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// Copyright 2009 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.
// Use an external test to avoid os/exec -> net/http -> crypto/x509 -> os/exec
// circular dependency on non-cgo darwin.
package exec_test
import (
"bufio"
"bytes"
"context"
"errors"
"flag"
"fmt"
"internal/poll"
"internal/testenv"
"io"
"log"
"net"
"net/http"
"net/http/httptest"
"os"
"os/exec"
"os/exec/internal/fdtest"
"os/signal"
"path/filepath"
"runtime"
"runtime/debug"
"strconv"
"strings"
"sync"
"sync/atomic"
"testing"
"time"
)
// haveUnexpectedFDs is set at init time to report whether any file descriptors
// were open at program start.
var haveUnexpectedFDs bool
func init() {
godebug := os.Getenv("GODEBUG")
if godebug != "" {
godebug += ","
}
godebug += "execwait=2"
os.Setenv("GODEBUG", godebug)
if os.Getenv("GO_EXEC_TEST_PID") != "" {
return
}
if runtime.GOOS == "windows" {
return
}
for fd := uintptr(3); fd <= 100; fd++ {
if poll.IsPollDescriptor(fd) {
continue
}
if fdtest.Exists(fd) {
haveUnexpectedFDs = true
return
}
}
}
// TestMain allows the test binary to impersonate many other binaries,
// some of which may manipulate os.Stdin, os.Stdout, and/or os.Stderr
// (and thus cannot run as an ordinary Test function, since the testing
// package monkey-patches those variables before running tests).
func TestMain(m *testing.M) {
flag.Parse()
pid := os.Getpid()
if os.Getenv("GO_EXEC_TEST_PID") == "" {
os.Setenv("GO_EXEC_TEST_PID", strconv.Itoa(pid))
code := m.Run()
if code == 0 && flag.Lookup("test.run").Value.String() == "" && flag.Lookup("test.list").Value.String() == "" {
for cmd := range helperCommands {
if _, ok := helperCommandUsed.Load(cmd); !ok {
fmt.Fprintf(os.Stderr, "helper command unused: %q\n", cmd)
code = 1
}
}
}
if !testing.Short() {
// Run a couple of GC cycles to increase the odds of detecting
// process leaks using the finalizers installed by GODEBUG=execwait=2.
runtime.GC()
runtime.GC()
}
os.Exit(code)
}
args := flag.Args()
if len(args) == 0 {
fmt.Fprintf(os.Stderr, "No command\n")
os.Exit(2)
}
cmd, args := args[0], args[1:]
f, ok := helperCommands[cmd]
if !ok {
fmt.Fprintf(os.Stderr, "Unknown command %q\n", cmd)
os.Exit(2)
}
f(args...)
os.Exit(0)
}
// registerHelperCommand registers a command that the test process can impersonate.
// A command should be registered in the same source file in which it is used.
// If all tests are run and pass, all registered commands must be used.
// (This prevents stale commands from accreting if tests are removed or
// refactored over time.)
func registerHelperCommand(name string, f func(...string)) {
if helperCommands[name] != nil {
panic("duplicate command registered: " + name)
}
helperCommands[name] = f
}
// maySkipHelperCommand records that the test that uses the named helper command
// was invoked, but may call Skip on the test before actually calling
// helperCommand.
func maySkipHelperCommand(name string) {
helperCommandUsed.Store(name, true)
}
// helperCommand returns an exec.Cmd that will run the named helper command.
func helperCommand(t *testing.T, name string, args ...string) *exec.Cmd {
t.Helper()
return helperCommandContext(t, nil, name, args...)
}
// helperCommandContext is like helperCommand, but also accepts a Context under
// which to run the command.
func helperCommandContext(t *testing.T, ctx context.Context, name string, args ...string) (cmd *exec.Cmd) {
helperCommandUsed.LoadOrStore(name, true)
t.Helper()
testenv.MustHaveExec(t)
cs := append([]string{name}, args...)
if ctx != nil {
cmd = exec.CommandContext(ctx, exePath(t), cs...)
} else {
cmd = exec.Command(exePath(t), cs...)
}
return cmd
}
// exePath returns the path to the running executable.
func exePath(t testing.TB) string {
exeOnce.Do(func() {
// Use os.Executable instead of os.Args[0] in case the caller modifies
// cmd.Dir: if the test binary is invoked like "./exec.test", it should
// not fail spuriously.
exeOnce.path, exeOnce.err = os.Executable()
})
if exeOnce.err != nil {
if t == nil {
panic(exeOnce.err)
}
t.Fatal(exeOnce.err)
}
return exeOnce.path
}
var exeOnce struct {
path string
err error
sync.Once
}
var helperCommandUsed sync.Map
var helperCommands = map[string]func(...string){
"echo": cmdEcho,
"echoenv": cmdEchoEnv,
"cat": cmdCat,
"pipetest": cmdPipeTest,
"stdinClose": cmdStdinClose,
"exit": cmdExit,
"describefiles": cmdDescribeFiles,
"stderrfail": cmdStderrFail,
"yes": cmdYes,
"hang": cmdHang,
}
func cmdEcho(args ...string) {
iargs := []any{}
for _, s := range args {
iargs = append(iargs, s)
}
fmt.Println(iargs...)
}
func cmdEchoEnv(args ...string) {
for _, s := range args {
fmt.Println(os.Getenv(s))
}
}
func cmdCat(args ...string) {
if len(args) == 0 {
io.Copy(os.Stdout, os.Stdin)
return
}
exit := 0
for _, fn := range args {
f, err := os.Open(fn)
if err != nil {
fmt.Fprintf(os.Stderr, "Error: %v\n", err)
exit = 2
} else {
defer f.Close()
io.Copy(os.Stdout, f)
}
}
os.Exit(exit)
}
func cmdPipeTest(...string) {
bufr := bufio.NewReader(os.Stdin)
for {
line, _, err := bufr.ReadLine()
if err == io.EOF {
break
} else if err != nil {
os.Exit(1)
}
if bytes.HasPrefix(line, []byte("O:")) {
os.Stdout.Write(line)
os.Stdout.Write([]byte{'\n'})
} else if bytes.HasPrefix(line, []byte("E:")) {
os.Stderr.Write(line)
os.Stderr.Write([]byte{'\n'})
} else {
os.Exit(1)
}
}
}
func cmdStdinClose(...string) {
b, err := io.ReadAll(os.Stdin)
if err != nil {
fmt.Fprintf(os.Stderr, "Error: %v\n", err)
os.Exit(1)
}
if s := string(b); s != stdinCloseTestString {
fmt.Fprintf(os.Stderr, "Error: Read %q, want %q", s, stdinCloseTestString)
os.Exit(1)
}
}
func cmdExit(args ...string) {
n, _ := strconv.Atoi(args[0])
os.Exit(n)
}
func cmdDescribeFiles(args ...string) {
f := os.NewFile(3, fmt.Sprintf("fd3"))
ln, err := net.FileListener(f)
if err == nil {
fmt.Printf("fd3: listener %s\n", ln.Addr())
ln.Close()
}
}
func cmdStderrFail(...string) {
fmt.Fprintf(os.Stderr, "some stderr text\n")
os.Exit(1)
}
func cmdYes(args ...string) {
if len(args) == 0 {
args = []string{"y"}
}
s := strings.Join(args, " ") + "\n"
for {
_, err := os.Stdout.WriteString(s)
if err != nil {
os.Exit(1)
}
}
}
func TestEcho(t *testing.T) {
t.Parallel()
bs, err := helperCommand(t, "echo", "foo bar", "baz").Output()
if err != nil {
t.Errorf("echo: %v", err)
}
if g, e := string(bs), "foo bar baz\n"; g != e {
t.Errorf("echo: want %q, got %q", e, g)
}
}
func TestCommandRelativeName(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "echo", "foo")
// Run our own binary as a relative path
// (e.g. "_test/exec.test") our parent directory.
base := filepath.Base(os.Args[0]) // "exec.test"
dir := filepath.Dir(os.Args[0]) // "/tmp/go-buildNNNN/os/exec/_test"
if dir == "." {
t.Skip("skipping; running test at root somehow")
}
parentDir := filepath.Dir(dir) // "/tmp/go-buildNNNN/os/exec"
dirBase := filepath.Base(dir) // "_test"
if dirBase == "." {
t.Skipf("skipping; unexpected shallow dir of %q", dir)
}
cmd.Path = filepath.Join(dirBase, base)
cmd.Dir = parentDir
out, err := cmd.Output()
if err != nil {
t.Errorf("echo: %v", err)
}
if g, e := string(out), "foo\n"; g != e {
t.Errorf("echo: want %q, got %q", e, g)
}
}
func TestCatStdin(t *testing.T) {
t.Parallel()
// Cat, testing stdin and stdout.
input := "Input string\nLine 2"
p := helperCommand(t, "cat")
p.Stdin = strings.NewReader(input)
bs, err := p.Output()
if err != nil {
t.Errorf("cat: %v", err)
}
s := string(bs)
if s != input {
t.Errorf("cat: want %q, got %q", input, s)
}
}
func TestEchoFileRace(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "echo")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatalf("StdinPipe: %v", err)
}
if err := cmd.Start(); err != nil {
t.Fatalf("Start: %v", err)
}
wrote := make(chan bool)
go func() {
defer close(wrote)
fmt.Fprint(stdin, "echo\n")
}()
if err := cmd.Wait(); err != nil {
t.Fatalf("Wait: %v", err)
}
<-wrote
}
func TestCatGoodAndBadFile(t *testing.T) {
t.Parallel()
// Testing combined output and error values.
bs, err := helperCommand(t, "cat", "/bogus/file.foo", "exec_test.go").CombinedOutput()
if _, ok := err.(*exec.ExitError); !ok {
t.Errorf("expected *exec.ExitError from cat combined; got %T: %v", err, err)
}
errLine, body, ok := strings.Cut(string(bs), "\n")
if !ok {
t.Fatalf("expected two lines from cat; got %q", bs)
}
if !strings.HasPrefix(errLine, "Error: open /bogus/file.foo") {
t.Errorf("expected stderr to complain about file; got %q", errLine)
}
if !strings.Contains(body, "func TestCatGoodAndBadFile(t *testing.T)") {
t.Errorf("expected test code; got %q (len %d)", body, len(body))
}
}
func TestNoExistExecutable(t *testing.T) {
t.Parallel()
// Can't run a non-existent executable
err := exec.Command("/no-exist-executable").Run()
if err == nil {
t.Error("expected error from /no-exist-executable")
}
}
func TestExitStatus(t *testing.T) {
t.Parallel()
// Test that exit values are returned correctly
cmd := helperCommand(t, "exit", "42")
err := cmd.Run()
want := "exit status 42"
switch runtime.GOOS {
case "plan9":
want = fmt.Sprintf("exit status: '%s %d: 42'", filepath.Base(cmd.Path), cmd.ProcessState.Pid())
}
if werr, ok := err.(*exec.ExitError); ok {
if s := werr.Error(); s != want {
t.Errorf("from exit 42 got exit %q, want %q", s, want)
}
} else {
t.Fatalf("expected *exec.ExitError from exit 42; got %T: %v", err, err)
}
}
func TestExitCode(t *testing.T) {
t.Parallel()
// Test that exit code are returned correctly
cmd := helperCommand(t, "exit", "42")
cmd.Run()
want := 42
if runtime.GOOS == "plan9" {
want = 1
}
got := cmd.ProcessState.ExitCode()
if want != got {
t.Errorf("ExitCode got %d, want %d", got, want)
}
cmd = helperCommand(t, "/no-exist-executable")
cmd.Run()
want = 2
if runtime.GOOS == "plan9" {
want = 1
}
got = cmd.ProcessState.ExitCode()
if want != got {
t.Errorf("ExitCode got %d, want %d", got, want)
}
cmd = helperCommand(t, "exit", "255")
cmd.Run()
want = 255
if runtime.GOOS == "plan9" {
want = 1
}
got = cmd.ProcessState.ExitCode()
if want != got {
t.Errorf("ExitCode got %d, want %d", got, want)
}
cmd = helperCommand(t, "cat")
cmd.Run()
want = 0
got = cmd.ProcessState.ExitCode()
if want != got {
t.Errorf("ExitCode got %d, want %d", got, want)
}
// Test when command does not call Run().
cmd = helperCommand(t, "cat")
want = -1
got = cmd.ProcessState.ExitCode()
if want != got {
t.Errorf("ExitCode got %d, want %d", got, want)
}
}
func TestPipes(t *testing.T) {
t.Parallel()
check := func(what string, err error) {
if err != nil {
t.Fatalf("%s: %v", what, err)
}
}
// Cat, testing stdin and stdout.
c := helperCommand(t, "pipetest")
stdin, err := c.StdinPipe()
check("StdinPipe", err)
stdout, err := c.StdoutPipe()
check("StdoutPipe", err)
stderr, err := c.StderrPipe()
check("StderrPipe", err)
outbr := bufio.NewReader(stdout)
errbr := bufio.NewReader(stderr)
line := func(what string, br *bufio.Reader) string {
line, _, err := br.ReadLine()
if err != nil {
t.Fatalf("%s: %v", what, err)
}
return string(line)
}
err = c.Start()
check("Start", err)
_, err = stdin.Write([]byte("O:I am output\n"))
check("first stdin Write", err)
if g, e := line("first output line", outbr), "O:I am output"; g != e {
t.Errorf("got %q, want %q", g, e)
}
_, err = stdin.Write([]byte("E:I am error\n"))
check("second stdin Write", err)
if g, e := line("first error line", errbr), "E:I am error"; g != e {
t.Errorf("got %q, want %q", g, e)
}
_, err = stdin.Write([]byte("O:I am output2\n"))
check("third stdin Write 3", err)
if g, e := line("second output line", outbr), "O:I am output2"; g != e {
t.Errorf("got %q, want %q", g, e)
}
stdin.Close()
err = c.Wait()
check("Wait", err)
}
const stdinCloseTestString = "Some test string."
// Issue 6270.
func TestStdinClose(t *testing.T) {
t.Parallel()
check := func(what string, err error) {
if err != nil {
t.Fatalf("%s: %v", what, err)
}
}
cmd := helperCommand(t, "stdinClose")
stdin, err := cmd.StdinPipe()
check("StdinPipe", err)
// Check that we can access methods of the underlying os.File.`
if _, ok := stdin.(interface {
Fd() uintptr
}); !ok {
t.Error("can't access methods of underlying *os.File")
}
check("Start", cmd.Start())
var wg sync.WaitGroup
wg.Add(1)
defer wg.Wait()
go func() {
defer wg.Done()
_, err := io.Copy(stdin, strings.NewReader(stdinCloseTestString))
check("Copy", err)
// Before the fix, this next line would race with cmd.Wait.
if err := stdin.Close(); err != nil && !errors.Is(err, os.ErrClosed) {
t.Errorf("Close: %v", err)
}
}()
check("Wait", cmd.Wait())
}
// Issue 17647.
// It used to be the case that TestStdinClose, above, would fail when
// run under the race detector. This test is a variant of TestStdinClose
// that also used to fail when run under the race detector.
// This test is run by cmd/dist under the race detector to verify that
// the race detector no longer reports any problems.
func TestStdinCloseRace(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "stdinClose")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatalf("StdinPipe: %v", err)
}
if err := cmd.Start(); err != nil {
t.Fatalf("Start: %v", err)
}
var wg sync.WaitGroup
wg.Add(2)
defer wg.Wait()
go func() {
defer wg.Done()
// We don't check the error return of Kill. It is
// possible that the process has already exited, in
// which case Kill will return an error "process
// already finished". The purpose of this test is to
// see whether the race detector reports an error; it
// doesn't matter whether this Kill succeeds or not.
cmd.Process.Kill()
}()
go func() {
defer wg.Done()
// Send the wrong string, so that the child fails even
// if the other goroutine doesn't manage to kill it first.
// This test is to check that the race detector does not
// falsely report an error, so it doesn't matter how the
// child process fails.
io.Copy(stdin, strings.NewReader("unexpected string"))
if err := stdin.Close(); err != nil && !errors.Is(err, os.ErrClosed) {
t.Errorf("stdin.Close: %v", err)
}
}()
if err := cmd.Wait(); err == nil {
t.Fatalf("Wait: succeeded unexpectedly")
}
}
// Issue 5071
func TestPipeLookPathLeak(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("we don't currently suppore counting open handles on windows")
}
// Not parallel: checks for leaked file descriptors
openFDs := func() []uintptr {
var fds []uintptr
for i := uintptr(0); i < 100; i++ {
if fdtest.Exists(i) {
fds = append(fds, i)
}
}
return fds
}
old := map[uintptr]bool{}
for _, fd := range openFDs() {
old[fd] = true
}
for i := 0; i < 6; i++ {
cmd := exec.Command("something-that-does-not-exist-executable")
cmd.StdoutPipe()
cmd.StderrPipe()
cmd.StdinPipe()
if err := cmd.Run(); err == nil {
t.Fatal("unexpected success")
}
}
// Since this test is not running in parallel, we don't expect any new file
// descriptors to be opened while it runs. However, if there are additional
// FDs present at the start of the test (for example, opened by libc), those
// may be closed due to a timeout of some sort. Allow those to go away, but
// check that no new FDs are added.
for _, fd := range openFDs() {
if !old[fd] {
t.Errorf("leaked file descriptor %v", fd)
}
}
}
func TestExtraFiles(t *testing.T) {
if testing.Short() {
t.Skipf("skipping test in short mode that would build a helper binary")
}
if haveUnexpectedFDs {
// The point of this test is to make sure that any
// descriptors we open are marked close-on-exec.
// If haveUnexpectedFDs is true then there were other
// descriptors open when we started the test,
// so those descriptors are clearly not close-on-exec,
// and they will confuse the test. We could modify
// the test to expect those descriptors to remain open,
// but since we don't know where they came from or what
// they are doing, that seems fragile. For example,
// perhaps they are from the startup code on this
// system for some reason. Also, this test is not
// system-specific; as long as most systems do not skip
// the test, we will still be testing what we care about.
t.Skip("skipping test because test was run with FDs open")
}
testenv.MustHaveExec(t)
testenv.MustHaveGoBuild(t)
// This test runs with cgo disabled. External linking needs cgo, so
// it doesn't work if external linking is required.
testenv.MustInternalLink(t, false)
if runtime.GOOS == "windows" {
t.Skipf("skipping test on %q", runtime.GOOS)
}
// Force network usage, to verify the epoll (or whatever) fd
// doesn't leak to the child,
ln, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
t.Fatal(err)
}
defer ln.Close()
// Make sure duplicated fds don't leak to the child.
f, err := ln.(*net.TCPListener).File()
if err != nil {
t.Fatal(err)
}
defer f.Close()
ln2, err := net.FileListener(f)
if err != nil {
t.Fatal(err)
}
defer ln2.Close()
// Force TLS root certs to be loaded (which might involve
// cgo), to make sure none of that potential C code leaks fds.
ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
// quiet expected TLS handshake error "remote error: bad certificate"
ts.Config.ErrorLog = log.New(io.Discard, "", 0)
ts.StartTLS()
defer ts.Close()
_, err = http.Get(ts.URL)
if err == nil {
t.Errorf("success trying to fetch %s; want an error", ts.URL)
}
tf, err := os.CreateTemp("", "")
if err != nil {
t.Fatalf("TempFile: %v", err)
}
defer os.Remove(tf.Name())
defer tf.Close()
const text = "Hello, fd 3!"
_, err = tf.Write([]byte(text))
if err != nil {
t.Fatalf("Write: %v", err)
}
_, err = tf.Seek(0, io.SeekStart)
if err != nil {
t.Fatalf("Seek: %v", err)
}
tempdir := t.TempDir()
exe := filepath.Join(tempdir, "read3.exe")
c := testenv.Command(t, testenv.GoToolPath(t), "build", "-o", exe, "read3.go")
// Build the test without cgo, so that C library functions don't
// open descriptors unexpectedly. See issue 25628.
c.Env = append(os.Environ(), "CGO_ENABLED=0")
if output, err := c.CombinedOutput(); err != nil {
t.Logf("go build -o %s read3.go\n%s", exe, output)
t.Fatalf("go build failed: %v", err)
}
// Use a deadline to try to get some output even if the program hangs.
ctx := context.Background()
if deadline, ok := t.Deadline(); ok {
// Leave a 20% grace period to flush output, which may be large on the
// linux/386 builders because we're running the subprocess under strace.
deadline = deadline.Add(-time.Until(deadline) / 5)
var cancel context.CancelFunc
ctx, cancel = context.WithDeadline(ctx, deadline)
defer cancel()
}
c = exec.CommandContext(ctx, exe)
var stdout, stderr strings.Builder
c.Stdout = &stdout
c.Stderr = &stderr
c.ExtraFiles = []*os.File{tf}
if runtime.GOOS == "illumos" {
// Some facilities in illumos are implemented via access
// to /proc by libc; such accesses can briefly occupy a
// low-numbered fd. If this occurs concurrently with the
// test that checks for leaked descriptors, the check can
// become confused and report a spurious leaked descriptor.
// (See issue #42431 for more detailed analysis.)
//
// Attempt to constrain the use of additional threads in the
// child process to make this test less flaky:
c.Env = append(os.Environ(), "GOMAXPROCS=1")
}
err = c.Run()
if err != nil {
t.Fatalf("Run: %v\n--- stdout:\n%s--- stderr:\n%s", err, stdout.String(), stderr.String())
}
if stdout.String() != text {
t.Errorf("got stdout %q, stderr %q; want %q on stdout", stdout.String(), stderr.String(), text)
}
}
func TestExtraFilesRace(t *testing.T) {
if runtime.GOOS == "windows" {
maySkipHelperCommand("describefiles")
t.Skip("no operating system support; skipping")
}
t.Parallel()
listen := func() net.Listener {
ln, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
t.Fatal(err)
}
return ln
}
listenerFile := func(ln net.Listener) *os.File {
f, err := ln.(*net.TCPListener).File()
if err != nil {
t.Fatal(err)
}
return f
}
runCommand := func(c *exec.Cmd, out chan<- string) {
bout, err := c.CombinedOutput()
if err != nil {
out <- "ERROR:" + err.Error()
} else {
out <- string(bout)
}
}
for i := 0; i < 10; i++ {
if testing.Short() && i >= 3 {
break
}
la := listen()
ca := helperCommand(t, "describefiles")
ca.ExtraFiles = []*os.File{listenerFile(la)}
lb := listen()
cb := helperCommand(t, "describefiles")
cb.ExtraFiles = []*os.File{listenerFile(lb)}
ares := make(chan string)
bres := make(chan string)
go runCommand(ca, ares)
go runCommand(cb, bres)
if got, want := <-ares, fmt.Sprintf("fd3: listener %s\n", la.Addr()); got != want {
t.Errorf("iteration %d, process A got:\n%s\nwant:\n%s\n", i, got, want)
}
if got, want := <-bres, fmt.Sprintf("fd3: listener %s\n", lb.Addr()); got != want {
t.Errorf("iteration %d, process B got:\n%s\nwant:\n%s\n", i, got, want)
}
la.Close()
lb.Close()
for _, f := range ca.ExtraFiles {
f.Close()
}
for _, f := range cb.ExtraFiles {
f.Close()
}
}
}
type delayedInfiniteReader struct{}
func (delayedInfiniteReader) Read(b []byte) (int, error) {
time.Sleep(100 * time.Millisecond)
for i := range b {
b[i] = 'x'
}
return len(b), nil
}
// Issue 9173: ignore stdin pipe writes if the program completes successfully.
func TestIgnorePipeErrorOnSuccess(t *testing.T) {
t.Parallel()
testWith := func(r io.Reader) func(*testing.T) {
return func(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "echo", "foo")
var out strings.Builder
cmd.Stdin = r
cmd.Stdout = &out
if err := cmd.Run(); err != nil {
t.Fatal(err)
}
if got, want := out.String(), "foo\n"; got != want {
t.Errorf("output = %q; want %q", got, want)
}
}
}
t.Run("10MB", testWith(strings.NewReader(strings.Repeat("x", 10<<20))))
t.Run("Infinite", testWith(delayedInfiniteReader{}))
}
type badWriter struct{}
func (w *badWriter) Write(data []byte) (int, error) {
return 0, io.ErrUnexpectedEOF
}
func TestClosePipeOnCopyError(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "yes")
cmd.Stdout = new(badWriter)
err := cmd.Run()
if err == nil {
t.Errorf("yes unexpectedly completed successfully")
}
}
func TestOutputStderrCapture(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "stderrfail")
_, err := cmd.Output()
ee, ok := err.(*exec.ExitError)
if !ok {
t.Fatalf("Output error type = %T; want ExitError", err)
}
got := string(ee.Stderr)
want := "some stderr text\n"
if got != want {
t.Errorf("ExitError.Stderr = %q; want %q", got, want)
}
}
func TestContext(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
c := helperCommandContext(t, ctx, "pipetest")
stdin, err := c.StdinPipe()
if err != nil {
t.Fatal(err)
}
stdout, err := c.StdoutPipe()
if err != nil {
t.Fatal(err)
}
if err := c.Start(); err != nil {
t.Fatal(err)
}
if _, err := stdin.Write([]byte("O:hi\n")); err != nil {
t.Fatal(err)
}
buf := make([]byte, 5)
n, err := io.ReadFull(stdout, buf)
if n != len(buf) || err != nil || string(buf) != "O:hi\n" {
t.Fatalf("ReadFull = %d, %v, %q", n, err, buf[:n])
}
go cancel()
if err := c.Wait(); err == nil {
t.Fatal("expected Wait failure")
}
}
func TestContextCancel(t *testing.T) {
if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm64" {
maySkipHelperCommand("cat")
testenv.SkipFlaky(t, 42061)
}
// To reduce noise in the final goroutine dump,
// let other parallel tests complete if possible.
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
c := helperCommandContext(t, ctx, "cat")
stdin, err := c.StdinPipe()
if err != nil {
t.Fatal(err)
}
defer stdin.Close()
if err := c.Start(); err != nil {
t.Fatal(err)
}
// At this point the process is alive. Ensure it by sending data to stdin.
if _, err := io.WriteString(stdin, "echo"); err != nil {
t.Fatal(err)
}
cancel()
// Calling cancel should have killed the process, so writes
// should now fail. Give the process a little while to die.
start := time.Now()
delay := 1 * time.Millisecond
for {
if _, err := io.WriteString(stdin, "echo"); err != nil {
break
}
if time.Since(start) > time.Minute {
// Panic instead of calling t.Fatal so that we get a goroutine dump.
// We want to know exactly what the os/exec goroutines got stuck on.
debug.SetTraceback("system")
panic("canceling context did not stop program")
}
// Back off exponentially (up to 1-second sleeps) to give the OS time to
// terminate the process.
delay *= 2
if delay > 1*time.Second {
delay = 1 * time.Second
}
time.Sleep(delay)
}
if err := c.Wait(); err == nil {
t.Error("program unexpectedly exited successfully")
} else {
t.Logf("exit status: %v", err)
}
}
// test that environment variables are de-duped.
func TestDedupEnvEcho(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "echoenv", "FOO")
cmd.Env = append(cmd.Environ(), "FOO=bad", "FOO=good")
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatal(err)
}
if got, want := strings.TrimSpace(string(out)), "good"; got != want {
t.Errorf("output = %q; want %q", got, want)
}
}
func TestEnvNULCharacter(t *testing.T) {
if runtime.GOOS == "plan9" {
t.Skip("plan9 explicitly allows NUL in the environment")
}
cmd := helperCommand(t, "echoenv", "FOO", "BAR")
cmd.Env = append(cmd.Environ(), "FOO=foo\x00BAR=bar")
out, err := cmd.CombinedOutput()
if err == nil {
t.Errorf("output = %q; want error", string(out))
}
}
func TestString(t *testing.T) {
t.Parallel()
echoPath, err := exec.LookPath("echo")
if err != nil {
t.Skip(err)
}
tests := [...]struct {
path string
args []string
want string
}{
{"echo", nil, echoPath},
{"echo", []string{"a"}, echoPath + " a"},
{"echo", []string{"a", "b"}, echoPath + " a b"},
}
for _, test := range tests {
cmd := exec.Command(test.path, test.args...)
if got := cmd.String(); got != test.want {
t.Errorf("String(%q, %q) = %q, want %q", test.path, test.args, got, test.want)
}
}
}
func TestStringPathNotResolved(t *testing.T) {
t.Parallel()
_, err := exec.LookPath("makemeasandwich")
if err == nil {
t.Skip("wow, thanks")
}
cmd := exec.Command("makemeasandwich", "-lettuce")
want := "makemeasandwich -lettuce"
if got := cmd.String(); got != want {
t.Errorf("String(%q, %q) = %q, want %q", "makemeasandwich", "-lettuce", got, want)
}
}
func TestNoPath(t *testing.T) {
err := new(exec.Cmd).Start()
want := "exec: no command"
if err == nil || err.Error() != want {
t.Errorf("new(Cmd).Start() = %v, want %q", err, want)
}
}
// TestDoubleStartLeavesPipesOpen checks for a regression in which calling
// Start twice, which returns an error on the second call, would spuriously
// close the pipes established in the first call.
func TestDoubleStartLeavesPipesOpen(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "pipetest")
in, err := cmd.StdinPipe()
if err != nil {
t.Fatal(err)
}
out, err := cmd.StdoutPipe()
if err != nil {
t.Fatal(err)
}
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
t.Cleanup(func() {
if err := cmd.Wait(); err != nil {
t.Error(err)
}
})
if err := cmd.Start(); err == nil || !strings.HasSuffix(err.Error(), "already started") {
t.Fatalf("second call to Start returned a nil; want an 'already started' error")
}
outc := make(chan []byte, 1)
go func() {
b, err := io.ReadAll(out)
if err != nil {
t.Error(err)
}
outc <- b
}()
const msg = "O:Hello, pipe!\n"
_, err = io.WriteString(in, msg)
if err != nil {
t.Fatal(err)
}
in.Close()
b := <-outc
if !bytes.Equal(b, []byte(msg)) {
t.Fatalf("read %q from stdout pipe; want %q", b, msg)
}
}
func cmdHang(args ...string) {
sleep, err := time.ParseDuration(args[0])
if err != nil {
panic(err)
}
fs := flag.NewFlagSet("hang", flag.ExitOnError)
exitOnInterrupt := fs.Bool("interrupt", false, "if true, commands should exit 0 on os.Interrupt")
subsleep := fs.Duration("subsleep", 0, "amount of time for the 'hang' helper to leave an orphaned subprocess sleeping with stderr open")
probe := fs.Duration("probe", 0, "if nonzero, the 'hang' helper should write to stderr at this interval, and exit nonzero if a write fails")
read := fs.Bool("read", false, "if true, the 'hang' helper should read stdin to completion before sleeping")
fs.Parse(args[1:])
pid := os.Getpid()
if *subsleep != 0 {
cmd := exec.Command(exePath(nil), "hang", subsleep.String(), "-read=true", "-probe="+probe.String())
cmd.Stdin = os.Stdin
cmd.Stderr = os.Stderr
out, err := cmd.StdoutPipe()
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
cmd.Start()
buf := new(strings.Builder)
if _, err := io.Copy(buf, out); err != nil {
fmt.Fprintln(os.Stderr, err)
cmd.Process.Kill()
cmd.Wait()
os.Exit(1)
}
fmt.Fprintf(os.Stderr, "%d: started %d: %v\n", pid, cmd.Process.Pid, cmd)
go cmd.Wait() // Release resources if cmd happens not to outlive this process.
}
if *exitOnInterrupt {
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
go func() {
sig := <-c
fmt.Fprintf(os.Stderr, "%d: received %v\n", pid, sig)
os.Exit(0)
}()
} else {
signal.Ignore(os.Interrupt)
}
// Signal that the process is set up by closing stdout.
os.Stdout.Close()
if *read {
if pipeSignal != nil {
signal.Ignore(pipeSignal)
}
r := bufio.NewReader(os.Stdin)
for {
line, err := r.ReadBytes('\n')
if len(line) > 0 {
// Ignore write errors: we want to keep reading even if stderr is closed.
fmt.Fprintf(os.Stderr, "%d: read %s", pid, line)
}
if err != nil {
fmt.Fprintf(os.Stderr, "%d: finished read: %v", pid, err)
break
}
}
}
if *probe != 0 {
ticker := time.NewTicker(*probe)
go func() {
for range ticker.C {
if _, err := fmt.Fprintf(os.Stderr, "%d: ok\n", pid); err != nil {
os.Exit(1)
}
}
}()
}
if sleep != 0 {
time.Sleep(sleep)
fmt.Fprintf(os.Stderr, "%d: slept %v\n", pid, sleep)
}
}
// A tickReader reads an unbounded sequence of timestamps at no more than a
// fixed interval.
type tickReader struct {
interval time.Duration
lastTick time.Time
s string
}
func newTickReader(interval time.Duration) *tickReader {
return &tickReader{interval: interval}
}
func (r *tickReader) Read(p []byte) (n int, err error) {
if len(r.s) == 0 {
if d := r.interval - time.Since(r.lastTick); d > 0 {
time.Sleep(d)
}
r.lastTick = time.Now()
r.s = r.lastTick.Format(time.RFC3339Nano + "\n")
}
n = copy(p, r.s)
r.s = r.s[n:]
return n, nil
}
func startHang(t *testing.T, ctx context.Context, hangTime time.Duration, interrupt os.Signal, waitDelay time.Duration, flags ...string) *exec.Cmd {
t.Helper()
args := append([]string{hangTime.String()}, flags...)
cmd := helperCommandContext(t, ctx, "hang", args...)
cmd.Stdin = newTickReader(1 * time.Millisecond)
cmd.Stderr = new(strings.Builder)
if interrupt == nil {
cmd.Cancel = nil
} else {
cmd.Cancel = func() error {
return cmd.Process.Signal(interrupt)
}
}
cmd.WaitDelay = waitDelay
out, err := cmd.StdoutPipe()
if err != nil {
t.Fatal(err)
}
t.Log(cmd)
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
// Wait for cmd to close stdout to signal that its handlers are installed.
buf := new(strings.Builder)
if _, err := io.Copy(buf, out); err != nil {
t.Error(err)
cmd.Process.Kill()
cmd.Wait()
t.FailNow()
}
if buf.Len() > 0 {
t.Logf("stdout %v:\n%s", cmd.Args, buf)
}
return cmd
}
func TestWaitInterrupt(t *testing.T) {
t.Parallel()
// tooLong is an arbitrary duration that is expected to be much longer than
// the test runs, but short enough that leaked processes will eventually exit
// on their own.
const tooLong = 10 * time.Minute
// Control case: with no cancellation and no WaitDelay, we should wait for the
// process to exit.
t.Run("Wait", func(t *testing.T) {
t.Parallel()
cmd := startHang(t, context.Background(), 1*time.Millisecond, os.Kill, 0)
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
if err != nil {
t.Errorf("Wait: %v; want <nil>", err)
}
if ps := cmd.ProcessState; !ps.Exited() {
t.Errorf("cmd did not exit: %v", ps)
} else if code := ps.ExitCode(); code != 0 {
t.Errorf("cmd.ProcessState.ExitCode() = %v; want 0", code)
}
})
// With a very long WaitDelay and no Cancel function, we should wait for the
// process to exit even if the command's Context is cancelled.
t.Run("WaitDelay", func(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skipf("skipping: os.Interrupt is not implemented on Windows")
}
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
cmd := startHang(t, ctx, tooLong, nil, tooLong, "-interrupt=true")
cancel()
time.Sleep(1 * time.Millisecond)
// At this point cmd should still be running (because we passed nil to
// startHang for the cancel signal). Sending it an explicit Interrupt signal
// should succeed.
if err := cmd.Process.Signal(os.Interrupt); err != nil {
t.Error(err)
}
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
// This program exits with status 0,
// but pretty much always does so during the wait delay.
// Since the Cmd itself didn't do anything to stop the process when the
// context expired, a successful exit is valid (even if late) and does
// not merit a non-nil error.
if err != nil {
t.Errorf("Wait: %v; want nil", err)
}
if ps := cmd.ProcessState; !ps.Exited() {
t.Errorf("cmd did not exit: %v", ps)
} else if code := ps.ExitCode(); code != 0 {
t.Errorf("cmd.ProcessState.ExitCode() = %v; want 0", code)
}
})
// If the context is cancelled and the Cancel function sends os.Kill,
// the process should be terminated immediately, and its output
// pipes should be closed (causing Wait to return) after WaitDelay
// even if a child process is still writing to them.
t.Run("SIGKILL-hang", func(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
cmd := startHang(t, ctx, tooLong, os.Kill, 10*time.Millisecond, "-subsleep=10m", "-probe=1ms")
cancel()
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
// This test should kill the child process after 10ms,
// leaving a grandchild process writing probes in a loop.
// The child process should be reported as failed,
// and the grandchild will exit (or die by SIGPIPE) once the
// stderr pipe is closed.
if ee := new(*exec.ExitError); !errors.As(err, ee) {
t.Errorf("Wait error = %v; want %T", err, *ee)
}
})
// If the process exits with status 0 but leaves a child behind writing
// to its output pipes, Wait should only wait for WaitDelay before
// closing the pipes and returning. Wait should return ErrWaitDelay
// to indicate that the piped output may be incomplete even though the
// command returned a “success” code.
t.Run("Exit-hang", func(t *testing.T) {
t.Parallel()
cmd := startHang(t, context.Background(), 1*time.Millisecond, nil, 10*time.Millisecond, "-subsleep=10m", "-probe=1ms")
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
// This child process should exit immediately,
// leaving a grandchild process writing probes in a loop.
// Since the child has no ExitError to report but we did not
// read all of its output, Wait should return ErrWaitDelay.
if !errors.Is(err, exec.ErrWaitDelay) {
t.Errorf("Wait error = %v; want %T", err, exec.ErrWaitDelay)
}
})
// If the Cancel function sends a signal that the process can handle, and it
// handles that signal without actually exiting, then it should be terminated
// after the WaitDelay.
t.Run("SIGINT-ignored", func(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skipf("skipping: os.Interrupt is not implemented on Windows")
}
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
cmd := startHang(t, ctx, tooLong, os.Interrupt, 10*time.Millisecond, "-interrupt=false")
cancel()
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
// This command ignores SIGINT, sleeping until it is killed.
// Wait should return the usual error for a killed process.
if ee := new(*exec.ExitError); !errors.As(err, ee) {
t.Errorf("Wait error = %v; want %T", err, *ee)
}
})
// If the process handles the cancellation signal and exits with status 0,
// Wait should report a non-nil error (because the process had to be
// interrupted), and it should be a context error (because there is no error
// to report from the child process itself).
t.Run("SIGINT-handled", func(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skipf("skipping: os.Interrupt is not implemented on Windows")
}
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
cmd := startHang(t, ctx, tooLong, os.Interrupt, 0, "-interrupt=true")
cancel()
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
if !errors.Is(err, ctx.Err()) {
t.Errorf("Wait error = %v; want %v", err, ctx.Err())
}
if ps := cmd.ProcessState; !ps.Exited() {
t.Errorf("cmd did not exit: %v", ps)
} else if code := ps.ExitCode(); code != 0 {
t.Errorf("cmd.ProcessState.ExitCode() = %v; want 0", code)
}
})
// If the Cancel function sends SIGQUIT, it should be handled in the usual
// way: a Go program should dump its goroutines and exit with non-success
// status. (We expect SIGQUIT to be a common pattern in real-world use.)
t.Run("SIGQUIT", func(t *testing.T) {
if quitSignal == nil {
t.Skipf("skipping: SIGQUIT is not supported on %v", runtime.GOOS)
}
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
cmd := startHang(t, ctx, tooLong, quitSignal, 0)
cancel()
err := cmd.Wait()
t.Logf("stderr:\n%s", cmd.Stderr)
t.Logf("[%d] %v", cmd.Process.Pid, err)
if ee := new(*exec.ExitError); !errors.As(err, ee) {
t.Errorf("Wait error = %v; want %v", err, ctx.Err())
}
if ps := cmd.ProcessState; !ps.Exited() {
t.Errorf("cmd did not exit: %v", ps)
} else if code := ps.ExitCode(); code != 2 {
// The default os/signal handler exits with code 2.
t.Errorf("cmd.ProcessState.ExitCode() = %v; want 2", code)
}
if !strings.Contains(fmt.Sprint(cmd.Stderr), "\n\ngoroutine ") {
t.Errorf("cmd.Stderr does not contain a goroutine dump")
}
})
}
func TestCancelErrors(t *testing.T) {
t.Parallel()
// If Cancel returns a non-ErrProcessDone error and the process
// exits successfully, Wait should wrap the error from Cancel.
t.Run("success after error", func(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
cmd := helperCommandContext(t, ctx, "pipetest")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatal(err)
}
errArbitrary := errors.New("arbitrary error")
cmd.Cancel = func() error {
stdin.Close()
t.Logf("Cancel returning %v", errArbitrary)
return errArbitrary
}
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
cancel()
err = cmd.Wait()
t.Logf("[%d] %v", cmd.Process.Pid, err)
if !errors.Is(err, errArbitrary) || err == errArbitrary {
t.Errorf("Wait error = %v; want an error wrapping %v", err, errArbitrary)
}
})
// If Cancel returns an error equivalent to ErrProcessDone,
// Wait should ignore that error. (ErrProcessDone indicates that the
// process was already done before we tried to interrupt it — maybe we
// just didn't notice because Wait hadn't been called yet.)
t.Run("success after ErrProcessDone", func(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
cmd := helperCommandContext(t, ctx, "pipetest")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatal(err)
}
stdout, err := cmd.StdoutPipe()
if err != nil {
t.Fatal(err)
}
// We intentionally race Cancel against the process exiting,
// but ensure that the process wins the race (and return ErrProcessDone
// from Cancel to report that).
interruptCalled := make(chan struct{})
done := make(chan struct{})
cmd.Cancel = func() error {
close(interruptCalled)
<-done
t.Logf("Cancel returning an error wrapping ErrProcessDone")
return fmt.Errorf("%w: stdout closed", os.ErrProcessDone)
}
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
cancel()
<-interruptCalled
stdin.Close()
io.Copy(io.Discard, stdout) // reaches EOF when the process exits
close(done)
err = cmd.Wait()
t.Logf("[%d] %v", cmd.Process.Pid, err)
if err != nil {
t.Errorf("Wait error = %v; want nil", err)
}
})
// If Cancel returns an error and the process is killed after
// WaitDelay, Wait should report the usual SIGKILL ExitError, not the
// error from Cancel.
t.Run("killed after error", func(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
cmd := helperCommandContext(t, ctx, "pipetest")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatal(err)
}
defer stdin.Close()
errArbitrary := errors.New("arbitrary error")
var interruptCalled atomic.Bool
cmd.Cancel = func() error {
t.Logf("Cancel called")
interruptCalled.Store(true)
return errArbitrary
}
cmd.WaitDelay = 1 * time.Millisecond
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
cancel()
err = cmd.Wait()
t.Logf("[%d] %v", cmd.Process.Pid, err)
// Ensure that Cancel actually had the opportunity to
// return the error.
if !interruptCalled.Load() {
t.Errorf("Cancel was not called when the context was canceled")
}
// This test should kill the child process after 1ms,
// To maximize compatibility with existing uses of exec.CommandContext, the
// resulting error should be an exec.ExitError without additional wrapping.
if ee, ok := err.(*exec.ExitError); !ok {
t.Errorf("Wait error = %v; want %T", err, *ee)
}
})
// If Cancel returns ErrProcessDone but the process is not actually done
// (and has to be killed), Wait should report the usual SIGKILL ExitError,
// not the error from Cancel.
t.Run("killed after spurious ErrProcessDone", func(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
cmd := helperCommandContext(t, ctx, "pipetest")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatal(err)
}
defer stdin.Close()
var interruptCalled atomic.Bool
cmd.Cancel = func() error {
t.Logf("Cancel returning an error wrapping ErrProcessDone")
interruptCalled.Store(true)
return fmt.Errorf("%w: stdout closed", os.ErrProcessDone)
}
cmd.WaitDelay = 1 * time.Millisecond
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
cancel()
err = cmd.Wait()
t.Logf("[%d] %v", cmd.Process.Pid, err)
// Ensure that Cancel actually had the opportunity to
// return the error.
if !interruptCalled.Load() {
t.Errorf("Cancel was not called when the context was canceled")
}
// This test should kill the child process after 1ms,
// To maximize compatibility with existing uses of exec.CommandContext, the
// resulting error should be an exec.ExitError without additional wrapping.
if ee, ok := err.(*exec.ExitError); !ok {
t.Errorf("Wait error of type %T; want %T", err, ee)
}
})
// If Cancel returns an error and the process exits with an
// unsuccessful exit code, the process error should take precedence over the
// Cancel error.
t.Run("nonzero exit after error", func(t *testing.T) {
t.Parallel()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
cmd := helperCommandContext(t, ctx, "stderrfail")
stderr, err := cmd.StderrPipe()
if err != nil {
t.Fatal(err)
}
errArbitrary := errors.New("arbitrary error")
interrupted := make(chan struct{})
cmd.Cancel = func() error {
close(interrupted)
return errArbitrary
}
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
cancel()
<-interrupted
io.Copy(io.Discard, stderr)
err = cmd.Wait()
t.Logf("[%d] %v", cmd.Process.Pid, err)
if ee, ok := err.(*exec.ExitError); !ok || ee.ProcessState.ExitCode() != 1 {
t.Errorf("Wait error = %v; want exit status 1", err)
}
})
}
// TestConcurrentExec is a regression test for https://go.dev/issue/61080.
//
// Forking multiple child processes concurrently would sometimes hang on darwin.
// (This test hung on a gomote with -count=100 after only a few iterations.)
func TestConcurrentExec(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
// This test will spawn nHangs subprocesses that hang reading from stdin,
// and nExits subprocesses that exit immediately.
//
// When issue #61080 was present, a long-lived "hang" subprocess would
// occasionally inherit the fork/exec status pipe from an "exit" subprocess,
// causing the parent process (which expects to see an EOF on that pipe almost
// immediately) to unexpectedly block on reading from the pipe.
var (
nHangs = runtime.GOMAXPROCS(0)
nExits = runtime.GOMAXPROCS(0)
hangs, exits sync.WaitGroup
)
hangs.Add(nHangs)
exits.Add(nExits)
// ready is done when the goroutines have done as much work as possible to
// prepare to create subprocesses. It isn't strictly necessary for the test,
// but helps to increase the repro rate by making it more likely that calls to
// syscall.StartProcess for the "hang" and "exit" goroutines overlap.
var ready sync.WaitGroup
ready.Add(nHangs + nExits)
for i := 0; i < nHangs; i++ {
go func() {
defer hangs.Done()
cmd := helperCommandContext(t, ctx, "pipetest")
stdin, err := cmd.StdinPipe()
if err != nil {
ready.Done()
t.Error(err)
return
}
cmd.Cancel = stdin.Close
ready.Done()
ready.Wait()
if err := cmd.Start(); err != nil {
if !errors.Is(err, context.Canceled) {
t.Error(err)
}
return
}
cmd.Wait()
}()
}
for i := 0; i < nExits; i++ {
go func() {
defer exits.Done()
cmd := helperCommandContext(t, ctx, "exit", "0")
ready.Done()
ready.Wait()
if err := cmd.Run(); err != nil {
t.Error(err)
}
}()
}
exits.Wait()
cancel()
hangs.Wait()
}