[Haskell-cafe] advanced cabal configuration

[Jonas Scholl]

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Couldn't you write something like this?

foreign import ccall unsafe "sendfile64"
    c_sendfile64 :: Fd -> Fd -> Ptr COff -> CSize -> IO (#type ssize_t)

foreign import ccall unsafe "sendfile"
    c_sendfile32 :: Fd -> Fd -> Ptr COff -> CSize -> IO (#type ssize_t)

c_sendfile :: Fd -> Fd -> Ptr COff -> CSize -> IO (#type ssize_t)
c_sendfile = case sizeOf (undefined :: COff) of
    4 -> c_sendfile32
    8 -> c_sendfile64
    _ -> error "COff has an unsupported size"

Jonas

On 05/19/2015 02:06 PM, Kazu Yamamoto (????) wrote:
> Hi,
> 
> I'm a maintainer of simple-sendfile and need to implement the 
> following is to rescue 32bit Linux:
> 
> - If the COff size is 8, the following FFI is used:
> 
> foreign import ccall unsafe "sendfile64" c_sendfile :: Fd -> Fd ->
> Ptr COff -> CSize -> IO (#type ssize_t)
> 
> - Otherwise, the following FFI is used:
> 
> foreign import ccall unsafe "sendfile" c_sendfile :: Fd -> Fd ->
> Ptr COff -> CSize -> IO (#type ssize_t)
> 
> How can I implement this?
> 
> I guess that Setup.hs should evaluate (sizeOf (1 :: COff)) and
> define a C macro, say LARGE_OFFSET and write the following code.
> 
> #ifdef LARGE_OFFSET foreign import ccall unsafe "sendfile64" #else 
> foreign import ccall unsafe "sendfile" #endif
> 
> I have no experience to use Build-Type: other than Simple in cabal 
> files.  Would someone explain how to implement it concretely or 
> suggest examples which implement similar things?
> 
> For more informaion, please read: 
> https://github.com/yesodweb/wai/issues/372
> 
> Thanks.
> 
> --Kazu _______________________________________________ Haskell-Cafe
> mailing list Haskell-Cafe at haskell.org 
> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
> 

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