[PseudoC] Fix handling of struct field accesses

* Accesses at offset zero were not handled.
* The pointer arithmetic and casts that were generated were incorrect
  in some cases.

Fixes #6825.

Author: plafosse

lang/c/pseudoc.cpp

@@ -2569,91 +2569,97 @@ void PseudoCFunction::GetExprTextInternal(const HighLevelILInstruction& instr, H
 			if (type && (type->GetClass() == NamedTypeReferenceClass))
 				type = GetFunction()->GetView()->GetTypeByRef(type->GetNamedTypeReference());
 
-			bool derefOffset = false;
+			// Try to resolve as a structure member access
 			if (type && (type->GetClass() == StructureTypeClass))
 			{
-				std::optional<size_t> memberIndexHint;
-				if (memberIndex != BN_INVALID_EXPR)
-					memberIndexHint = memberIndex;
+				auto memberIndexHint = memberIndex != BN_INVALID_EXPR ? std::make_optional(memberIndex) : std::nullopt;
 
 				bool outer = true;
-				if (type->GetStructure()->ResolveMemberOrBaseMember(GetFunction()->GetView(), offset, 0,
-						[&](NamedTypeReference*, Structure* s, size_t memberIndex, uint64_t structOffset,
-							uint64_t adjustedOffset, const StructureMember& member) {
-							BNSymbolDisplayResult symbolType;
-							if (srcExpr.operation == HLIL_CONST_PTR)
-							{
-								const auto constant = srcExpr.GetConstant<HLIL_CONST_PTR>();
-								symbolType = tokens.AppendPointerTextToken(
-									srcExpr, constant, settings, DisplaySymbolOnly, precedence);
-							}
-							else
-							{
-								GetExprTextInternal(srcExpr, tokens, settings, MemberAndFunctionOperatorPrecedence);
-								symbolType = OtherSymbolResult;
-							}
-
-							const auto displayDeref = symbolType != DataSymbolResult;
-							if (displayDeref && outer)
-								tokens.Append(OperationToken, "->");
-							else
-								tokens.Append(OperationToken, ".");
-							outer = false;
-
-							vector<string> nameList {member.name};
-							HighLevelILTokenEmitter::AddNamesForOuterStructureMembers(
-								GetFunction()->GetView(), type, srcExpr, nameList);
-
-							tokens.Append(FieldNameToken, member.name, structOffset + member.offset, 0, 0,
-								BN_FULL_CONFIDENCE, nameList);
-						}),
-					memberIndexHint)
+				auto renderMember = [&](NamedTypeReference*, Structure* s, size_t memberIndex, 
+						uint64_t structOffset, uint64_t adjustedOffset, const StructureMember& member) {
+					BNSymbolDisplayResult symbolType;
+					if (srcExpr.operation == HLIL_CONST_PTR)
+					{
+						const auto constant = srcExpr.GetConstant<HLIL_CONST_PTR>();
+						symbolType = tokens.AppendPointerTextToken(
+							srcExpr, constant, settings, DisplaySymbolOnly, precedence);
+					}
+					else
+					{
+						GetExprTextInternal(srcExpr, tokens, settings, MemberAndFunctionOperatorPrecedence);
+						symbolType = OtherSymbolResult;
+					}
+
+					const auto useArrow = (symbolType != DataSymbolResult) && outer;
+					tokens.Append(OperationToken, useArrow ? "->" : ".");
+					outer = false;
+
+					vector<string> nameList {member.name};
+					HighLevelILTokenEmitter::AddNamesForOuterStructureMembers(
+						GetFunction()->GetView(), type, srcExpr, nameList);
+
+					tokens.Append(FieldNameToken, member.name, structOffset + member.offset, 0, 0,
+						BN_FULL_CONFIDENCE, nameList);
+				};
+
+				bool memberResolved = type->GetStructure()->ResolveMemberOrBaseMember(
+					GetFunction()->GetView(), offset, 0, renderMember, memberIndexHint);
+
+				if (memberResolved)
 					return;
 			}
-			else if (type && (type->GetClass() == StructureTypeClass))
-			{
-				derefOffset = true;
-			}
 
-			if (derefOffset || offset != 0)
-			{
-				bool parens = precedence > UnaryOperatorPrecedence;
-				if (parens)
-					tokens.AppendOpenParen();
+			// Member resolution failed or not a structure - render as pointer arithmetic
+			// Structure: *(type_cast)(char_cast pointer + offset)
 
-				tokens.Append(OperationToken, "*");
-				if (!settings || settings->IsOptionSet(ShowTypeCasts))
-				{
-					tokens.AppendOpenParen();
-					AppendSizeToken(!derefOffset ? srcExpr.size : instr.size, true, tokens);
-					tokens.Append(TextToken, "*");
-					tokens.AppendCloseParen();
-				}
+			bool needsOuterParens = precedence > UnaryOperatorPrecedence;
+			bool showsTypeCasts = !settings || settings->IsOptionSet(ShowTypeCasts);
+			bool needsTypeCast = instr.size > 1 && showsTypeCasts;
+			bool hasOffset = offset != 0;
+			
+			if (needsOuterParens)
 				tokens.AppendOpenParen();
-				if (!settings || settings->IsOptionSet(ShowTypeCasts))
+			
+			tokens.Append(OperationToken, "*");
+			
+			if (needsTypeCast)
+			{
+				tokens.AppendOpenParen();
+				AppendSizeToken(instr.size, true, tokens);
+				tokens.Append(TextToken, "*");
+				tokens.AppendCloseParen();
+			}
+			
+			if (hasOffset) {
+				tokens.AppendOpenParen();
+				if (showsTypeCasts)
 				{
 					tokens.AppendOpenParen();
-					tokens.Append(TypeNameToken, "char");
+					tokens.Append(KeywordToken, "char");
 					tokens.Append(TextToken, "*");
 					tokens.AppendCloseParen();
 				}
-
-				if (srcExpr.operation == HLIL_CONST_PTR)
-				{
-					const auto constant = srcExpr.GetConstant<HLIL_CONST_PTR>();
-					tokens.AppendPointerTextToken(srcExpr, constant, settings, DisplaySymbolOnly, precedence);
-				}
-				else
-				{
-					GetExprTextInternal(srcExpr, tokens, settings, AddOperatorPrecedence);
-				}
-
+			}
+			
+			if (srcExpr.operation == HLIL_CONST_PTR)
+			{
+				const auto constant = srcExpr.GetConstant<HLIL_CONST_PTR>();
+				tokens.AppendPointerTextToken(srcExpr, constant, settings, DisplaySymbolOnly, precedence);
+			}
+			else
+			{
+				GetExprTextInternal(srcExpr, tokens, settings, AddOperatorPrecedence);
+			}
+			
+			if (hasOffset)
+			{
 				tokens.Append(OperationToken, " + ");
 				tokens.AppendIntegerTextToken(instr, offset, instr.size);
-				tokens.AppendCloseParen();
-				if (parens)
-					tokens.AppendCloseParen();
+				tokens.AppendCloseParen(); // Close (ptr + offset)
 			}
+			
+			if (needsOuterParens)
+				tokens.AppendCloseParen();
 
 			if (statement)
 				tokens.AppendSemicolon();