This package will tell you whether or not a golang application was opened in the terminal. Very useful for `fyne` or any other UI libs, when you plan on having both a GUI and a CLI. We're using this to make an app that can be used heedlessly, for the advanced users, and with a GUI using fyne so the less experienced users can use the tool too.

opened.go

// +build windows

package opened

import (
	"syscall"
	"unsafe"
)

// <Unsafe>

var (
	// TODO:
	// Replace these calls with golang.org/x/sys/windows
	// Right now, syscall.NewLazyDLL is subjected to potential DLL preloading
	// attacks.
	moduser32   = syscall.NewLazyDLL("user32.dll")
	modkernel32 = syscall.NewLazyDLL("kernel32.dll")

	getConsoleWindowProc         = modkernel32.NewProc("GetConsoleWindow")
	getCurrentProcessIDProc      = modkernel32.NewProc("GetCurrentProcessId")
	getWindowThreadProcessIDProc = moduser32.NewProc("GetWindowThreadProcessId")
)

func getWindowThreadProcessID(hwnd uintptr) (uintptr, uint32) {
	var processID uint32
	ret, _, _ := getWindowThreadProcessIDProc.Call(
		hwnd,
		uintptr(unsafe.Pointer(&processID)),
	)
	return ret, processID
}

func getCurrentProcessID() uint32 {
	id, _, _ := getCurrentProcessIDProc.Call()
	return uint32(id)
}

func getConsoleWindow() uintptr {
	// Note:
	// If you build with -ldflags -H=windowsgui
	// You will need to check the error, it'll be like "The handle is invalid."
	hwnd, _, _ := getConsoleWindowProc.Call()
	return hwnd
}

// </Unsafe>

// WithTerminal returns if the application was opened with a terminal or with
// the desktop.
func WithTerminal() bool {
	console := getConsoleWindow()
	if console != 0 {
		_, consoleProcID := getWindowThreadProcessID(console)
		if getCurrentProcessID() == consoleProcID {
			return false
		}
	}

	return true
}