Re: [PATCH v2 1/2] configure: Fix building with SASL on Windows

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Mar 09, 2020 at 01:24:53PM +0100, Philippe Mathieu-Daudé wrote:
> The Simple Authentication and Security Layer (SASL) library
> re-defines the struct iovec on Win32 [*]. QEMU also re-defines
> it in "qemu/osdep.h". The two definitions then clash on a MinGW
> build.
> We can avoid the SASL definition by defining STRUCT_IOVEC_DEFINED.
> Since QEMU already defines 'struct iovec' if it is missing, add
> the definition to vnc_sasl_cflags to avoid SASL re-defining it.
> 
> [*] https://github.com/cyrusimap/cyrus-sasl/blob/cyrus-sasl-2.1.27/include/sasl.h#L187
> 
> Cc: Alexey Pavlov <alexpux@gmail.com>
> Cc: Biswapriyo Nath <nathbappai@gmail.com>
> Reported-by: Youry Metlitsky <winaes@yandex.ru>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v2:
> Since QEMU provides 'struct iovec' if missing, always define
> STRUCT_IOVEC_DEFINED (danpb review).
> ---
>  configure | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index cbf864bff1..a4cd4bccfb 100755
> --- a/configure
> +++ b/configure
> @@ -3349,7 +3349,9 @@ if test "$vnc" = "yes" && test "$vnc_sasl" != "no" ; then
>  int main(void) { sasl_server_init(NULL, "qemu"); return 0; }
>  EOF
>    # Assuming Cyrus-SASL installed in /usr prefix
> -  vnc_sasl_cflags=""
> +  # QEMU defines struct iovec in "qemu/osdep.h",
> +  # we don't want libsasl to redefine it in <sasl/sasl.h>.
> +  vnc_sasl_cflags="-DSTRUCT_IOVEC_DEFINED"
>    vnc_sasl_libs="-lsasl2"
>    if compile_prog "$vnc_sasl_cflags" "$vnc_sasl_libs" ; then
>      vnc_sasl=yes

This works so:

  Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


however, I'm wondering if we'd be better doing this in a more
localized place. This applies to everything we compile, but
only one place imports sasl.h, so should we instead do

   #define STRUCT_IOVEC_DEFINED
   #include <sasl/saslh.>

in vnc-auth-sasl.h, so we localize the namespace pollution.


Regards,
Daniel
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