Current File : //usr/local/go119/src/crypto/internal/edwards25519/field/fe_alias_test.go
// Copyright (c) 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package field
import (
"testing"
"testing/quick"
)
func checkAliasingOneArg(f func(v, x *Element) *Element) func(v, x Element) bool {
return func(v, x Element) bool {
x1, v1 := x, x
// Calculate a reference f(x) without aliasing.
if out := f(&v, &x); out != &v && isInBounds(out) {
return false
}
// Test aliasing the argument and the receiver.
if out := f(&v1, &v1); out != &v1 || v1 != v {
return false
}
// Ensure the arguments was not modified.
return x == x1
}
}
func checkAliasingTwoArgs(f func(v, x, y *Element) *Element) func(v, x, y Element) bool {
return func(v, x, y Element) bool {
x1, y1, v1 := x, y, Element{}
// Calculate a reference f(x, y) without aliasing.
if out := f(&v, &x, &y); out != &v && isInBounds(out) {
return false
}
// Test aliasing the first argument and the receiver.
v1 = x
if out := f(&v1, &v1, &y); out != &v1 || v1 != v {
return false
}
// Test aliasing the second argument and the receiver.
v1 = y
if out := f(&v1, &x, &v1); out != &v1 || v1 != v {
return false
}
// Calculate a reference f(x, x) without aliasing.
if out := f(&v, &x, &x); out != &v {
return false
}
// Test aliasing the first argument and the receiver.
v1 = x
if out := f(&v1, &v1, &x); out != &v1 || v1 != v {
return false
}
// Test aliasing the second argument and the receiver.
v1 = x
if out := f(&v1, &x, &v1); out != &v1 || v1 != v {
return false
}
// Test aliasing both arguments and the receiver.
v1 = x
if out := f(&v1, &v1, &v1); out != &v1 || v1 != v {
return false
}
// Ensure the arguments were not modified.
return x == x1 && y == y1
}
}
// TestAliasing checks that receivers and arguments can alias each other without
// leading to incorrect results. That is, it ensures that it's safe to write
//
// v.Invert(v)
//
// or
//
// v.Add(v, v)
//
// without any of the inputs getting clobbered by the output being written.
func TestAliasing(t *testing.T) {
type target struct {
name string
oneArgF func(v, x *Element) *Element
twoArgsF func(v, x, y *Element) *Element
}
for _, tt := range []target{
{name: "Absolute", oneArgF: (*Element).Absolute},
{name: "Invert", oneArgF: (*Element).Invert},
{name: "Negate", oneArgF: (*Element).Negate},
{name: "Set", oneArgF: (*Element).Set},
{name: "Square", oneArgF: (*Element).Square},
{name: "Pow22523", oneArgF: (*Element).Pow22523},
{
name: "Mult32",
oneArgF: func(v, x *Element) *Element {
return v.Mult32(x, 0xffffffff)
},
},
{name: "Multiply", twoArgsF: (*Element).Multiply},
{name: "Add", twoArgsF: (*Element).Add},
{name: "Subtract", twoArgsF: (*Element).Subtract},
{
name: "SqrtRatio",
twoArgsF: func(v, x, y *Element) *Element {
r, _ := v.SqrtRatio(x, y)
return r
},
},
{
name: "Select0",
twoArgsF: func(v, x, y *Element) *Element {
return v.Select(x, y, 0)
},
},
{
name: "Select1",
twoArgsF: func(v, x, y *Element) *Element {
return v.Select(x, y, 1)
},
},
} {
var err error
switch {
case tt.oneArgF != nil:
err = quick.Check(checkAliasingOneArg(tt.oneArgF), &quick.Config{MaxCountScale: 1 << 8})
case tt.twoArgsF != nil:
err = quick.Check(checkAliasingTwoArgs(tt.twoArgsF), &quick.Config{MaxCountScale: 1 << 8})
}
if err != nil {
t.Errorf("%v: %v", tt.name, err)
}
}
}
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