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// 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.
//go:build freebsd || linux
package syscall_test
import (
"bufio"
"fmt"
"io"
"os"
"os/exec"
"os/signal"
"path/filepath"
"syscall"
"testing"
"time"
)
func TestDeathSignal(t *testing.T) {
if os.Getuid() != 0 {
t.Skip("skipping root only test")
}
// Copy the test binary to a location that a non-root user can read/execute
// after we drop privileges
tempDir, err := os.MkdirTemp("", "TestDeathSignal")
if err != nil {
t.Fatalf("cannot create temporary directory: %v", err)
}
defer os.RemoveAll(tempDir)
os.Chmod(tempDir, 0755)
tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
src, err := os.Open(os.Args[0])
if err != nil {
t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
}
defer src.Close()
dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
if err != nil {
t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
}
if _, err := io.Copy(dst, src); err != nil {
t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
}
err = dst.Close()
if err != nil {
t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
}
cmd := exec.Command(tmpBinary)
cmd.Env = append(os.Environ(), "GO_DEATHSIG_PARENT=1")
chldStdin, err := cmd.StdinPipe()
if err != nil {
t.Fatalf("failed to create new stdin pipe: %v", err)
}
chldStdout, err := cmd.StdoutPipe()
if err != nil {
t.Fatalf("failed to create new stdout pipe: %v", err)
}
cmd.Stderr = os.Stderr
err = cmd.Start()
defer cmd.Wait()
if err != nil {
t.Fatalf("failed to start first child process: %v", err)
}
chldPipe := bufio.NewReader(chldStdout)
if got, err := chldPipe.ReadString('\n'); got == "start\n" {
syscall.Kill(cmd.Process.Pid, syscall.SIGTERM)
go func() {
time.Sleep(5 * time.Second)
chldStdin.Close()
}()
want := "ok\n"
if got, err = chldPipe.ReadString('\n'); got != want {
t.Fatalf("expected %q, received %q, %v", want, got, err)
}
} else {
t.Fatalf("did not receive start from child, received %q, %v", got, err)
}
}
func deathSignalParent() {
cmd := exec.Command(os.Args[0])
cmd.Env = append(os.Environ(),
"GO_DEATHSIG_PARENT=",
"GO_DEATHSIG_CHILD=1",
)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
attrs := syscall.SysProcAttr{
Pdeathsig: syscall.SIGUSR1,
// UID/GID 99 is the user/group "nobody" on RHEL/Fedora and is
// unused on Ubuntu
Credential: &syscall.Credential{Uid: 99, Gid: 99},
}
cmd.SysProcAttr = &attrs
err := cmd.Start()
if err != nil {
fmt.Fprintf(os.Stderr, "death signal parent error: %v\n", err)
os.Exit(1)
}
cmd.Wait()
os.Exit(0)
}
func deathSignalChild() {
c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGUSR1)
go func() {
<-c
fmt.Println("ok")
os.Exit(0)
}()
fmt.Println("start")
buf := make([]byte, 32)
os.Stdin.Read(buf)
// We expected to be signaled before stdin closed
fmt.Println("not ok")
os.Exit(1)
}
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