Re: [PATCH v2 3/3] crypto: Allow building with GnuTLS but without Libtasn1

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

On Thu, May 02, 2024 at 11:56:42AM +0200, Philippe Mathieu-Daudé wrote:
> We only use Libtasn1 in unit tests. As noted in commit d47b83b118
> ("tests: add migration tests of TLS with x509 credentials"), having
> GnuTLS without Libtasn1 is a valid configuration, so do not require
> Libtasn1, to avoid:
> 
>   Dependency gnutls found: YES 3.7.1 (cached)
>   Run-time dependency libtasn1 found: NO (tried pkgconfig)
> 
>   ../meson.build:1914:10: ERROR: Dependency "libtasn1" not found, tried pkgconfig

Did you actually try to build without libtasn1 present ?

If I remove /usr/lib64/pkgconfig/libtasn1.pc, then the prior
check for 'gnutls' itself will fail, as libtasn1 is declared
to be a dep of gnutls in its pkg-config file, regardless of
what QEMU askes for:

$ pkg-config --cflags --libs gnutls
Package libtasn1 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libtasn1.pc'
to the PKG_CONFIG_PATH environment variable
Package 'libtasn1', required by 'gnutls', not found

I'm still willing to merge this, because from QEMU's POV,
libtasn1 isn't required.

> 
> Fixes: ba7ed407e6 ("configure, meson: convert libtasn1 detection to meson")
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>  meson.build | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/meson.build b/meson.build
> index 5db2dbc12e..837a2bdb56 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -1912,6 +1912,7 @@ endif
>  tasn1 = not_found
>  if gnutls.found()
>    tasn1 = dependency('libtasn1',
> +                     required: false,
>                       method: 'pkg-config')
>  endif
>  keyutils = not_found
> -- 
> 2.41.0
> 

With regards,
Daniel
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