diff options
Diffstat (limited to 'shared/nm-default.h')
| -rw-r--r-- | shared/nm-default.h | 61 |
1 files changed, 57 insertions, 4 deletions
diff --git a/shared/nm-default.h b/shared/nm-default.h index e3e3ea4414..9e2377cf80 100644 --- a/shared/nm-default.h +++ b/shared/nm-default.h @@ -52,15 +52,68 @@ #define NM_VERSION_MAX_ALLOWED NM_VERSION_NEXT_STABLE #define NM_VERSION_MIN_REQUIRED NM_VERSION_0_9_8 +#ifndef NM_MORE_ASSERTS +#define NM_MORE_ASSERTS 0 +#endif + +#if NM_MORE_ASSERTS == 0 +/* The cast macros like NM_TYPE() are implemented via G_TYPE_CHECK_INSTANCE_CAST() + * and _G_TYPE_CIC(). The latter, by default performs runtime checks of the type + * by calling g_type_check_instance_cast(). + * This check has a certain overhead without being helpful. + * + * Example 1: + * static void foo (NMType *obj) + * { + * access_obj_without_check (obj); + * } + * foo ((NMType *) obj); + * // There is no runtime check and passing an invalid pointer + * // leads to a crash. + * + * Example 2: + * static void foo (NMType *obj) + * { + * access_obj_without_check (obj); + * } + * foo (NM_TYPE (obj)); + * // There is a runtime check which prints a g_warning(), but that doesn't + * // avoid the crash as NM_TYPE() cannot do anything then passing on the + * // invalid pointer. + * + * Example 3: + * static void foo (NMType *obj) + * { + * g_return_if_fail (NM_IS_TYPE (obj)); + * access_obj_without_check (obj); + * } + * foo ((NMType *) obj); + * // There is a runtime check which prints a g_critical() which also avoids + * // the crash. That is actually helpful to catch bugs and avoid crashes. + * + * Example 4: + * static void foo (NMType *obj) + * { + * g_return_if_fail (NM_IS_TYPE (obj)); + * access_obj_without_check (obj); + * } + * foo (NM_TYPE (obj)); + * // The runtime check is performed twice, with printing a g_warning() and + * // a g_critical() and avoiding the crash. + * + * Example 3 is how it should be done. Type checks in NM_TYPE() are pointless. + * Disable them for our production builds. + */ +#ifndef G_DISABLE_CAST_CHECKS +#define G_DISABLE_CAST_CHECKS +#endif +#endif + #include <stdlib.h> #include <glib.h> /*****************************************************************************/ -#ifndef NM_MORE_ASSERTS -#define NM_MORE_ASSERTS 0 -#endif - #if NM_MORE_ASSERTS == 0 /* glib assertions (g_return_*(), g_assert*()) contain a textual representation |