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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2022 WireGuard LLC. All Rights Reserved.
*/
package tun
import (
"reflect"
"testing"
"unsafe"
)
func checkAlignment(t *testing.T, name string, offset uintptr) {
t.Helper()
if offset%8 != 0 {
t.Errorf("offset of %q within struct is %d bytes, which does not align to 64-bit word boundaries (missing %d bytes). Atomic operations will crash on 32-bit systems.", name, offset, 8-(offset%8))
}
}
// TestRateJugglerAlignment checks that atomically-accessed fields are
// aligned to 64-bit boundaries, as required by the atomic package.
//
// Unfortunately, violating this rule on 32-bit platforms results in a
// hard segfault at runtime.
func TestRateJugglerAlignment(t *testing.T) {
var r rateJuggler
typ := reflect.TypeOf(&r).Elem()
t.Logf("Peer type size: %d, with fields:", typ.Size())
for i := 0; i < typ.NumField(); i++ {
field := typ.Field(i)
t.Logf("\t%30s\toffset=%3v\t(type size=%3d, align=%d)",
field.Name,
field.Offset,
field.Type.Size(),
field.Type.Align(),
)
}
checkAlignment(t, "rateJuggler.current", unsafe.Offsetof(r.current))
checkAlignment(t, "rateJuggler.nextByteCount", unsafe.Offsetof(r.nextByteCount))
checkAlignment(t, "rateJuggler.nextStartTime", unsafe.Offsetof(r.nextStartTime))
}
// TestNativeTunAlignment checks that atomically-accessed fields are
// aligned to 64-bit boundaries, as required by the atomic package.
//
// Unfortunately, violating this rule on 32-bit platforms results in a
// hard segfault at runtime.
func TestNativeTunAlignment(t *testing.T) {
var tun NativeTun
typ := reflect.TypeOf(&tun).Elem()
t.Logf("Peer type size: %d, with fields:", typ.Size())
for i := 0; i < typ.NumField(); i++ {
field := typ.Field(i)
t.Logf("\t%30s\toffset=%3v\t(type size=%3d, align=%d)",
field.Name,
field.Offset,
field.Type.Size(),
field.Type.Align(),
)
}
checkAlignment(t, "NativeTun.rate", unsafe.Offsetof(tun.rate))
}
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