Hi,
>> If I have a C function which allocates memory for a C string and returns a
>> pointer to this memory (return type char *).
>> How do I deallocate this memory? Should I use
>>`foreign-string-free' or `foreign-free'.
>I have been meaning to look into this. Right now, you'd have to use
>something like (foreign-funcall "free" :pointer <your-pointer>)
I don't understand why there's something unclear here.
I thought that's why :string+ptr had been invented.
This is exactly the pattern of :string+ptr, and it's embodied in
tests/misc-types.lisp:deftest misc-types.string+ptr:
a) return string and
b) (foreign-free pointer)
Is that testcase broken? "Just" non-portable?
Well, since foreign-free's specification is to free only things allocated with
foreign-alloc, maybe CFFI must export the general C free() as well?
The :string+ptr type should then documented this.
Note that malloc()/free() is fine for a UNIX shared library. It's somewhat
meaningless in the context of a DLL on MS-Windows. But there, one will probably
not encounter such a protocol and will have to call the resource free'ing
function via the FFI as well.
Regards,
Jorg Hohle.
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