Shutting down windows using golang code - windows

Question

I am making a program that automates some tedious tasks for me, after the program is done I want to shutdown windows. I know this can be done in for example C#
How can I shutdown window using golang?

Answer 1

There is no "Shutdown OS" function in the syscall package, because there is no common interface provided for that by all operating systems.
Note: there is a syscall.Shutdown() function, but that is to shutdown a socket, and not to shutdown the operating system.
The easiest would be to just execute the shutdown command using the os/exec package, e.g.
if err := exec.Command("cmd", "/C", "shutdown", "/s").Run(); err != nil {
fmt.Println("Failed to initiate shutdown:", err)
}
The above command initiates a shutdown sequence which usually takes 1 minute to really shut down the system (and there's room to abort it with shutdown /a). You may provide different arguments to the shutdown command to not wait 1 minute but proceed immediately: shutdown /t 0 /s (execute shutdown /? to get a list of all options).
There is also a Windows API call to shutdown the system: ExitWindowsEx(). It has 2 parameters, first is the flags to define the shutdown type (0x08 means Shuts down the system and turns off the power.), second is to provide a reason for the shutdown. To call this from Go, you can do that like this:
user32 := syscall.MustLoadDLL("user32")
defer user32.Release()
exitwin := user32.MustFindProc("ExitWindowsEx")
r1, _, err := exitwin.Call(0x08, 0)
if r1 != 1 {
fmt.Println("Failed to initiate shutdown:", err)
}
But know that you need SE_SHUTDOWN_NAME privilege to call ExitWindowsEx(), else you get an error message like:
Failed to initiate shutdown: A required privilege is not held by the client.
See this example how to acquire the required privilege.

Answer 2

Thanks for the post, very helpful.
here is a complete function that performs a reboot. It follows exactly the Microsoft example as noted before. should help saving time in figuring out the structs:
import (
"fmt"
"syscall"
"unsafe"
)
// error is nil on success
func reboot() error {
user32 := syscall.MustLoadDLL("user32")
defer user32.Release()
kernel32 := syscall.MustLoadDLL("kernel32")
defer user32.Release()
advapi32 := syscall.MustLoadDLL("advapi32")
defer advapi32.Release()
ExitWindowsEx := user32.MustFindProc("ExitWindowsEx")
GetCurrentProcess := kernel32.MustFindProc("GetCurrentProcess")
GetLastError := kernel32.MustFindProc("GetLastError")
OpenProdcessToken := advapi32.MustFindProc("OpenProcessToken")
LookupPrivilegeValue := advapi32.MustFindProc("LookupPrivilegeValueW")
AdjustTokenPrivileges := advapi32.MustFindProc("AdjustTokenPrivileges")
currentProcess, _, _ := GetCurrentProcess.Call()
const tokenAdjustPrivileges = 0x0020
const tokenQuery = 0x0008
var hToken uintptr
result, _, err := OpenProdcessToken.Call(currentProcess, tokenAdjustPrivileges|tokenQuery, uintptr(unsafe.Pointer(&hToken)))
if result != 1 {
fmt.Println("OpenProcessToken(): ", result, " err: ", err)
return err
}
//fmt.Println("hToken: ", hToken)
const SeShutdownName = "SeShutdownPrivilege"
type Luid struct {
lowPart uint32 // DWORD
highPart int32 // long
}
type LuidAndAttributes struct {
luid Luid // LUID
attributes uint32 // DWORD
}
type TokenPrivileges struct {
privilegeCount uint32 // DWORD
privileges [1]LuidAndAttributes
}
var tkp TokenPrivileges
result, _, err = LookupPrivilegeValue.Call(uintptr(0), uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(SeShutdownName))), uintptr(unsafe.Pointer(&(tkp.privileges[0].luid))))
if result != 1 {
fmt.Println("LookupPrivilegeValue(): ", result, " err: ", err)
return err
}
//fmt.Println("LookupPrivilegeValue luid: ", tkp.privileges[0].luid)
const SePrivilegeEnabled uint32 = 0x00000002
tkp.privilegeCount = 1
tkp.privileges[0].attributes = SePrivilegeEnabled
result, _, err = AdjustTokenPrivileges.Call(hToken, 0, uintptr(unsafe.Pointer(&tkp)), 0, uintptr(0), 0)
if result != 1 {
fmt.Println("AdjustTokenPrivileges() ", result, " err: ", err)
return err
}
result, _, _ = GetLastError.Call()
if result != 0 {
fmt.Println("GetLastError() ", result)
return err
}
const ewxForceIfHung = 0x00000010
const ewxReboot = 0x00000002
const shutdownReasonMajorSoftware = 0x00030000
result, _, err = ExitWindowsEx.Call(ewxReboot|ewxForceIfHung, shutdownReasonMajorSoftware)
if result != 1 {
fmt.Println("Failed to initiate reboot:", err)
return err
}
return nil
}