去+ cgo和链接 [英] go + cgo and linking

问题描述

  #include< X11 / extensions / scrnsaver.h> 
 
 main（）{
 XScreenSaverInfo * info = XScreenSaverAllocInfo（）; 
显示* display = XOpenDisplay（0）; 
 
 XScreenSaverQueryInfo（display，DefaultRootWindow（display），info）; 
 printf（％u ms \ n，info-> idle）; 
 
 $ / code $ / pre 
 $ b $ p  
 
 
  gcc -o idle printXIdleTime.c -lX11 -lXss 
  
我重写了Go的cgo代码： 
 
 
 包工具
 
 // #cgo pkg -config：x11 
 // #include< X11 / extensions / scrnsaver.h> 
导入C
 
 func GetIdleTime（）（idleTime uint32）{
 var info * C.XScreenSaverInfo 
 var display * C.Display 
 
 info = C.XScreenSaverAllocInfo（）
 display = C.XOpenDisplay（0）
 
 defaultRootWindow：= C.XDefaultRootWindow（display）
 
 C.XScreenSaverQueryInfo （display，defaultRootWindow，info）
 idleTime = info.idle 
 
 return 
} 
  
试着编译： 
 
 
  go build -gccgoflags = -  lXss -lX11
  
但是我收到链接错误： 
 
 
 
 
 /tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o：In 
 function  _cgo_c0e279f6f16e_Cfunc_XScreenSaverAllocInfo'：./x11。 go：52：
未定义引用 XScreenSaverAllocInfo'
 /tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o：In 
函数 _cgo_c0e279f6f16e_Cfunc_XScreenSaverQue ryInfo'：./x11.go:65：
未定义引用 XScreenSaverQueryInfo'collect2：错误：ld 
返回1退出状态
 
  blockquote> 
 
 
我做错了什么？
解决方案
建立。请注意 #cgo LDFLAGS 这一行，这可能是您所缺少的。我必须做一些其他更改才能构建。它似乎是在我的Linux机器上返回正确答案！
 包工具
 
 //＃ cgo LDFLAGS：-lXss -lX11 
 // #include< X11 / extensions / scrnsaver.h> 
导入C
 
 func GetIdleTime（）（idleTime uint32）{
 var info * C.XScreenSaverInfo 
 var display * C.Display 
 
 info = C.XScreenSaverAllocInfo（）
 display = C.XOpenDisplay（nil）
 
 defaultRootWindow：= C.XDefaultRootWindow（display）
 
 C.XScreenSaverQueryInfo （display，C.Drawable（defaultRootWindow），info）
 idleTime = uint32（info.idle）
 
 return 
} 
  
 
i want to use the following c as Go's cgo:
#include <X11/extensions/scrnsaver.h>

main() {
  XScreenSaverInfo *info = XScreenSaverAllocInfo();
  Display *display = XOpenDisplay(0);

  XScreenSaverQueryInfo(display, DefaultRootWindow(display), info);
  printf("%u ms\n", info->idle);
}
build with:
gcc -o idle printXIdleTime.c -lX11 -lXss
i re-wrote that code for Go's cgo:
package tools

// #cgo pkg-config: x11
// #include <X11/extensions/scrnsaver.h>
import "C"

func GetIdleTime() (idleTime uint32) {
    var info *C.XScreenSaverInfo
    var display *C.Display 

    info = C.XScreenSaverAllocInfo()
    display = C.XOpenDisplay(0)

    defaultRootWindow := C.XDefaultRootWindow(display)

    C.XScreenSaverQueryInfo(display, defaultRootWindow, info)
    idleTime = info.idle

    return
}
tried to compile with:
go build -gccgoflags="-lXss -lX11"
however i'm getting linker errors:

  
/tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o: In
  function _cgo_c0e279f6f16e_Cfunc_XScreenSaverAllocInfo': ./x11.go:52:
  undefined reference toXScreenSaverAllocInfo'
  /tmp/go-build076004816/opensource.stdk/lib/tools/_obj/x11.cgo2.o: In
  function _cgo_c0e279f6f16e_Cfunc_XScreenSaverQueryInfo': ./x11.go:65:
  undefined reference toXScreenSaverQueryInfo' collect2: error: ld
  returned 1 exit status
what am i doing wrong?
解决方案
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!
package tools

// #cgo LDFLAGS: -lXss -lX11
// #include <X11/extensions/scrnsaver.h>
import "C"

func GetIdleTime() (idleTime uint32) {
    var info *C.XScreenSaverInfo
    var display *C.Display

    info = C.XScreenSaverAllocInfo()
    display = C.XOpenDisplay(nil)

    defaultRootWindow := C.XDefaultRootWindow(display)

    C.XScreenSaverQueryInfo(display, C.Drawable(defaultRootWindow), info)
    idleTime = uint32(info.idle)

    return
}


                        
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