fix(machine): signal downcast causes gvproxy and vfkit/krunkit exit prematurely (#74)

这个 PR 修复了主进程收到 ctrl-C 信号向下广播信号导致 gvproxy 和 vfkit/krunkit 过早退出导致 DiskSync
失败的问题。

setpgid 将被调用进程的进程组 ID 设置为它自己的进程 ID，从而创建了一个新的进程组，被调用的进程成为了组长，当 signal
发生时，signal 则信号不会被传递到被调用进程，与此同时，ctx 仍能控制被调用进程何时结束(SIGKILL)。
https://pubs.opengroup.org/onlinepubs/009604599/functions/setpgid.html

Author: ihexon

pkg/machine/shim/network_darwin.go

@@ -8,12 +8,15 @@ package shim
 import (
 	"context"
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"reflect"
 	"time"
 	"unsafe"
 
+	"bauklotze/pkg/pty"
+
 	gvproxy "github.com/containers/gvisor-tap-vsock/pkg/types"
 	"github.com/containers/storage/pkg/fileutils"
 	"github.com/sirupsen/logrus"
@@ -84,14 +87,17 @@ func startForwarder(ctx context.Context, mc *vmconfig.MachineConfig, socksOnHost
 	mc.GvProxy.Sockets = bArray
 
 	gvpExecCmd := exec.CommandContext(ctx, gvpBin.GetPath(), gvproxyCommand.ToCmdline()...)
-	gvpExecCmd.Stdout = os.Stdout
-	gvpExecCmd.Stderr = os.Stderr
 
 	logrus.Infof("GVPROXY FULL CMDLINE: %q", gvpExecCmd.Args)
 	events.NotifyRun(events.StartGvProxy, "staring...")
-	if err := gvpExecCmd.Start(); err != nil {
+
+	ptmx, err := pty.RunInPty(gvpExecCmd)
+	if err != nil {
 		return fmt.Errorf("unable to execute: %q: %w", gvpExecCmd.Args, err)
 	}
+	go func() {
+		_, _ = io.Copy(os.Stdout, ptmx)
+	}()
 
 	events.NotifyRun(events.StartGvProxy, "finished")
 

pkg/pty/pty.go

@@ -22,5 +22,7 @@ func RunInPty(c *exec.Cmd) (*os.File, error) {
 		Rows: rows,
 		X:    rows,
 		Y:    cols,
-	}, &syscall.SysProcAttr{})
+	}, &syscall.SysProcAttr{
+		Setpgid: true,
+	})
 }