From eda8da01f4cbbe16564bb1d71a81cae7176a6bc8 Mon Sep 17 00:00:00 2001
From: ISSOtm <me@eldred.fr>
Date: Fri, 23 Aug 2024 02:55:00 +0200
Subject: [PATCH] Make section size and related variables 16-bit

This avoids type size inconsistencies which lead to platform-dependent
failures to enforce overflow checks.

Did I mention I *hate* integer promotion, and C(++) more largely? T_T
---
 include/asm/section.hpp                | 12 ++++++------
 src/asm/section.cpp                    | 12 ++++++------
 test/asm/section-unsigned-overflow.asm |  4 ++--
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/asm/section.hpp b/include/asm/section.hpp
index d6754fd41..3a61186ac 100644
--- a/include/asm/section.hpp
+++ b/include/asm/section.hpp
@@ -30,15 +30,15 @@ struct Patch {
 
 struct Section {
 	std::string name;
-	SectionType type;
-	SectionModifier modifier;
 	std::shared_ptr<FileStackNode> src; // Where the section was defined
 	uint32_t fileLine;                  // Line where the section was defined
-	uint32_t size;
 	uint32_t org;
 	uint32_t bank;
-	uint8_t align; // Exactly as specified in `ALIGN[]`
+	uint16_t size;
 	uint16_t alignOfs;
+	uint8_t align; // Exactly as specified in `ALIGN[]`
+	SectionType type;
+	SectionModifier modifier;
 	std::deque<Patch> patches;
 	std::vector<uint8_t> data;
 
@@ -73,8 +73,8 @@ void sect_SetLoadSection(
 void sect_EndLoadSection();
 
 Section *sect_GetSymbolSection();
-uint32_t sect_GetSymbolOffset();
-uint32_t sect_GetOutputOffset();
+uint16_t sect_GetSymbolOffset();
+uint16_t sect_GetOutputOffset();
 uint32_t sect_GetAlignBytes(uint8_t alignment, uint16_t offset);
 void sect_AlignPC(uint8_t alignment, uint16_t offset);
 
diff --git a/src/asm/section.cpp b/src/asm/section.cpp
index 705738b88..c020ed696 100644
--- a/src/asm/section.cpp
+++ b/src/asm/section.cpp
@@ -43,11 +43,11 @@ std::stack<UnionStackEntry> currentUnionStack;
 std::deque<SectionStackEntry> sectionStack;
 std::deque<Section> sectionList;
 std::unordered_map<std::string, size_t> sectionMap; // Indexes into `sectionList`
-uint32_t curOffset; // Offset into the current section (see sect_GetSymbolOffset)
+uint16_t curOffset; // Offset into the current section (see sect_GetSymbolOffset)
 Section *currentSection = nullptr;
 static Section *currentLoadSection = nullptr;
 std::optional<std::string> currentLoadScope = std::nullopt;
-int32_t loadOffset; // Offset into the LOAD section's parent (see sect_GetOutputOffset)
+int16_t loadOffset; // Offset into the LOAD section's parent (see sect_GetOutputOffset)
 
 // A quick check to see if we have an initialized section
 [[nodiscard]] static bool requireSection() {
@@ -78,7 +78,7 @@ void sect_CheckSizes() {
 	for (Section const &sect : sectionList) {
 		if (uint32_t maxSize = sectionTypeInfo[sect.type].size; sect.size > maxSize)
 			error(
-			    "Section '%s' grew too big (max size = 0x%" PRIX32 " bytes, reached 0x%" PRIX32
+			    "Section '%s' grew too big (max size = 0x%" PRIX32 " bytes, reached 0x%" PRIX16
 			    ").\n",
 			    sect.name.c_str(),
 			    maxSize,
@@ -494,11 +494,11 @@ Section *sect_GetSymbolSection() {
 }
 
 // The offset into the section above
-uint32_t sect_GetSymbolOffset() {
+uint16_t sect_GetSymbolOffset() {
 	return curOffset;
 }
 
-uint32_t sect_GetOutputOffset() {
+uint16_t sect_GetOutputOffset() {
 	return curOffset + loadOffset;
 }
 
@@ -558,7 +558,7 @@ void sect_AlignPC(uint8_t alignment, uint16_t offset) {
 }
 
 static void growSection(uint32_t growth) {
-	if (curOffset > UINT32_MAX - growth)
+	if (growth > UINT16_MAX || curOffset > UINT16_MAX - growth)
 		fatalerror("Section size would overflow internal counter\n");
 	curOffset += growth;
 	if (curOffset + loadOffset > currentSection->size)
diff --git a/test/asm/section-unsigned-overflow.asm b/test/asm/section-unsigned-overflow.asm
index 0817389c4..2b19b2ef9 100644
--- a/test/asm/section-unsigned-overflow.asm
+++ b/test/asm/section-unsigned-overflow.asm
@@ -1,9 +1,9 @@
 section "overflow", rom0
 rept 10
-	ds $4000_0000
+	ds $4000
 endr
 
 section "moar overflow", romx
 rept 10
-	ds $4000_0000
+	ds $4000
 endr