Re: [Xen-devel] [PATCH 04/20] autoconf: New test for openpty et al.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2012-04-13 at 19:39 +0100, Ian Jackson wrote:
> We may need to #include <libutil.h>, and/or link with -lutil, to use
> openpty, login_tty, and the like.  Provide INCLUDE_LIBUTIL_H
> (preprocessor constant, not always defined) and PTYFUNCS_LIBS
> (makefile variable).
> 
> We link libxl against PTYFUNCS_LIBS (which comes from autoconf) rather
> than UTIL_LIBS, and #include <libutil.h> where appropriate.
> 
> Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> ---
>  config/Tools.mk.in             |    2 +
>  tools/configure                |   51 
> ++++++++++++++++++++++++++++++++++++++++
>  tools/configure.ac             |    2 +
>  tools/libxl/Makefile           |    2 +-
>  tools/libxl/libxl_bootloader.c |    4 +++
>  tools/m4/ptyfuncs.m4           |   24 ++++++++++++++++++
>  6 files changed, 84 insertions(+), 1 deletions(-)
>  create mode 100644 tools/m4/ptyfuncs.m4
> 
> diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
> index e5ea867..5ba144f 100644
> --- a/tools/libxl/Makefile
> +++ b/tools/libxl/Makefile
> @@ -20,7 +20,7 @@ LIBUUID_LIBS += -luuid
>  endif
>  
>  LIBXL_LIBS =
> -LIBXL_LIBS = $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) 
> $(LDLIBS_libxenstore) $(LDLIBS_libblktapctl) $(UTIL_LIBS) $(LIBUUID_LIBS)
> +LIBXL_LIBS = $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) 
> $(LDLIBS_libxenstore) $(LDLIBS_libblktapctl) $(PTYFUNCS_LIBS) $(LIBUUID_LIBS)

Did you intend to remove the definition of UTIL_LIBS? I don't see a hunk
which does that.

> diff --git a/tools/m4/ptyfuncs.m4 b/tools/m4/ptyfuncs.m4
> new file mode 100644
> index 0000000..2846a6d
> --- /dev/null
> +++ b/tools/m4/ptyfuncs.m4
> @@ -0,0 +1,24 @@
> +AC_DEFUN([AX_CHECK_PTYFUNCS], [
> +    AC_CHECK_HEADER([libutil.h],[
> +      AC_DEFINE([INCLUDE_LIBUTIL_H],[<libutil.h>],[libutil header file name])
> +    ])
> +    AC_CACHE_CHECK([for openpty et al], [ax_cv_ptyfuncs_libs], [
> +        ax_cv_ptyfuncs_libs=-lutil
> +        AX_SAVEVAR_SAVE(LIBS)
> +        LIBS="$LIBS $ax_cv_ptyfuncs_libs"
> +        AC_LINK_IFELSE([
> +#ifdef INCLUDE_LIBUTIL_H
> +#include INCLUDE_LIBUTIL_H
> +#endif
> +int main(void) {
> +  openpty(0,0,0,0,0);
> +  login_tty(0);
> +}
> +])
> +        AX_SAVEVAR_RESTORE(LIBS)],
> +    [],[
> +        AC_MSG_FAILURE([Unable to find -lutil for openpty and login_tty])
> +    ])
> +    PTYFUNCS_LIBS="$ax_cv_ptyfuncs_libs"
> +    AC_SUBST(PTYFUNCS_LIBS)
> +])

Does this fail if -lutil isn't available? My (perhaps mistaken) reading
of the commit message was that -lutil was only needed on some platforms?

On the other hand the AC_MSG_FAILURE doesn't see to have appeared in the
configure output -- so maybe I just understand what all these macros are
actually doing.

Ian.



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