#2189: hSetBuffer stdin NoBuffering doesn't seem to work in ghc 6.8.2 on Windows
XP
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Reporter: FalconNL | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.8.3
Component: GHCi | Version: 6.8.2
Severity: normal | Resolution:
Keywords: hsetbuffering buffering buffer | Difficulty: Unknown
Testcase: | Architecture: x86
Os: Windows |
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Comment (by judah):
There is code in {{{base/cbits/consUtils.c:set_console_buffering}}} to
disable Windows line buffering (by calling the Win32 function
`SetConsoleMode`).
However, the code in `GHC.Handle` which is supposed to call that function
was `#ifdef`'ed out on mingw in the following commit:
http://cvs.haskell.org/cgi-
bin/cvsweb.cgi/fptools/libraries/base/GHC/Handle.hs#rev1.14
From the comments in `System.Posix.Internals`:
{{{
-- 'raw' mode for Win32 means turn off 'line input' (=> buffering and
-- character translation for the console.) The Win32 API for doing
-- this is GetConsoleMode(), which also requires echoing to be disabled
-- when turning off 'line input' processing. Notice that turning off
-- 'line input' implies enter/return is reported as '\r' (and it won't
-- report that character until another character is input..odd.) This
-- latter feature doesn't sit too well with IO actions like IO.hGetLine..
}}}
I'm not that experienced with Windows programming, but maybe instead of
changing the `ConsoleMode`, we could call the lower-level
`ReadConsoleInput/PeekConsoleInput` when we want to read only one
character at a time.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2189#comment:4>
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