Added <errno.h> and made kernel use it

kernel/src/idt.c

@@ -1,5 +1,7 @@
 #include <kernel.h>
 #include <string.h>
+#include <system.h>
+#include <errno.h>
 #include <gdt.h>
 #include <idt.h>
 
@@ -7,25 +9,27 @@ __align(16) // performace
 static struct idt_entry idt[IDT_ENTRIES];
 static struct idt_pointer idtp;
 
-void idt_set_gate(uint8_t i, void* handler, uint8_t attrib) {
+void idt_set_gate(uint8_t i, void* handler, uint8_t attrib, uint8_t ist) {
 	size_t addr = (size_t)handler;
 	idt[i].offset_low = (uint16_t)addr;
 	idt[i].selector = GDT_KERNEL_CODE;
-	idt[i].ist = 0;
-	idt[i].__reserved = 0;
+	idt[i].ist = ist & 7;
 	idt[i].attrib = attrib;
 	idt[i].offset_mid = (uint16_t)(addr >> 16);
 	idt[i].offset_high = (uint32_t)(addr >> 32);
+	idt[i].__reserved = 0;
 }
 
 int idt_init(void) {
+	memset(idt, 0, sizeof(idt));
+
 	idtp.size = sizeof(idt) - 1;
-	idtp.offset = (size_t)&idt;
+	idtp.offset = (uintptr_t)&idt;
 
 	// Load IDT instruction
+	cli();
 	__asm__ volatile ("lidt %0" : : "m"(idtp));
 
-	debugf("[idt] IDT initalized.\n");
-	return 0;
+	return SUCCESS;
 }