英文:
Using Go 1.5 buildmode=c-archive with net/http.Server linked from C
问题
Go 1.5的即将发布将带来新的构建模式,允许将Go符号导出到C代码中进行链接和调用。我已经尝试了一些基本的“Hello world”示例,并成功运行,但是现在我正在尝试链接一个启动net/http.Server
的Go库,但是失败了。代码如下(也可以在这里找到):
gohttplib.go:
package main
import "C"
import "net/http"
//export ListenAndServe
func ListenAndServe(caddr *C.char) {
addr := C.GoString(caddr)
http.ListenAndServe(addr, nil)
}
func main() {}
examples/c/main.c:
#include <stdio.h>
#include "../../gohttplib.h"
int main()
{
ListenAndServe(":8000");
return 0;
}
生成静态链接的对象和头文件没有问题:
$ go build -buildmode=c-archive
但是编译失败:
$ gcc -o gohttp-c examples/c/main.c gohttplib.a -lpthread
Undefined symbols for architecture x86_64:
"_CFArrayGetCount", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFArrayGetValueAtIndex", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFDataAppendBytes", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFDataCreateMutable", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFDataGetBytePtr", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
__cgo_6dbb806e9976_Cfunc_CFDataGetBytePtr in gohttplib.a(000003.o)
(maybe you meant: __cgo_6dbb806e9976_Cfunc_CFDataGetBytePtr)
"_CFDataGetLength", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
__cgo_6dbb806e9976_Cfunc_CFDataGetLength in gohttplib.a(000003.o)
(maybe you meant: __cgo_6dbb806e9976_Cfunc_CFDataGetLength)
"_CFRelease", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
__cgo_6dbb806e9976_Cfunc_CFRelease in gohttplib.a(000003.o)
(maybe you meant: __cgo_6dbb806e9976_Cfunc_CFRelease)
"_SecKeychainItemExport", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_SecTrustCopyAnchorCertificates", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_kCFAllocatorDefault", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [example-c] Error 1
这是在OS X 10.9.5上使用Go github存储库的最新版本(38e3427)进行的。我知道Go 1.5尚未发布,并且不能保证其正常工作,但我正在进行教育目的的尝试,我怀疑我可能遗漏了一些东西。
相关版本信息:
$ ld -v
@(#)PROGRAM:ld PROJECT:ld64-241.9
configured to support archs: armv6 armv7 armv7s arm64 i386 x86_64 x86_64h armv6m armv7m armv7em
LTO support using: LLVM version 3.5svn
$ gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix
英文:
The upcoming release of Go 1.5 comes with new buildmodes which allow for exporting Go symbols to be linked and called from C code. I've been playing around with it and got basic "Hello world" examples working, but now I'm trying to link a Go library which starts a net/http.Server
and it's failing. The code looks like this (it's also available here):
gohttplib.go:
package main
import "C"
import "net/http"
//export ListenAndServe
func ListenAndServe(caddr *C.char) {
addr := C.GoString(caddr)
http.ListenAndServe(addr, nil)
}
func main() {}
examples/c/main.c:
#include <stdio.h>
#include "../../gohttplib.h"
int main()
{
ListenAndServe(":8000");
return 0;
}
Producing the statically-linked object and headers works fine:
$ go build -buildmode=c-archive
But compiling against it is failing:
$ gcc -o gohttp-c examples/c/main.c gohttplib.a -lpthread
Undefined symbols for architecture x86_64:
"_CFArrayGetCount", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFArrayGetValueAtIndex", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFDataAppendBytes", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFDataCreateMutable", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_CFDataGetBytePtr", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
__cgo_6dbb806e9976_Cfunc_CFDataGetBytePtr in gohttplib.a(000003.o)
(maybe you meant: __cgo_6dbb806e9976_Cfunc_CFDataGetBytePtr)
"_CFDataGetLength", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
__cgo_6dbb806e9976_Cfunc_CFDataGetLength in gohttplib.a(000003.o)
(maybe you meant: __cgo_6dbb806e9976_Cfunc_CFDataGetLength)
"_CFRelease", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
__cgo_6dbb806e9976_Cfunc_CFRelease in gohttplib.a(000003.o)
(maybe you meant: __cgo_6dbb806e9976_Cfunc_CFRelease)
"_SecKeychainItemExport", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_SecTrustCopyAnchorCertificates", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
"_kCFAllocatorDefault", referenced from:
_FetchPEMRoots in gohttplib.a(000003.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [example-c] Error 1
This is using a recent version from the Go github repository (38e3427) on OS X 10.9.5. I understand that Go 1.5 is not released yet and that there are no guarantees about it working, but I'm doing this for educational purposes and I suspect I'm missing something.
Related versions:
$ ld -v
@(#)PROGRAM:ld PROJECT:ld64-241.9
configured to support archs: armv6 armv7 armv7s arm64 i386 x86_64 x86_64h armv6m armv7m armv7em
LTO support using: LLVM version 3.5svn
$ gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix
答案1
得分: 8
原来这个问题存在于OSX/darwin上。为了解决这个问题,我们需要在gcc链接命令中添加-framework CoreFoundation -framework Security
选项。最终的命令如下所示:
$ gcc -o gohttp-c examples/c/main.c gohttplib.a \
-framework CoreFoundation -framework Security -lpthread
这个要求可能会在将来的Go版本中被移除。关于这个问题的更多讨论可以在这里找到:https://github.com/golang/go/issues/11258
英文:
Turns out this problem exists on OSX/darwin. To work around it, we need to add -framework CoreFoundation -framework Security
options to the gcc linking command. The final command looks like this:
$ gcc -o gohttp-c examples/c/main.c gohttplib.a \
-framework CoreFoundation -framework Security -lpthread
This requirement might be removed in a future version of Go. More discussion on this issue here: https://github.com/golang/go/issues/11258
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