func (ctx *context) testProg(p *prog.Prog, duration time.Duration, opts csource.Options, reboot bool) (crashed bool, err error) {
	inst := <-ctx.instances
	if inst == nil {
		return false, fmt.Errorf("all VMs failed to boot")
	}
	defer func() {
		ctx.returnInstance(inst, reboot, crashed)
	}()

	pstr := p.Serialize()
	progFile, err := fileutil.WriteTempFile(pstr)
	if err != nil {
		return false, err
	}
	defer os.Remove(progFile)
	vmProgFile, err := inst.Copy(progFile)
	if err != nil {
		return false, fmt.Errorf("failed to copy to VM: %v", err)
	}

	repeat := "1"
	if opts.Repeat {
		repeat = "0"
	}
	command := fmt.Sprintf("%v -executor %v -cover=0 -procs=%v -repeat=%v -sandbox %v -threaded=%v -collide=%v %v",
		inst.execprogBin, inst.executorBin, opts.Procs, repeat, opts.Sandbox, opts.Threaded, opts.Collide, vmProgFile)
	Logf(2, "reproducing crash '%v': testing program (duration=%v, %+v): %s",
		ctx.crashDesc, duration, opts, p)
	return ctx.testImpl(inst, command, duration)
}

func testProg(cfg *config.Config, p *prog.Prog, multiplier int, threaded, collide bool) (res bool) {
	log.Printf("booting VM")
	inst := <-instances
	defer func() {
		returnInstance(inst, res)
	}()

	pstr := p.Serialize()
	progFile, err := fileutil.WriteTempFile(pstr)
	if err != nil {
		log.Fatalf("%v", err)
	}
	defer os.Remove(progFile)
	bin, err := inst.Copy(progFile)
	if err != nil {
		log.Fatalf("failed to copy to VM: %v", err)
	}

	repeat := 100
	timeoutSec := 10 * repeat / cfg.Procs
	if threaded {
		repeat *= 10
		timeoutSec *= 1
	}
	repeat *= multiplier
	timeoutSec *= multiplier
	timeout := time.Duration(timeoutSec) * time.Second
	command := fmt.Sprintf("%v -executor %v -cover=0 -procs=%v -repeat=%v -threaded=%v -collide=%v %v",
		inst.execprogBin, inst.executorBin, cfg.Procs, repeat, threaded, collide, bin)
	log.Printf("testing program (threaded=%v, collide=%v, repeat=%v, timeout=%v):\n%s\n",
		threaded, collide, repeat, timeout, pstr)
	return testImpl(inst, command, timeout)
}

func execute(pid int, env *ipc.Env, p *prog.Prog, stat *uint64) {
	allCover := execute1(pid, env, p, stat)
	coverMu.RLock()
	defer coverMu.RUnlock()
	for i, cov := range allCover {
		if len(cov) == 0 {
			continue
		}
		c := p.Calls[i].Meta
		diff := cover.Difference(cov, maxCover[c.CallID])
		diff = cover.Difference(diff, flakes)
		if len(diff) != 0 {
			coverMu.RUnlock()
			coverMu.Lock()
			maxCover[c.CallID] = cover.Union(maxCover[c.CallID], diff)
			coverMu.Unlock()
			coverMu.RLock()

			inp := Input{p.Clone(), i, cover.Copy(cov)}
			triageMu.Lock()
			triage = append(triage, inp)
			triageMu.Unlock()
		}
	}
}

func execute(pid int, env *ipc.Env, p *prog.Prog) {
	if *flagExecutor == "" {
		return
	}
	atomic.AddUint64(&statExec, 1)
	if *flagLogProg {
		ticket := gate.Enter()
		defer gate.Leave(ticket)
		outMu.Lock()
		fmt.Printf("executing program %v\n%s\n", pid, p.Serialize())
		outMu.Unlock()
	}

	output, _, _, failed, hanged, err := env.Exec(p)
	if err != nil {
		fmt.Printf("failed to execute executor: %v\n", err)
	}
	paniced := failedRe.Match(output)
	if failed || hanged || paniced || err != nil {
		fmt.Printf("PROGRAM:\n%s\n", p.Serialize())
	}
	if failed || hanged || paniced || err != nil || *flagOutput {
		os.Stdout.Write(output)
	}
}

func main() {
	flag.Parse()
	corpus := readCorpus()
	flags := ipc.FlagThreaded
	if *flagDebug {
		flags |= ipc.FlagDebug
	}
	env, err := ipc.MakeEnv(*flagExecutor, 4*time.Second, flags)
	if err != nil {
		failf("failed to create execution environment: %v", err)
	}
	rs := rand.NewSource(time.Now().UnixNano())
	rnd := rand.New(rs)
	for i := 0; ; i++ {
		var p *prog.Prog
		if len(corpus) == 0 || i%10 != 0 {
			p = prog.Generate(rs, 50, nil)
			execute(env, p)
			p.Mutate(rs, 50, nil)
			execute(env, p)
		} else {
			p = corpus[rnd.Intn(len(corpus))].Clone()
			p.Mutate(rs, 50, nil)
			execute(env, p)
		}
	}
}

func execute(env *ipc.Env, p *prog.Prog) {
	allCover := execute1(env, p)
	for i, cov := range allCover {
		if len(cov) == 0 {
			continue
		}
		c := p.Calls[i].Meta
		diff := cover.Difference(cov, maxCover[c.CallID])
		diff = cover.Difference(diff, flakes)
		if len(diff) != 0 {
			triage = append(triage, Input{p.Clone(), i, cover.Copy(cov)})
		}
	}
}

func testOne(t *testing.T, p *prog.Prog, opts Options) {
	src := Write(p, opts)
	srcf, err := fileutil.WriteTempFile(src)
	if err != nil {
		t.Logf("program:\n%s\n", p.Serialize())
		t.Fatalf("%v", err)
	}
	defer os.Remove(srcf)
	bin, err := Build(srcf)
	if err != nil {
		t.Logf("program:\n%s\n", p.Serialize())
		t.Fatalf("%v", err)
	}
	defer os.Remove(bin)
}

func execute(env *ipc.Env, p *prog.Prog) {
	if *flagExecutor == "" {
		return
	}
	output, _, _, _, _, err := env.Exec(p)
	if err != nil {
		fmt.Printf("failed to execute executor: %v\n", err)
	}
	failed := failedRe.Match(output)
	if failed {
		fmt.Printf("PROGRAM:\n%s\n", p.Serialize())
	}
	if failed || *flagOutput {
		os.Stdout.Write(output)
	}
}

func execute(env *ipc.Env, p *prog.Prog, workerId int) []Input {
	allCover := execute1(env, p, workerId)
	var inputs []Input
	for i, cov := range allCover {
		if len(cov) == 0 {
			continue
		}
		c := p.Calls[i].Meta
		diff := cover.Difference(cov, maxCover[c.CallID])
		diff = cover.Difference(diff, flakes)
		if len(diff) != 0 {
			p1 := p.Clone()
			p1.TrimAfter(i)
			inputs = append(inputs, Input{p1, i, cover.Copy(cov)})
		}
	}
	return inputs
}

func main() {
	flag.Parse()
	corpus := readCorpus()
	log.Printf("parsed %v programs", len(corpus))

	calls := buildCallList()
	prios := prog.CalculatePriorities(corpus)
	ct := prog.BuildChoiceTable(prios, calls)

	var flags uint64
	if *flagThreaded {
		flags |= ipc.FlagThreaded
	}
	if *flagCollide {
		flags |= ipc.FlagCollide
	}
	if *flagNobody {
		flags |= ipc.FlagDropPrivs
	}
	if *flagDebug {
		flags |= ipc.FlagDebug
	}
	if *flagNoPgid {
		flags |= ipc.FlagNoSetpgid
	}

	gate = ipc.NewGate(2 * *flagProcs)
	for pid := 0; pid < *flagProcs; pid++ {
		pid := pid
		go func() {
			env, err := ipc.MakeEnv(*flagExecutor, *flagTimeout, flags)
			if err != nil {
				failf("failed to create execution environment: %v", err)
			}
			rs := rand.NewSource(time.Now().UnixNano() + int64(pid)*1e12)
			rnd := rand.New(rs)
			for i := 0; ; i++ {
				var p *prog.Prog
				if len(corpus) == 0 || i%4 != 0 {
					p = prog.Generate(rs, programLength, ct)
					execute(pid, env, p)
					p.Mutate(rs, programLength, ct)
					execute(pid, env, p)
				} else {
					p = corpus[rnd.Intn(len(corpus))].Clone()
					p.Mutate(rs, programLength, ct)
					execute(pid, env, p)
					p.Mutate(rs, programLength, ct)
					execute(pid, env, p)
				}
			}
		}()
	}
	for range time.NewTicker(5 * time.Second).C {
		log.Printf("executed %v programs", atomic.LoadUint64(&statExec))
	}
}

func main() {
	flag.Parse()
	corpus := readCorpus()
	var flags uint64
	if *flagThreaded {
		flags |= ipc.FlagThreaded
	}
	if *flagCollide {
		flags |= ipc.FlagCollide
	}
	if *flagNobody {
		flags |= ipc.FlagDropPrivs
	}
	if *flagDebug {
		flags |= ipc.FlagDebug
	}

	for p := 0; p < *flagProcs; p++ {
		go func() {
			env, err := ipc.MakeEnv(*flagExecutor, 10*time.Second, flags)
			if err != nil {
				failf("failed to create execution environment: %v", err)
			}
			rs := rand.NewSource(time.Now().UnixNano())
			rnd := rand.New(rs)
			for i := 0; ; i++ {
				var p *prog.Prog
				if len(corpus) == 0 || i%10 != 0 {
					p = prog.Generate(rs, 50, nil)
					execute(env, p)
					p.Mutate(rs, 50, nil)
					execute(env, p)
				} else {
					p = corpus[rnd.Intn(len(corpus))].Clone()
					p.Mutate(rs, 50, nil)
					execute(env, p)
				}
			}
		}()
	}
	select {}
}

func execute1(env *ipc.Env, p *prog.Prog, stat *uint64) []cover.Cover {
	if *flagSaveProg {
		f, err := os.Create(fmt.Sprintf("%v.prog", *flagName))
		if err == nil {
			f.Write(p.Serialize())
			f.Close()
		}
	} else {
		// The following output helps to understand what program crashed kernel.
		// It must not be intermixed.
		logMu.Lock()
		log.Printf("executing program:\n%s", p.Serialize())
		logMu.Unlock()
	}

	try := 0
retry:
	*stat++
	output, strace, rawCover, failed, hanged, err := env.Exec(p)
	if err != nil {
		if try > 10 {
			panic(err)
		}
		try++
		debug.FreeOSMemory()
		time.Sleep(time.Second)
		goto retry
	}
	logf(4, "result failed=%v hanged=%v:\n%v\n", failed, hanged, string(output))
	if len(strace) != 0 {
		logf(4, "strace:\n%s\n", strace)
	}
	cov := make([]cover.Cover, len(p.Calls))
	for i, c := range rawCover {
		cov[i] = cover.Cover(c)
	}
	return cov
}

func main() {
	flag.Parse()
	corpus := readCorpus()
	Logf(0, "parsed %v programs", len(corpus))

	calls := buildCallList()
	prios := prog.CalculatePriorities(corpus)
	ct := prog.BuildChoiceTable(prios, calls)

	flags, timeout, err := ipc.DefaultFlags()
	if err != nil {
		Fatalf("%v", err)
	}
	gate = ipc.NewGate(2**flagProcs, nil)
	for pid := 0; pid < *flagProcs; pid++ {
		pid := pid
		go func() {
			env, err := ipc.MakeEnv(*flagExecutor, timeout, flags, pid)
			if err != nil {
				Fatalf("failed to create execution environment: %v", err)
			}
			rs := rand.NewSource(time.Now().UnixNano() + int64(pid)*1e12)
			rnd := rand.New(rs)
			for i := 0; ; i++ {
				var p *prog.Prog
				if len(corpus) == 0 || i%4 != 0 {
					p = prog.Generate(rs, programLength, ct)
					execute(pid, env, p)
					p.Mutate(rs, programLength, ct, corpus)
					execute(pid, env, p)
				} else {
					p = corpus[rnd.Intn(len(corpus))].Clone()
					p.Mutate(rs, programLength, ct, corpus)
					execute(pid, env, p)
					p.Mutate(rs, programLength, ct, corpus)
					execute(pid, env, p)
				}
			}
		}()
	}
	for range time.NewTicker(5 * time.Second).C {
		Logf(0, "executed %v programs", atomic.LoadUint64(&statExec))
	}
}

// Exec starts executor binary to execute program p and returns information about the execution:
// output: process output
// cov: per-call coverage, len(cov) == len(p.Calls)
// failed: true if executor has detected a kernel bug
// hanged: program hanged and was killed
// err0: failed to start process, or executor has detected a logical error
func (env *Env) Exec(p *prog.Prog) (output []byte, cov [][]uint32, errnos []int, failed, hanged bool, err0 error) {
	if p != nil {
		// Copy-in serialized program.
		progData := p.SerializeForExec(env.pid)
		if len(progData) > len(env.In) {
			err0 = fmt.Errorf("executor %v: program is too long: %v/%v", env.pid, len(progData), len(env.In))
			return
		}
		copy(env.In, progData)
	}
	if env.flags&FlagCover != 0 {
		// Zero out the first word (ncmd), so that we don't have garbage there
		// if executor crashes before writing non-garbage there.
		for i := 0; i < 4; i++ {
			env.Out[i] = 0
		}
	}

	atomic.AddUint64(&env.StatExecs, 1)
	if env.cmd == nil {
		atomic.AddUint64(&env.StatRestarts, 1)
		env.cmd, err0 = makeCommand(env.pid, env.bin, env.timeout, env.flags, env.inFile, env.outFile)
		if err0 != nil {
			return
		}
	}
	var restart bool
	output, failed, hanged, restart, err0 = env.cmd.exec()
	if err0 != nil || restart {
		env.cmd.close()
		env.cmd = nil
		return
	}

	if env.flags&FlagCover == 0 || p == nil {
		return
	}
	// Read out coverage information.
	r := bytes.NewReader(env.Out)
	var ncmd uint32
	if err := binary.Read(r, binary.LittleEndian, &ncmd); err != nil {
		err0 = fmt.Errorf("executor %v: failed to read output coverage: %v", env.pid, err)
		return
	}
	cov = make([][]uint32, len(p.Calls))
	errnos = make([]int, len(p.Calls))
	for i := range errnos {
		errnos[i] = -1 // not executed
	}
	dumpCov := func() string {
		buf := new(bytes.Buffer)
		for i, c := range cov {
			str := "nil"
			if c != nil {
				str = fmt.Sprint(len(c))
			}
			fmt.Fprintf(buf, "%v:%v|", i, str)
		}
		return buf.String()
	}
	for i := uint32(0); i < ncmd; i++ {
		var callIndex, callNum, errno, coverSize, pc uint32
		if err := binary.Read(r, binary.LittleEndian, &callIndex); err != nil {
			err0 = fmt.Errorf("executor %v: failed to read output coverage: %v", env.pid, err)
			return
		}
		if err := binary.Read(r, binary.LittleEndian, &callNum); err != nil {
			err0 = fmt.Errorf("executor %v: failed to read output coverage: %v", env.pid, err)
			return
		}
		if err := binary.Read(r, binary.LittleEndian, &errno); err != nil {
			err0 = fmt.Errorf("executor %v: failed to read output errno: %v", env.pid, err)
			return
		}
		if err := binary.Read(r, binary.LittleEndian, &coverSize); err != nil {
			err0 = fmt.Errorf("executor %v: failed to read output coverage: %v", env.pid, err)
			return
		}
		if int(callIndex) > len(cov) {
			err0 = fmt.Errorf("executor %v: failed to read output coverage: record %v, call %v, total calls %v (cov: %v)",
				env.pid, i, callIndex, len(cov), dumpCov())
			return
		}
		if cov[callIndex] != nil {
			err0 = fmt.Errorf("executor %v: failed to read output coverage: double coverage for call %v (cov: %v)",
				env.pid, callIndex, dumpCov())
			return
		}
		c := p.Calls[callIndex]
		if num := c.Meta.ID; uint32(num) != callNum {
			err0 = fmt.Errorf("executor %v: failed to read output coverage: call %v: expect syscall %v, got %v, executed %v (cov: %v)",
				env.pid, callIndex, num, callNum, ncmd, dumpCov())
			return
		}
//.........这里部分代码省略.........

func execute1(pid int, env *ipc.Env, p *prog.Prog, stat *uint64) []cover.Cover {
	if false {
		// For debugging, this function must not be executed with locks held.
		corpusMu.Lock()
		corpusMu.Unlock()
		coverMu.Lock()
		coverMu.Unlock()
		triageMu.Lock()
		triageMu.Unlock()
	}

	// Limit concurrency window and do leak checking once in a while.
	idx := gate.Enter()
	defer gate.Leave(idx, func() {
		if idx == 0 && *flagLeak && atomic.LoadUint32(&allTriaged) != 0 {
			// Scan for leaks once in a while (it is damn slow).
			kmemleakScan(true)
		}
	})

	// The following output helps to understand what program crashed kernel.
	// It must not be intermixed.
	switch *flagOutput {
	case "none":
		// This case intentionally left blank.
	case "stdout":
		data := p.Serialize()
		logMu.Lock()
		log.Printf("executing program %v:\n%s", pid, data)
		logMu.Unlock()
	case "dmesg":
		fd, err := syscall.Open("/dev/kmsg", syscall.O_WRONLY, 0)
		if err == nil {
			buf := new(bytes.Buffer)
			fmt.Fprintf(buf, "syzkaller: executing program %v:\n%s", pid, p.Serialize())
			syscall.Write(fd, buf.Bytes())
			syscall.Close(fd)
		}
	case "file":
		f, err := os.Create(fmt.Sprintf("%v-%v.prog", *flagName, pid))
		if err == nil {
			f.Write(p.Serialize())
			f.Close()
		}
	}

	try := 0
retry:
	atomic.AddUint64(stat, 1)
	output, rawCover, errnos, failed, hanged, err := env.Exec(p)
	_ = errnos
	if failed {
		// BUG in output should be recognized by manager.
		logf(0, "BUG: executor-detected bug:\n%s", output)
		// Don't return any cover so that the input is not added to corpus.
		return make([]cover.Cover, len(p.Calls))
	}
	if err != nil {
		if try > 10 {
			panic(err)
		}
		try++
		debug.FreeOSMemory()
		time.Sleep(time.Second)
		goto retry
	}
	logf(4, "result failed=%v hanged=%v:\n%v\n", failed, hanged, string(output))
	cov := make([]cover.Cover, len(p.Calls))
	for i, c := range rawCover {
		cov[i] = cover.Cover(c)
	}
	return cov
}

// Exec starts executor binary to execute program p and returns information about the execution:
// output: process output
// strace: strace output if env is created with FlagStrace
// cov: per-call coverage, len(cov) == len(p.Calls)
// failed: true if executor has detected a kernel bug
// hanged: program hanged and was killed
// err0: failed to start process, or executor has detected a logical error
func (env *Env) Exec(p *prog.Prog) (output, strace []byte, cov [][]uint32, failed, hanged bool, err0 error) {
	if p != nil {
		// Copy-in serialized program.
		progData := p.SerializeForExec()
		if len(progData) > len(env.In) {
			panic("program is too long")
		}
		copy(env.In, progData)
	}
	if env.flags&FlagCover != 0 {
		// Zero out the first word (ncmd), so that we don't have garbage there
		// if executor crashes before writing non-garbage there.
		for i := 0; i < 4; i++ {
			env.Out[i] = 0
		}
	}

	atomic.AddUint64(&env.StatExecs, 1)
	if env.cmd == nil {
		atomic.AddUint64(&env.StatRestarts, 1)
		env.cmd, err0 = makeCommand(env.bin, env.timeout, env.flags, env.inFile, env.outFile)
		if err0 != nil {
			return
		}
	}
	output, strace, failed, hanged, err0 = env.cmd.exec()
	if err0 != nil {
		env.cmd.close()
		env.cmd = nil
		return
	}

	if env.flags&FlagCover == 0 || p == nil {
		return
	}
	// Read out coverage information.
	r := bytes.NewReader(env.Out)
	var ncmd uint32
	if err := binary.Read(r, binary.LittleEndian, &ncmd); err != nil {
		err0 = fmt.Errorf("failed to read output coverage: %v", err)
		return
	}
	cov = make([][]uint32, len(p.Calls))
	for i := uint32(0); i < ncmd; i++ {
		var callIndex, callNum, coverSize, pc uint32
		if err := binary.Read(r, binary.LittleEndian, &callIndex); err != nil {
			err0 = fmt.Errorf("failed to read output coverage: %v", err)
			return
		}
		if err := binary.Read(r, binary.LittleEndian, &callNum); err != nil {
			err0 = fmt.Errorf("failed to read output coverage: %v", err)
			return
		}
		if err := binary.Read(r, binary.LittleEndian, &coverSize); err != nil {
			err0 = fmt.Errorf("failed to read output coverage: %v", err)
			return
		}
		if int(callIndex) > len(cov) {
			err0 = fmt.Errorf("failed to read output coverage: expect index %v, got %v", i, callIndex)
			return
		}
		if cov[callIndex] != nil {
			err0 = fmt.Errorf("failed to read output coverage: double coverage for call %v", callIndex)
			return
		}
		c := p.Calls[callIndex]
		if num := c.Meta.ID; uint32(num) != callNum {
			err0 = fmt.Errorf("failed to read output coverage: call %v: expect syscall %v, got %v, executed %v", callIndex, num, callNum, ncmd)
			return
		}
		cov1 := make([]uint32, coverSize)
		for j := uint32(0); j < coverSize; j++ {
			if err := binary.Read(r, binary.LittleEndian, &pc); err != nil {
				err0 = fmt.Errorf("failed to read output coverage: expect index %v, got %v", i, callIndex)
				return
			}
			cov1[j] = pc
		}
		cov[callIndex] = cov1
	}
	return
}

func Write(p *prog.Prog, opts Options) ([]byte, error) {
	exec := p.SerializeForExec(0)
	w := new(bytes.Buffer)

	fmt.Fprint(w, "// autogenerated by syzkaller (http://github.com/google/syzkaller)\n\n")

	handled := make(map[string]int)
	for _, c := range p.Calls {
		handled[c.Meta.CallName] = c.Meta.NR
	}
	for name, nr := range handled {
		fmt.Fprintf(w, "#ifndef __NR_%v\n", name)
		fmt.Fprintf(w, "#define __NR_%v %v\n", name, nr)
		fmt.Fprintf(w, "#endif\n")
	}
	fmt.Fprintf(w, "\n")

	enableTun := "false"
	if _, ok := handled["syz_emit_ethernet"]; ok {
		enableTun = "true"
	}

	hdr, err := preprocessCommonHeader(opts, handled)
	if err != nil {
		return nil, err
	}
	fmt.Fprint(w, hdr)
	fmt.Fprint(w, "\n")

	calls, nvar := generateCalls(exec)
	fmt.Fprintf(w, "long r[%v];\n", nvar)

	if !opts.Repeat {
		generateTestFunc(w, opts, calls, "loop")

		fmt.Fprint(w, "int main()\n{\n")
		fmt.Fprintf(w, "\tsetup_main_process(0, %v);\n", enableTun)
		fmt.Fprintf(w, "\tint pid = do_sandbox_%v();\n", opts.Sandbox)
		fmt.Fprint(w, "\tint status = 0;\n")
		fmt.Fprint(w, "\twhile (waitpid(pid, &status, __WALL) != pid) {}\n")
		fmt.Fprint(w, "\treturn 0;\n}\n")
	} else {
		generateTestFunc(w, opts, calls, "test")
		if opts.Procs <= 1 {
			fmt.Fprint(w, "int main()\n{\n")
			fmt.Fprintf(w, "\tsetup_main_process(0, %v);\n", enableTun)
			fmt.Fprintf(w, "\tint pid = do_sandbox_%v();\n", opts.Sandbox)
			fmt.Fprint(w, "\tint status = 0;\n")
			fmt.Fprint(w, "\twhile (waitpid(pid, &status, __WALL) != pid) {}\n")
			fmt.Fprint(w, "\treturn 0;\n}\n")
		} else {
			fmt.Fprint(w, "int main()\n{\n")
			fmt.Fprint(w, "\tint i;")
			fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", opts.Procs)
			fmt.Fprint(w, "\t\tif (fork() == 0) {\n")
			fmt.Fprintf(w, "\t\t\tsetup_main_process(i, %v);\n", enableTun)
			fmt.Fprintf(w, "\t\t\tdo_sandbox_%v();\n", opts.Sandbox)
			fmt.Fprint(w, "\t\t}\n")
			fmt.Fprint(w, "\t}\n")
			fmt.Fprint(w, "\tsleep(1000000);\n")
			fmt.Fprint(w, "\treturn 0;\n}\n")
		}
	}
	// Remove duplicate new lines.
	out := w.Bytes()
	for {
		out1 := bytes.Replace(out, []byte{'\n', '\n', '\n'}, []byte{'\n', '\n'}, -1)
		if len(out) == len(out1) {
			break
		}
		out = out1
	}
	return out, nil
}

func Write(p *prog.Prog, opts Options) []byte {
	exec := p.SerializeForExec()
	w := new(bytes.Buffer)

	fmt.Fprint(w, "// autogenerated by syzkaller (http://github.com/google/syzkaller)\n\n")

	handled := make(map[string]int)
	for _, c := range p.Calls {
		handled[c.Meta.CallName] = c.Meta.NR
	}
	for _, c := range sys.Calls {
		if strings.HasPrefix(c.CallName, "syz_") {
			handled[c.CallName] = c.NR
		}
	}
	for name, nr := range handled {
		fmt.Fprintf(w, "#ifndef __NR_%v\n", name)
		fmt.Fprintf(w, "#define __NR_%v %v\n", name, nr)
		fmt.Fprintf(w, "#endif\n")
	}
	fmt.Fprintf(w, "\n")

	fmt.Fprint(w, commonHeader)
	fmt.Fprint(w, "\n")

	calls, nvar := generateCalls(exec)
	fmt.Fprintf(w, "long r[%v];\n", nvar)

	if !opts.Threaded && !opts.Collide {
		fmt.Fprint(w, `
int main()
{
	install_segv_handler();
	memset(r, -1, sizeof(r));
`)
		for _, c := range calls {
			fmt.Fprintf(w, "%s", c)
		}
		fmt.Fprintf(w, "\treturn 0;\n}\n")
	} else {
		fmt.Fprintf(w, "void *thr(void *arg)\n{\n")
		fmt.Fprintf(w, "\tswitch ((long)arg) {\n")
		for i, c := range calls {
			fmt.Fprintf(w, "\tcase %v:\n", i)
			fmt.Fprintf(w, "%s", strings.Replace(c, "\t", "\t\t", -1))
			fmt.Fprintf(w, "\t\tbreak;\n")
		}
		fmt.Fprintf(w, "\t}\n")
		fmt.Fprintf(w, "\treturn 0;\n}\n\n")

		fmt.Fprintf(w, "int main()\n{\n")
		fmt.Fprintf(w, "\tlong i;\n")
		fmt.Fprintf(w, "\tpthread_t th[%v];\n", 2*len(calls))
		fmt.Fprintf(w, "\n")
		fmt.Fprintf(w, "install_segv_handler();\n")
		fmt.Fprintf(w, "\tmemset(r, -1, sizeof(r));\n")
		fmt.Fprintf(w, "\tsrand(getpid());\n")
		fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
		fmt.Fprintf(w, "\t\tpthread_create(&th[i], 0, thr, (void*)i);\n")
		fmt.Fprintf(w, "\t\tusleep(10000);\n")
		fmt.Fprintf(w, "\t}\n")
		if opts.Collide {
			fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
			fmt.Fprintf(w, "\t\tpthread_create(&th[%v+i], 0, thr, (void*)i);\n", len(calls))
			fmt.Fprintf(w, "\t\tif (rand()%%2)\n")
			fmt.Fprintf(w, "\t\t\tusleep(rand()%%10000);\n")
			fmt.Fprintf(w, "\t}\n")
		}
		fmt.Fprintf(w, "\tusleep(100000);\n")
		fmt.Fprintf(w, "\treturn 0;\n}\n")
	}
	return w.Bytes()
}

func Write(p *prog.Prog, opts Options) []byte {
	exec := p.SerializeForExec()
	w := new(bytes.Buffer)

	fmt.Fprintf(w, `// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <stdint.h>
#include <pthread.h>

`)

	handled := make(map[string]bool)
	for _, c := range p.Calls {
		name := c.Meta.CallName
		if handled[name] {
			continue
		}
		handled[name] = true
		fmt.Fprintf(w, "#ifndef SYS_%v\n", name)
		fmt.Fprintf(w, "#define SYS_%v %v\n", name, c.Meta.NR)
		fmt.Fprintf(w, "#endif\n")
	}
	fmt.Fprintf(w, "\n")

	calls, nvar := generateCalls(exec)
	fmt.Fprintf(w, "long r[%v];\n\n", nvar)

	if !opts.Threaded && !opts.Collide {
		fmt.Fprintf(w, "int main()\n{\n")
		fmt.Fprintf(w, "\tmemset(r, -1, sizeof(r));\n")
		for _, c := range calls {
			fmt.Fprintf(w, "%s", c)
		}
		fmt.Fprintf(w, "\treturn 0;\n}\n")
	} else {
		fmt.Fprintf(w, "void *thr(void *arg)\n{\n")
		fmt.Fprintf(w, "\tswitch ((long)arg) {\n")
		for i, c := range calls {
			fmt.Fprintf(w, "\tcase %v:\n", i)
			fmt.Fprintf(w, "%s", strings.Replace(c, "\t", "\t\t", -1))
			fmt.Fprintf(w, "\t\tbreak;\n")
		}
		fmt.Fprintf(w, "\t}\n")
		fmt.Fprintf(w, "\treturn 0;\n}\n\n")

		fmt.Fprintf(w, "int main()\n{\n")
		fmt.Fprintf(w, "\tlong i;\n")
		fmt.Fprintf(w, "\tpthread_t th[%v];\n", len(calls))
		fmt.Fprintf(w, "\n")
		fmt.Fprintf(w, "\tmemset(r, -1, sizeof(r));\n")
		fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
		fmt.Fprintf(w, "\t\tpthread_create(&th[i], 0, thr, (void*)i);\n")
		fmt.Fprintf(w, "\t\tusleep(10000);\n")
		fmt.Fprintf(w, "\t}\n")
		if opts.Collide {
			fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
			fmt.Fprintf(w, "\t\tpthread_create(&th[i], 0, thr, (void*)i);\n")
			fmt.Fprintf(w, "\t\tif (i%%2==0)\n")
			fmt.Fprintf(w, "\t\t\tusleep(10000);\n")
			fmt.Fprintf(w, "\t}\n")
		}
		fmt.Fprintf(w, "\tusleep(100000);\n")
		fmt.Fprintf(w, "\treturn 0;\n}\n")
	}
	return w.Bytes()
}