/// <param name="offset">Within the PST file</param>
public static void FreeAllocation(PSTFile file, long offset, int allocationLength)
{
int numberOfPages = file.Header.root.NumberOfAllocationMapPages;
if (offset < AllocationMapPage.FirstPageOffset)
{
throw new ArgumentException("Allocation offset to free cannot be before the first AMAP");
}
int pageIndex = (int)((offset - AllocationMapPage.FirstPageOffset) / AllocationMapPage.MapppedLength);
if (pageIndex >= numberOfPages)
{
throw new ArgumentException("Allocation offset to free cannot be after the area mapped by the last AMAP");
}
AllocationMapPage page = AllocationMapPage.ReadAllocationMapPage(file, pageIndex);
int pageStartOffset = (int)((offset - AllocationMapPage.FirstPageOffset) % AllocationMapPage.MapppedLength);
if (pageStartOffset < AllocationMapPage.Length)
{
throw new ArgumentException("Allocation offset to free cannot be within the AMAP page");
}
page.FreeAllocatedSpace(pageStartOffset, allocationLength);
page.WriteAllocationMapPage(file, pageIndex);
UpdateFMap(file, page, pageIndex);
file.Header.root.cbAMapFree += (uint)allocationLength;
}
/// <returns>Offset of space allocated</returns>
private static long AllocateSpace(PSTFile file, int allocationLength, bool pageAligned)
{
if (allocationLength > MaxAllocationLength)
{
throw new Exception("Invalid allocation length requested");
}
int numberOfPages = file.Header.root.NumberOfAllocationMapPages;
AllocationMapPage targetPage = null;
int targetPageIndex = 0;
for (int index = 0; index < numberOfPages; index++)
{
AllocationMapPage page = AllocationMapPage.ReadAllocationMapPage(file, index);
int startOffset = page.FindContiguousSpace(allocationLength, pageAligned);
if (startOffset > 0) // 0 is allocated to the AMAP itself and is not a valid value
{
targetPage = page;
targetPageIndex = index;
break;
}
}
if (targetPage == null)
{
// no space was found within existing pages
targetPageIndex = numberOfPages;
targetPage = GrowPST(file, targetPageIndex);
}
int targetPageStartOffset = targetPage.FindContiguousSpace(allocationLength, pageAligned);
targetPage.AllocateSpace(targetPageStartOffset, allocationLength);
targetPage.WriteAllocationMapPage(file, targetPageIndex);
UpdateFMap(file, targetPage, targetPageIndex);
file.Header.root.cbAMapFree -= (uint)allocationLength;
//InvalidatePMap(file);
//InvalidateDList(file);
return(AllocationMapPage.FirstPageOffset + (long)targetPageIndex * AllocationMapPage.MapppedLength + targetPageStartOffset);
}