Prefer zero terminated string array over length based arrays.

src/Generation/Generator/Renderer/Internal/Parameter/Converter/PlatformStringArray.cs

@@ -11,12 +11,18 @@ public bool Supports(GirModel.AnyType anyType)
 
     public RenderableParameter Convert(GirModel.Parameter parameter)
     {
-        return parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length is null
-            ? ParameterWithoutLength(parameter)
-            : ParameterWithLength(parameter);
+        var arrayType = parameter.AnyTypeOrVarArgs.AsT0.AsT1;
+
+        if (arrayType.IsZeroTerminated)
+            return NullTerminatedArray(parameter);
+
+        if (arrayType.Length is not null)
+            return SizeBasedArray(parameter);
+
+        throw new Exception("Unknown kind of array");
     }
 
-    private static RenderableParameter ParameterWithLength(GirModel.Parameter parameter)
+    private static RenderableParameter SizeBasedArray(GirModel.Parameter parameter)
     {
         var length = parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length ?? throw new Exception("Length must not be null");
 
@@ -28,21 +34,18 @@ private static RenderableParameter ParameterWithLength(GirModel.Parameter parame
         );
     }
 
-    private static RenderableParameter ParameterWithoutLength(GirModel.Parameter parameter)
+    private static RenderableParameter NullTerminatedArray(GirModel.Parameter parameter)
     {
         return parameter.Direction switch
         {
-            GirModel.Direction.In => ParameterWithoutLengthIn(parameter),
-            GirModel.Direction.Out => ParameterWithoutLengthOut(parameter),
+            GirModel.Direction.In => NullTerminatedArrayIn(parameter),
+            GirModel.Direction.Out => NullTerminatedArrayOut(parameter),
             _ => throw new Exception("Unknown direction for parameter")
         };
     }
 
-    private static RenderableParameter ParameterWithoutLengthIn(GirModel.Parameter parameter)
+    private static RenderableParameter NullTerminatedArrayIn(GirModel.Parameter parameter)
     {
-        if (parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length is not null)
-            throw new Exception("Length must be null");
-
         if (parameter.Direction != GirModel.Direction.In)
             throw new Exception("Direction must be in");
 
@@ -62,11 +65,8 @@ private static RenderableParameter ParameterWithoutLengthIn(GirModel.Parameter p
         );
     }
 
-    private static RenderableParameter ParameterWithoutLengthOut(GirModel.Parameter parameter)
+    private static RenderableParameter NullTerminatedArrayOut(GirModel.Parameter parameter)
     {
-        if (parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length is not null)
-            throw new Exception("Length must be null");
-
         if (parameter.Direction != GirModel.Direction.Out)
             throw new Exception("Direction must be out");
 

src/Generation/Generator/Renderer/Internal/Parameter/Converter/Utf8StringArray.cs

@@ -11,12 +11,18 @@ public bool Supports(GirModel.AnyType anyType)
 
     public RenderableParameter Convert(GirModel.Parameter parameter)
     {
-        return parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length is null
-            ? ParameterWithoutLength(parameter)
-            : ParameterWithLength(parameter);
+        var arrayType = parameter.AnyTypeOrVarArgs.AsT0.AsT1;
+
+        if (arrayType.IsZeroTerminated)
+            return NullTerminatedArray(parameter);
+
+        if (arrayType.Length is not null)
+            return SizeBasedArray(parameter);
+
+        throw new Exception("Unknown kind of array");
     }
 
-    private static RenderableParameter ParameterWithLength(GirModel.Parameter parameter)
+    private static RenderableParameter SizeBasedArray(GirModel.Parameter parameter)
     {
         var length = parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length ?? throw new Exception("Length must not be null");
 
@@ -28,21 +34,18 @@ private static RenderableParameter ParameterWithLength(GirModel.Parameter parame
         );
     }
 
-    private static RenderableParameter ParameterWithoutLength(GirModel.Parameter parameter)
+    private static RenderableParameter NullTerminatedArray(GirModel.Parameter parameter)
     {
         return parameter.Direction switch
         {
-            GirModel.Direction.In => ParameterWithoutLengthIn(parameter),
-            GirModel.Direction.Out => ParameterWithoutLengthOut(parameter),
+            GirModel.Direction.In => NullTerminatedArrayIn(parameter),
+            GirModel.Direction.Out => NullTerminatedArrayOut(parameter),
             _ => throw new Exception("Unknown direction for parameter")
         };
     }
 
-    private static RenderableParameter ParameterWithoutLengthIn(GirModel.Parameter parameter)
+    private static RenderableParameter NullTerminatedArrayIn(GirModel.Parameter parameter)
     {
-        if (parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length is not null)
-            throw new Exception("Length must be null");
-
         if (parameter.Direction != GirModel.Direction.In)
             throw new Exception("Direction must be in");
 
@@ -62,11 +65,8 @@ private static RenderableParameter ParameterWithoutLengthIn(GirModel.Parameter p
         );
     }
 
-    private static RenderableParameter ParameterWithoutLengthOut(GirModel.Parameter parameter)
+    private static RenderableParameter NullTerminatedArrayOut(GirModel.Parameter parameter)
     {
-        if (parameter.AnyTypeOrVarArgs.AsT0.AsT1.Length is not null)
-            throw new Exception("Length must be null");
-
         if (parameter.Direction != GirModel.Direction.Out)
             throw new Exception("Direction must be out");
 

src/Generation/Generator/Renderer/Internal/ParameterToManagedExpression/Converter/PlatformStringArray.cs

@@ -11,10 +11,13 @@ public bool Supports(GirModel.AnyType type)
     public void Initialize(ParameterToManagedData parameterData, IEnumerable<ParameterToManagedData> parameters)
     {
         var arrayType = parameterData.Parameter.AnyTypeOrVarArgs.AsT0.AsT1;
-        if (arrayType.Length is null)
+
+        if (arrayType.IsZeroTerminated)
             NullTerminatedArray(parameterData);
-        else
+        else if (arrayType.Length is not null)
             SizeBasedArray(parameterData);
+        else
+            throw new Exception("Unknown kind of array");
     }
 
     private static void NullTerminatedArray(ParameterToManagedData parameterData)

src/Generation/Generator/Renderer/Internal/ParameterToManagedExpression/Converter/Utf8StringArray.cs

@@ -11,10 +11,13 @@ public bool Supports(GirModel.AnyType type)
     public void Initialize(ParameterToManagedData parameterData, IEnumerable<ParameterToManagedData> parameters)
     {
         var arrayType = parameterData.Parameter.AnyTypeOrVarArgs.AsT0.AsT1;
-        if (arrayType.Length is null)
+
+        if (arrayType.IsZeroTerminated)
             NullTerminatedArray(parameterData);
-        else
+        else if (arrayType.Length is not null)
             SizeBasedArray(parameterData);
+        else
+            throw new Exception("Unknown kind of array");
     }
 
     private static void NullTerminatedArray(ParameterToManagedData parameterData)

src/Generation/Generator/Renderer/Internal/ReturnType/Converter/PlatformStringArray.cs

@@ -13,26 +13,30 @@ public RenderableReturnType Convert(GirModel.ReturnType returnType)
     {
         var arrayType = returnType.AnyType.AsT1;
 
-        var nullableTypeName = arrayType.Length is null
-            ? NullTerminatedArray(returnType)
-            : SizeBasedArray();
+        if (arrayType.IsZeroTerminated)
+            return NullTerminatedArray(returnType);
 
-        return new RenderableReturnType(nullableTypeName);
+        if (arrayType.Length is not null)
+            return SizeBasedArray();
+
+        throw new Exception("Unknown kind of array");
     }
 
-    private static string NullTerminatedArray(GirModel.ReturnType returnType)
+    private static RenderableReturnType NullTerminatedArray(GirModel.ReturnType returnType)
     {
-        return returnType switch
+        var typeName = returnType switch
         {
             { Transfer: GirModel.Transfer.Full } => Model.PlatformStringArray.GetInternalOwnedHandleName(),
             { Transfer: GirModel.Transfer.None } => Model.PlatformStringArray.GetInternalUnownedHandleName(),
             { Transfer: GirModel.Transfer.Container } => Model.PlatformStringArray.GetInternalContainerHandleName(),
             _ => throw new Exception("Unknown transfer type for platform string array return value")
         };
+
+        return new RenderableReturnType(typeName);
     }
 
-    private static string SizeBasedArray()
+    private static RenderableReturnType SizeBasedArray()
     {
-        return "string[]";
+        return new RenderableReturnType("string[]");
     }
 }

src/Generation/Generator/Renderer/Internal/ReturnType/Converter/Utf8StringArray.cs

@@ -13,26 +13,30 @@ public RenderableReturnType Convert(GirModel.ReturnType returnType)
     {
         var arrayType = returnType.AnyType.AsT1;
 
-        var nullableTypeName = arrayType.Length is null
-            ? NullTerminatedArray(returnType)
-            : SizeBasedArray();
+        if (arrayType.IsZeroTerminated)
+            return NullTerminatedArray(returnType);
 
-        return new RenderableReturnType(nullableTypeName);
+        if (arrayType.Length is not null)
+            return SizeBasedArray();
+
+        throw new Exception("Unknown kind of array");
     }
 
-    private static string NullTerminatedArray(GirModel.ReturnType returnType)
+    private static RenderableReturnType NullTerminatedArray(GirModel.ReturnType returnType)
     {
-        return returnType switch
+        var typeName = returnType switch
         {
             { Transfer: GirModel.Transfer.Full } => Model.Utf8StringArray.GetInternalOwnedHandleName(),
             { Transfer: GirModel.Transfer.None } => Model.Utf8StringArray.GetInternalUnownedHandleName(),
             { Transfer: GirModel.Transfer.Container } => Model.Utf8StringArray.GetInternalContainerHandleName(),
             _ => throw new Exception("Unknown transfer type for utf8 string array return value")
         };
+
+        return new RenderableReturnType(typeName);
     }
 
-    private static string SizeBasedArray()
+    private static RenderableReturnType SizeBasedArray()
     {
-        return "string[]";
+        return new RenderableReturnType("string[]");
     }
 }

src/Generation/Generator/Renderer/Public/ParameterToNativeExpression/Converter/PlatformStringArray.cs

@@ -11,10 +11,13 @@ public bool Supports(GirModel.AnyType type)
     public void Initialize(ParameterToNativeData parameter, IEnumerable<ParameterToNativeData> _)
     {
         var arrayType = parameter.Parameter.AnyTypeOrVarArgs.AsT0.AsT1;
-        if (arrayType.Length == null)
+
+        if (arrayType.IsZeroTerminated)
             NullTerminatedArray(parameter);
-        else
+        else if (arrayType.Length is not null)
             SizeBasedArray(parameter);
+        else
+            throw new Exception("Unknown kind of array");
     }
 
     private static void NullTerminatedArray(ParameterToNativeData parameter)

src/Generation/Generator/Renderer/Public/ParameterToNativeExpression/Converter/Utf8StringArray.cs

@@ -11,10 +11,13 @@ public bool Supports(GirModel.AnyType type)
     public void Initialize(ParameterToNativeData parameter, IEnumerable<ParameterToNativeData> _)
     {
         var arrayType = parameter.Parameter.AnyTypeOrVarArgs.AsT0.AsT1;
-        if (arrayType.Length is null)
+
+        if (arrayType.IsZeroTerminated)
             NullTerminatedArray(parameter);
-        else
+        else if (arrayType.Length is not null)
             SizeBasedArray(parameter);
+        else
+            throw new Exception("Unknown kind of array");
     }
 
     private static void NullTerminatedArray(ParameterToNativeData parameter)

src/Generation/Generator/Renderer/Public/ReturnTypeToManagedExpression/Converter/PlatformStringArray.cs

@@ -1,4 +1,6 @@
-namespace Generator.Renderer.Public.ReturnTypeToManagedExpressions;
+using System;
+
+namespace Generator.Renderer.Public.ReturnTypeToManagedExpressions;
 
 internal class PlatformStringArray : ReturnTypeConverter
 {
@@ -7,10 +9,14 @@ public bool Supports(GirModel.AnyType type)
 
     public string GetString(GirModel.ReturnType returnType, string fromVariableName)
     {
-        if (returnType.AnyType.AsT1.Length == null)
+        var arrayType = returnType.AnyType.AsT1;
+        if (arrayType.IsZeroTerminated)
             return NullTerminatedArray(returnType, fromVariableName);
-        else
+
+        if (arrayType.Length is not null)
             return SizeBasedArray(returnType, fromVariableName);
+
+        throw new Exception("Unknown kind of array");
     }
 
     private static string NullTerminatedArray(GirModel.ReturnType returnType, string fromVariableName)

src/Generation/Generator/Renderer/Public/ReturnTypeToManagedExpression/Converter/Utf8StringArray.cs

@@ -1,4 +1,6 @@
-namespace Generator.Renderer.Public.ReturnTypeToManagedExpressions;
+using System;
+
+namespace Generator.Renderer.Public.ReturnTypeToManagedExpressions;
 
 internal class Utf8StringArray : ReturnTypeConverter
 {
@@ -7,10 +9,14 @@ public bool Supports(GirModel.AnyType type)
 
     public string GetString(GirModel.ReturnType returnType, string fromVariableName)
     {
-        if (returnType.AnyType.AsT1.Length == null)
+        var arrayType = returnType.AnyType.AsT1;
+        if (arrayType.IsZeroTerminated)
             return NullTerminatedArray(returnType, fromVariableName);
-        else
+
+        if (arrayType.Length is not null)
             return SizeBasedArray(returnType, fromVariableName);
+
+        throw new Exception("Unknown kind of array");
     }
 
     private static string NullTerminatedArray(GirModel.ReturnType returnType, string fromVariableName)

src/Generation/GirLoader/Input/ArrayType.cs

@@ -11,7 +11,7 @@ public class ArrayType : AnyType
     public string? Length { get; set; }
 
     [XmlAttribute("zero-terminated")]
-    public string? ZeroTerminated { get; set; }
+    public bool ZeroTerminated { get; set; }
 
     [XmlAttribute("fixed-size")]
     public string? FixedSize { get; set; }

src/Generation/GirLoader/Output/TypeReferenceFactory.cs

@@ -52,7 +52,6 @@ private bool TryCreateArrayTypeReference(Input.AnyType anyType, [NotNullWhen(tru
 
         int? length = int.TryParse(anyType.Array.Length, out var l) ? l : null;
         int? fixedSize = int.TryParse(anyType.Array.FixedSize, out var f) ? f : null;
-        bool? zeroTerminated = bool.TryParse(anyType.Array.ZeroTerminated, out var b) ? b : null;
 
         var reference = new ArrayTypeReference(
             typeReference: typeReference,
@@ -61,11 +60,9 @@ private bool TryCreateArrayTypeReference(Input.AnyType anyType, [NotNullWhen(tru
         {
             Length = length,
             FixedSize = fixedSize,
-            // TODO: The zero-terminated attribute is not consistently present in the gir file.
-            // If there isn't a length and fixed size treat as zero-terminated anyways. The GLib
-            // array types are never zero-terminated and always reset the flag.
-            // This can be removed if the C gir generator changes this behavior.
-            IsZeroTerminated = zeroTerminated ?? (length is null && fixedSize is null)
+            //The fallback is required as gobject-introspection expects an array to be zero terminated,
+            //if neither length nor fixedSize are given.
+            IsZeroTerminated = anyType.Array.ZeroTerminated || (length is null && fixedSize is null)
         };
 
         arrayTypeReference = anyType.Array.Name switch