EFI_TEXT_ATTR (EFI_WHITE, EFI_BLACK));
+          Status          = EFI_SUCCESS;
+          mSetupConfState = SetupConfUpdateSerialHint;
+          break;
+        } else if (EFI_ERROR (Status)) {
           mSetupConfState = SetupConfExit;
         }
       }