Hello everyone, first time here so please bear with me. I got the tipp of asking this rather fringe case question here from comments on my /r/golang post.
In brief I want to create a shared library out of a golang project so that it can be dynamically loaded by applications written in another language on IBM AIX 7.2. I am aware that go build -buildmode=c-shared is unsupported on AIX at the time of writing, so I am currently trying to work my way around this limitation by creating first a static archive first with "go build -buildmode=c-archive" and have that compiled with gcc into a shared object for dynamic linking. A quick, probably nicer to read version of this has been posted on this reddit post <https://www.reddit.com/r/golang/comments/tk65e0/creating_a_shared_c_library_out_of_go_project_to/> . To test my endeavour I have created a simple .go library and main.c file: sharedLibTest.go package main import ( "fmt" ) import "C" func main() { fmt.Printf("%s\n", "Golang: main was called") MyPackage_Init() MyPackage_Create() } //export MyPackage_Init func MyPackage_Init() { fmt.Printf("%s\n", "Golang: MyPackage_Init was called") } //export MyPackage_Create func MyPackage_Create() { fmt.Printf("%s\n", "Golang: MyPackage_Create was called") } main.c #include <stdio.h> #include "sharedLibTest.h" int main() { printf("%s\n", "C: main() called"); MyPackage_Init(); MyPackage_Create(); } On my local linux machine I am able to compile these two files together both statically as well as dynamically with a native shared object as well as through the detour of a static archive. Please refer to the reddit post for the details of that. To try and compile it on AIX I can create a static archive, have that compiled into a shared object with gcc8 and, due to AIX weirdness, have that resulting .so file renamed to .a because AIX's linker does not look for .so files for reasons best known to IBM. $ go build -v -buildmode=c-archive -mod vendor -o /home/myuser/workspace/go_proj/sharedLibTest/sharedLibTest.a /home/myuser/workspace/go_proj/sharedLibTest/sharedLibTest.go $ cat > symbols.export << EOF > MyPackage_Init > MyPackage_Create > EOF $ gcc -fPIC -DPIC -g -O2 -mcpu=power7 -maix64 -shared -lpthread -Wl,-bE:symbols.export -o libsharedLibTest.so -Wl,-bnoobjreorder ./sharedLibTest.a $ mv libsharedLibTest.so libsharedLibTest.a I can finally link that that with my main.c file $ gcc -L. -g -O2 -mcpu=power7 -maix64 -Wl,-bnoobjreorder -lsharedLibTest -lpthreads main.c But when I try to run that I get $ LD_LIBRARY_PATH=/home/myuser/workspace/go_proj/sharedLibTest ./a.out exec(): 0509-036 Cannot load program ./a.out because of the following errors: 0509-150 Dependent module /home/myuser/workspace/go_proj/sharedLibTest/libsharedLibTest.a(libsharedLibTest.so) could not be loaded. 0509-187 The local-exec model was used for thread-local storage, but the module is not the main program. 0509-193 Examine the .loader section header with the 'dump -Hv' command. Now so far I have gathered, that if I can make the go static archive compile with whatever the equivalent of gcc's -fPIC option is, that archive produces Position Independent Code that can be loaded dynamically, a thing that is currently failing, according to my understanding of that loader's error message. Adding -gcflags="-shared" to my go build invocation leads to an error that I presume is the base of the issue and why c-shared plainly prints the that shared libs are unsupported $ go build -buildmode=c-archive -gcflags=-shared -ldflags=-linkmode=external -mod vendor -o sharedLibTest.a sharedLibTest.go # command-line-arguments main.main: unknown reloc to .TOC.: 48 (R_ADDRPOWER_PCREL) _cgoexp_87081e778e87_MyPackage_Init: unknown reloc to .TOC.: 48 (R_ADDRPOWER_PCREL) _cgoexp_87081e778e87_MyPackage_Create: unknown reloc to .TOC.: 48 (R_ADDRPOWER_PCREL) So alas: my question finally is, Is there any way for golang projects to one way or another be compiled down into a shared library that can be loaded dynamically by other applications? I have gotten yet another hint just now from an IBM forum post, that I may try gcc-go, however I am wondering if this really hasn't been done yet by anyone else. Best regards, miecc -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/8fa0f5df-20a6-4a19-aacf-1e9fd06699bdn%40googlegroups.com.
