common: Make issetugid check simpler

common/compat.c

@@ -40,10 +40,6 @@
  */
 #define _XOPEN_SOURCE 700
 
-#if defined(HAVE_ISSETUGID) && defined(__FreeBSD__)
-#define __BSD_VISIBLE 1
-#endif
-
 #include "compat.h"
 #include "debug.h"
 
@@ -819,7 +815,8 @@ getauxval (unsigned long type)
 		extern int __libc_enable_secure;
 		secure = __libc_enable_secure;
 
-#elif defined(HAVE_ISSETUGID) && defined(HAVE_ISSETUGID_OPENBSD)
+#elif defined(HAVE_ISSETUGID) && \
+	!((defined __APPLE__ && defined __MACH__) || (defined __FREEBSD__))
 		secure = issetugid ();
 
 #elif defined(OS_UNIX)

configure.ac

@@ -115,21 +115,7 @@ if test "$os_unix" = "yes"; then
 	AC_CHECK_FUNCS([setenv])
 	AC_CHECK_FUNCS([getpeereid])
 	AC_CHECK_FUNCS([getpeerucred])
-
-	# Check if issetugid() is available and has compatible behavior with OpenBSD
-	AC_CHECK_FUNCS([issetugid], [
-		AC_CACHE_CHECK([whether issetugid() can detect setuid/setgid],
-			[ac_cv_issetugid_openbsd],
-			[ac_cv_issetugid_openbsd=no
-			AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>]],
-				[[return issetugid ();]])],
-				[chmod 02777 ./conftest$EXEEXT; ./conftest$EXEEXT || ac_cv_issetugid_openbsd=yes],
-				[ac_cv_issetugid_openbsd=no],
-				[ac_cv_issetugid_openbsd="guessing no"])])
-		if test "$ac_cv_issetugid_openbsd" = yes; then
-			AC_DEFINE([HAVE_ISSETUGID_OPENBSD], [1], [Whether issetugid() has compatible behavior with OpenBSD])
-		fi
-	])
+	AC_CHECK_FUNCS([issetugid])
 
 	AC_CACHE_CHECK([for thread-local storage class],
 		[ac_cv_tls_keyword],