[PATCH 1/2] xfree86: Check for issetugid declaration

[Mark Kettenis]

> From: Julien Cristau <jcristau at debian.org>
> Date: Sat, 27 Jul 2013 21:08:28 +0200
> 
> Avoids 'implicit function declaration' build error on gnu/kfreebsd.

That's seriously backwards.  You should make sure the right headers
get included such that there is a proper function declaration.  Or, as
a last a resort, if the header files for your OS are broken beyond
repair, provide a function declaration yourself.  But no using
issetugid() when it is available is a security risk.

> Signed-off-by: Julien Cristau <jcristau at debian.org>
> ---
>  configure.ac                 |    1 +
>  hw/xfree86/common/xf86Init.c |    2 +-
>  include/xorg-config.h.in     |    4 ++++
>  3 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/configure.ac b/configure.ac
> index c6ecba4..a93e903 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -213,6 +213,7 @@ AC_CHECK_FUNC([dlopen], [],
>  AC_SUBST(DLOPEN_LIBS)
>  
>  dnl Checks for library functions.
> +AC_CHECK_DECLS([issetugid])
>  AC_CHECK_FUNCS([backtrace ffs geteuid getuid issetugid getresuid \
>  	getdtablesize getifaddrs getpeereid getpeerucred getzoneid \
>  	mmap shmctl64 strncasecmp vasprintf vsnprintf walkcontext])
> diff --git a/hw/xfree86/common/xf86Init.c b/hw/xfree86/common/xf86Init.c
> index 91ec4c8..6caaa51 100644
> --- a/hw/xfree86/common/xf86Init.c
> +++ b/hw/xfree86/common/xf86Init.c
> @@ -253,7 +253,7 @@ xf86PrivsElevated(void)
>              privsElevated = TRUE;
>          }
>          else {
> -#if defined(HAVE_ISSETUGID)
> +#if defined(HAVE_ISSETUGID) && HAVE_DECL_ISSETUGID
>              privsElevated = issetugid();
>  #elif defined(HAVE_GETRESUID)
>              uid_t ruid, euid, suid;
> diff --git a/include/xorg-config.h.in b/include/xorg-config.h.in
> index a71b25d..d9e7ec5 100644
> --- a/include/xorg-config.h.in
> +++ b/include/xorg-config.h.in
> @@ -130,6 +130,10 @@
>  /* Use libpciaccess */
>  #undef XSERVER_LIBPCIACCESS
>  
> +/* Define to 1 if you have the declaration of `issetugid', and to 0 if you
> +   don't. */
> +#undef HAVE_DECL_ISSETUGID
> +
>  /* Have setugid */
>  #undef HAVE_ISSETUGID
>  
> -- 
> 1.7.10.4
> 
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