From 3fb475dc701b7cb6adcc92a6c088ca394bb72216 Mon Sep 17 00:00:00 2001
From: Midgard <midgard@zeus.ugent.be>
Date: Sat, 1 Feb 2020 23:13:50 +0100
Subject: [PATCH] Ringbuffer: add null checks and more const

---
 kernel/util/ringbuffer.c | 44 ++++++++++++++++++++++++++++++++++------
 1 file changed, 38 insertions(+), 6 deletions(-)

diff --git a/kernel/util/ringbuffer.c b/kernel/util/ringbuffer.c
index c1031c5..aa631a1 100644
--- a/kernel/util/ringbuffer.c
+++ b/kernel/util/ringbuffer.c
@@ -4,7 +4,21 @@
 #include "ringbuffer.h"
 #include "../memory.c"
 
-struct ringbuffer* rbfr_create(const int capacity, void (*destroy_element)(void*)) {
+#define ERROR(msg) \
+	do { \
+		/* TODO Do something error-ish */ \
+	} while(0)
+
+#define ASSERT_NONNULL_ARG(argument) { \
+	if (argument == NULL) { \
+		ERROR(__func__ " got NULL for argument '" #argument "'"); \
+	} \
+}
+
+
+struct ringbuffer* rbfr_create(const int capacity, void (*const destroy_element)(void*)) {
+	ASSERT_NONNULL_ARG(destroy_element);
+
 	struct ringbuffer* const this = alloc(sizeof (struct ringbuffer));
 
 	this->buffer = alloc(capacity * sizeof (void*));
@@ -17,21 +31,31 @@ struct ringbuffer* rbfr_create(const int capacity, void (*destroy_element)(void*
 	return this;
 }
 
-void rbfr_destroy(struct ringbuffer* this) {
+void rbfr_destroy(struct ringbuffer* const this) {
+	ASSERT_NONNULL_ARG(this);
+
 	rbfr_clear(this);
+
 	free(this->buffer);
+	this->buffer = NULL;
+
 	free(this);
 }
 
-int rbfr_size(const struct ringbuffer* this) {
+int rbfr_size(const struct ringbuffer* const this) {
+	ASSERT_NONNULL_ARG(this);
+
 	return this->size;
 }
 
 int rbfr_capacity(const struct ringbuffer* this) {
+	ASSERT_NONNULL_ARG(this);
 	return this->buffer_n;
 }
 
-void rbfr_enqueue(struct ringbuffer* this, void* element) {
+void rbfr_enqueue(struct ringbuffer* this, void* const element) {
+	ASSERT_NONNULL_ARG(this);
+
 	if (this->buffer_n == 0) {
 		return;
 	}
@@ -49,7 +73,10 @@ void rbfr_enqueue(struct ringbuffer* this, void* element) {
 	return;
 }
 
-bool rbfr_peek(const struct ringbuffer* this, void** element) {
+bool rbfr_peek(const struct ringbuffer *const this, void** element) {
+	ASSERT_NONNULL_ARG(this);
+	ASSERT_NONNULL_ARG(element);
+
 	if (this->size == 0) {
 		return false;
 	}
@@ -57,7 +84,10 @@ bool rbfr_peek(const struct ringbuffer* this, void** element) {
 	return true;
 }
 
-bool rbfr_dequeue(struct ringbuffer* this, void** element) {
+bool rbfr_dequeue(struct ringbuffer *const this, void** element) {
+	ASSERT_NONNULL_ARG(this);
+	ASSERT_NONNULL_ARG(element);
+
 	if (!rbfr_peek(this, element)) {
 		return false;
 	}
@@ -70,6 +100,8 @@ bool rbfr_dequeue(struct ringbuffer* this, void** element) {
 }
 
 void rbfr_clear(struct ringbuffer* this) {
+	ASSERT_NONNULL_ARG(this);
+
 	void* element;
 	while (rbfr_dequeue(this, &element)) {
 		this->destroy_element(element);