Re: an admittedly lazy programmer question...
- From: "J.-F. Cap" <jfdotcap.ml@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Tue, 29 May 2012 10:19:11 +0200
2012/5/28 William Adams <william_a_adams@xxxxxxx>
>
>
> I am doing some interop, and the C function looks like this:
>
>
>
> void somefunc(FILE *f)
>
>
>
> Meaning, it expects to the a FILE structure. Typically because it's going to
> do the reading from the file on its own. I really don't like these kinds of
> interfaces, but there you have it.
>
>
>
> Question:
>
>
>
> Would LuaJIT ffi do anything for me to translate from Luas io to this FILE
> structure? Can I simply do:
>
>
>
> fh = io.open(file)
>
> somefunc(fh)
>
>
>
> And have it work? Assuming I've defined FILE in some FFI place.
>
>
>
> Alternatively, I could redefine the function signature:
>
>
>
> void somefunc(void *f)
>
>
>
> But still, the question remains, is the io.open returning something I could
> feed to this function in some way?
>
>
>
> -- William
>
>
>
> ===============================
>
> - Shaping clay is easier than digging it out of the ground.
>
>
> http://williamaadams.wordpress.com
> http://www.thingiverse.com/WilliamAAdams
> https://github.com/Wiladams
This works here (i386 GNU/Linux).
ffi.cdef[[
struct _IO_FILE;
typedef struct _IO_FILE FILE;
size_t fwrite(const void *ptr, size_t size, size_t nmemb,FILE *stream);
typedef struct {
FILE *fp; /* File handle. */
uint32_t type; /* File type. */
} IOFileUD;
]]
local function fwrite(file,offset,data)
local f=assert(type(file)=='userdata' and ffi.cast('IOFileUD
*',file))
local fp=f.fp
ffi.C.fwrite(...,...,...,fp)
end
...
local file=io.open(....)
fwrite(file, ....)
file:close()
JF
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