Windows: Get rid of the terminal window in the background

[amo13]

Currently the app is not started as a GUI app but as a command line app. This is the standard for binaries built with go build. Therefore, a terminal is attached to the launched app. Alternatively, we can launch the app as a GUI application without attached terminal. This is the standard for apps packaged with fyne package. Additionally, the packaged app gets displayed with its application icon. This way would be ideal.

Unfortunately, if we launch the app as a GUI app without terminal attached, terminal windows pop up every second on top of the app window even stealing focus. This is because the app needs to call binaries periodically in the background (adb, fastboot and heimdall) and evalutate what they return. An ideal solution would find a way to make the calls to the binaries without making a terminals pop up.

[j0le]

Here are some ideas, I have, that might work:

• Configure the go compiler to create a GUI app (IMAGE_SUBSYSTEM_WINDOWS_GUI )
• Find a way to call Native Windows Functions from Go
• Create a (hidden) console window with AllocConsole() (or hide the window later). See also Creation of a Console – Microsoft Docs
• If the Window is not yet hidden, get a window handle (HWND) to control the window. See How to obtain a Console Window Handle (HWND) – Microsoft Docs or to do it another way use GetConsoleWindow()
• Use ShowWindow() with SW_HIDE to hide the window of the console

I did not test any of this. It will most likely fail, because I forgot something. But it might be a good starting point.

Another way to reach the goal, would be to use a relatively new MS Windows feature: Pseudo Consoles. They should work like pseudo terminals (PTYs) on Unix/Linux. tmux and terminal emulators use them to play the role of a terminal. All whats left to do is to read all input comming from the stdouts of the started processes through the pty stuff and ignore it. See a post from the Windows Command Line blog Windows Command-Line: Introducing the Windows Pseudo Console (ConPTY) or Microsoft Docs. This mechanism is used by the new GUI terminal/console emulator “Windows Terminal”.

Another way to hide a console window would be, to look at the code of the terminal emulator ConEmu or the library winpty, which use a hidden console window and not the new Windows feature “pseudo console”.

[j0le]

I’ve written a C++ application to test all this. It works 😀. You can see it in my fork (j0le/Anarchy-Droid) in the branch no-console-wnd. The latest commit is https://github.com/j0le/Anarchy-Droid/commit/6415651371aaffe43ff1bc8d1e94d76656dda459 . Now the only thing, what’s left to do, is to port this from C++ to go. I didn’t request a pull yet, because it’s not finished yet.

These two blog posts might help porting it to go:

• https://medium.com/@justen.walker/breaking-all-the-rules-using-go-to-call-windows-api-2cbfd8c79724
• https://anubissec.github.io/How-To-Call-Windows-APIs-In-Golang/#

[j0le]

Here is a funny little program, that works, if the program allready has a console:

package main

import (
    "fmt"
    "syscall"
    "time"

    "golang.org/x/sys/windows"
)

func main() {
    fmt.Print("Hello World")
    var kernel32_dll = windows.NewLazySystemDLL("Kernel32.dll")
    var user32_dll = windows.NewLazySystemDLL("User32.dll")

    var proc_GetConsoleWindow = kernel32_dll.NewProc("GetConsoleWindow")
    var proc_ShowWindow = user32_dll.NewProc("ShowWindow")

    var console_hwnd uintptr
    console_hwnd, _, err := proc_GetConsoleWindow.Call()

    if err != syscall.Errno(0) {
        return
    }

    if console_hwnd == 0 {
        return
    }

    for {

        proc_ShowWindow.Call(console_hwnd, 0) // hide

        time.Sleep(1 * time.Second)

        proc_ShowWindow.Call(console_hwnd, 5) // show

        time.Sleep(1 * time.Second)
    }

}

[j0le]

Another update: https://github.com/j0le/Anarchy-Droid/blob/25d65ff35e14ce409c840c9da56302e5bf32d60c/cpp-no-console-wnd-test/main.go

Use this commandline to make it a GUI application (IMAGE_SUBSYSTEM_WINDOWS_GUI):

go build -ldflags="-H windowsgui"

[amo13]

Amazing! Done.

[j0le]

nice! Just for reference: The pull request, that fixed this, is #13.

[j0le]

Just some random info: The python people had the same issue of a terminal window popping up on Windows. “pythonw.exe or python.exe?” – Stack Overflow