mirror of
https://github.com/golang/go
synced 2024-11-14 23:20:27 -07:00
b2fd76ab8d
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
|
|
|
|
//go:build linux || darwin
|
|
|
|
// Copyright 2015 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.
|
|
|
|
// Test that if a slice access causes a fault, a deferred func
|
|
// sees the most recent value of the variables it accesses.
|
|
// This is true today; the role of the test is to ensure it stays true.
|
|
//
|
|
// In the test, memcopy is the function that will fault, during dst[i] = src[i].
|
|
// The deferred func recovers from the error and returns, making memcopy
|
|
// return the current value of n. If n is not being flushed to memory
|
|
// after each modification, the result will be a stale value of n.
|
|
//
|
|
// The test is set up by mmapping a 64 kB block of memory and then
|
|
// unmapping a 16 kB hole in the middle of it. Running memcopy
|
|
// on the resulting slice will fault when it reaches the hole.
|
|
|
|
package main
|
|
|
|
import (
|
|
"log"
|
|
"runtime/debug"
|
|
"syscall"
|
|
)
|
|
|
|
func memcopy(dst, src []byte) (n int, err error) {
|
|
defer func() {
|
|
if r, ok := recover().(error); ok {
|
|
err = r
|
|
}
|
|
}()
|
|
|
|
for i := 0; i < len(dst) && i < len(src); i++ {
|
|
dst[i] = src[i]
|
|
n++
|
|
}
|
|
return
|
|
}
|
|
|
|
func main() {
|
|
// Turn the eventual fault into a panic, not a program crash,
|
|
// so that memcopy can recover.
|
|
debug.SetPanicOnFault(true)
|
|
|
|
size := syscall.Getpagesize()
|
|
|
|
// Map 16 pages of data with a 4-page hole in the middle.
|
|
data, err := syscall.Mmap(-1, 0, 16*size, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
|
|
if err != nil {
|
|
log.Fatalf("mmap: %v", err)
|
|
}
|
|
|
|
// Create a hole in the mapping that's PROT_NONE.
|
|
// Note that we can't use munmap here because the Go runtime
|
|
// could create a mapping that ends up in this hole otherwise,
|
|
// invalidating the test.
|
|
hole := data[len(data)/2 : 3*(len(data)/4)]
|
|
if err := syscall.Mprotect(hole, syscall.PROT_NONE); err != nil {
|
|
log.Fatalf("mprotect: %v", err)
|
|
}
|
|
|
|
// Check that memcopy returns the actual amount copied
|
|
// before the fault.
|
|
const offset = 5
|
|
n, err := memcopy(data[offset:], make([]byte, len(data)))
|
|
if err == nil {
|
|
log.Fatal("no error from memcopy across memory hole")
|
|
}
|
|
if expect := len(data)/2 - offset; n != expect {
|
|
log.Fatalf("memcopy returned %d, want %d", n, expect)
|
|
}
|
|
}
|