github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/gohacks/gohacks_test.go (about)

     1  // Copyright 2021 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package gohacks
    16  
    17  import (
    18  	"io/ioutil"
    19  	"math/rand"
    20  	"os"
    21  	"runtime/debug"
    22  	"testing"
    23  
    24  	"golang.org/x/sys/unix"
    25  )
    26  
    27  func randBuf(size int) []byte {
    28  	b := make([]byte, size)
    29  	for i := range b {
    30  		b[i] = byte(rand.Intn(256))
    31  	}
    32  	return b
    33  }
    34  
    35  // Size of a page in bytes. Cloned from hostarch.PageSize to avoid a circular
    36  // dependency.
    37  const pageSize = 4096
    38  
    39  func testCopy(dst, src []byte) (panicked bool) {
    40  	defer func() {
    41  		if r := recover(); r != nil {
    42  			panicked = true
    43  		}
    44  	}()
    45  	debug.SetPanicOnFault(true)
    46  	copy(dst, src)
    47  	return panicked
    48  }
    49  
    50  func TestSegVOnMemmove(t *testing.T) {
    51  	// Test that SIGSEGVs received by runtime.memmove when *not* doing
    52  	// CopyIn or CopyOut work gets propagated to the runtime.
    53  	const bufLen = pageSize
    54  	a, err := unix.Mmap(-1, 0, bufLen, unix.PROT_NONE, unix.MAP_ANON|unix.MAP_PRIVATE)
    55  	if err != nil {
    56  		t.Fatalf("Mmap failed: %v", err)
    57  
    58  	}
    59  	defer unix.Munmap(a)
    60  	b := randBuf(bufLen)
    61  
    62  	if !testCopy(b, a) {
    63  		t.Fatalf("testCopy didn't panic when it should have")
    64  	}
    65  
    66  	if !testCopy(a, b) {
    67  		t.Fatalf("testCopy didn't panic when it should have")
    68  	}
    69  }
    70  
    71  func TestSigbusOnMemmove(t *testing.T) {
    72  	// Test that SIGBUS received by runtime.memmove when *not* doing
    73  	// CopyIn or CopyOut work gets propagated to the runtime.
    74  	const bufLen = pageSize
    75  	f, err := ioutil.TempFile("", "sigbus_test")
    76  	if err != nil {
    77  		t.Fatalf("TempFile failed: %v", err)
    78  	}
    79  	os.Remove(f.Name())
    80  	defer f.Close()
    81  
    82  	a, err := unix.Mmap(int(f.Fd()), 0, bufLen, unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED)
    83  	if err != nil {
    84  		t.Fatalf("Mmap failed: %v", err)
    85  
    86  	}
    87  	defer unix.Munmap(a)
    88  	b := randBuf(bufLen)
    89  
    90  	if !testCopy(b, a) {
    91  		t.Fatalf("testCopy didn't panic when it should have")
    92  	}
    93  
    94  	if !testCopy(a, b) {
    95  		t.Fatalf("testCopy didn't panic when it should have")
    96  	}
    97  }