Re: [ros-dev] [EVENTVWR/EVENTLOG] Fix a double off-by-one bug

[Love Nystrom]

Hi Gabriel, Eric,

Isn't the real issue why LogFile->Header.CurrentRecordNumber is off by one ?
If that is found and fixed, this patch will make the error re-emerge as an
off by -1.
And if CurrentRecordNumber is actually used as the next *pending* record
number,
the identifier is somewhat mis-leading .. ?

Just my penny to the pot
Best Regards
L.

---------- Forwarded message ----------
>   From: Gabriel ilardi <gabrielilardi(a)hotmail.it>
>  To: ros-dev <ros-dev(a)reactos.org>
>  Date: Mon, 2 May 2011 21:50:03 +0200
>  Subject: Re: [ros-dev] [ros-diffs] [ekohl] 51558: [EVENTVWR/EVENTLOG] Fix a
>  double off-by-one bug: - The eventlog service was reporting one event more
>  than was available (+1). - The event viewer did not display the latest event
>  from...
>   Great work on event service and event viewer... keep it up Eric :)
>
>
> >   Date: Mon, 2 May 2011 19:38:24 +0000
> >  To: ros-diffs(a)reactos.org
> >  From: ekohl(a)svn.reactos.org
> >  Subject: [ros-diffs] [ekohl] 51558: [EVENTVWR/EVENTLOG] Fix a double 
>  off-by-one
> bug: - The eventlog service was reporting one event more than was
>  available (+1). - The event viewer did not display the latest event from...
> >  
> >  Author: ekohl
> >  Date: Mon May 2 19:38:23 2011
> >  New Revision: 51558
> >
> >  URL: http://svn.reactos.org/svn/reactos?rev=51558&view=rev
> >  Log:
> >  [EVENTVWR/EVENTLOG]
> >  Fix a double off-by-one bug:
> >  - The eventlog service was reporting one event more than was available 
>  (+1).
> >   - The event viewer did not display the latest
> > event from the eventlog 
>  service (-1).
> >  
> >  See issue #6182 for more details.
> >
> >  Modified:
> >  trunk/reactos/base/applications/mscutils/eventvwr/eventvwr.c
> >  trunk/reactos/base/services/eventlog/rpc.c
> >
> >  Modified: trunk/reactos/base/applications/mscutils/eventvwr/eventvwr.c
> >  URL: 
> http://svn.reactos.org/svn/reactos/trunk/reactos/base/applications/mscutils…
> >   
> ==============================================================================
> >   ---
> > trunk/reactos/base/applications/mscutils/eventvwr/eventvwr.c 
>  [iso-8859-1]
> (original)
> >   +++
> > trunk/reactos/base/applications/mscutils/eventvwr/eventvwr.c 
>  [iso-8859-1] Mon May 2
> 19:38:23 2011
> >   @@ -503,7 +503,7 @@
> >  HWND hwndDlg;
> >  HANDLE hEventLog;
> >  EVENTLOGRECORD *pevlr;
> >  - DWORD dwRead, dwNeeded, dwThisRecord, dwTotalRecords = 0, 
>  dwCurrentRecord = 1,
> dwRecordsToRead = 0, dwFlags, dwMaxLength;
> >   + DWORD dwRead, dwNeeded, dwThisRecord,
> > dwTotalRecords = 0, 
>  dwCurrentRecord = 0, dwRecordsToRead = 0, dwFlags,
> dwMaxLength;
>  > LPWSTR lpSourceName;
>  > LPWSTR lpComputerName;
>  > LPSTR lpData;
> >   
>  > Modified:
> trunk/reactos/base/services/eventlog/rpc.c
>  > URL:
>
> http://svn.reactos.org/svn/reactos/trunk/reactos/base/services/eventlog/rpc…
> >   
> ==============================================================================
> >   --- trunk/reactos/base/services/eventlog/rpc.c
> > [iso-8859-1] (original)
> >  +++ trunk/reactos/base/services/eventlog/rpc.c [iso-8859-1] Mon May 2 
>  19:38:23
> 2011
>  > @@ -199,6 +199,7 @@
>  > DWORD *NumberOfRecords)
>  > {
>  > PLOGHANDLE lpLogHandle;
>  > + DWORD dwRecords;
> >   
>  > lpLogHandle =
> ElfGetLogHandleEntryByHandle(LogHandle);
>  > if (!lpLogHandle)
>  > @@ -206,7 +207,9 @@
>  > return STATUS_INVALID_HANDLE;
>  > }
> >   
>  > - *NumberOfRecords =
> lpLogHandle->LogFile->Header.CurrentRecordNumber;
>  > + dwRecords = lpLogHandle->LogFile->Header.CurrentRecordNumber;
>  > +
>  > + *NumberOfRecords = (dwRecords > 0) ? (dwRecords - 1) : 0;
> >   
>  > return STATUS_SUCCESS;
>  > }
> >   
> >  
>