3.1.1 ReactOS系统中二叉树创建一个MEMORY_AREA节点

二叉树中创建一个MEMORY_AREA节点：

二叉树中创建一个MEMORY_AREA节点：
MmCreateMemoryArea()
参数AddressSpace是MADDRESS SPACE结构指针，所指向的数据结构代表着一个进程的用 户空间。
参数BaseAddress是个指针，用来给定和返回内存区块的基地址

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MmCreateMemoryArea()

/*** @name MmCreateMemoryArea** Create a memory area.** @param AddressSpace*        Address space to create the area in.* @param Type*        Type of the memory area.* @param BaseAddress*        Base address for the memory area we're about the create. On*        input it contains either 0 (auto-assign address) or preferred*        address. On output it contains the starting address of the*        newly created area.* @param Length*        Length of the area to allocate.* @param Attributes*        Protection attributes for the memory area.* @param Result*        Receives a pointer to the memory area on successful exit.** @return Status** @remarks Lock the address space before calling this function.*/NTSTATUS STDCALL
MmCreateMemoryArea(PMADDRESS_SPACE AddressSpace,ULONG Type,PVOID *BaseAddress,ULONG_PTR Length,ULONG Protect,PMEMORY_AREA *Result,BOOLEAN FixedAddress,ULONG AllocationFlags,PHYSICAL_ADDRESS BoundaryAddressMultiple)
{PVOID EndAddress;ULONG Granularity;ULONG tmpLength;PMEMORY_AREA MemoryArea;DPRINT("MmCreateMemoryArea(Type %d, BaseAddress %p, ""*BaseAddress %p, Length %p, AllocationFlags %x, ""FixedAddress %x, Result %p)\n",Type, BaseAddress, *BaseAddress, Length, AllocationFlags,FixedAddress, Result);MmVerifyMemoryAreas(AddressSpace);//检测该AVL树是否存在问题//根据Type选择相应的粒度Granularity = (MEMORY_AREA_VIRTUAL_MEMORY == Type ? MM_VIRTMEM_GRANULARITY : PAGE_SIZE);//if 用户不要求从固定地址处开始分配if ((*BaseAddress) == 0 && !FixedAddress){//不受给定地址的约束,只要找到一个够大的空隙即可tmpLength = PAGE_ROUND_UP(Length);//根据用户空间找到一块符合的Area，并返回其首地址*BaseAddress = MmFindGap(AddressSpace,tmpLength,Granularity,(AllocationFlags & MEM_TOP_DOWN) == MEM_TOP_DOWN);if ((*BaseAddress) == 0){DPRINT("No suitable gap\n");return STATUS_NO_MEMORY;}}else//用户给定了基址，就必须从那儿开始分配{tmpLength = Length + ((ULONG_PTR) *BaseAddress- (ULONG_PTR) MM_ROUND_DOWN(*BaseAddress, Granularity));*BaseAddress = MM_ROUND_DOWN(*BaseAddress, Granularity);if (AddressSpace->LowestAddress == MmSystemRangeStart &&*BaseAddress < MmSystemRangeStart){//给定的空间为系统空间，但是地址落在用户空间，严重错误CHECKPOINT;CHECKPOINT;return STATUS_ACCESS_VIOLATION;}if (AddressSpace->LowestAddress < MmSystemRangeStart &&(ULONG_PTR)(*BaseAddress) + tmpLength > (ULONG_PTR)MmSystemRangeStart){//所要求的区间跨越用户空间和系统空间的分界，严重错误CHECKPOINT;CHECKPOINT;return STATUS_ACCESS_VIOLATION;}//测试要分配的区域完全落在指定地址空间内部if (BoundaryAddressMultiple.QuadPart != 0){EndAddress = ((char*)(*BaseAddress)) + tmpLength-1;ASSERT(((ULONG_PTR)*BaseAddress/BoundaryAddressMultiple.QuadPart) == ((DWORD_PTR)EndAddress/BoundaryAddressMultiple.QuadPart));}//确认所要求的区间尚术分配if (MmLocateMemoryAreaByRegion(AddressSpace,*BaseAddress,tmpLength) != NULL){//所要求的区间已经分配，失敗DPRINT("Memory area already occupied\n");return STATUS_CONFLICTING_ADDRESSES;}}//创建MEMORY AREA节点，把这块区域分配出去MemoryArea = ExAllocatePoolWithTag(NonPagedPool, sizeof(MEMORY_AREA),TAG_MAREA);RtlZeroMemory(MemoryArea, sizeof(MEMORY_AREA));MemoryArea->Type = Type;MemoryArea->StartingAddress = *BaseAddress;MemoryArea->EndingAddress = (PVOID)((ULONG_PTR)*BaseAddress + tmpLength);MemoryArea->Protect = Protect;MemoryArea->Flags = AllocationFlags;//MemoryArea->LockCount = 0;MemoryArea->PageOpCount = 0;MemoryArea->DeleteInProgress = FALSE;//将所创建节点插入一又树MmInsertMemoryArea(AddressSpace, MemoryArea);*Result = MemoryArea;DPRINT("MmCreateMemoryArea() succeeded (%p)\n", *BaseAddress);return STATUS_SUCCESS;
}

//二叉树中创建-个MEMORY AREA节点
/*
参数AddressSpace是MADDRESS SPACE结构指针，所指向的数据结构代表着一个进程的用 户空间。
参数BaseAddress是个指针，用来给定和返回内存区块的基地址 :
参数Length、Protect的意义 则不言自明。
参数FixedAddress为TRUE说明给定的地址不容改变，为FALSE则表示若不能满足 要求也可以浮动, 。
参数AllocationFlags : 分配标志TopDown ? TopUp
参数BoundaryAddressMultiple此分配不得跨越的物理地址倍数
*/