Fix crash related to unparseable/invalid media resource paths

src/cascadia/TerminalApp/AppLogic.cpp

@@ -27,10 +27,11 @@ namespace winrt
 // !!! IMPORTANT !!!
 // Make sure that these keys are in the same order as the
 // SettingsLoadWarnings/Errors enum is!
-static const std::array<std::wstring_view, 3> settingsLoadWarningsLabels {
+static const std::array<std::wstring_view, 4> settingsLoadWarningsLabels {
     USES_RESOURCE(L"MissingDefaultProfileText"),
     USES_RESOURCE(L"DuplicateProfileText"),
-    USES_RESOURCE(L"UnknownColorSchemeText")
+    USES_RESOURCE(L"UnknownColorSchemeText"),
+    USES_RESOURCE(L"InvalidBackgroundImage")
 };
 static const std::array<std::wstring_view, 2> settingsLoadErrorsLabels {
     USES_RESOURCE(L"NoProfilesText"),

src/cascadia/TerminalApp/CascadiaSettings.cpp

@@ -198,6 +198,9 @@ void CascadiaSettings::_ValidateSettings()
     // just use the hardcoded defaults
     _ValidateAllSchemesExist();
 
+    // Ensure all profile's with specified background images have valid files
+    _ValidateBackgroundImages();
+
     // TODO:GH#2548 ensure there's at least one key bound. Display a warning if
     // there's _NO_ keys bound to any actions. That's highly irregular, and
     // likely an indication of an error somehow.
@@ -424,6 +427,43 @@ void CascadiaSettings::_ValidateAllSchemesExist()
     }
 }
 
+// Method Description:
+// - Ensures that all specified background images are valid files existing on the local machine.
+//   This does not verify that the background image file is encoded as an image.
+// Arguments:
+// - <none>
+// Return Value:
+// - <none>
+// - Appends a SettingsLoadWarnings::InvalidBackgroundImage to our list of warnings if
+//   we find any invalid background images.
+void CascadiaSettings::_ValidateBackgroundImages()
+{
+    bool invalidImage{ false };
+
+    for (auto& profile : _profiles)
+    {
+        if (profile.HasBackgroundImage())
+        {
+            // Attempt to convert the path to a URI, the ctor will throw if it's invalid/unparseable.
+            // This covers file paths on the machine, app data, URLs, and other resource paths.
+            try
+            {
+                winrt::Windows::Foundation::Uri imagePath{ profile.GetExpandedBackgroundImagePath() };
+            }
+            catch (...)
+            {
+                profile.ResetBackgroundImagePath();
+                invalidImage = true;
+            }
+        }
+    }
+
+    if (invalidImage)
+    {
+        _warnings.push_back(::TerminalApp::SettingsLoadWarnings::InvalidBackgroundImage);
+    }
+}
+
 // Method Description:
 // - Create a TerminalSettings object for the provided newTerminalArgs. We'll
 //   use the newTerminalArgs to look up the profile that should be used to

src/cascadia/TerminalApp/CascadiaSettings.h

@@ -115,6 +115,7 @@ class TerminalApp::CascadiaSettings final
     void _ReorderProfilesToMatchUserSettingsOrder();
     void _RemoveHiddenProfiles();
     void _ValidateAllSchemesExist();
+    void _ValidateBackgroundImages();
 
     friend class TerminalAppLocalTests::SettingsTests;
     friend class TerminalAppLocalTests::ProfileTests;

src/cascadia/TerminalApp/Profile.cpp

@@ -880,6 +880,14 @@ winrt::hstring Profile::GetExpandedBackgroundImagePath() const
     return result;
 }
 
+// Method Description:
+// - Resets the std::optional holding the background image file path string.
+//   HasBackgroundImage() will return false after the execution of this function.
+void Profile::ResetBackgroundImagePath()
+{
+    _backgroundImage.reset();
+}
+
 // Method Description:
 // - Returns the name of this profile.
 // Arguments:

src/cascadia/TerminalApp/Profile.h

@@ -92,6 +92,7 @@ class TerminalApp::Profile final
 
     bool HasBackgroundImage() const noexcept;
     winrt::hstring GetExpandedBackgroundImagePath() const;
+    void ResetBackgroundImagePath();
 
     CloseOnExitMode GetCloseOnExitMode() const noexcept;
     bool GetSuppressApplicationTitle() const noexcept;

src/cascadia/TerminalApp/Resources/en-US/Resources.resw

@@ -1,17 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <root>
-  <!--
-    Microsoft ResX Schema
-
+  <!-- 
+    Microsoft ResX Schema 
+    
     Version 2.0
-
-    The primary goals of this format is to allow a simple XML format
-    that is mostly human readable. The generation and parsing of the
-    various data types are done through the TypeConverter classes
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
     associated with the data types.
-
+    
     Example:
-
+    
     ... ado.net/XML headers & schema ...
     <resheader name="resmimetype">text/microsoft-resx</resheader>
     <resheader name="version">2.0</resheader>
@@ -26,36 +26,36 @@
         <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
         <comment>This is a comment</comment>
     </data>
-
-    There are any number of "resheader" rows that contain simple
+                
+    There are any number of "resheader" rows that contain simple 
     name/value pairs.
-
-    Each data row contains a name, and value. The row also contains a
-    type or mimetype. Type corresponds to a .NET class that support
-    text/value conversion through the TypeConverter architecture.
-    Classes that don't support this are serialized and stored with the
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
     mimetype set.
-
-    The mimetype is used for serialized objects, and tells the
-    ResXResourceReader how to depersist the object. This is currently not
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
     extensible. For a given mimetype the value must be set accordingly:
-
-    Note - application/x-microsoft.net.object.binary.base64 is the format
-    that the ResXResourceWriter will generate, however the reader can
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
     read any of the formats listed below.
-
+    
     mimetype: application/x-microsoft.net.object.binary.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
             : and then encoded with base64 encoding.
-
+    
     mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
             : and then encoded with base64 encoding.
 
     mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array
+    value   : The object must be serialized into a byte array 
             : using a System.ComponentModel.TypeConverter
             : and then encoded with base64 encoding.
     -->
@@ -210,4 +210,7 @@ Temporarily using the Windows Terminal default settings.
   <data name="CloseWindowWarningTitle" xml:space="preserve">
     <value>Do you want to close all tabs?</value>
   </data>
-</root>
+  <data name="InvalidBackgroundImage" xml:space="preserve">
+    <value>Found a profile with an invalid "backgroundImage". Defaulting that profile to have no background image. Make sure that when setting a "backgroundImage", the value is a valid file path to an image.</value>
+  </data>
+</root>

src/cascadia/TerminalApp/TerminalWarnings.h

@@ -23,7 +23,8 @@ namespace TerminalApp
     {
         MissingDefaultProfile = 0,
         DuplicateProfile = 1,
-        UnknownColorScheme = 2
+        UnknownColorScheme = 2,
+        InvalidBackgroundImage = 3
     };
 
     // SettingsLoadWarnings are scenarios where the settings had invalid state