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![Richard Musiol](/assets/img/avatar_default.png)
The general policy for the current state of js/wasm is that it only has to support tests that are also supported by nacl. The test nilptr3.go makes assumptions about which nil checks can be removed. Since WebAssembly does not signal on reading a null pointer, all nil checks have to be explicit. Updates #18892 Change-Id: I06a687860b8d22ae26b1c391499c0f5183e4c485 Reviewed-on: https://go-review.googlesource.com/110096 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
81 lines
1.9 KiB
Go
81 lines
1.9 KiB
Go
// run
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// windows doesn't work, because Windows exception handling
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// delivers signals based on the current PC, and that current PC
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// doesn't go into the Go runtime.
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// +build !windows
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// wasm does not work, because the linear memory is not executable.
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// +build !wasm
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package main
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import (
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"encoding/binary"
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"runtime"
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"runtime/debug"
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"unsafe"
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)
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func main() {
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debug.SetPanicOnFault(true)
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defer func() {
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if err := recover(); err == nil {
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panic("not panicking")
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}
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pc, _, _, _ := runtime.Caller(10)
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f := runtime.FuncForPC(pc)
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if f == nil || f.Name() != "main.f" {
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if f == nil {
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println("no func for ", unsafe.Pointer(pc))
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} else {
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println("found func:", f.Name())
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}
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panic("cannot find main.f on stack")
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}
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}()
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f(20)
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}
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func f(n int) {
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if n > 0 {
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f(n - 1)
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}
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var f struct {
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x uintptr
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}
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// We want to force an illegal instruction, to get a crash
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// at a PC value != 0.
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// Not all systems make the data section non-executable.
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ill := make([]byte, 64)
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switch runtime.GOARCH {
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case "386", "amd64":
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binary.LittleEndian.PutUint16(ill, 0x0b0f) // ud2
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case "arm":
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binary.LittleEndian.PutUint32(ill, 0xe7f000f0) // no name, but permanently undefined
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case "arm64":
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binary.LittleEndian.PutUint32(ill, 0xd4207d00) // brk #1000
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case "ppc64":
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binary.BigEndian.PutUint32(ill, 0x7fe00008) // trap
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case "ppc64le":
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binary.LittleEndian.PutUint32(ill, 0x7fe00008) // trap
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case "mips", "mips64":
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binary.BigEndian.PutUint32(ill, 0x00000034) // trap
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case "mipsle", "mips64le":
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binary.LittleEndian.PutUint32(ill, 0x00000034) // trap
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case "s390x":
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binary.BigEndian.PutUint32(ill, 0) // undefined instruction
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default:
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// Just leave it as 0 and hope for the best.
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}
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f.x = uintptr(unsafe.Pointer(&ill[0]))
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fn := *(*func())(unsafe.Pointer(&f))
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fn()
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}
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