libgo/go/syscall/syscall_linux_test.go

   1 // Copyright 2015 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package syscall_test
   6
   7 import (
   8         "bufio"
   9         "fmt"
  10         "io"
  11         "io/ioutil"
  12         "os"
  13         "os/exec"
  14         "os/signal"
  15         "path/filepath"
  16         "syscall"
  17         "testing"
  18         "time"
  19 )
  20
  21 func TestMain(m *testing.M) {
  22         if os.Getenv("GO_DEATHSIG_PARENT") == "1" {
  23                 deathSignalParent()
  24         } else if os.Getenv("GO_DEATHSIG_CHILD") == "1" {
  25                 deathSignalChild()
  26         }
  27
  28         os.Exit(m.Run())
  29 }
  30
  31 func TestLinuxDeathSignal(t *testing.T) {
  32         if os.Getuid() != 0 {
  33                 t.Skip("skipping root only test")
  34         }
  35
  36         // Copy the test binary to a location that a non-root user can read/execute
  37         // after we drop privileges
  38         tempDir, err := ioutil.TempDir("", "TestDeathSignal")
  39         if err != nil {
  40                 t.Fatalf("cannot create temporary directory: %v", err)
  41         }
  42         defer os.RemoveAll(tempDir)
  43         os.Chmod(tempDir, 0755)
  44
  45         tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
  46
  47         src, err := os.Open(os.Args[0])
  48         if err != nil {
  49                 t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
  50         }
  51         defer src.Close()
  52
  53         dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
  54         if err != nil {
  55                 t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
  56         }
  57         if _, err := io.Copy(dst, src); err != nil {
  58                 t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
  59         }
  60         err = dst.Close()
  61         if err != nil {
  62                 t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
  63         }
  64
  65         cmd := exec.Command(tmpBinary)
  66         cmd.Env = []string{"GO_DEATHSIG_PARENT=1"}
  67         chldStdin, err := cmd.StdinPipe()
  68         if err != nil {
  69                 t.Fatalf("failed to create new stdin pipe: %v", err)
  70         }
  71         chldStdout, err := cmd.StdoutPipe()
  72         if err != nil {
  73                 t.Fatalf("failed to create new stdout pipe: %v", err)
  74         }
  75         cmd.Stderr = os.Stderr
  76
  77         err = cmd.Start()
  78         defer cmd.Wait()
  79         if err != nil {
  80                 t.Fatalf("failed to start first child process: %v", err)
  81         }
  82
  83         chldPipe := bufio.NewReader(chldStdout)
  84
  85         if got, err := chldPipe.ReadString('\n'); got == "start\n" {
  86                 syscall.Kill(cmd.Process.Pid, syscall.SIGTERM)
  87
  88                 go func() {
  89                         time.Sleep(5 * time.Second)
  90                         chldStdin.Close()
  91                 }()
  92
  93                 want := "ok\n"
  94                 if got, err = chldPipe.ReadString('\n'); got != want {
  95                         t.Fatalf("expected %q, received %q, %v", want, got, err)
  96                 }
  97         } else {
  98                 t.Fatalf("did not receive start from child, received %q, %v", got, err)
  99         }
 100 }
 101
 102 func deathSignalParent() {
 103         cmd := exec.Command(os.Args[0])
 104         cmd.Env = []string{"GO_DEATHSIG_CHILD=1"}
 105         cmd.Stdin = os.Stdin
 106         cmd.Stdout = os.Stdout
 107         attrs := syscall.SysProcAttr{
 108                 Pdeathsig: syscall.SIGUSR1,
 109                 // UID/GID 99 is the user/group "nobody" on RHEL/Fedora and is
 110                 // unused on Ubuntu
 111                 Credential: &syscall.Credential{Uid: 99, Gid: 99},
 112         }
 113         cmd.SysProcAttr = &attrs
 114
 115         err := cmd.Start()
 116         if err != nil {
 117                 fmt.Fprintf(os.Stderr, "death signal parent error: %v\n", err)
 118                 os.Exit(1)
 119         }
 120         cmd.Wait()
 121         os.Exit(0)
 122 }
 123
 124 func deathSignalChild() {
 125         c := make(chan os.Signal, 1)
 126         signal.Notify(c, syscall.SIGUSR1)
 127         go func() {
 128                 <-c
 129                 fmt.Println("ok")
 130                 os.Exit(0)
 131         }()
 132         fmt.Println("start")
 133
 134         buf := make([]byte, 32)
 135         os.Stdin.Read(buf)
 136
 137         // We expected to be signaled before stdin closed
 138         fmt.Println("not ok")
 139         os.Exit(1)
 140 }