[GHC] #14262: fdReady cannot wait more than 49 days

[GHC]

#14262: fdReady cannot wait more than 49 days
-------------------------------------+-------------------------------------
        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
                                     |  (amd64)
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8684, #13497,    |  Differential Rev(s):
  #14267                             |
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by bgamari):

 * status:  new => closed
 * resolution:   => fixed
 * milestone:   => 8.4.1


Old description:

> {{{
> import System.IO
> hWaitForInput stdin 4294968296
> }}}
>
> This code waits for 1 second instead of 49.something days.
>
> The culprit:
>
> {{{
> hWaitForInput :: Handle -> Int -> IO Bool
> fdReady(..., int msecs, ...)
> }}}
>
> Haskell `Int` is usally 64 bits. C `int` is usually 32 bits.
>
> Called here:
>
> {{{
> ready :: FD -> Bool -> Int -> IO Bool
> ready fd write msecs = do
>   r <- throwErrnoIfMinus1Retry "GHC.IO.FD.ready" $
>           fdReady (fdFD fd) (fromIntegral $ fromEnum $ write)
>                             (fromIntegral msecs)
>
> foreign import ccall safe "fdReady"
>   fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
> }}}
>
> We `fromIntegral` `Int` to `CInt` (== `Int32`), overflowing.

New description:

 {{{#!hs
 import System.IO
 hWaitForInput stdin 4294968296
 }}}

 This code waits for 1 second instead of 49.something days.

 The culprit:

 {{{#!hs
 hWaitForInput :: Handle -> Int -> IO Bool
 fdReady(..., int msecs, ...)
 }}}

 Haskell `Int` is usally 64 bits. C `int` is usually 32 bits.

 Called here:

 {{{#!hs
 ready :: FD -> Bool -> Int -> IO Bool
 ready fd write msecs = do
   r <- throwErrnoIfMinus1Retry "GHC.IO.FD.ready" $
           fdReady (fdFD fd) (fromIntegral $ fromEnum $ write)
                             (fromIntegral msecs)

 foreign import ccall safe "fdReady"
   fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
 }}}

 We `fromIntegral` `Int` to `CInt` (== `Int32`), overflowing.

--

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14262#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler