#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