LAB 4 IS DONE.

lab/inc/error.h

@@ -0,0 +1,23 @@
+/* See COPYRIGHT for copyright information. */
+
+#ifndef JOS_INC_ERROR_H
+#define JOS_INC_ERROR_H
+
+enum {
+	// Kernel error codes -- keep in sync with list in lib/printfmt.c.
+	E_UNSPECIFIED	= 1,	// Unspecified or unknown problem
+	E_BAD_ENV	,	// Environment doesn't exist or otherwise
+				// cannot be used in requested action
+	E_INVAL		,	// Invalid parameter
+	E_NO_MEM	,	// Request failed due to memory shortage
+	E_NO_FREE_ENV	,	// Attempt to create a new environment beyond
+				// the maximum allowed
+	E_FAULT		,	// Memory fault
+
+	E_IPC_NOT_RECV	,	// Attempt to send to env that is not recving
+	E_EOF		,	// Unexpected end of file
+
+	MAXERROR
+};
+
+#endif	// !JOS_INC_ERROR_H */