mirror of https://go.googlesource.com/go
479 lines
12 KiB
Go
479 lines
12 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test broken pipes on Unix systems.
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//
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//go:build !plan9 && !js && !wasip1
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package os_test
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import (
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"bufio"
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"bytes"
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"fmt"
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"internal/testenv"
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"io"
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"io/fs"
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"os"
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"os/exec"
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"os/signal"
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"runtime"
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"strconv"
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"strings"
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"sync"
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"syscall"
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"testing"
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"time"
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)
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func TestEPIPE(t *testing.T) {
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// This test cannot be run in parallel because of a race similar
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// to the one reported in https://go.dev/issue/22315.
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//
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// Even though the pipe is opened with O_CLOEXEC, if another test forks in
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// between the call to os.Pipe and the call to r.Close, that child process can
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// retain an open copy of r's file descriptor until it execs. If one of our
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// Write calls occurs during that interval it can spuriously succeed,
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// buffering the write to the child's copy of the pipe (even though the child
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// will not actually read the buffered bytes).
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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if err := r.Close(); err != nil {
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t.Fatal(err)
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}
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expect := syscall.EPIPE
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if runtime.GOOS == "windows" {
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// 232 is Windows error code ERROR_NO_DATA, "The pipe is being closed".
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expect = syscall.Errno(232)
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}
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// Every time we write to the pipe we should get an EPIPE.
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for i := 0; i < 20; i++ {
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_, err = w.Write([]byte("hi"))
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if err == nil {
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t.Fatal("unexpected success of Write to broken pipe")
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}
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if pe, ok := err.(*fs.PathError); ok {
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err = pe.Err
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}
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if se, ok := err.(*os.SyscallError); ok {
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err = se.Err
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}
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if err != expect {
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t.Errorf("iteration %d: got %v, expected %v", i, err, expect)
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}
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}
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}
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func TestStdPipe(t *testing.T) {
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switch runtime.GOOS {
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case "windows":
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t.Skip("Windows doesn't support SIGPIPE")
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}
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if os.Getenv("GO_TEST_STD_PIPE_HELPER") != "" {
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if os.Getenv("GO_TEST_STD_PIPE_HELPER_SIGNAL") != "" {
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signal.Notify(make(chan os.Signal, 1), syscall.SIGPIPE)
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}
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switch os.Getenv("GO_TEST_STD_PIPE_HELPER") {
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case "1":
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os.Stdout.Write([]byte("stdout"))
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case "2":
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os.Stderr.Write([]byte("stderr"))
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case "3":
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if _, err := os.NewFile(3, "3").Write([]byte("3")); err == nil {
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os.Exit(3)
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}
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default:
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panic("unrecognized value for GO_TEST_STD_PIPE_HELPER")
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}
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// For stdout/stderr, we should have crashed with a broken pipe error.
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// The caller will be looking for that exit status,
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// so just exit normally here to cause a failure in the caller.
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// For descriptor 3, a normal exit is expected.
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os.Exit(0)
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}
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testenv.MustHaveExec(t)
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// This test cannot be run in parallel due to the same race as for TestEPIPE.
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// (We expect a write to a closed pipe can fail, but a concurrent fork of a
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// child process can cause the pipe to unexpectedly remain open.)
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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if err := r.Close(); err != nil {
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t.Fatal(err)
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}
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// Invoke the test program to run the test and write to a closed pipe.
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// If sig is false:
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// writing to stdout or stderr should cause an immediate SIGPIPE;
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// writing to descriptor 3 should fail with EPIPE and then exit 0.
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// If sig is true:
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// all writes should fail with EPIPE and then exit 0.
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for _, sig := range []bool{false, true} {
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for dest := 1; dest < 4; dest++ {
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cmd := testenv.Command(t, os.Args[0], "-test.run", "TestStdPipe")
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cmd.Stdout = w
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cmd.Stderr = w
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cmd.ExtraFiles = []*os.File{w}
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cmd.Env = append(os.Environ(), fmt.Sprintf("GO_TEST_STD_PIPE_HELPER=%d", dest))
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if sig {
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cmd.Env = append(cmd.Env, "GO_TEST_STD_PIPE_HELPER_SIGNAL=1")
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}
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if err := cmd.Run(); err == nil {
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if !sig && dest < 3 {
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t.Errorf("unexpected success of write to closed pipe %d sig %t in child", dest, sig)
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}
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} else if ee, ok := err.(*exec.ExitError); !ok {
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t.Errorf("unexpected exec error type %T: %v", err, err)
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} else if ws, ok := ee.Sys().(syscall.WaitStatus); !ok {
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t.Errorf("unexpected wait status type %T: %v", ee.Sys(), ee.Sys())
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} else if ws.Signaled() && ws.Signal() == syscall.SIGPIPE {
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if sig || dest > 2 {
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t.Errorf("unexpected SIGPIPE signal for descriptor %d sig %t", dest, sig)
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}
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} else {
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t.Errorf("unexpected exit status %v for descriptor %d sig %t", err, dest, sig)
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}
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}
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}
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// Test redirecting stdout but not stderr. Issue 40076.
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cmd := testenv.Command(t, os.Args[0], "-test.run", "TestStdPipe")
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cmd.Stdout = w
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var stderr bytes.Buffer
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cmd.Stderr = &stderr
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cmd.Env = append(cmd.Environ(), "GO_TEST_STD_PIPE_HELPER=1")
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if err := cmd.Run(); err == nil {
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t.Errorf("unexpected success of write to closed stdout")
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} else if ee, ok := err.(*exec.ExitError); !ok {
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t.Errorf("unexpected exec error type %T: %v", err, err)
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} else if ws, ok := ee.Sys().(syscall.WaitStatus); !ok {
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t.Errorf("unexpected wait status type %T: %v", ee.Sys(), ee.Sys())
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} else if !ws.Signaled() || ws.Signal() != syscall.SIGPIPE {
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t.Errorf("unexpected exit status %v for write to closed stdout", err)
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}
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if output := stderr.Bytes(); len(output) > 0 {
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t.Errorf("unexpected output on stderr: %s", output)
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}
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}
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func testClosedPipeRace(t *testing.T, read bool) {
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// This test cannot be run in parallel due to the same race as for TestEPIPE.
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// (We expect a write to a closed pipe can fail, but a concurrent fork of a
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// child process can cause the pipe to unexpectedly remain open.)
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limit := 1
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if !read {
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// Get the amount we have to write to overload a pipe
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// with no reader.
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limit = 131073
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if b, err := os.ReadFile("/proc/sys/fs/pipe-max-size"); err == nil {
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if i, err := strconv.Atoi(strings.TrimSpace(string(b))); err == nil {
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limit = i + 1
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}
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}
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t.Logf("using pipe write limit of %d", limit)
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}
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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defer r.Close()
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defer w.Close()
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// Close the read end of the pipe in a goroutine while we are
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// writing to the write end, or vice-versa.
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go func() {
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// Give the main goroutine a chance to enter the Read or
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// Write call. This is sloppy but the test will pass even
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// if we close before the read/write.
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time.Sleep(20 * time.Millisecond)
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var err error
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if read {
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err = r.Close()
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} else {
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err = w.Close()
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}
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if err != nil {
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t.Error(err)
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}
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}()
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b := make([]byte, limit)
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if read {
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_, err = r.Read(b[:])
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} else {
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_, err = w.Write(b[:])
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}
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if err == nil {
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t.Error("I/O on closed pipe unexpectedly succeeded")
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} else if pe, ok := err.(*fs.PathError); !ok {
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t.Errorf("I/O on closed pipe returned unexpected error type %T; expected fs.PathError", pe)
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} else if pe.Err != fs.ErrClosed {
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t.Errorf("got error %q but expected %q", pe.Err, fs.ErrClosed)
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} else {
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t.Logf("I/O returned expected error %q", err)
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}
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}
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func TestClosedPipeRaceRead(t *testing.T) {
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testClosedPipeRace(t, true)
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}
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func TestClosedPipeRaceWrite(t *testing.T) {
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testClosedPipeRace(t, false)
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}
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// Issue 20915: Reading on nonblocking fd should not return "waiting
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// for unsupported file type." Currently it returns EAGAIN; it is
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// possible that in the future it will simply wait for data.
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func TestReadNonblockingFd(t *testing.T) {
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switch runtime.GOOS {
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case "windows":
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t.Skip("Windows doesn't support SetNonblock")
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}
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if os.Getenv("GO_WANT_READ_NONBLOCKING_FD") == "1" {
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fd := syscallDescriptor(os.Stdin.Fd())
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syscall.SetNonblock(fd, true)
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defer syscall.SetNonblock(fd, false)
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_, err := os.Stdin.Read(make([]byte, 1))
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if err != nil {
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if perr, ok := err.(*fs.PathError); !ok || perr.Err != syscall.EAGAIN {
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t.Fatalf("read on nonblocking stdin got %q, should have gotten EAGAIN", err)
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}
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}
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os.Exit(0)
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}
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testenv.MustHaveExec(t)
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t.Parallel()
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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defer r.Close()
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defer w.Close()
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cmd := testenv.Command(t, os.Args[0], "-test.run=^"+t.Name()+"$")
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cmd.Env = append(cmd.Environ(), "GO_WANT_READ_NONBLOCKING_FD=1")
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cmd.Stdin = r
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output, err := cmd.CombinedOutput()
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t.Logf("%s", output)
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if err != nil {
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t.Errorf("child process failed: %v", err)
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}
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}
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func TestCloseWithBlockingReadByNewFile(t *testing.T) {
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t.Parallel()
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var p [2]syscallDescriptor
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err := syscall.Pipe(p[:])
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if err != nil {
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t.Fatal(err)
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}
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// os.NewFile returns a blocking mode file.
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testCloseWithBlockingRead(t, os.NewFile(uintptr(p[0]), "reader"), os.NewFile(uintptr(p[1]), "writer"))
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}
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func TestCloseWithBlockingReadByFd(t *testing.T) {
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t.Parallel()
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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// Calling Fd will put the file into blocking mode.
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_ = r.Fd()
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testCloseWithBlockingRead(t, r, w)
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}
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// Test that we don't let a blocking read prevent a close.
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func testCloseWithBlockingRead(t *testing.T, r, w *os.File) {
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var (
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enteringRead = make(chan struct{})
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done = make(chan struct{})
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)
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go func() {
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var b [1]byte
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close(enteringRead)
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_, err := r.Read(b[:])
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if err == nil {
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t.Error("I/O on closed pipe unexpectedly succeeded")
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}
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if pe, ok := err.(*fs.PathError); ok {
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err = pe.Err
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}
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if err != io.EOF && err != fs.ErrClosed {
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t.Errorf("got %v, expected EOF or closed", err)
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}
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close(done)
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}()
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// Give the goroutine a chance to enter the Read
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// or Write call. This is sloppy but the test will
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// pass even if we close before the read/write.
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<-enteringRead
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time.Sleep(20 * time.Millisecond)
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if err := r.Close(); err != nil {
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t.Error(err)
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}
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// r.Close has completed, but since we assume r is in blocking mode that
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// probably didn't unblock the call to r.Read. Close w to unblock it.
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w.Close()
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<-done
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}
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func TestPipeEOF(t *testing.T) {
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t.Parallel()
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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testPipeEOF(t, r, w)
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}
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// testPipeEOF tests that when the write side of a pipe or FIFO is closed,
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// a blocked Read call on the reader side returns io.EOF.
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//
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// This scenario previously failed to unblock the Read call on darwin.
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// (See https://go.dev/issue/24164.)
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func testPipeEOF(t *testing.T, r io.ReadCloser, w io.WriteCloser) {
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// parkDelay is an arbitrary delay we wait for a pipe-reader goroutine to park
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// before issuing the corresponding write. The test should pass no matter what
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// delay we use, but with a longer delay is has a higher chance of detecting
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// poller bugs.
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parkDelay := 10 * time.Millisecond
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if testing.Short() {
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parkDelay = 100 * time.Microsecond
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}
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writerDone := make(chan struct{})
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defer func() {
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if err := r.Close(); err != nil {
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t.Errorf("error closing reader: %v", err)
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}
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<-writerDone
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}()
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write := make(chan int, 1)
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go func() {
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defer close(writerDone)
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for i := range write {
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time.Sleep(parkDelay)
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_, err := fmt.Fprintf(w, "line %d\n", i)
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if err != nil {
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t.Errorf("error writing to fifo: %v", err)
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return
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}
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}
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time.Sleep(parkDelay)
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if err := w.Close(); err != nil {
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t.Errorf("error closing writer: %v", err)
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}
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}()
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rbuf := bufio.NewReader(r)
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for i := 0; i < 3; i++ {
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write <- i
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b, err := rbuf.ReadBytes('\n')
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if err != nil {
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t.Fatal(err)
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}
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t.Logf("%s\n", bytes.TrimSpace(b))
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}
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close(write)
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b, err := rbuf.ReadBytes('\n')
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if err != io.EOF || len(b) != 0 {
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t.Errorf(`ReadBytes: %q, %v; want "", io.EOF`, b, err)
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}
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}
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// Issue 24481.
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func TestFdRace(t *testing.T) {
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// This test starts 100 simultaneous goroutines, which could bury a more
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// interesting stack if this or some other test happens to panic. It is also
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// nearly instantaneous, so any latency benefit from running it in parallel
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// would be minimal.
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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defer r.Close()
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defer w.Close()
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var wg sync.WaitGroup
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call := func() {
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defer wg.Done()
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w.Fd()
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}
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const tries = 100
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for i := 0; i < tries; i++ {
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wg.Add(1)
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go call()
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}
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wg.Wait()
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}
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func TestFdReadRace(t *testing.T) {
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t.Parallel()
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r, w, err := os.Pipe()
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if err != nil {
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t.Fatal(err)
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}
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defer r.Close()
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defer w.Close()
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const count = 10
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c := make(chan bool, 1)
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var wg sync.WaitGroup
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wg.Add(1)
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go func() {
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defer wg.Done()
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var buf [count]byte
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r.SetReadDeadline(time.Now().Add(time.Minute))
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c <- true
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if _, err := r.Read(buf[:]); os.IsTimeout(err) {
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t.Error("read timed out")
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}
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}()
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wg.Add(1)
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go func() {
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defer wg.Done()
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<-c
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// Give the other goroutine a chance to enter the Read.
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// It doesn't matter if this occasionally fails, the test
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// will still pass, it just won't test anything.
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time.Sleep(10 * time.Millisecond)
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r.Fd()
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// The bug was that Fd would hang until Read timed out.
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// If the bug is fixed, then writing to w and closing r here
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// will cause the Read to exit before the timeout expires.
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w.Write(make([]byte, count))
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r.Close()
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}()
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wg.Wait()
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}
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