signalexec.go

Documentation: runtime/testdata/testprognet

     1  // Copyright 2017 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  // +build darwin dragonfly freebsd linux netbsd openbsd
     6  
     7  // This is in testprognet instead of testprog because testprog
     8  // must not import anything (like net, but also like os/signal)
     9  // that kicks off background goroutines during init.
    10  
    11  package main
    12  
    13  import (
    14  	"fmt"
    15  	"os"
    16  	"os/exec"
    17  	"os/signal"
    18  	"sync"
    19  	"syscall"
    20  	"time"
    21  )
    22  
    23  func init() {
    24  	register("SignalDuringExec", SignalDuringExec)
    25  	register("Nop", Nop)
    26  }
    27  
    28  func SignalDuringExec() {
    29  	pgrp := syscall.Getpgrp()
    30  
    31  	const tries = 10
    32  
    33  	var wg sync.WaitGroup
    34  	c := make(chan os.Signal, tries)
    35  	signal.Notify(c, syscall.SIGWINCH)
    36  	wg.Add(1)
    37  	go func() {
    38  		defer wg.Done()
    39  		for range c {
    40  		}
    41  	}()
    42  
    43  	for i := 0; i < tries; i++ {
    44  		time.Sleep(time.Microsecond)
    45  		wg.Add(2)
    46  		go func() {
    47  			defer wg.Done()
    48  			cmd := exec.Command(os.Args[0], "Nop")
    49  			cmd.Stdout = os.Stdout
    50  			cmd.Stderr = os.Stderr
    51  			if err := cmd.Run(); err != nil {
    52  				fmt.Printf("Start failed: %v", err)
    53  			}
    54  		}()
    55  		go func() {
    56  			defer wg.Done()
    57  			syscall.Kill(-pgrp, syscall.SIGWINCH)
    58  		}()
    59  	}
    60  
    61  	signal.Stop(c)
    62  	close(c)
    63  	wg.Wait()
    64  
    65  	fmt.Println("OK")
    66  }
    67  
    68  func Nop() {
    69  	// This is just for SignalDuringExec.
    70  }
    71
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