Merge lp:~bregma/geis/sentinel-check into lp:geis

[Stephen M. Webb]

Adds a GCC attribute to warn when a NULL terminator is missing from a variadic argument list.

No new tests are supplied: the functionality of this tweak can be verified by manually removing the terminating NULL from a geis_new() or geis_filter_add_term() call and attempting to build the test suite. Unlike older established tools, our test tools can not handle expected compile failures so testing must be done manually.

This change closes no bugs but reduces the incidents of help requests due to incorrect use of the API.

[Chase Douglas (chasedouglas)]

The change is definitely good to have. +1.

I don't think we need a test for this because it merely emits a warning, but we could actually provide a test if we wanted to. I wrote a compile test for utouch-frame _Generic support, for example. There's nothing in our test setup that would prohibit this.

review: Approve

=== modified file 'include/geis/geis.h'
--- include/geis/geis.h	2012-04-18 19:00:07 +0000
+++ include/geis/geis.h	2012-04-19 13:32:20 +0000
@@ -630,7 +630,7 @@
  * If no initialization arguments are passed, the parameter list consists of a
  * single NULL argument.
  */
-GEIS_API Geis geis_new(GeisString init_arg_name, ...);
+GEIS_API GEIS_VARARG Geis geis_new(GeisString init_arg_name, ...);
 
 /**
  * Cleans up an instance of the GEIS v2.0 API.
@@ -1656,9 +1656,9 @@
  *
  * @returns a newly created region, or NULL on failure.
  */
-GEIS_API GeisRegion geis_region_new(Geis       geis,
-                                    GeisString name,
-                                    GeisString init_arg_name, ...);
+GEIS_API GEIS_VARARG GeisRegion geis_region_new(Geis       geis,
+                                                GeisString name,
+                                                GeisString init_arg_name, ...);
 
 /**
  * Destroys a GEIS v2.0 region.
@@ -1787,9 +1787,9 @@
  *   NULL);
  * @endcode
  */
-GEIS_API GeisStatus geis_filter_add_term(GeisFilter         filter,
-                                         GeisFilterFacility facility,
-                                         ...);
+GEIS_API GEIS_VARARG GeisStatus geis_filter_add_term(GeisFilter         filter,
+                                                     GeisFilterFacility facility,
+                                                     ...);
 
 /* @} */
 

=== modified file 'libutouch-geis/geis/geisimpl.h'
--- libutouch-geis/geis/geisimpl.h	2010-12-20 18:06:36 +0000
+++ libutouch-geis/geis/geisimpl.h	2012-04-19 13:32:20 +0000
@@ -23,6 +23,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+/* Provide some cross-platform symbol export decorations. */
 #if defined _WIN32 || defined __CYGWIN__
   #define GEIS_HELPER_DSO_IMPORT __declspec(dllimport)
   #define GEIS_HELPER_DSO_EXPORT __declspec(dllexport)
@@ -51,6 +52,13 @@
   #define GEIS_LOCAL
 #endif /* GEIS_BUILDING_DSO */
 
+/* If available, provide a NULL terminator check decoration. */
+#if __GNUC__ >= 4
+# define GEIS_VARARG __attribute__((sentinel(0)))
+#else
+# define GEIS_VARARG 
+#endif
+
 /**
  * Portability types
  */