Re: [libvirt] [PATCH v3 01/35] util: alloc: add macros for implementing automatic cleanup functionality

On Sat, Jun 30, 2018 at 02:30:05PM +0530, Sukrit Bhatnagar wrote: > New macros are introduced which help in adding GNU C's cleanup > attribute to variable declarations. Variables declared with these > macros will have their allocated memory freed automatically when > they go out of scope. > > Signed-off-by: Sukrit Bhatnagar <skrtbhtngr(a)gmail.com&gt; > --- > src/util/viralloc.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 44 insertions(+) > > diff --git a/src/util/viralloc.h b/src/util/viralloc.h > index 69d0f90..5c1d0d5 100644 > --- a/src/util/viralloc.h > +++ b/src/util/viralloc.h > @@ -596,4 +596,48 @@ void virAllocTestInit(void); > int virAllocTestCount(void); > void virAllocTestOOM(int n, int m); > void virAllocTestHook(void (*func)(int, void*), void *data); > + > +# define VIR_AUTOPTR_TYPE_NAME(type) type##AutoPtr > +# define VIR_AUTOPTR_FUNC_NAME(type) type##AutoPtrFree > + > +/** > + * VIR_DEFINE_AUTOPTR_FUNC: > + * @type: type of the variable to be freed automatically > + * @func: cleanup function to be automatically called > + * > + * This macro defines a function for automatic freeing of > + * resources allocated to a variable of type @type. This newly > + * defined function works as a necessary wrapper around @func. > + */ > +# define VIR_DEFINE_AUTOPTR_FUNC(type, func) \ > + typedef type *VIR_AUTOPTR_TYPE_NAME(type); \ So, it's not visible at first glance how ^this typedef is used... > + static inline void VIR_AUTOPTR_FUNC_NAME(type)(type **_ptr) \ > + { \ > + if (*_ptr) \ > + (func)(*_ptr); \ > + *_ptr = NULL; \ > + } \ ...therefore I'd write it explicitly as VIR_AUTOPTR_FUNC_NAME(type)(VIR_AUTOPTR_TYPE_NAME(type) *_ptr) > + > +# define VIR_AUTOPTR(type) \ > + __attribute__((cleanup(VIR_AUTOPTR_FUNC_NAME(type)))) VIR_AUTOPTR_TYPE_NAME(type) > + Also, since we're going to use it like this: VIR_AUTOPTR(virDomainDef) foo instead of this: VIR_AUTOPTR(virDomainDefPtr) foo why do we need VIR_AUTOPTR_TYPE_NAME anyway, since you could just use "type *" in the VIR_AUTOPTR macro definition and that should work for external types as well.