Re: [Qemu-devel] [PATCH] configure: Add a proper check for openpty() in libutil

[Eric Blake]

On 1/17/19 11:14 AM, Thomas Huth wrote:
> On Linux (and maybe some BSDs), we require libutil for the openpty()
> function. However, this library is not available on some other systems, so
> we currently use a fragile if-statement in the configure script to check
> whether we need the library or not. Unfortunately, we also hard-coded a
> "-lutil" in the tests/Makefile.include file, so this breaks the build on
> Solaris, for example (see buglink below). To fix the issue, add the "-lutil"
> to "libs_tools" in the configure script instead, then this gets properly
> propagated to the tests, too.
> And while we're at it, also replace the fragile if-statement in the confi-
> gure script with a proper link-check for the availablity of this function.

Interesting that you split "confi-" and "gure" across lines, I guess to
appear less ragged.

s/availablity/availability/

> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1777252
> Signed-off-by: Thomas Huth <address@hidden>
> ---
>  configure              | 12 ++++++++++--
>  tests/Makefile.include |  4 ----
>  2 files changed, 10 insertions(+), 6 deletions(-)

Feature-based testing is always better than hard-coded knowledge ;)

> -if test "$darwin" != "yes" -a "$mingw32" != "yes" -a "$solaris" != yes -a \
> -        "$haiku" != "yes" ; then
> +# Check whether we need to link libutil for openpty()
> +cat > $TMPC << EOF
> +extern int openpty(int *am, int *as, char *name, void *termp, void *winp);
> +int main(void) { return openpty(0, 0, 0, 0, 0); }
> +EOF
> +
> +if ! compile_prog "" "" ; then
> +  if compile_prog "" "-lutil" ; then
>      libs_softmmu="-lutil $libs_softmmu"
> +    libs_tools="-lutil $libs_tools"
> +  fi
>  fi

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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