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