From c66b05216d911923aeda4ce3561fa08196b3f31f Mon Sep 17 00:00:00 2001
From: fef <owo@fef.moe>
Date: Sun, 24 Oct 2021 21:55:54 +0200
Subject: [PATCH] clist: add better debugging facilities

---
 cmake/config.cmake      |  4 +++-
 include/gay/clist.h     | 21 +++++++++++++++++
 include/gay/config.h.in |  3 +++
 include/gay/util.h      | 16 ++++---------
 kernel/clist.c          | 51 ++++++++++++++++++++++++++++++++++++++---
 5 files changed, 80 insertions(+), 15 deletions(-)

diff --git a/cmake/config.cmake b/cmake/config.cmake
index fbba136..5bbcc95 100644
--- a/cmake/config.cmake
+++ b/cmake/config.cmake
@@ -14,7 +14,9 @@ option(CFG_POISON_PAGES "Poison pages after allocate and free" ON)
 
 option(CFG_POISON_HEAP "Poison heap memory after kmalloc() and kfree()" ON)
 
-option(CFG_DEBUG_IRQ "Debug IRQs" ON)
+option(CFG_DEBUG_IRQ "Debug IRQs" ${DEBUG})
+
+option(CFG_DEBUG_CLIST "Sanitize clist operations" ${DEBUG})
 
 option(CFG_DEBUG_PAGE_ALLOCS "Debug page frame allocations" OFF)
 
diff --git a/include/gay/clist.h b/include/gay/clist.h
index 57cb5c7..fc26ae1 100644
--- a/include/gay/clist.h
+++ b/include/gay/clist.h
@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <gay/config.h>
 #include <gay/util.h>
 
 /**
@@ -62,6 +63,26 @@ void clist_add_first(struct clist *head, struct clist *new);
  */
 void clist_del(struct clist *node);
 
+/**
+ * @brief Remove and return the first node in a clist.
+ * If the list is empty and `CFG_DEBUG_CLIST` is defined, this returns nil.
+ * If `CFG_DEBUG_CLIST` is not defined in this case, it will blow up.
+ *
+ * @param head Head of the list
+ * @return The deleted node
+ */
+struct clist *clist_del_first(struct clist *head);
+
+/**
+ * @brief Remove and return the last node in a clist.
+ * If the list is empty and `CFG_DEBUG_CLIST` is defined, this returns nil.
+ * If `CFG_DEBUG_CLIST` is not defined in this case, it will blow up.
+ *
+ * @param head Head of the list
+ * @return The deleted node
+ */
+struct clist *clist_del_last(struct clist *head);
+
 /**
  * @brief Return whether a clist is empty.
  *
diff --git a/include/gay/config.h.in b/include/gay/config.h.in
index 822789c..4efd91b 100644
--- a/include/gay/config.h.in
+++ b/include/gay/config.h.in
@@ -34,6 +34,9 @@
 /** @brief Debug IRQs */
 #cmakedefine01 CFG_DEBUG_IRQ
 
+/** @brief Sanitize clist operations */
+#cmakedefine01 CFG_DEBUG_CLIST
+
 /** @brief Debug page frame allocations */
 #cmakedefine01 CFG_DEBUG_PAGE_ALLOCS
 
diff --git a/include/gay/util.h b/include/gay/util.h
index 99e534b..98f1078 100644
--- a/include/gay/util.h
+++ b/include/gay/util.h
@@ -41,17 +41,11 @@
 #define container_of(ptr, type, member) \
 	((type *)( (void *)(ptr) - offsetof(type, member) ))
 
-/**
- * @brief Do an evil raw cast.
- *
- * @param type Type to cast to
- * @param expr Expression to cast
- * @returns The raw value of `expr`, cast to `type`
- */
-#define raw_cast(type, expr) ({		\
-	typeof(expr) __expr = (expr);	\
-	*(type *)&__expr;		\
-})
+/** @brief Determine whether `ptr` is kinda sus. */
+static __always_inline bool sus_nil(const void *ptr)
+{
+	return ptr < (void *)0x1000;
+}
 
 /**
  * @brief Align `ptr` such that `ptr % n == 0`.
diff --git a/kernel/clist.c b/kernel/clist.c
index 19353b8..45f7cf8 100644
--- a/kernel/clist.c
+++ b/kernel/clist.c
@@ -2,15 +2,32 @@
 
 #include <gay/clist.h>
 #include <gay/config.h>
+#include <gay/kprintf.h>
 
 void clist_init(struct clist *head)
 {
+#	if CFG_DEBUG_CLIST
+		if (head->next == head && head->prev == head)
+			kprintf("clist_init(%p) called multiple times\n", head);
+#	endif
+
 	head->next = head;
 	head->prev = head;
 }
 
 void clist_add(struct clist *head, struct clist *new)
 {
+#	if CFG_DEBUG_CLIST
+		if (sus_nil(head->next) || sus_nil(head->prev)) {
+			kprintf("clist_add(%p, %p): head seems uninitialized\n", head, new);
+			return;
+		}
+		if (sus_nil(new)) {
+			kprintf("clist_add(%p, %p): new node is NULL!\n", head, new);
+			return;
+		}
+#	endif
+
 	head->prev->next = new;
 	new->next = head;
 
@@ -32,10 +49,38 @@ void clist_del(struct clist *node)
 	node->next->prev = node->prev;
 	node->prev->next = node->next;
 
-#	ifdef DEBUG
-		node->next = NULL;
-		node->prev = NULL;
+#	if CFG_DEBUG_CLIST
+		node->next = nil;
+		node->prev = nil;
+#	endif
+}
+
+struct clist *clist_del_first(struct clist *head)
+{
+#	if CFG_DEBUG_CLIST
+		if (clist_is_empty(head)) {
+			kprintf("clist_del_first(%p): empty list!\n", head);
+			return nil;
+		}
 #	endif
+
+	struct clist *first = head->next;
+	clist_del(first);
+	return first;
+}
+
+struct clist *clist_del_last(struct clist *head)
+{
+#	ifdef CFG_DEBUG_CLIST
+		if (clist_is_empty(head)) {
+			kprintf("clist_del_last(%p): empty list!\n", head);
+			return nil;
+		}
+#	endif
+
+	struct clist *last = head->prev;
+	clist_del(last);
+	return last;
 }
 
 /*