I'm forwarding this to the FFI list in the hope that
someone can help Chris.
Simon
| -----Original Message-----
| From: Chris Ryder [mailto:[EMAIL PROTECTED]]
| Sent: 11 August 2000 12:05
| To: Simon Peyton-Jones
| Subject: HDirect + String Arrays.
|
|
| Hi,
|
| I'm trying to call a C function from Haskell (GHC 4.04,
| HDirect 0.16) that
| returns an array of strings. eg :
|
| char **myCfunc(void);
|
| or, perhaps :
|
| void myCfunc (int* size, char*** array);
|
| I have an IDL file that specifies :
|
| module Thing {
| void myCfunc([out]int* asize, [out,string,size_is(asize)]
| char*** arr);
| };
|
| This generates marshalling code that looks correct (its shown
| at the end
| of this message) but when run, only the first string seems to
| be correctly
| marshalled - all subsequent strings in the array become NULL
| (represented
| as Nothing ?) The strings are definatly allocated in the C
| function, so
| I'm sure it is a marshalling problem.
|
| Is there something I'm missing or doing incorrectly ?
|
| Many Thanks,
| Chris Ryder.
|
| --- Haskell code generated by ihc ---
|
| -- Automatically generated by HaskellDirect (ihc), snapshot 300600
| -- Created: 11:41 BST, Friday 11 August, 1900
| -- Command line: -fhs-to-c Test.idl
|
| module Thing
| ( doSomething
| ) where
|
| import qualified Prelude
| import qualified Addr (Addr, addrToInt)
| import qualified HDirect (sizeofInt32, allocBytes, sizeofAddr,
| readInt32, readString, readunique,
| int32ToWord32, unmarshalllist,
| free, doThenFree)
| import qualified GlaExts (toInt)
|
| doSomething :: Prelude.IO [Prelude.Maybe Prelude.String]
| doSomething =
| do
| asize <- HDirect.allocBytes (GlaExts.toInt HDirect.sizeofInt32)
| query <- HDirect.allocBytes ((GlaExts.toInt
| HDirect.sizeofAddr Prelude.* Addr.addrToInt asize))
| prim_Thing_doSomething asize query
| asize <- HDirect.readInt32 asize
| HDirect.doThenFree HDirect.free (HDirect.unmarshalllist
| HDirect.sizeofAddr 0 (HDirect.int32ToWord32 asize)
| (HDirect.readunique HDirect.readString)) query
|
| foreign import "doSomething" prim_Thing_doSomething ::
| Addr.Addr -> Addr.Addr -> Prelude.IO ()
|
|
