调用Windows的SendMessageW函数从GO语言中永远不会返回。

huangapple
go评论131阅读模式
英文:

Calling Windows SendMessageW from GOlang never returns

问题

尝试编写一个非常简单的用于关闭 Windows 显示器的 GO 程序。代码如下：

  1. //go:build windows
  2. // +build windows
  4. package main
  6. import (
  7. 	log "github.com/sirupsen/logrus"
  9. 	"golang.org/x/sys/windows"
  10. )
  12. func main() {
  13. 	user32DLL := windows.NewLazyDLL("user32.dll")
  14. 	procSendMsg := user32DLL.NewProc("SendMessageW")
  16. 	a, b, err := procSendMsg.Call(0xFFFF, 0x0112, 0xF170, 2)
  17. 	if err != nil {
  18. 		log.Errorf("Error returned from SendMsg: %v", err)
  19. 	}
  20. 	log.Infof("a = %v, b = %v:", a, b)
  21. }

该程序确实可以工作（即关闭显示器），但是在 procSendMsg.Call() 后没有返回，没有错误，并且我看不到 a 和 b 的输出。我必须使用 Ctrl-C 来退出程序。

显然，我在调用 user32.dll 函数方面做错了什么...这是我第一次尝试使用 GO 编写 Windows 程序。

我做错了什么？

[提示：我从这个 PowerShell 脚本中得到了灵感：

  1. (Add-Type -MemberDefinition "[DllImport(""user32.dll"")]`npublic static extern int SendMessage(int hWnd, int hMsg, int wParam, int lParam);" -Name "Win32SendMessage" -Namespace Win32Functions -PassThru)::SendMessage(0xffff, 0x0112, 0xF170, 2)
  2. ]
  4. 谢谢你的反馈！
  6. <details>
  7. <summary>英文:</summary>
  9. Trying to write a very simple GO program for Windows that turns off the monitor.  The code looks like this:
  11.     //go:build windows
  12.     // +build windows
  13.     
  14.     package main
  15.     
  16.     import (
  17.     	log &quot;github.com/sirupsen/logrus&quot;
  18.     
  19.     	&quot;golang.org/x/sys/windows&quot;
  20.     )
  21.     
  22.     func main() {
  23.     	user32DLL := windows.NewLazyDLL(&quot;user32.dll&quot;)
  24.     	procSendMsg := user32DLL.NewProc(&quot;SendMessageW&quot;)
  25.     
  26.     	a, b, err := procSendMsg.Call(0xFFFF, 0x0112, 0xF170, 2)
  27.     	if err != nil {
  28.     		log.Errorf(&quot;Error returned from SendMsg: %v&quot;, err)
  29.     	}
  30.     	log.Infof(&quot;a = %v, b = %v:&quot;, a, b)
  31.     }
  33. The program does work (IE&gt; the monitor turns off), but never returns from the procSendMsg.Call() -- no errors, and I never see the output of &#39;a&#39; and &#39;b&#39;. I have to Ctrl-C to get out of the program.
  35. Obviously I&#39;m doing something wrong w.r.t. calling the user32.dll function...this IS my first attempt at writing a Windows program with GO.
  37. What am I doing wrong?
  39. [FYI: I got the idea from this PowerShell script:
  41.     (Add-Type -MemberDefinition &quot;[DllImport(&quot;&quot;user32.dll&quot;&quot;)]`npublic static extern int SendMessage(int hWnd, int hMsg, int wParam, int lParam);&quot; -Name &quot;Win32SendMessage&quot; -Namespace Win32Functions -PassThru)::SendMessage(0xffff, 0x0112, 0xF170, 2)
  42. ]
  44. Thanks for your feedback!!
  46. </details>
  49. # 答案1
  50. **得分**: 1
  52. FYI：这是工作版本。
  54.     //go:build windows
  55.     // +build windows
  56.     
  57.     package main
  58.     
  59.     //
  60.     //  turnOffMonitor  --  关闭Windows上的显示器信号。相比使用'scrnsave.scr /s'只是屏幕变黑，这是更好的省电方式。
  61.     //
  62.     //  John D. Allen
  63.     //  2022年9月
  64.     //
  65.     
  66.     import (
  67.     	"strings"
  68.     
  69.     	log "github.com/sirupsen/logrus"
  70.     
  71.     	"golang.org/x/sys/windows"
  72.     )
  73.     
  74.     func main() {
  75.     	user32DLL := windows.NewLazyDLL("user32.dll")
  76.     	procPostMsg := user32DLL.NewProc("PostMessageW")
  77.     
  78.     	_, _, err := procPostMsg.Call(0xFFFF, 0x0112, 0xF170, 2)
  79.     
  80.     	//
  81.     	// 当我以没有SYSTEM权限的用户运行时，我会收到“拒绝访问”的错误...但出于某种原因它仍然可以工作。
  82.     	if err != nil && !strings.Contains(err.Error(), "Access is denied.") {
  83.     		log.Errorf("从PostMsg()返回的错误：%v", err)
  84.     	}
  85.     }
  87. <details>
  88. <summary>英文:</summary>
  90. FYI: Here is the working version.
  92.     //go:build windows
  93.     // +build windows
  94.     
  95.     package main
  96.     
  97.     //
  98.     //  turnOffMonitor  --  Shuts down the signal to the monitor on Windows.  A better power saver
  99.     //    over using &#39;scrnsave.scr /s&#39; to just blank the screen.
  100.     //
  101.     //  John D. Allen
  102.     //  September, 2022
  103.     //
  104.     
  105.     import (
  106.     	&quot;strings&quot;
  107.     
  108.     	log &quot;github.com/sirupsen/logrus&quot;
  109.     
  110.     	&quot;golang.org/x/sys/windows&quot;
  111.     )
  112.     
  113.     func main() {
  114.     	user32DLL := windows.NewLazyDLL(&quot;user32.dll&quot;)
  115.     	procPostMsg := user32DLL.NewProc(&quot;PostMessageW&quot;)
  116.     
  117.     	_, _, err := procPostMsg.Call(0xFFFF, 0x0112, 0xF170, 2)
  118.     
  119.     	//
  120.     	// I get a &quot;Access is denied.&quot; error when I run this from a user that does
  121.     	// not have SYSTEM rights...but it still works anyway for some reason.
  122.     	if err != nil &amp;&amp; !strings.Contains(err.Error(), &quot;Access is denied.&quot;) {
  123.     		log.Errorf(&quot;Error returned from PostMsg(): %v&quot;, err)
  124.     	}
  125.     }
  130. </details>

huangapple
  • 本文由 发表于 2022年9月8日 22:26:42
  • 转载请务必保留本文链接：https://go.coder-hub.com/73650720.html
  • go
  • user32
  • windows
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