Do not rename test files on-the-fly to share functions

Instead this commit moves some functions that could be used by fuzzers.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

integration/client/daemon.go

@@ -0,0 +1,140 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package client
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"runtime"
+	"sync"
+	"syscall"
+
+	. "github.com/containerd/containerd"
+	exec "golang.org/x/sys/execabs"
+)
+
+type daemon struct {
+	sync.Mutex
+	addr string
+	cmd  *exec.Cmd
+}
+
+func (d *daemon) start(name, address string, args []string, stdout, stderr io.Writer) error {
+	d.Lock()
+	defer d.Unlock()
+	if d.cmd != nil {
+		return errors.New("daemon is already running")
+	}
+	args = append(args, []string{"--address", address}...)
+	cmd := exec.Command(name, args...)
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+	if err := cmd.Start(); err != nil {
+		cmd.Wait()
+		return fmt.Errorf("failed to start daemon: %w", err)
+	}
+	d.addr = address
+	d.cmd = cmd
+	return nil
+}
+
+func (d *daemon) waitForStart(ctx context.Context) (*Client, error) {
+	var (
+		client  *Client
+		serving bool
+		err     error
+	)
+
+	client, err = New(d.addr)
+	if err != nil {
+		return nil, err
+	}
+	serving, err = client.IsServing(ctx)
+	if !serving {
+		client.Close()
+		if err == nil {
+			err = errors.New("connection was successful but service is not available")
+		}
+		return nil, err
+	}
+	return client, err
+}
+
+func (d *daemon) Stop() error {
+	d.Lock()
+	defer d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+	return d.cmd.Process.Signal(syscall.SIGTERM)
+}
+
+func (d *daemon) Kill() error {
+	d.Lock()
+	defer d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+	return d.cmd.Process.Kill()
+}
+
+func (d *daemon) Wait() error {
+	d.Lock()
+	defer d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+	err := d.cmd.Wait()
+	d.cmd = nil
+	return err
+}
+
+func (d *daemon) Restart(stopCb func()) error {
+	d.Lock()
+	defer d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+
+	signal := syscall.SIGTERM
+	if runtime.GOOS == "windows" {
+		signal = syscall.SIGKILL
+	}
+	var err error
+	if err = d.cmd.Process.Signal(signal); err != nil {
+		return fmt.Errorf("failed to signal daemon: %w", err)
+	}
+
+	d.cmd.Wait()
+
+	if stopCb != nil {
+		stopCb()
+	}
+
+	cmd := exec.Command(d.cmd.Path, d.cmd.Args[1:]...)
+	cmd.Stdout = d.cmd.Stdout
+	cmd.Stderr = d.cmd.Stderr
+	if err := cmd.Start(); err != nil {
+		cmd.Wait()
+		return fmt.Errorf("failed to start new daemon instance: %w", err)
+	}
+	d.cmd = cmd
+
+	return nil
+}