[ros-kernel] Re: Kernel Bug

[Jason F. <jas...@ya...>]

Has anyone tested/updated the tree with this update and the latest
one from Jack?

Jack: it seems that most developers prefer that you send them the
"diffs".. but I don't think I have diff installed?..

- Jason

--- "Jack (Butch) Griffin" <bu...@qw...> wrote:
> I have been playing with the ReactOS operating system and trying to
> get a
> console mode app written in vistual C++ to run.  The app is your
> basic hello
> world application.  I did not really expect that the complete
> infra-structure was in place for this to run, but I figured it
> would point
> out what was missing and give me a starting point for beginning to
> learn
> about the design of this OS.
> 
> Anyway I have found a problem and do not know who should get the
> updated
> code.  The problem is in MiReadPage() and the updated code is
> below.  The
> only change is that STATUS_END_OF_FILE is a legimate return from
> IoPageRead().  It does not mean an error occurred, just that the
> file did
> not contain enough data to fill the page.  Function that call
> MiReadPage()
> assume that the data read are OK if the return value is
> STATUS_END_OF_FILE,
> so the update of the Page pointer must be done in this case.
> 
> Thanks
> Jack Griffin
> 
> 
> NTSTATUS
> MiReadPage(PMEMORY_AREA MemoryArea,
> 	   PLARGE_INTEGER Offset,
> 	   PVOID* Page)
> {
>   IO_STATUS_BLOCK IoStatus;
>   PFILE_OBJECT FileObject;
>   PMDL Mdl;
>   NTSTATUS Status;
>   PREACTOS_COMMON_FCB_HEADER Fcb;
> 
>   FileObject = MemoryArea->Data.SectionData.Section->FileObject;
>   Fcb = (PREACTOS_COMMON_FCB_HEADER)FileObject->FsContext;
> 
>   if (FileObject->Flags & FO_DIRECT_CACHE_PAGING_READ &&
>       (Offset->QuadPart % PAGESIZE) == 0)
>     {
>       ULONG BaseOffset;
>       PVOID BaseAddress;
>       BOOLEAN UptoDate;
>       PCACHE_SEGMENT CacheSeg;
>       LARGE_INTEGER SegOffset;
>       PHYSICAL_ADDRESS Addr;
>       Status = CcRosGetCacheSegment(Fcb->Bcb,
> 				 (ULONG)Offset->QuadPart,
> 				 &BaseOffset,
> 				 &BaseAddress,
> 				 &UptoDate,
> 				 &CacheSeg);
>       if (!NT_SUCCESS(Status))
> 	{
> 	  return(Status);
> 	}
>       if (!UptoDate)
> 	{
> 	  Mdl = MmCreateMdl(NULL, BaseAddress,
> Fcb->Bcb->CacheSegmentSize);
> 	  MmBuildMdlForNonPagedPool(Mdl);
> 	  SegOffset.QuadPart = BaseOffset;
> 	  Status = IoPageRead(FileObject,
> 			      Mdl,
> 			      &SegOffset,
> 			      &IoStatus,
> 			      TRUE);
> 	  if (!NT_SUCCESS(Status) && Status != STATUS_END_OF_FILE)
> 	    {
> 	      CcRosReleaseCacheSegment(Fcb->Bcb, CacheSeg, FALSE);
> 	      return(Status);
> 	    }
> 	}
>       Addr = MmGetPhysicalAddress(BaseAddress +
> 				  Offset->QuadPart - BaseOffset);
>       (*Page) = (PVOID)(ULONG)Addr.QuadPart;
>       MmReferencePage((*Page));
> 
>       CcRosReleaseCacheSegment(Fcb->Bcb, CacheSeg, TRUE);
>       return(STATUS_SUCCESS);
>     }
>   else
>     {
>       /*
>        * Allocate a page, this is rather complicated by the
> possibility
>        * we might have to move other things out of memory
>        */
>       (*Page) = MmAllocPage(0);
>       while ((*Page) == NULL)
> 	{
> 	  MmWaitForFreePages();
> 	  (*Page) = MmAllocPage(0);
> 	}
> 
>       /*
>        * Create an mdl to hold the page we are going to read data
> into.
>        */
>       Mdl = MmCreateMdl(NULL, NULL, PAGESIZE);
>       MmBuildMdlFromPages(Mdl, (PULONG)Page);
>       /*
>        * Call the FSD to read the page
>        */
>       Status = IoPageRead(FileObject,
> 			  Mdl,
> 			  Offset,
> 			  &IoStatus,
> 			  FALSE);
>       return(Status);
>     }
> }
> 
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