Use Get/SetThreadErrorMode if it is available (on Windows 7 and above).

[Peter Rosin]

Hi!

A few minutes after pushing the GetErrorMode patch [1] I found out that
Win7 and 2k8R2 have added the functions Get/SetThreadErrorMode which
addresses this concern raised in [2]:

> That said, a potential race is still there since the error mode is
> process global and we are trying to save the current error mode and
> restore it afterwards, some other thread might do the same and we'd get
> into an inconsistent state if unlucky. There's no way to deal with that
> though, short of adding some locking mechanism and requiring client code
> to follow our lead.

This patch makes use of the new functions if they are available and
falls back to the previous behavior if they are not (i.e. use GetErrorMode
if it is available, otherwise simulate it with SetErrorMode).

I have been quite busy lately, so I didn't have time to test it properly
for a number of weeks which is why the commit is oldish. But now I have
done testing (on 2k8R2 with Get/SetThreadErrorMode, on (old) Wine with
GetErrorMode and on XP without GetErrorMode) and it behaves as desired.
Recent Wine versions implements Get/SetThreadErrorMode so that was why
I tested with an old Wine version from before the addition of those APIs.

Cheers,
Peter

[1] http://lists.gnu.org/archive/html/libtool-patches/2010-01/msg00004.html
[2] http://lists.gnu.org/archive/html/libtool-patches/2010-01/msg00037.html


2010-01-21  Peter Rosin  <address@hidden>

        Use Get/SetThreadErrorMode if they are available.
        * libltdl/loaders/loadlibrary.c (wrap_geterrormode): Replaced...
        (wrap_getthreaderrormode): ...by this function that checks
        first for GetThreadErrorMode, then GetErrorMode and makes use
        of either of those or...
        (fallback_getthreaderrormode): ...else falls back to this
        replacement function that implements the old workaround, which
        was previously implemented in...
        (fallback_geterrormode): ...this now renamed function.
        (geterrormode): Replaced...
        (getthreaderrormode): ...by this function pointer that points
        at either of wrap_getthreaderrormode, GetThreadErrorMode,
        GetErrorMode or fallback_getthreaderrormode.
        (wrap_setthreaderrormode): New function that checks if
        SetThreadErrorMode is supported by the system and makes use of
        it if it is.
        (fallback_setthreaderrormode): New function that is used
        otherwise that implements the old version using SetErrorMode.
        (setthreaderrormode): New function pointer that points at
        either of wrap_setthreaderrormode, SetThreadErrorMode or
        fallback_setthreaderrormode.
        (vm_open): Adjust to the above.

--
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thread-error-mode.patch
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