Freeing memory from C

[Chris]

On Tuesday, 3 December 2013 at 12:31:16 UTC, John Colvin wrote:
> On Tuesday, 3 December 2013 at 10:57:51 UTC, Chris wrote:
>> I have a C module that dynamically allocates memory for a 
>> string like so:
>>
>> char *result = (char*)malloc(length + 1); // 'length' has been 
>> calculated
>>
>> When I call it from D (via extern (C)), is it ok to free it 
>> from there like so:
>>
>> void callFunction() {
>>  auto result = callToCFunction(); // Returns above *result
>>  // ...
>>  std.c.stdlib.free(result);
>> }
>>
>> The problem is that, as it is now, *result is allocated in a 
>> different place in the C module (not in "callToCFunction()) 
>> and cannot be freed before D has called it.
>>
>> If D cannot free it in this way, I'll have a serious memory 
>> leak and I'll have to rewrite the existing C module (which is 
>> probably better given the awkward situation above).
>
> You should be fine to free in that way as long as you haven't 
> done anything crazy like separately static linking libc.
>
> core.stdc.stdlib; is the correct module to use, std.c.* only 
> exist for backwards compatibility.

Ok. Thanks for the answer. std.c.stdlib.free() is mentioned on 
the "How to interface to C" page 
(http://dlang.org/interfaceToC.html). So maybe that needs an 
update.