Re: [Libguestfs] [PATCH nbdkit] Set visibility to default for exported symbols

In plugins we expect the plugin_init function to be exported as well as *_debug_* variables. In the server various nbdkit_* functions should be exported. If you compile nbdkit with -fvisibility=hidden some of these symbols are not exported at all even though the linker script says they should be. This option can be useful as it allows the compiler to generate simpler and hence faster code, and it's required for Clang CFI. Set the visibility to "default" for all symbols we expect to be exported. In theory this should also be required for all the nbdkit_* functions exported by the server, but I found that it is not needed by either GCC or Clang. --- include/nbdkit-common.h | 6 +++++- include/nbdkit-filter.h | 1 + include/nbdkit-plugin.h | 1 + tests/Makefile.am | 1 + plugins/ocaml/bindings.c | 26 +++++++++++++------------- plugins/ocaml/plugin.c | 14 +++++++------- tests/dummy-vddk.c | 30 ++++++++++++++++-------------- 7 files changed, 44 insertions(+), 35 deletions(-) diff --git a/include/nbdkit-common.h b/include/nbdkit-common.h index 51a6264c..f43ebe59 100644 --- a/include/nbdkit-common.h +++ b/include/nbdkit-common.h @@ -83,10 +83,14 @@ extern "C" { #define NBDKIT_EXTENT_ZERO (1<<1) /* Same as NBD_STATE_ZERO */ #ifndef WIN32 -#define NBDKIT_EXTERN_DECL(ret, fn, args) extern ret fn args +#define NBDKIT_EXTERN_DECL(ret, fn, args) \ + __attribute__((__visibility__("default"))) \ + extern ret fn args +#define NBDKIT_DLL_PUBLIC __attribute__((__visibility__("default"))) #else #define NBDKIT_EXTERN_DECL(ret, fn, args) \ extern __declspec(dllexport) ret fn args +#define NBDKIT_DLL_PUBLIC __declspec(dllimport) #endif