[ros-kernel] Kernel Bug

[Jack \(Butch\) G. <bu...@qw...>]

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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