On Wed, Jun 02, 2021 at 09:05:26PM +0100, Richard W.M. Jones wrote:
> 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
>
Looks reasonable to me.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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