Gracefully handle json data with the wrong value types (#4961)

## Summary of the Pull Request

Currently, if the Terminal attempts to parse a setting that _should_ be a `bool`
and the user provided a string, then we'll throw an exception while parsing the
settings, and display an error message that's pretty unrelated to the actual
problem.

The same goes for `bool`s as `int`s, `float`s as `int`s, etc.

This PR instead updates our settings parsing to ensure that we check the type of
a json value before actually trying to get its parsed value.

## References

## PR Checklist
* [x] Closes #4299
* [x] I work here
* [x] Tests added/passed
* [n/a] Requires documentation to be updated

## Detailed Description of the Pull Request / Additional comments

I made a bunch of `JsonUtils` helpers for this in the same vein as the
`GetOptionalValue` ones.

Notably, any other value type can safely be treated as a string value.

## Validation Steps Performed
* added tests
* ran the Terminal and verified we can parse settings with the wrong types

src/cascadia/TerminalApp/CascadiaSettings.h

@@ -34,6 +34,7 @@ namespace TerminalAppLocalTests
 namespace TerminalAppUnitTests
 {
     class DynamicProfileTests;
+    class JsonTests;
 };
 
 namespace TerminalApp
@@ -124,4 +125,5 @@ class TerminalApp::CascadiaSettings final
     friend class TerminalAppLocalTests::KeyBindingsTests;
     friend class TerminalAppLocalTests::TabTests;
     friend class TerminalAppUnitTests::DynamicProfileTests;
+    friend class TerminalAppUnitTests::JsonTests;
 };

src/cascadia/TerminalApp/GlobalAppSettings.cpp

@@ -262,22 +262,14 @@ void GlobalAppSettings::LayerJson(const Json::Value& json)
         _defaultProfile = guid;
     }
 
-    if (auto alwaysShowTabs{ json[JsonKey(AlwaysShowTabsKey)] })
-    {
-        _alwaysShowTabs = alwaysShowTabs.asBool();
-    }
-    if (auto confirmCloseAllTabs{ json[JsonKey(ConfirmCloseAllKey)] })
-    {
-        _confirmCloseAllTabs = confirmCloseAllTabs.asBool();
-    }
-    if (auto initialRows{ json[JsonKey(InitialRowsKey)] })
-    {
-        _initialRows = initialRows.asInt();
-    }
-    if (auto initialCols{ json[JsonKey(InitialColsKey)] })
-    {
-        _initialCols = initialCols.asInt();
-    }
+    JsonUtils::GetBool(json, AlwaysShowTabsKey, _alwaysShowTabs);
+
+    JsonUtils::GetBool(json, ConfirmCloseAllKey, _confirmCloseAllTabs);
+
+    JsonUtils::GetInt(json, InitialRowsKey, _initialRows);
+
+    JsonUtils::GetInt(json, InitialColsKey, _initialCols);
+
     if (auto rowsToScroll{ json[JsonKey(RowsToScrollKey)] })
     {
         //if it's not an int we fall back to setting it to 0, which implies using the system setting. This will be the case if it's set to "system"
@@ -290,29 +282,19 @@ void GlobalAppSettings::LayerJson(const Json::Value& json)
             _rowsToScroll = 0;
         }
     }
+
     if (auto initialPosition{ json[JsonKey(InitialPositionKey)] })
     {
         _ParseInitialPosition(GetWstringFromJson(initialPosition), _initialX, _initialY);
     }
-    if (auto showTitleInTitlebar{ json[JsonKey(ShowTitleInTitlebarKey)] })
-    {
-        _showTitleInTitlebar = showTitleInTitlebar.asBool();
-    }
 
-    if (auto showTabsInTitlebar{ json[JsonKey(ShowTabsInTitlebarKey)] })
-    {
-        _showTabsInTitlebar = showTabsInTitlebar.asBool();
-    }
+    JsonUtils::GetBool(json, ShowTitleInTitlebarKey, _showTitleInTitlebar);
 
-    if (auto wordDelimiters{ json[JsonKey(WordDelimitersKey)] })
-    {
-        _wordDelimiters = GetWstringFromJson(wordDelimiters);
-    }
+    JsonUtils::GetBool(json, ShowTabsInTitlebarKey, _showTabsInTitlebar);
 
-    if (auto copyOnSelect{ json[JsonKey(CopyOnSelectKey)] })
-    {
-        _copyOnSelect = copyOnSelect.asBool();
-    }
+    JsonUtils::GetWstring(json, WordDelimitersKey, _wordDelimiters);
+
+    JsonUtils::GetBool(json, CopyOnSelectKey, _copyOnSelect);
 
     if (auto launchMode{ json[JsonKey(LaunchModeKey)] })
     {
@@ -341,10 +323,7 @@ void GlobalAppSettings::LayerJson(const Json::Value& json)
         _keybindingsWarnings.insert(_keybindingsWarnings.end(), warnings.begin(), warnings.end());
     }
 
-    if (auto snapToGridOnResize{ json[JsonKey(SnapToGridOnResizeKey)] })
-    {
-        _SnapToGridOnResize = snapToGridOnResize.asBool();
-    }
+    JsonUtils::GetBool(json, SnapToGridOnResizeKey, _SnapToGridOnResize);
 }
 
 // Method Description:

src/cascadia/TerminalApp/JsonUtils.cpp

@@ -52,8 +52,74 @@ void TerminalApp::JsonUtils::GetOptionalDouble(const Json::Value& json,
     const auto conversionFn = [](const Json::Value& value) -> double {
         return value.asFloat();
     };
+    const auto validationFn = [](const Json::Value& value) -> bool {
+        return value.isNumeric();
+    };
     GetOptionalValue(json,
                      key,
                      target,
-                     conversionFn);
+                     conversionFn,
+                     validationFn);
+}
+
+void TerminalApp::JsonUtils::GetInt(const Json::Value& json,
+                                    std::string_view key,
+                                    int& target)
+{
+    const auto conversionFn = [](const Json::Value& value) -> int {
+        return value.asInt();
+    };
+    const auto validationFn = [](const Json::Value& value) -> bool {
+        return value.isInt();
+    };
+    GetValue(json, key, target, conversionFn, validationFn);
+}
+
+void TerminalApp::JsonUtils::GetUInt(const Json::Value& json,
+                                     std::string_view key,
+                                     uint32_t& target)
+{
+    const auto conversionFn = [](const Json::Value& value) -> uint32_t {
+        return value.asUInt();
+    };
+    const auto validationFn = [](const Json::Value& value) -> bool {
+        return value.isUInt();
+    };
+    GetValue(json, key, target, conversionFn, validationFn);
+}
+
+void TerminalApp::JsonUtils::GetDouble(const Json::Value& json,
+                                       std::string_view key,
+                                       double& target)
+{
+    const auto conversionFn = [](const Json::Value& value) -> double {
+        return value.asFloat();
+    };
+    const auto validationFn = [](const Json::Value& value) -> bool {
+        return value.isNumeric();
+    };
+    GetValue(json, key, target, conversionFn, validationFn);
+}
+
+void TerminalApp::JsonUtils::GetBool(const Json::Value& json,
+                                     std::string_view key,
+                                     bool& target)
+{
+    const auto conversionFn = [](const Json::Value& value) -> bool {
+        return value.asBool();
+    };
+    const auto validationFn = [](const Json::Value& value) -> bool {
+        return value.isBool();
+    };
+    GetValue(json, key, target, conversionFn, validationFn);
+}
+
+void TerminalApp::JsonUtils::GetWstring(const Json::Value& json,
+                                        std::string_view key,
+                                        std::wstring& target)
+{
+    const auto conversionFn = [](const Json::Value& value) -> std::wstring {
+        return GetWstringFromJson(value);
+    };
+    GetValue(json, key, target, conversionFn, nullptr);
 }

src/cascadia/TerminalApp/JsonUtils.h

@@ -46,24 +46,99 @@ namespace TerminalApp::JsonUtils
     // - target: the optional object to receive the value from json
     // - conversion: a std::function<T(const Json::Value&)> which can be used to
     //   convert the Json::Value to the appropriate type.
+    // - validation: optional, if provided, will be called first to ensure that
+    //   the json::value is of the correct type before attempting to call
+    //   `conversion`.
     // Return Value:
     // - <none>
     template<typename T, typename F>
     void GetOptionalValue(const Json::Value& json,
                           std::string_view key,
                           std::optional<T>& target,
-                          F&& conversion)
+                          F&& conversion,
+                          const std::function<bool(const Json::Value&)>& validation = nullptr)
     {
         if (json.isMember(JsonKey(key)))
         {
             if (auto jsonVal{ json[JsonKey(key)] })
             {
-                target = conversion(jsonVal);
+                if (validation == nullptr || validation(jsonVal))
+                {
+                    target = conversion(jsonVal);
+                }
             }
             else
             {
+                // This branch is hit when the json object contained the key,
+                // but the key was set to `null`. In this case, explicitly clear
+                // the target.
                 target = std::nullopt;
             }
         }
     }
+
+    // Method Description:
+    // - Helper that can be used for retrieving a value from a json
+    //   object, and parsing it's value to set on a given target object.
+    //    - If the key we're looking for _doesn't_ exist in the json object,
+    //      we'll leave the target object unmodified.
+    //    - If the key exists in the json object, we'll use the provided
+    //      `validation` function to ensure that the json value is of the
+    //      correct type.
+    //    - If we successfully validate the json value type (or no validation
+    //      function was provided), then we'll use `conversion` to parse the
+    //      value and place the result into `target`
+    // - Each caller should provide a conversion function that takes a
+    //   Json::Value and returns an object of the same type as target.
+    // - Unlike GetOptionalValue, if the key exists but is set to `null`, we'll
+    //   just ignore it.
+    // Arguments:
+    // - json: The json object to search for the given key
+    // - key: The key to look for in the json object
+    // - target: the optional object to receive the value from json
+    // - conversion: a std::function<T(const Json::Value&)> which can be used to
+    //   convert the Json::Value to the appropriate type.
+    // - validation: optional, if provided, will be called first to ensure that
+    //   the json::value is of the correct type before attempting to call
+    //   `conversion`.
+    // Return Value:
+    // - <none>
+    template<typename T, typename F>
+    void GetValue(const Json::Value& json,
+                  std::string_view key,
+                  T& target,
+                  F&& conversion,
+                  const std::function<bool(const Json::Value&)>& validation = nullptr)
+    {
+        if (json.isMember(JsonKey(key)))
+        {
+            if (auto jsonVal{ json[JsonKey(key)] })
+            {
+                if (validation == nullptr || validation(jsonVal))
+                {
+                    target = conversion(jsonVal);
+                }
+            }
+        }
+    }
+
+    void GetInt(const Json::Value& json,
+                std::string_view key,
+                int& target);
+
+    void GetUInt(const Json::Value& json,
+                 std::string_view key,
+                 uint32_t& target);
+
+    void GetDouble(const Json::Value& json,
+                   std::string_view key,
+                   double& target);
+
+    void GetBool(const Json::Value& json,
+                 std::string_view key,
+                 bool& target);
+
+    void GetWstring(const Json::Value& json,
+                    std::string_view key,
+                    std::wstring& target);
 };

src/cascadia/TerminalApp/Profile.cpp

@@ -628,19 +628,11 @@ bool Profile::_ConvertJsonToBool(const Json::Value& json)
 void Profile::LayerJson(const Json::Value& json)
 {
     // Profile-specific Settings
-    if (json.isMember(JsonKey(NameKey)))
-    {
-        auto name{ json[JsonKey(NameKey)] };
-        _name = GetWstringFromJson(name);
-    }
+    JsonUtils::GetWstring(json, NameKey, _name);
 
     JsonUtils::GetOptionalGuid(json, GuidKey, _guid);
 
-    if (json.isMember(JsonKey(HiddenKey)))
-    {
-        auto hidden{ json[JsonKey(HiddenKey)] };
-        _hidden = hidden.asBool();
-    }
+    JsonUtils::GetBool(json, HiddenKey, _hidden);
 
     // Core Settings
     JsonUtils::GetOptionalColor(json, ForegroundKey, _defaultForeground);
@@ -672,22 +664,14 @@ void Profile::LayerJson(const Json::Value& json)
             i++;
         }
     }
-    if (json.isMember(JsonKey(HistorySizeKey)))
-    {
-        auto historySize{ json[JsonKey(HistorySizeKey)] };
-        // TODO:MSFT:20642297 - Use a sentinel value (-1) for "Infinite scrollback"
-        _historySize = historySize.asInt();
-    }
-    if (json.isMember(JsonKey(SnapOnInputKey)))
-    {
-        auto snapOnInput{ json[JsonKey(SnapOnInputKey)] };
-        _snapOnInput = snapOnInput.asBool();
-    }
-    if (json.isMember(JsonKey(CursorHeightKey)))
-    {
-        auto cursorHeight{ json[JsonKey(CursorHeightKey)] };
-        _cursorHeight = cursorHeight.asUInt();
-    }
+
+    // TODO:MSFT:20642297 - Use a sentinel value (-1) for "Infinite scrollback"
+    JsonUtils::GetInt(json, HistorySizeKey, _historySize);
+
+    JsonUtils::GetBool(json, SnapOnInputKey, _snapOnInput);
+
+    JsonUtils::GetUInt(json, CursorHeightKey, _cursorHeight);
+
     if (json.isMember(JsonKey(CursorShapeKey)))
     {
         auto cursorShape{ json[JsonKey(CursorShapeKey)] };
@@ -698,46 +682,25 @@ void Profile::LayerJson(const Json::Value& json)
     // Control Settings
     JsonUtils::GetOptionalGuid(json, ConnectionTypeKey, _connectionType);
 
-    if (json.isMember(JsonKey(CommandlineKey)))
-    {
-        auto commandline{ json[JsonKey(CommandlineKey)] };
-        _commandline = GetWstringFromJson(commandline);
-    }
-    if (json.isMember(JsonKey(FontFaceKey)))
-    {
-        auto fontFace{ json[JsonKey(FontFaceKey)] };
-        _fontFace = GetWstringFromJson(fontFace);
-    }
-    if (json.isMember(JsonKey(FontSizeKey)))
-    {
-        auto fontSize{ json[JsonKey(FontSizeKey)] };
-        _fontSize = fontSize.asInt();
-    }
-    if (json.isMember(JsonKey(AcrylicTransparencyKey)))
-    {
-        auto acrylicTransparency{ json[JsonKey(AcrylicTransparencyKey)] };
-        _acrylicTransparency = acrylicTransparency.asFloat();
-    }
-    if (json.isMember(JsonKey(UseAcrylicKey)))
-    {
-        auto useAcrylic{ json[JsonKey(UseAcrylicKey)] };
-        _useAcrylic = useAcrylic.asBool();
-    }
-    if (json.isMember(JsonKey(SuppressApplicationTitleKey)))
-    {
-        auto suppressApplicationTitle{ json[JsonKey(SuppressApplicationTitleKey)] };
-        _suppressApplicationTitle = suppressApplicationTitle.asBool();
-    }
+    JsonUtils::GetWstring(json, CommandlineKey, _commandline);
+
+    JsonUtils::GetWstring(json, FontFaceKey, _fontFace);
+
+    JsonUtils::GetInt(json, FontSizeKey, _fontSize);
+
+    JsonUtils::GetDouble(json, AcrylicTransparencyKey, _acrylicTransparency);
+
+    JsonUtils::GetBool(json, UseAcrylicKey, _useAcrylic);
+
+    JsonUtils::GetBool(json, SuppressApplicationTitleKey, _suppressApplicationTitle);
+
     if (json.isMember(JsonKey(CloseOnExitKey)))
     {
         auto closeOnExit{ json[JsonKey(CloseOnExitKey)] };
         _closeOnExitMode = ParseCloseOnExitMode(closeOnExit);
     }
-    if (json.isMember(JsonKey(PaddingKey)))
-    {
-        auto padding{ json[JsonKey(PaddingKey)] };
-        _padding = GetWstringFromJson(padding);
-    }
+
+    JsonUtils::GetWstring(json, PaddingKey, _padding);
 
     JsonUtils::GetOptionalString(json, ScrollbarStateKey, _scrollbarState);