Re: [PATCH 5/6] Use AC_CHECK_{DECLS, FUNCS, HEADERS}_ONCE more in specific-check macros.

On 09/15/2013 10:24 AM, Zack Weinberg wrote:
>  * lib/autoconf/functions.m4 (AC_FUNC_CHOWN): No need to check for unistd.h.
>    (_AC_LIBOBJ_FNMATCH): Use AC_CHECK_DECLS_ONCE and AC_CHECK_FUNCS_ONCE.
>    (_AC_LIBOBJ_GETLOADAVG): Use AC_CHECK_FUNCS_ONCE for setlocale.
>    (AC_FUNC_MMAP): Use AC_CHECK_FUNCS_ONCE for getpagesize.
>    (AC_FUNC_SELECT_ARGTYPES): Use AC_CHECK_HEADERS_ONCE for sys/select.h and
>    sys/socket.h.
>    (AC_FUNC_STRERROR_R): Use AC_CHECK_DECLS_ONCE + AC_CHECK_FUNCS_ONCE for
>    strerror_r.
>    (AC_FUNC_UTIME_NULL): Use AC_CHECK_HEADERS_ONCE for utime.h.
>    (AC_FUNC_FORK): Use AC_CHECK_HEADERS_ONCE and AC_CHECK_FUNCS_ONCE.
>    (AC_FUNC_VPRINTF): Use AC_CHECK_FUNCS_ONCE for vprintf (but not _doprnt).
> 
>  * lib/autoconf/headers.m4 (AC_HEADER_TIME, AC_MEMORY_H): Use
>    AC_CHECK_HEADERS_ONCE.
> 

> +AC_CHECK_FUNCS_ONCE([fork vfork])
>  if test "x$ac_cv_func_fork" = xyes; then
>    _AC_FUNC_FORK
>  else
> @@ -1988,12 +1986,12 @@ AU_ALIAS([AC_VFORK], [AC_FUNC_FORK])
>  # Why the heck is that _doprnt does not define HAVE__DOPRNT???
>  # That the logical name!
>  AC_DEFUN([AC_FUNC_VPRINTF],
> -[AC_CHECK_FUNCS(vprintf, [],
> -[AC_CHECK_FUNC(_doprnt,
> -	       [AC_DEFINE(HAVE_DOPRNT, 1,
> +[AC_CHECK_FUNCS_ONCE([vprintf])
> +AS_IF([test $ac_cv_func_vprintf = no],

Unsafe - the user can pre-populate the cache with something that would
break 'test'.  Use what we do elsewhere:

AS_IF([test "x$ac_cv_func_vprintf" = xno],

ACK with that fix.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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