github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/syscall/exec_pdeathsig_test.go (about) 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 //go:build freebsd || linux 6 7 package syscall_test 8 9 import ( 10 "bufio" 11 "fmt" 12 "io" 13 "os" 14 "os/exec" 15 "os/signal" 16 "path/filepath" 17 "syscall" 18 "testing" 19 "time" 20 ) 21 22 func TestDeathSignal(t *testing.T) { 23 if os.Getuid() != 0 { 24 t.Skip("skipping root only test") 25 } 26 27 // Copy the test binary to a location that a non-root user can read/execute 28 // after we drop privileges 29 tempDir, err := os.MkdirTemp("", "TestDeathSignal") 30 if err != nil { 31 t.Fatalf("cannot create temporary directory: %v", err) 32 } 33 defer os.RemoveAll(tempDir) 34 os.Chmod(tempDir, 0755) 35 36 tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0])) 37 38 src, err := os.Open(os.Args[0]) 39 if err != nil { 40 t.Fatalf("cannot open binary %q, %v", os.Args[0], err) 41 } 42 defer src.Close() 43 44 dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755) 45 if err != nil { 46 t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err) 47 } 48 if _, err := io.Copy(dst, src); err != nil { 49 t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err) 50 } 51 err = dst.Close() 52 if err != nil { 53 t.Fatalf("failed to close test binary %q, %v", tmpBinary, err) 54 } 55 56 cmd := exec.Command(tmpBinary) 57 cmd.Env = append(os.Environ(), "GO_DEATHSIG_PARENT=1") 58 chldStdin, err := cmd.StdinPipe() 59 if err != nil { 60 t.Fatalf("failed to create new stdin pipe: %v", err) 61 } 62 chldStdout, err := cmd.StdoutPipe() 63 if err != nil { 64 t.Fatalf("failed to create new stdout pipe: %v", err) 65 } 66 cmd.Stderr = os.Stderr 67 68 err = cmd.Start() 69 defer cmd.Wait() 70 if err != nil { 71 t.Fatalf("failed to start first child process: %v", err) 72 } 73 74 chldPipe := bufio.NewReader(chldStdout) 75 76 if got, err := chldPipe.ReadString('\n'); got == "start\n" { 77 syscall.Kill(cmd.Process.Pid, syscall.SIGTERM) 78 79 go func() { 80 time.Sleep(5 * time.Second) 81 chldStdin.Close() 82 }() 83 84 want := "ok\n" 85 if got, err = chldPipe.ReadString('\n'); got != want { 86 t.Fatalf("expected %q, received %q, %v", want, got, err) 87 } 88 } else { 89 t.Fatalf("did not receive start from child, received %q, %v", got, err) 90 } 91 } 92 93 func deathSignalParent() { 94 cmd := exec.Command(os.Args[0]) 95 cmd.Env = append(os.Environ(), 96 "GO_DEATHSIG_PARENT=", 97 "GO_DEATHSIG_CHILD=1", 98 ) 99 cmd.Stdin = os.Stdin 100 cmd.Stdout = os.Stdout 101 attrs := syscall.SysProcAttr{ 102 Pdeathsig: syscall.SIGUSR1, 103 // UID/GID 99 is the user/group "nobody" on RHEL/Fedora and is 104 // unused on Ubuntu 105 Credential: &syscall.Credential{Uid: 99, Gid: 99}, 106 } 107 cmd.SysProcAttr = &attrs 108 109 err := cmd.Start() 110 if err != nil { 111 fmt.Fprintf(os.Stderr, "death signal parent error: %v\n", err) 112 os.Exit(1) 113 } 114 cmd.Wait() 115 os.Exit(0) 116 } 117 118 func deathSignalChild() { 119 c := make(chan os.Signal, 1) 120 signal.Notify(c, syscall.SIGUSR1) 121 go func() { 122 <-c 123 fmt.Println("ok") 124 os.Exit(0) 125 }() 126 fmt.Println("start") 127 128 buf := make([]byte, 32) 129 os.Stdin.Read(buf) 130 131 // We expected to be signaled before stdin closed 132 fmt.Println("not ok") 133 os.Exit(1) 134 }