On 7/31/19 9:04 AM, Alex Bennée wrote:
>
> Daniel P. Berrangé <berra...@redhat.com> writes:
>
>> Both GCC and CLang support a C extension attribute((cleanup)) which
>> allows you to define a function that is invoked when a stack variable
>> exits scope. This typically used to free the memory allocated to it,
>> though you're not restricted to this. For example it could be used to
>> unlock a mutex.
> <snip>
>>
>> GOOD:
>> g_autofree char *wibble = g_strdup("wibble")
>> ...
>> return g_steal_pointer(wibble);
>>
>> g_steal_pointer is an inline function which simply copies
>> the pointer to a new variable, and sets the original variable
>> to NULL, thus avoiding cleanup.
>
> Surely this is a particular use case where you wouldn't use g_autofree
> to declare the variable as you intending to return it to the outer scope?
Actually, it's still quite useful if you have intermediate returns:
g_autofree char *wibble = NULL;
if (something)
return NULL;
wibble = g_strdup("wibble");
if (something_else)
return NULL;
return g_steal_pointer(wibble);
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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