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// Copyright 2017 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 darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
package net
import (
"bytes"
"syscall"
"testing"
"time"
)
// Test that a client can't trigger an endless loop of write system
// calls on the server by shutting down the write side on the client.
// Possibility raised in the discussion of https://golang.org/cl/71973.
func TestEndlessWrite(t *testing.T) {
t.Parallel()
c := make(chan bool)
server := func(cs *TCPConn) error {
cs.CloseWrite()
<-c
return nil
}
client := func(ss *TCPConn) error {
// Tell the server to return when we return.
defer close(c)
// Loop writing to the server. The server is not reading
// anything, so this will eventually block, and then time out.
b := bytes.Repeat([]byte{'a'}, 8192)
cagain := 0
for {
n, err := ss.conn.fd.pfd.WriteOnce(b)
if n > 0 {
cagain = 0
}
switch err {
case nil:
case syscall.EAGAIN:
if cagain == 0 {
// We've written enough data to
// start blocking. Set a deadline
// so that we will stop.
ss.SetWriteDeadline(time.Now().Add(5 * time.Millisecond))
}
cagain++
if cagain > 20 {
t.Error("looping on EAGAIN")
return nil
}
if err = ss.conn.fd.pfd.WaitWrite(); err != nil {
t.Logf("client WaitWrite: %v", err)
return nil
}
default:
// We expect to eventually get an error.
t.Logf("client WriteOnce: %v", err)
return nil
}
}
}
withTCPConnPair(t, client, server)
}
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