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Most of the test cases in the test directory use the new go:build syntax already. Convert the rest. In general, try to place the build constraint line below the test directive comment in more places. For #41184. For #60268. Change-Id: I11c41a0642a8a26dc2eda1406da908645bbc005b Cq-Include-Trybots: luci.golang.try:gotip-linux-386-longtest,gotip-linux-amd64-longtest,gotip-windows-amd64-longtest Reviewed-on: https://go-review.googlesource.com/c/go/+/536236 Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
77 lines
2.2 KiB
Go
77 lines
2.2 KiB
Go
// run
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//go:build linux || darwin
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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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// Test that if a slice access causes a fault, a deferred func
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// sees the most recent value of the variables it accesses.
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// This is true today; the role of the test is to ensure it stays true.
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//
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// In the test, memcopy is the function that will fault, during dst[i] = src[i].
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// The deferred func recovers from the error and returns, making memcopy
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// return the current value of n. If n is not being flushed to memory
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// after each modification, the result will be a stale value of n.
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//
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// The test is set up by mmapping a 64 kB block of memory and then
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// unmapping a 16 kB hole in the middle of it. Running memcopy
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// on the resulting slice will fault when it reaches the hole.
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package main
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import (
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"log"
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"runtime/debug"
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"syscall"
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)
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func memcopy(dst, src []byte) (n int, err error) {
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defer func() {
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if r, ok := recover().(error); ok {
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err = r
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}
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}()
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for i := 0; i < len(dst) && i < len(src); i++ {
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dst[i] = src[i]
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n++
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}
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return
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}
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func main() {
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// Turn the eventual fault into a panic, not a program crash,
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// so that memcopy can recover.
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debug.SetPanicOnFault(true)
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size := syscall.Getpagesize()
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// Map 16 pages of data with a 4-page hole in the middle.
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data, err := syscall.Mmap(-1, 0, 16*size, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
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if err != nil {
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log.Fatalf("mmap: %v", err)
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}
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// Create a hole in the mapping that's PROT_NONE.
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// Note that we can't use munmap here because the Go runtime
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// could create a mapping that ends up in this hole otherwise,
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// invalidating the test.
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hole := data[len(data)/2 : 3*(len(data)/4)]
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if err := syscall.Mprotect(hole, syscall.PROT_NONE); err != nil {
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log.Fatalf("mprotect: %v", err)
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}
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// Check that memcopy returns the actual amount copied
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// before the fault.
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const offset = 5
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n, err := memcopy(data[offset:], make([]byte, len(data)))
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if err == nil {
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log.Fatal("no error from memcopy across memory hole")
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}
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if expect := len(data)/2 - offset; n != expect {
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log.Fatalf("memcopy returned %d, want %d", n, expect)
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}
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}
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