IIRC, at one point, someone had said something along the lines that under certain criteria variables used inside SEH2 blocks had to be declared with volatile.
Not sure if this had been fixed but either way it does looks like an SEH problem.

martin

> Date: Sat, 18 Apr 2009 12:36:31 +0200
> From: timo.kreuzer@web.de
> To: ros-dev@reactos.org
> Subject: Re: [ros-dev] [ros-diffs] [mjmartin] 40557: - Add volatile to variables in OutputDebugStringA. Fix #1 of ? for 3424.
>
> Can you explain, why the variables need to be volatile? This looks like
> a SEH problem.
>
> mjmartin@svn.reactos.org schrieb:
> > Author: mjmartin
> > Date: Fri Apr 17 13:59:03 2009
> > New Revision: 40557
> >
> > URL: http://svn.reactos.org/svn/reactos?rev=40557&view=rev
> > Log:
> > - Add volatile to variables in OutputDebugStringA. Fix #1 of ? for 3424.
> >
> > Modified:
> > trunk/reactos/dll/win32/kernel32/debug/output.c
> >
> > Modified: trunk/reactos/dll/win32/kernel32/debug/output.c
> > URL: http://svn.reactos.org/svn/reactos/trunk/reactos/dll/win32/kernel32/debug/output.c?rev=40557&r1=40556&r2=40557&view=diff
> > ==============================================================================
> > --- trunk/reactos/dll/win32/kernel32/debug/output.c [iso-8859-1] (original)
> > +++ trunk/reactos/dll/win32/kernel32/debug/output.c [iso-8859-1] Fri Apr 17 13:59:03 2009
> > @@ -219,9 +219,9 @@
> > static BOOL s_bDBMonMutexTriedOpen = FALSE;
> >
> > /* local copy of the mutex handle */
> > - HANDLE hDBMonMutex = s_hDBMonMutex;
> > + volatile HANDLE hDBMonMutex = s_hDBMonMutex;
> > /* handle to the Section of the shared buffer */
> > - HANDLE hDBMonBuffer = NULL;
> > + volatile HANDLE hDBMonBuffer = NULL;
> >
> > /* pointer to the mapped view of the shared buffer. It consist of the current
> > process id followed by the message string */
> > @@ -229,11 +229,11 @@
> >
> > /* event: signaled by the debug message monitor when OutputDebugString can write
> > to the shared buffer */
> > - HANDLE hDBMonBufferReady = NULL;
> > + volatile HANDLE hDBMonBufferReady = NULL;
> >
> > /* event: to be signaled by OutputDebugString when it's done writing to the
> > shared buffer */
> > - HANDLE hDBMonDataReady = NULL;
> > + volatile HANDLE hDBMonDataReady = NULL;
> >
> > /* mutex not opened, and no previous attempts to open/create it */
> > if(hDBMonMutex == NULL && !s_bDBMonMutexTriedOpen)
> > @@ -295,10 +295,10 @@
> > _SEH2_TRY
> > {
> > /* size of the current output block */
> > - SIZE_T nRoundLen;
> > + volatile SIZE_T nRoundLen;
> >
> > /* size of the remainder of the string */
> > - SIZE_T nOutputStringLen;
> > + volatile SIZE_T nOutputStringLen;
> >
> > /* output the whole string */
> > nOutputStringLen = strlen(_OutputString);
> > @@ -339,11 +339,12 @@
> > else
> > {
> > /* output in blocks of 512 characters */
> > - CHAR a_cBuffer[512];
> > + volatile PCHAR a_cBuffer;
> > + a_cBuffer = (CHAR*)HeapAlloc(GetProcessHeap(), 0, 512);
> >
> > /* write a maximum of 511 bytes */
> > - if(nOutputStringLen > (sizeof(a_cBuffer) - 2))
> > - nRoundLen = sizeof(a_cBuffer) - 2;
> > + if(nOutputStringLen > 510)
> > + nRoundLen = 510;
> > else
> > nRoundLen = nOutputStringLen;
> >
> > @@ -355,6 +356,8 @@
> >
> > /* send the current block to the kernel debugger */
> > DbgPrint("%s", a_cBuffer);
> > +
> > + HeapFree(GetProcessHeap(), 0, a_cBuffer);
> > }
> >
> > /* move to the next block */
> >
> >
> >
>
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