kernel: user safe strlen

src/include/kernel/sched.h

@@ -42,6 +42,8 @@ typedef struct _thread_t{
 	vmm_context* ctx;
 	pid_t tid;
 	int priority;
+	int umemoperror;
+	void (*umemopfailaddr)();
 } thread_t;
 
 typedef struct _proc_t{

src/include/kernel/ustring.h

@@ -0,0 +1,9 @@
+#ifndef _USTRING_H_INCLUDE
+#define _USTRING_H_INCLUDE
+
+#include <stddef.h>
+
+int u_strlen(const char* str, size_t* size);
+
+
+#endif