NTSTATUS NTAPI MmAlterRegion	(	PMMSUPPORT	AddressSpace,
		PVOID	BaseAddress,
		PLIST_ENTRY	RegionListHead,
		PVOID	StartAddress,
		SIZE_T	Length,
		ULONG	NewType,
		ULONG	NewProtect,
		PMM_ALTER_REGION_FUNC	AlterFunc
	)
Definition at line 108 of file region.c.
Referenced by MiRosAllocateVirtualMemory(), and MmProtectSectionView().
{
   PMM_REGION InitialRegion;
   PVOID InitialBaseAddress = NULL;
   PMM_REGION NewRegion;
   PLIST_ENTRY CurrentEntry;
   PMM_REGION CurrentRegion = NULL;
   PVOID CurrentBaseAddress;
   SIZE_T RemainingLength;

   /*
    * Find the first region containing part of the range of addresses to
    * be altered.
    */
   InitialRegion = MmFindRegion(BaseAddress, RegionListHead, StartAddress,
                                &InitialBaseAddress);
   /*
    * If necessary then split the region into the affected and unaffected parts.
    */
   if (InitialRegion->Type != NewType || InitialRegion->Protect != NewProtect)
   {
      NewRegion = MmSplitRegion(InitialRegion, InitialBaseAddress,
                                StartAddress, Length, NewType, NewProtect,
                                AddressSpace, AlterFunc);
      if (NewRegion == NULL)
      {
         return(STATUS_NO_MEMORY);
      }
      if(NewRegion->Length < Length)
         RemainingLength = Length - NewRegion->Length;
      else
         RemainingLength = 0;
   }
   else
   {
      NewRegion = InitialRegion;
      if(((ULONG_PTR)InitialBaseAddress + NewRegion->Length) <
            ((ULONG_PTR)StartAddress + Length))
         RemainingLength = ((ULONG_PTR)StartAddress + Length) - ((ULONG_PTR)InitialBaseAddress + NewRegion->Length);
      else
         RemainingLength = 0;
   }

   /*
    * Free any complete regions that are containing in the range of addresses
    * and call the helper function to actually do the changes.
    */
   CurrentEntry = NewRegion->RegionListEntry.Flink;
   CurrentRegion = CONTAINING_RECORD(CurrentEntry, MM_REGION,
                                     RegionListEntry);
   CurrentBaseAddress = (char*)StartAddress + NewRegion->Length;
   while (RemainingLength > 0 && CurrentRegion->Length <= RemainingLength &&
          CurrentEntry != RegionListHead)
   {
      if (CurrentRegion->Type != NewType ||
            CurrentRegion->Protect != NewProtect)
      {
         AlterFunc(AddressSpace, CurrentBaseAddress, CurrentRegion->Length,
                   CurrentRegion->Type, CurrentRegion->Protect,
                   NewType, NewProtect);
      }

      CurrentBaseAddress = (PVOID)((ULONG_PTR)CurrentBaseAddress + CurrentRegion->Length);
      NewRegion->Length += CurrentRegion->Length;
      RemainingLength -= CurrentRegion->Length;
      CurrentEntry = CurrentEntry->Flink;
      RemoveEntryList(&CurrentRegion->RegionListEntry);
      ExFreePoolWithTag(CurrentRegion, TAG_MM_REGION);
      CurrentRegion = CONTAINING_RECORD(CurrentEntry, MM_REGION,
                                        RegionListEntry);
   }

   /*
    * Split any final region.
    */
   if (RemainingLength > 0 && CurrentEntry != RegionListHead)
   {
      CurrentRegion = CONTAINING_RECORD(CurrentEntry, MM_REGION,
                                        RegionListEntry);
      if (CurrentRegion->Type != NewType ||
            CurrentRegion->Protect != NewProtect)
      {
         AlterFunc(AddressSpace, CurrentBaseAddress, RemainingLength,
                   CurrentRegion->Type, CurrentRegion->Protect,
                   NewType, NewProtect);
      }
      NewRegion->Length += RemainingLength;
      CurrentRegion->Length -= RemainingLength;
   }

   /*
    * If the region after the new region has the same type then merge them.
    */
   if (NewRegion->RegionListEntry.Flink != RegionListHead)
   {
      CurrentEntry = NewRegion->RegionListEntry.Flink;
      CurrentRegion = CONTAINING_RECORD(CurrentEntry, MM_REGION,
                                        RegionListEntry);
      if (CurrentRegion->Type == NewRegion->Type &&
            CurrentRegion->Protect == NewRegion->Protect)
      {
         NewRegion->Length += CurrentRegion->Length;
         RemoveEntryList(&CurrentRegion->RegionListEntry);
         ExFreePoolWithTag(CurrentRegion, TAG_MM_REGION);
      }
   }

   /*
    * If the region before the new region has the same type then merge them.
    */
   if (NewRegion->RegionListEntry.Blink != RegionListHead)
   {
      CurrentEntry = NewRegion->RegionListEntry.Blink;
      CurrentRegion = CONTAINING_RECORD(CurrentEntry, MM_REGION,
                                        RegionListEntry);
      if (CurrentRegion->Type == NewRegion->Type &&
            CurrentRegion->Protect == NewRegion->Protect)
      {
         NewRegion->Length += CurrentRegion->Length;
         RemoveEntryList(&CurrentRegion->RegionListEntry);
         ExFreePoolWithTag(CurrentRegion, TAG_MM_REGION);
      }
   }

   return(STATUS_SUCCESS);
}
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