你如何使用cgo静态链接ac库？

Question

所以团队中有很多东西建议你可以在go中执行此操作(尽管不在cgo文档中):

package bridge

import "fmt"

// #cgo CFLAGS: -I/Users/doug/projects/c/go-bridge/include
// #cgo LDFLAGS: /Users/doug/projects/c/go-bridge/build/libgb.a
// #include <junk.h>
import "C"

func Run() {
  fmt.Printf("Invoking c library...\n")
  C.x(10)
  fmt.Printf("Done\n")
}

但是,它似乎不起作用:

/var/folders/.../bridge.a(bridge.cgo2.o)(__TEXT/__text): x: not defined

这似乎可以正常使用动态库,并检查生成的文件,它实际上有符号'x':

/var/folders/rg/hj4s3qlj3sz1d1b5p50ws0vc0000gn/T/go-build442792776/bridge/_obj/_cgo_.o:
0000000100001048 S _NXArgc 
0000000100001050 S _NXArgv 
0000000100001060 S ___progname 
0000000100000dc0 T __cgo_2d7eefe3d6d4_Cfunc_x
0000000100000da0 T __cgo_allocate 
0000000100000db0 T __cgo_panic
0000000100000000 T __mh_execute_header 
0000000100000d90 T _crosscall2
0000000100001058 S _environ
                 U _exit 
0000000100000d80 T _main
                 U _puts 
0000000100001000 s _pvars 
0000000100000de0 T _x                <------- Exists
                 U dyld_stub_binder 
0000000100000d40 T start

但显然只是bridge.cgo2.o中的一个标记:

/var/folders/rg/hj4s3qlj3sz1d1b5p50ws0vc0000gn/T/go-build442792776/bridge.a(bridge.cgo2.o):
0000000000000368 s EH_frame0
0000000000000000 T __cgo_2d7eefe3d6d4_Cfunc_x
0000000000000380 S __cgo_2d7eefe3d6d4_Cfunc_x.eh
                 U _x

我究竟做错了什么？

对于ref,c头:

int x(int y);

和代码:

#include <junk.h>
#include <stdio.h>

int x(int y) {
  printf("Hello World\n");
  return y;
}

-

编辑:

不,-L和-l也不起作用; 实际上,有这个(-l /胡说/ blah.a)不能用于CGO工作,对谷歌组的一些具体讨论,正确的语法是实际上省略-l,只是列出某文件...但嘿,如果它有效,我会完全使用它.但它没有:

dougs-mini:go doug$ go run test.go
# bridge
ld: library not found for -l/Users/doug/projects/c/go-bridge/build/libgb.a
collect2: ld returned 1 exit status
dougs-mini:go doug$ ls -l /Users/doug/projects/c/go-bridge/build/libgb.a
-rw-r--r--  1 doug  staff  872 25 May 14:02 /Users/doug/projects/c/go-bridge/build/libgb.a

详细版本:

dougs-mini:go doug$ go build -work -x test.go
WORK=/var/folders/rg/hj4s3qlj3sz1d1b5p50ws0vc0000gn/T/go-build354497708
mkdir -p $WORK/bridge/_obj/
cd /Users/doug/projects/c/go-bridge/go/src/bridge
/Users/doug/projects/go/go/pkg/tool/darwin_amd64/cgo -objdir $WORK/bridge/_obj/ -- -I/Users/doug/projects/c/go-bridge/include -I $WORK/bridge/_obj/ bridge.go
/Users/doug/projects/go/go/pkg/tool/darwin_amd64/6c -FVw -I $WORK/bridge/_obj/ -I /Users/doug/projects/go/go/pkg/darwin_amd64 -o $WORK/bridge/_obj/_cgo_defun.6 -DGOOS_darwin -DGOARCH_amd64 $WORK/bridge/_obj/_cgo_defun.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I/Users/doug/projects/c/go-bridge/include -I $WORK/bridge/_obj/ -o $WORK/bridge/_obj/_cgo_main.o -c $WORK/bridge/_obj/_cgo_main.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I/Users/doug/projects/c/go-bridge/include -I $WORK/bridge/_obj/ -o $WORK/bridge/_obj/_cgo_export.o -c $WORK/bridge/_obj/_cgo_export.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I/Users/doug/projects/c/go-bridge/include -I $WORK/bridge/_obj/ -o $WORK/bridge/_obj/bridge.cgo2.o -c $WORK/bridge/_obj/bridge.cgo2.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -o $WORK/bridge/_obj/_cgo_.o $WORK/bridge/_obj/_cgo_main.o $WORK/bridge/_obj/_cgo_export.o $WORK/bridge/_obj/bridge.cgo2.o -l/Users/doug/projects/c/go-bridge/build/libgb.a
# bridge
ld: library not found for -l/Users/doug/projects/c/go-bridge/build/libgb.a
collect2: ld returned 1 exit status

值得注意的是,当你尝试像这样链接时(使用-l)失败是典型的gcc无法链接,因为你试图组合一组目标文件.

即.这个:

gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -o ... -l/path/libgb.a

永远不会在gcc下编译; 你必须像这样链接一个静态库:

gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -o ... /path/libgb.a

即.绝对不是我错过了-l或-L.

Answer 1

原来我的代码是100%罚款; 它是Go 1.0的副本; 根据去1.1这是有效的.在1.0以下,它没有.

(我知道,回答我自己的问题有点蹩脚;但是下面的'使用-L -l答案也不正确;它与此无关).

对于那些后来发现这个问题的人来说,这里有一个有效的解决方案示例:github

https://github.com/shadowmint/go-static-linking

简而言之,看起来像:

CGO_ENABLED=0 go build -a -installsuffix cgo -ldflags '-s' src/myapp/myapp.go

另见:https: //github.com/golang/go/issues/9344

Answer 2

您只需要链接-Ldirectory -lgb.

$ cat >toto.c
int x( int y ) { return y+1; }
$ cat >toto.h
int x(int);
$ gcc -O2 -c toto.c
$ ar q libgb.a toto.o
$ cat >test.go
package main

import "fmt"

// #cgo CFLAGS: -I.
// #cgo LDFLAGS: -L. -lgb 
// #include <toto.h>
import "C"

func main() {
  fmt.Printf("Invoking c library...\n")
  fmt.Println("Done ", C.x(10) )
}
$ go build test.go
$ ./test
Invoking c library...
Done  11

Answer 3

将 Go 代码与动态或静态库链接的简单 Makefile ：

static:
    gcc -c gb.c
    ar -rcs libgb.a gb.o
    go build -ldflags "-linkmode external -extldflags -static" bridge.go

dynamic:
    gcc -shared -o libgb.so gb.c
    go build bridge.go

bridge.go 中的指令：

/*
#cgo CFLAGS: -I.
#cgo LDFLAGS: -L. -lgb
#include "gb.h"
*/
import "C"
...