From 4680eaaef15171948332ad7d13def794635c095d Mon Sep 17 00:00:00 2001
From: Joe Richey <joerichey@google.com>
Date: Wed, 1 Mar 2017 16:57:27 -0800
Subject: util: convenience utilities for fscrypt

This commit adds in the util package. This package provides
two functions for creating errors. These functions are:
	- InvalidInputErrorF - bad input from user or caller
	- SystemErrorF - low level failure

It also adds in a small function for converting Go byte slices into C
void pointers. This will be very useful for interoperating with C.

Change-Id: I87ad7946dd5fa26e28927590aff4bcc9fd5ce4f7
---
 util/errors.go    | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 util/util.go      | 33 ++++++++++++++++++++++++++++++
 util/util_test.go | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 143 insertions(+)
 create mode 100644 util/errors.go
 create mode 100644 util/util.go
 create mode 100644 util/util_test.go

(limited to 'util')

diff --git a/util/errors.go b/util/errors.go
new file mode 100644
index 0000000..aafeadd
--- /dev/null
+++ b/util/errors.go
@@ -0,0 +1,50 @@
+/*
+ * errors.go - Custom errors and error functions used by fscrypt
+ *
+ * Copyright 2017 Google Inc.
+ * Author: Joe Richey (joerichey@google.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package util
+
+import (
+	"fmt"
+	"log"
+)
+
+// InvalidInputF creates an error that should indicate either bad input from a
+// caller of a public library function or bad user input.
+func InvalidInputF(format string, a ...interface{}) error {
+	return fmt.Errorf("invalid input: "+format, a...)
+}
+
+// InvalidLengthError indicates name should have had length expected.
+func InvalidLengthError(name string, expected int, actual int) error {
+	return InvalidInputF("expected %s of length %d, actual length was %d", name, expected, actual)
+}
+
+// SystemErrorF creates an error that should indicate something has gone wrong
+// in the underlying system (syscall failure, bad ioctl, etc...).
+func SystemErrorF(format string, a ...interface{}) error {
+	return fmt.Errorf("system error: "+format, a...)
+}
+
+// NeverError panics if a non-nil error is passed in. It should be used to check
+// for logic errors, not to handle recoverable errors.
+func NeverError(err error) {
+	if err != nil {
+		log.Panicf("NeverError() check failed: %v", err)
+	}
+}
diff --git a/util/util.go b/util/util.go
new file mode 100644
index 0000000..9439d0e
--- /dev/null
+++ b/util/util.go
@@ -0,0 +1,33 @@
+/*
+ * util.go - Various helpers used throughout fscrypt
+ *
+ * Copyright 2017 Google Inc.
+ * Author: Joe Richey (joerichey@google.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+// Package util contains useful components for simplifying Go code.
+//
+// The package contains common error types (errors.go) and functions for
+// converting arrays to pointers.
+package util
+
+import (
+	"unsafe"
+)
+
+// Ptr converts an Go byte array to a pointer to the start of the array.
+func Ptr(slice []byte) unsafe.Pointer {
+	return unsafe.Pointer(&slice[0])
+}
diff --git a/util/util_test.go b/util/util_test.go
new file mode 100644
index 0000000..65541b3
--- /dev/null
+++ b/util/util_test.go
@@ -0,0 +1,60 @@
+/*
+ * util_test.go - Tests the util package
+ *
+ * Copyright 2017 Google Inc.
+ * Author: Joe Richey (joerichey@google.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package util
+
+import (
+	"testing"
+)
+
+const offset = 3
+
+// Make sure the address behaves well under slicing
+func TestPtrOffset(t *testing.T) {
+	arr := []byte{'a', 'b', 'c', 'd'}
+	i1 := uintptr(Ptr(arr[offset:]))
+	i2 := uintptr(Ptr(arr))
+
+	if i1 != i2+offset {
+		t.Fatalf("pointers %v and %v do not have an offset of %v", i1, i2, offset)
+	}
+}
+
+// Make sure NeverError actually panics
+func TestNeverErrorPanic(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("NeverError did not panic")
+		}
+	}()
+
+	err := SystemErrorF("Hello")
+	NeverError(err)
+}
+
+// Make sure NeverError doesn't panic on nil
+func TestNeverErrorNoPanic(t *testing.T) {
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("NeverError panicked")
+		}
+	}()
+
+	NeverError(nil)
+}
-- 
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