From edbc60a3fb9b0a22808b569a97a0439f0b21135c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomasharte@Xiaoyuns-MacBook.local>
Date: Tue, 17 Oct 2017 20:50:46 -0400
Subject: [PATCH] Various undefined behaviour fixes.

Primarily around uninitialised variables, but also with an attempted use of a negative pointer.
---
 Machines/AmstradCPC/AmstradCPC.cpp       | 30 ++++++++----------------
 Outputs/CRT/Internals/ArrayBuilder.cpp   |  4 +---
 Outputs/CRT/Internals/ArrayBuilder.hpp   | 12 +++++-----
 Outputs/CRT/Internals/TextureBuilder.cpp | 10 ++++----
 4 files changed, 22 insertions(+), 34 deletions(-)

diff --git a/Machines/AmstradCPC/AmstradCPC.cpp b/Machines/AmstradCPC/AmstradCPC.cpp
index 4c04db4c4..78486a1d8 100644
--- a/Machines/AmstradCPC/AmstradCPC.cpp
+++ b/Machines/AmstradCPC/AmstradCPC.cpp
@@ -155,18 +155,8 @@ class AYDeferrer {
 class CRTCBusHandler {
 	public:
 		CRTCBusHandler(uint8_t *ram, InterruptTimer &interrupt_timer) :
-			cycles_(0),
-			was_enabled_(false),
-			was_sync_(false),
-			pixel_data_(nullptr),
-			pixel_pointer_(nullptr),
-			was_hsync_(false),
 			ram_(ram),
-			interrupt_timer_(interrupt_timer),
-			pixel_divider_(1),
-			mode_(2),
-			next_mode_(2),
-			cycles_into_hsync_(0) {
+			interrupt_timer_(interrupt_timer) {
 				establish_palette_hits();
 				build_mode_table();
 			}
@@ -500,19 +490,19 @@ class CRTCBusHandler {
 			return mapping[colour];
 		}
 
-		unsigned int cycles_;
+		unsigned int cycles_ = 0;
 
-		bool was_enabled_, was_sync_, was_hsync_, was_vsync_;
-		int cycles_into_hsync_;
+		bool was_enabled_ = false, was_sync_ = false, was_hsync_ = false, was_vsync_ = false;
+		int cycles_into_hsync_ = 0;
 
 		std::shared_ptr<Outputs::CRT::CRT> crt_;
-		uint8_t *pixel_data_, *pixel_pointer_;
+		uint8_t *pixel_data_ = nullptr, *pixel_pointer_ = nullptr;
 
-		uint8_t *ram_;
+		uint8_t *ram_ = nullptr;
 
-		int next_mode_, mode_;
+		int next_mode_ = 2, mode_ = 2;
 
-		unsigned int pixel_divider_;
+		unsigned int pixel_divider_ = 1;
 		uint16_t mode0_output_[256];
 		uint32_t mode1_output_[256];
 		uint64_t mode2_output_[256];
@@ -522,9 +512,9 @@ class CRTCBusHandler {
 		std::vector<uint8_t> mode1_palette_hits_[4];
 		std::vector<uint8_t> mode3_palette_hits_[4];
 
-		int pen_;
+		int pen_ = 0;
 		uint8_t palette_[16];
-		uint8_t border_;
+		uint8_t border_ = 0;
 
 		InterruptTimer &interrupt_timer_;
 };
diff --git a/Outputs/CRT/Internals/ArrayBuilder.cpp b/Outputs/CRT/Internals/ArrayBuilder.cpp
index 26216834c..1f09602f5 100644
--- a/Outputs/CRT/Internals/ArrayBuilder.cpp
+++ b/Outputs/CRT/Internals/ArrayBuilder.cpp
@@ -67,9 +67,7 @@ ArrayBuilder::Submission ArrayBuilder::submit() {
 }
 
 ArrayBuilder::Buffer::Buffer(size_t size, std::function<void(bool is_input, uint8_t *, size_t)> submission_function) :
-		is_full(false),
-		submission_function_(submission_function),
-		allocated_data(0), flushed_data(0), submitted_data(0) {
+		submission_function_(submission_function) {
 	if(!submission_function_) {
 		glGenBuffers(1, &buffer);
 		glBindBuffer(GL_ARRAY_BUFFER, buffer);
diff --git a/Outputs/CRT/Internals/ArrayBuilder.hpp b/Outputs/CRT/Internals/ArrayBuilder.hpp
index 1c02e5e68..adaf384ae 100644
--- a/Outputs/CRT/Internals/ArrayBuilder.hpp
+++ b/Outputs/CRT/Internals/ArrayBuilder.hpp
@@ -82,17 +82,17 @@ class ArrayBuilder {
 				void reset();
 
 			private:
-				bool is_full;
-				GLuint buffer;
+				bool is_full = false;
+				GLuint buffer = 0;
 				std::function<void(bool is_input, uint8_t *, size_t)> submission_function_;
 				std::vector<uint8_t> data;
-				size_t allocated_data;
-				size_t flushed_data;
-				size_t submitted_data;
+				size_t allocated_data = 0;
+				size_t flushed_data = 0;
+				size_t submitted_data = 0;
 		} output_, input_;
 		uint8_t *get_storage(size_t size, Buffer &buffer);
 
-		bool is_full_;
+		bool is_full_ = false;
 };
 
 }
diff --git a/Outputs/CRT/Internals/TextureBuilder.cpp b/Outputs/CRT/Internals/TextureBuilder.cpp
index 7fa46d955..945b440b1 100644
--- a/Outputs/CRT/Internals/TextureBuilder.cpp
+++ b/Outputs/CRT/Internals/TextureBuilder.cpp
@@ -99,13 +99,13 @@ void TextureBuilder::reduce_previous_allocation_to(size_t actual_length) {
 	// against rounding errors when this run is drawn.
 	// TODO: allow somebody else to specify the rule for generating a left-padding value and
 	// a right-padding value.
-	uint8_t *start_pointer = pointer_to_location(write_area_.x, write_area_.y);
-	memcpy(	&start_pointer[-bytes_per_pixel_],
-			start_pointer,
+	uint8_t *start_pointer = pointer_to_location(write_area_.x, write_area_.y) - bytes_per_pixel_;
+	memcpy(	start_pointer,
+			&start_pointer[bytes_per_pixel_],
 			bytes_per_pixel_);
 
-	memcpy(	&start_pointer[actual_length * bytes_per_pixel_],
-			&start_pointer[(actual_length - 1) * bytes_per_pixel_],
+	memcpy(	&start_pointer[(actual_length + 1) * bytes_per_pixel_],
+			&start_pointer[actual_length * bytes_per_pixel_],
 			bytes_per_pixel_);
 }