EFI_CONFIG_KEYWORD_HANDLER_PROTOCOL.SetData() lesson

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>

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+In this lesson we would investigate how to modify form elements that have keyword references.
+
+But rather than change some system variables let's add keyword references to our own application.
+
+# Adding keywords to form elements
+
+For an example let's take our `HIIFormDataElements` driver. Adding keywords is very simple. The only file that we would need to modify is UNI file (`Strings.uni` in this case).
+
+First we need to add a new namespace id. It is added via the new language definition with an identificator in a format `x-UEFI-*`. Let's use `x-UEFI-OEM` in our case. The language text representation is not important, here we use `"OEM_NameSpace"` as a placeholder:
+```
+#langdef x-UEFI-OEM "OEM_NameSpace"
+```
+
+Now we need to add `#language x-UEFI-OEM "<...>"` string translations to the prompts of all form elements that we want to refer by keywords. For example let's add keys to the Checkbox, Numeric and String elements:
+```
+...
+#string CHECKBOX_PROMPT        #language en-US  "Checkbox prompt"
+                               #language x-UEFI-OEM  "CheckboxKey"
+#string NUMERIC_PROMPT         #language en-US  "Numeric prompt"
+                               #language x-UEFI-OEM  "NumericKey"
+#string STRING_PROMPT          #language en-US  "String prompt"
+                               #language x-UEFI-OEM  "StringKey"
+...
+```
+The provided values inside these translation strings would act as keywords for these elements. Just in case, it is completely allowed to use space `" "` inside a key name.
+
+Now build the updated driver and load it in the UEFI shell. Here I've decided to create a new driver `HIIFormDataElementsWithKeywords` to keep some separation between the lessons, but generally it is just a copy of `HIIFormDataElements.efi` with the modifications described above:
+```
+FS0:\> load HIIFormDataElementsWithKeywords.efi
+Image 'FS0:\HIIFormDataElementsWithKeywords.efi' loaded at 6880000 - Success
+```
+
+Now use `HIIKeyword` application to dump all the keys of our new namespace:
+```
+FS0:\> HIIKeyword.efi get "NAMESPACE=x-UEFI-OEM" ""
+Response: NAMESPACE=x-UEFI-OEM&PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400&KEYWORD=CheckboxKey&VALUE=00&NAMESPACE=x-UEFI-OEM&PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400&KEYWORD=NumericKey&VALUE=0000&NAMESPACE=x-UEFI-OEM&PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400&KEYWORD=StringKey&VALUE=000000<...>
+
+
+NAMESPACE=x-UEFI-OEM
+PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400 (VenHw(C299F575-F1DD-4D7D-B7AA-E5064B3ECBD7))
+KEYWORD=CheckboxKey
+VALUE=00
+00                                               | .
+
+NAMESPACE=x-UEFI-OEM
+PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400 (VenHw(C299F575-F1DD-4D7D-B7AA-E5064B3ECBD7))
+KEYWORD=NumericKey
+VALUE=0000
+00 00                                            | ..
+
+NAMESPACE=x-UEFI-OEM
+PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400 (VenHw(C299F575-F1DD-4D7D-B7AA-E5064B3ECBD7))
+KEYWORD=StringKey
+VALUE=0000000000000000000000000000000000000000
+00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  | ................
+00 00 00 00                                      | ....
+
+```
+
+You can verify that it is possible to access individual keys:
+```
+FS0:\> HIIKeyword.efi get "NAMESPACE=x-UEFI-OEM" "KEYWORD=NumericKey"
+Response: NAMESPACE=x-UEFI-OEM&PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400&KEYWORD=NumericKey&VALUE=0000
+
+
+NAMESPACE=x-UEFI-OEM
+PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400 (VenHw(C299F575-F1DD-4D7D-B7AA-E5064B3ECBD7))
+KEYWORD=NumericKey
+VALUE=0000
+00 00                                            | ..
+
+```
+
+# Use `EFI_KEYWORD_HANDLER_PROTOCOL.SetData()` to modify keyword data
+
+Now we are ready to add support for keyword data modification to the `HIIKeyword` application. For this we will need `SetData()` function from the `EFI_KEYWORD_HANDLER_PROTOCOL`:
+```cpp
+EFI_KEYWORD_HANDLER_PROTOCOL.SetData()
+
+Summary:
+Set the data associated with a particular configuration namespace keyword.
+
+Prototype:
+
+typedef
+EFI_STATUS
+(EFIAPI *EFI_KEYWORD_HANDLER _SET_DATA) (
+ IN EFI_KEYWORD_HANDLER_PROTOCOL *This,
+ IN CONST EFI_STRING KeywordString,
+ OUT EFI_STRING *Progress,
+ OUT UINT32 *ProgressErr
+ );
+
+Parameters:
+This 		Pointer to the EFI_KEYWORD_HANDLER _PROTOCOL instance.
+KeywordString 	A null-terminated string in <MultiKeywordResp> format.
+Progress 	On return, points to a character in the KeywordString. Points to the string’s NULL terminator if the request was successful.
+		Points to the most recent ‘&’ before the first failing name / value pair (or the beginning of the string if the failure is in the first name / value pair) if the request was not successful.
+ProgressErr 	If during the processing of the KeywordString there was a failure, this parameter gives additional information about the possible source of the problem.
+
+Description:
+This function accepts a <MultiKeywordResp> formatted string, finds the associated keyword owners, creates a <MultiConfigResp> string from it and forwards it to the EFI_HII_ROUTING_PROTOCOL.RouteConfig function.
+```
+
+The call signature of our program would be modified like this:
+```cpp
+VOID Usage()
+{
+  Print(L"Usage:\n");
+  Print(L"HIIKeyword get <NamespaceStr> <KeywordStr>\n");
+  Print(L"HIIKeyword set <KeywordStr>\n");
+}
+```
+
+The support code is even simplier than in the `HIIKeyword get <...>` case:
+```cpp
+EFI_STRING Progress;
+UINT32 ProgressErr;
+if (!StrCmp(Argv[1], L"get")) {
+  <...>
+} else if (!StrCmp(Argv[1], L"set")) {
+  if (Argc != 3) {
+    Print(L"Wrong argument!\n");
+    Usage();
+    return EFI_INVALID_PARAMETER;
+  }
+  Status = gHiiConfigKeywordHandler->SetData(gHiiConfigKeywordHandler,
+                                             Argv[2],
+                                             &Progress,
+                                             &ProgressErr);
+  if (StrCmp(Progress, L'\0')) {
+    Print(L"Part of string was unparsed %s\n", Progress);
+  }
+  if (ProgressErr) {
+    Print(L"Error! ProgressErr=%s\n", ProgressErrorStr(ProgressErr));
+  }
+  if (EFI_ERROR(Status)) {
+    Print(L"Error! SetData returned %r\n", Status);
+    return Status;
+  }
+} else {
+  Print(L"Wrong argument!\n");
+  Usage();
+  return EFI_INVALID_PARAMETER;
+}
+```
+
+So let's rebuild `HIIKeyword.efi` and test this new functionality. Once again first load our custom form driver:
+```
+FS0:\> load HIIFormDataElementsWithKeywords.efi
+Image 'FS0:\HIIFormDataElementsWithKeywords.efi' loaded at 6880000 - Success
+```
+Now with the `HIIKeyword.efi` try to change numeric element value to 7:
+```
+FS0:\> HIIKeyword.efi set "NAMESPACE=x-UEFI-OEM&KEYWORD=NumericKey&VALUE=0007"
+```
+Verify that the modification was completed successfully:
+```
+FS0:\> HIIKeyword.efi get "NAMESPACE=x-UEFI-OEM" "KEYWORD=NumericKey"
+Response: NAMESPACE=x-UEFI-OEM&PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400&KEYWORD=NumericKey&VALUE=0007
+
+
+NAMESPACE=x-UEFI-OEM
+PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400 (VenHw(C299F575-F1DD-4D7D-B7AA-E5064B3ECBD7))
+KEYWORD=NumericKey
+VALUE=0007
+07 00                                            | ..
+```
+
+If you want to, you can even check the form browser:
+
+![1](1.png?raw=true "1")
+
+I want to point out that like in the `RouteConfig()` case, modification through the `EFI_KEYWORD_HANDLER_PROTOCOL.SetData()` call bypasses some of the VFR checks. For example even if the current numeric value limits are `0..10`
+```
+numeric
+  ...
+  minimum = 0,
+  maximum = 10,
+  ...
+endnumeric;
+```
+it is still possible to change it to something like `0xABCD` like this:
+```
+FS0:\> HIIKeyword.efi set "NAMESPACE=x-UEFI-OEM&KEYWORD=NumericKey&VALUE=ABCD"
+```
+Once again you can verify updated value with our program:
+```
+FS0:\> HIIKeyword.efi get "NAMESPACE=x-UEFI-OEM" "KEYWORD=NumericKey"
+Response: NAMESPACE=x-UEFI-OEM&PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400&KEYWORD=NumericKey&VALUE=abcd
+
+
+NAMESPACE=x-UEFI-OEM
+PATH=0104140075f599c2ddf17d4db7aae5064b3ecbd77fff0400 (VenHw(C299F575-F1DD-4D7D-B7AA-E5064B3ECBD7))
+KEYWORD=NumericKey
+VALUE=abcd
+CD AB                                            | ..
+```
+Or with the form browser:
+
+![2](2.png?raw=true "2")
+