go + cgo 和链接

huangapple
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英文:

go + cgo and linking

问题

我想将以下C代码作为Go的cgo使用：

  1. #include <X11/extensions/scrnsaver.h>
  3. main() {
  4.   XScreenSaverInfo *info = XScreenSaverAllocInfo();
  5.   Display *display = XOpenDisplay(0);
  7.   XScreenSaverQueryInfo(display, DefaultRootWindow(display), info);
  8.   printf("%u ms\n", info->idle);
  9. }

使用以下命令进行构建：

  1. gcc -o idle printXIdleTime.c -lX11 -lXss

我为Go的cgo重新编写了该代码：

  1. package tools
  3. // #cgo pkg-config: x11
  4. // #include <X11/extensions/scrnsaver.h>
  5. import "C"
  7. func GetIdleTime() (idleTime uint32) {
  8. 	var info *C.XScreenSaverInfo
  9. 	var display *C.Display 
  10. 	
  11. 	info = C.XScreenSaverAllocInfo()
  12. 	display = C.XOpenDisplay(0)
  14. 	defaultRootWindow := C.XDefaultRootWindow(display)
  16. 	C.XScreenSaverQueryInfo(display, defaultRootWindow, info)
  17. 	idleTime = info.idle
  19. 	return
  20. }

尝试使用以下命令进行编译：

  1. go build -gccgoflags="-lXss -lX11"

然而，我遇到了链接器错误：

/tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o: In
function _cgo_c0e279f6f16e_Cfunc_XScreenSaverAllocInfo': ./x11.go:52: undefined reference to XScreenSaverAllocInfo'
/tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o: In
function _cgo_c0e279f6f16e_Cfunc_XScreenSaverQueryInfo': ./x11.go:65: undefined reference to XScreenSaverQueryInfo' collect2: error: ld
returned 1 exit status

我做错了什么？

英文:

i want to use the following c as Go's cgo:

  1. #include &lt;X11/extensions/scrnsaver.h&gt;
  3. main() {
  4.   XScreenSaverInfo *info = XScreenSaverAllocInfo();
  5.   Display *display = XOpenDisplay(0);
  7.   XScreenSaverQueryInfo(display, DefaultRootWindow(display), info);
  8.   printf(&quot;%u ms\n&quot;, info-&gt;idle);
  9. }

build with:

  1. gcc -o idle printXIdleTime.c -lX11 -lXss

i re-wrote that code for Go's cgo:

  1. package tools
  3. // #cgo pkg-config: x11
  4. // #include &lt;X11/extensions/scrnsaver.h&gt;
  5. import &quot;C&quot;
  7. func GetIdleTime() (idleTime uint32) {
  8. 	var info *C.XScreenSaverInfo
  9. 	var display *C.Display 
  10. 	
  11. 	info = C.XScreenSaverAllocInfo()
  12. 	display = C.XOpenDisplay(0)
  14. 	defaultRootWindow := C.XDefaultRootWindow(display)
  16. 	C.XScreenSaverQueryInfo(display, defaultRootWindow, info)
  17. 	idleTime = info.idle
  19. 	return
  20. }

tried to compile with:

  1. go build -gccgoflags=&quot;-lXss -lX11&quot;

however i'm getting linker errors:

> /tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o: In
> function _cgo_c0e279f6f16e_Cfunc_XScreenSaverAllocInfo&#39;: ./x11.go:52:
&gt; undefined reference to XScreenSaverAllocInfo'
> /tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o: In
> function _cgo_c0e279f6f16e_Cfunc_XScreenSaverQueryInfo&#39;: ./x11.go:65:
&gt; undefined reference to XScreenSaverQueryInfo' collect2: error: ld
> returned 1 exit status

what am i doing wrong?

答案1

得分: 5

这是我构建它的方式。请注意#cgo LDFLAGS行，这可能是你所缺少的。我还必须进行一些其他更改才能构建它。在我的Linux机器上，它似乎返回了正确的答案！

  1. package tools
  3. // #cgo LDFLAGS: -lXss -lX11
  4. // #include <X11/extensions/scrnsaver.h>
  5. import "C"
  6.     
  7. func GetIdleTime() (idleTime uint32) {
  8.     var info *C.XScreenSaverInfo
  9.     var display *C.Display
  11.     info = C.XScreenSaverAllocInfo()
  12.     display = C.XOpenDisplay(nil)
  14.     defaultRootWindow := C.XDefaultRootWindow(display)
  16.     C.XScreenSaverQueryInfo(display, C.Drawable(defaultRootWindow), info)
  17.     idleTime = uint32(info.idle)
  19.     return
  20. }
英文:

This is how I got it to build. Note the #cgo LDFLAGS line which is probably what you are missing. I had to make a few other changes to make it build. It seems to be returning the right answer on my Linux machine!

  1. package tools
  3. // #cgo LDFLAGS: -lXss -lX11
  4. // #include &lt;X11/extensions/scrnsaver.h&gt;
  5. import &quot;C&quot;
  6.     
  7. func GetIdleTime() (idleTime uint32) {
  8. 	var info *C.XScreenSaverInfo
  9. 	var display *C.Display
  11. 	info = C.XScreenSaverAllocInfo()
  12. 	display = C.XOpenDisplay(nil)
  14. 	defaultRootWindow := C.XDefaultRootWindow(display)
  16. 	C.XScreenSaverQueryInfo(display, C.Drawable(defaultRootWindow), info)
  17.     idleTime = uint32(info.idle)
  19. 	return
  20. }

答案2

得分: 2

请注意，这可以通过本地的X Go Binding和ScreenSaver扩展来完成：

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"log"
  7. 	"github.com/BurntSushi/xgb"
  8. 	"github.com/BurntSushi/xgb/xproto"
  9. 	"github.com/BurntSushi/xgb/screensaver"
  10. )
  12. func main() {
  13. 	X, err := xgb.NewConn()
  14. 	if err != nil {
  15. 		log.Fatal(err)
  16. 	}
  18. 	if err = screensaver.Init(X); err != nil {
  19. 		log.Fatal(err)
  20. 	}
  22. 	root := xproto.Setup(X).DefaultScreen(X).Root
  23. 	info, err := screensaver.QueryInfo(X, xproto.Drawable(root)).Reply()
  24. 	if err != nil {
  25. 		log.Fatal(err)
  26. 	}
  28. 	fmt.Printf("Idle: %d\n", info.MsSinceUserInput)
  29. }

输出：

  1. [andrew@Liger go] go run xscreensaver_idle.go 
  2. Idle: 1040
英文:

Note that this can be done with the native X Go Binding and the ScreenSaver extension:

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;log&quot;
  7. 	&quot;github.com/BurntSushi/xgb&quot;
  8. 	&quot;github.com/BurntSushi/xgb/xproto&quot;
  9. 	&quot;github.com/BurntSushi/xgb/screensaver&quot;
  10. )
  12. func main() {
  13. 	X, err := xgb.NewConn()
  14. 	if err != nil {
  15. 		log.Fatal(err)
  16. 	}
  18. 	if err = screensaver.Init(X); err != nil {
  19. 		log.Fatal(err)
  20. 	}
  22. 	root := xproto.Setup(X).DefaultScreen(X).Root
  23. 	info, err := screensaver.QueryInfo(X, xproto.Drawable(root)).Reply()
  24. 	if err != nil {
  25. 		log.Fatal(err)
  26. 	}
  28. 	fmt.Printf(&quot;Idle: %d\n&quot;, info.MsSinceUserInput)
  29. }

Outputs:

  1. [andrew@Liger go] go run xscreensaver_idle.go 
  2. Idle: 1040

huangapple
  • 本文由 发表于 2013年2月13日 06:24:06
  • 转载请务必保留本文链接：https://go.coder-hub.com/14842980.html
  • cgo
  • go
  • linker
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