svn commit: r284917 - head/sys/sys

[Pedro F. Giffuni]

Author: pfg
Date: Mon Jun 29 00:30:30 2015
New Revision: 284917
URL: https://svnweb.freebsd.org/changeset/base/284917

Log:
  Add a new __sentinel attribute.
  
  The sentinel attribute was originally implemented in OpenBSD's gcc and
  later adopted by upstream GCC 4.0 (and clang). From the OpenBSD's
  gcc-local manpage:
  
  -   gcc recognizes the extra attribute __sentinel__, which can be used to
      mark varargs function that need a NULL pointer to mark argument
      termination, like execl(3).  This exposes latent bugs for 64-bit
      architectures, where a terminating 0 will expand to a 32-bit int, and
      not a full-fledged 64-bits pointer.
  
  While here sort the visibility attributes.
  
  Hinted-by:	OpenBSD

Modified:
  head/sys/sys/cdefs.h

Modified: head/sys/sys/cdefs.h
==============================================================================
--- head/sys/sys/cdefs.h	Sun Jun 28 21:36:00 2015	(r284916)
+++ head/sys/sys/cdefs.h	Mon Jun 29 00:30:30 2015	(r284917)
@@ -469,11 +469,13 @@
 #endif
 
 #if __GNUC_PREREQ__(4, 0)
-#define	__hidden	__attribute__((__visibility__("hidden")))
+#define	__sentinel	__attribute__((__sentinel__))
 #define	__exported	__attribute__((__visibility__("default")))
+#define	__hidden	__attribute__((__visibility__("hidden")))
 #else
-#define	__hidden
+#define	__sentinel
 #define	__exported
+#define	__hidden
 #endif
 
 /*