/// <summary>
/// Adds a protection to the list of protections.
/// </summary>
/// <param name="address">Address of the protected region</param>
/// <param name="size">Size of the protected region in bytes</param>
/// <param name="permission">Memory permissions of the region</param>
private void AddProtection(ulong address, ulong size, MemoryPermission permission)
{
ulong endAddress = address + size;
var overlaps = Array.Empty <IntervalTreeNode <ulong, MemoryPermission> >();
int count;
lock (_protections)
{
count = _protections.Get(address, endAddress, ref overlaps);
if (count == 1 &&
overlaps[0].Start <= address &&
overlaps[0].End >= endAddress &&
overlaps[0].Value == permission)
{
return;
}
ulong startAddress = address;
for (int index = 0; index < count; index++)
{
var protection = overlaps[index];
ulong protAddress = protection.Start;
ulong protEndAddress = protection.End;
MemoryPermission protPermission = protection.Value;
_protections.Remove(protection);
if (protection.Value == permission)
{
if (startAddress > protAddress)
{
startAddress = protAddress;
}
if (endAddress < protEndAddress)
{
endAddress = protEndAddress;
}
}
else
{
if (startAddress > protAddress)
{
_protections.Add(protAddress, startAddress, protPermission);
}
if (endAddress < protEndAddress)
{
_protections.Add(endAddress, protEndAddress, protPermission);
}
}
}
_protections.Add(startAddress, endAddress, permission);
}
}
/// <summary>
/// Unmaps the specified range of memory and marks it as mapped internally.
/// </summary>
/// <remarks>
/// Since this marks the range as mapped, the expectation is that the range will be mapped after calling this method.
/// </remarks>
/// <param name="location">Memory address to unmap and mark as mapped</param>
/// <param name="size">Size of the range in bytes</param>
public void UnmapAndMarkRangeAsMapped(IntPtr location, IntPtr size)
{
ulong startAddress = (ulong)location;
ulong unmapSize = (ulong)size;
ulong endAddress = startAddress + unmapSize;
var overlaps = Array.Empty <IntervalTreeNode <ulong, byte> >();
int count = 0;
lock (_mappings)
{
count = _mappings.Get(startAddress, endAddress, ref overlaps);
}
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
// Tree operations might modify the node start/end values, so save a copy before we modify the tree.
ulong overlapStart = overlap.Start;
ulong overlapEnd = overlap.End;
ulong overlapValue = overlap.Value;
_mappings.Remove(overlap);
ulong unmapStart = Math.Max(overlapStart, startAddress);
ulong unmapEnd = Math.Min(overlapEnd, endAddress);
if (overlapStart < startAddress)
{
startAddress = overlapStart;
}
if (overlapEnd > endAddress)
{
endAddress = overlapEnd;
}
ulong currentAddress = unmapStart;
while (currentAddress < unmapEnd)
{
WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)currentAddress, 2);
currentAddress += PageSize;
}
}
_mappings.Add(startAddress, endAddress, 0);
}
/// <summary>
/// Unreserves a range of memory that has been previously reserved with <see cref="ReserveRange"/>.
/// </summary>
/// <param name="address">Start address of the region to unreserve</param>
/// <param name="size">Size in bytes of the region to unreserve</param>
/// <exception cref="WindowsApiException">Thrown when the Windows API returns an error unreserving the memory</exception>
public void UnreserveRange(ulong address, ulong size)
{
ulong endAddress = address + size;
var overlaps = Array.Empty <IntervalTreeNode <ulong, ulong> >();
int count;
lock (_mappings)
{
count = _mappings.Get(address, endAddress, ref overlaps);
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
if (IsMapped(overlap.Value))
{
if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlap.Start, 2))
{
throw new WindowsApiException("UnmapViewOfFile2");
}
}
_mappings.Remove(overlap);
}
}
if (count > 1)
{
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)size,
AllocationType.Release | AllocationType.CoalescePlaceholders));
}
RemoveProtection(address, size);
}
/// <summary>
/// Splits a larger placeholder, slicing at the start and end address, for a new memory mapping.
/// </summary>
/// <param name="address">Address to split</param>
/// <param name="size">Size of the new region</param>
/// <param name="backingOffset">Offset in the shared memory that will be mapped</param>
private void SplitForMap(ulong address, ulong size, ulong backingOffset)
{
ulong endAddress = address + size;
var overlaps = Array.Empty <IntervalTreeNode <ulong, ulong> >();
lock (_mappings)
{
int count = _mappings.Get(address, endAddress, ref overlaps);
Debug.Assert(count == 1);
Debug.Assert(!IsMapped(overlaps[0].Value));
var overlap = overlaps[0];
// Tree operations might modify the node start/end values, so save a copy before we modify the tree.
ulong overlapStart = overlap.Start;
ulong overlapEnd = overlap.End;
ulong overlapValue = overlap.Value;
_mappings.Remove(overlap);
bool overlapStartsBefore = overlapStart < address;
bool overlapEndsAfter = overlapEnd > endAddress;
if (overlapStartsBefore && overlapEndsAfter)
{
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)size,
AllocationType.Release | AllocationType.PreservePlaceholder));
_mappings.Add(overlapStart, address, overlapValue);
_mappings.Add(endAddress, overlapEnd, AddBackingOffset(overlapValue, endAddress - overlapStart));
}
else if (overlapStartsBefore)
{
ulong overlappedSize = overlapEnd - address;
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)overlappedSize,
AllocationType.Release | AllocationType.PreservePlaceholder));
_mappings.Add(overlapStart, address, overlapValue);
}
else if (overlapEndsAfter)
{
ulong overlappedSize = endAddress - overlapStart;
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)overlapStart,
(IntPtr)overlappedSize,
AllocationType.Release | AllocationType.PreservePlaceholder));
_mappings.Add(endAddress, overlapEnd, AddBackingOffset(overlapValue, overlappedSize));
}
_mappings.Add(address, endAddress, backingOffset);
}
}
