From d5a4c4340655708b2fe4193ed7881159fc871b82 Mon Sep 17 00:00:00 2001
From: Achilleas Anagnostopoulos <achilleas.imap.mbox@gmail.com>
Date: Wed, 31 May 2017 14:10:49 +0100
Subject: [PATCH] Define type for kernel error messages

Since the Go memory allocator is not available to us we need to define
our own error type.
---
 kernel/error.go      | 18 ++++++++++++++++++
 kernel/error_test.go | 14 ++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 kernel/error.go
 create mode 100644 kernel/error_test.go

diff --git a/kernel/error.go b/kernel/error.go
new file mode 100644
index 0000000..c3accfd
--- /dev/null
+++ b/kernel/error.go
@@ -0,0 +1,18 @@
+package kernel
+
+// Error describes a kernel kerror. All kernel errors must be defined as global
+// variables that are pointers to the Error structure. This requirement stems
+// from the fact that the Go allocator is not available to us so we cannot use
+// errors.New.
+type Error struct {
+	// The module where the error occurred.
+	Module string
+
+	// The error message
+	Message string
+}
+
+// Error implements the error interface.
+func (e *Error) Error() string {
+	return e.Message
+}
diff --git a/kernel/error_test.go b/kernel/error_test.go
new file mode 100644
index 0000000..64d1b43
--- /dev/null
+++ b/kernel/error_test.go
@@ -0,0 +1,14 @@
+package kernel
+
+import "testing"
+
+func TestKernelError(t *testing.T) {
+	err := &Error{
+		Module:  "foo",
+		Message: "error message",
+	}
+
+	if err.Error() != err.Message {
+		t.Fatalf("expected to err.Error() to return %q; got %q", err.Message, err.Error())
+	}
+}