[Vm-dev] [Off-Topic] linking exported symbols into shared lib

[Nicolas Cellier]

Maybe google gcc export all symbols
a workaround would be -Wl,--export-all-symbols or something like that...
I find the end of
http://anadoxin.org/blog/control-over-symbol-exports-in-gcc.html
interesting though it's the inverse problem

2017-11-06 19:08 GMT+01:00 Ben Coman <btc at openinworld.com>:

>
>
> $ nm -A fpdfview.o | grep FPDF_Init
> fpdfview.o:0000000000000000  T   FPDF_InitLibrary
> fpdfview.o:0000000000000000  T   FPDF_InitLibraryWithConfig
> fpdfview.o:0000000000000000   t   FPDF_InitLibraryWithConfig.part.47
>
>
> IIUC, the capital "T" means the "FPDF_InitLibrary" symbol is exported and
> available for another program to link against. Browsing around, object
> files are composed into a shared library like this...
>
> $ g++ -fPIC -shared -o libmypdf.so fpdfview.o
>
>
> but now the "FPDF_InitLibrary" symbol shows as internal and I can't link
> against it.
>
> $ nm -A libmypdf.so | grep FPDF_Init
> libmypdf.so:0000000000003e60  t   FPDF_InitLibrary
> libmypdf.so:0000000000003e80  t   FPDF_InitLibraryWithConfig
> libmypdf.so:00000000000031f0   t   FPDF_InitLibraryWithConfig.part.47
>
>
> Here is my makefile...
>
> INC_DIR= -I ./public
> LIB_DIR= -L ./out
> STD_LIBS= -lpthread -lm -lc -lstdc++
> PDF_LIBS= -lmypdfium
> default:
>         gcc -o first first.c ${INC_DIR} ${LIB_DIR} ${PDF_LIBS} ${STD_LIBS}
>
> So I know it finds the library, since if I change its name the linker
> complains it can't find the file.
>
>
>
> I don't think the following adds useful extra info, but for
> completeness... The header file fpdfview.h has...
>
> #if defined(_WIN32) && defined(FPDFSDK_EXPORTS)
> // On Windows system, functions are exported in a DLL
> #define FPDF_EXPORT __declspec(dllexport)
> #define FPDF_CALLCONV __stdcall
> #else
> #define FPDF_EXPORT
> #define FPDF_CALLCONV
> #endif
>
> #ifdef __cplusplus
> extern "C" {
> #endif
>
> FPDF_EXPORT void FPDF_CALLCONV FPDF_InitLibrary();
>
> #ifdef __cplusplus
> }
> #endif
>
>
>
>
>
>
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