fix: windows build compat

cmd.go

@@ -12,7 +12,7 @@ func runCommand(args []string) *exec.Cmd {
 	cmd := exec.Command(args[0], args[1:]...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
-	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	setProcAttr(cmd)
 
 	fmt.Println("[*] running command:", cmd)
 	err := cmd.Start()
@@ -28,14 +28,8 @@ func stopCommand(cmd *exec.Cmd) {
 		return
 	}
 
-	err := syscall.Kill(-cmd.Process.Pid, syscall.Signal(0))
-	if err != nil && err.Error() == "operation not permitted" {
-		// process no longer running, nothing to do here
-		return
-	}
-
 	fmt.Println("[*] stopping process", cmd.Process.Pid)
-	e := syscall.Kill(-cmd.Process.Pid, syscall.SIGTERM)
+	e := cmd.Process.Signal(syscall.SIGTERM)
 	if e != nil {
 		fmt.Println("error killing child process:", e)
 	}

cmd_nix.go

@@ -0,0 +1,12 @@
+//go:build linux || darwin
+
+package vproxy
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+func setProcAttr(cmd *exec.Cmd) {
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+}

cmd_windows.go

@@ -0,0 +1,12 @@
+//go:build windows
+
+package vproxy
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+func setProcAttr(cmd *exec.Cmd) {
+	cmd.SysProcAttr = &syscall.SysProcAttr{}
+}