Kernel32VirtualAlloc(IntPtr, IntPtr, MemoryAllocationType, MemoryProtectionOptions) Method

[DllImportAttribute("Kernel32.dll", ExactSpelling = true, SetLastError = true)]
public static IntPtr VirtualAlloc(
	IntPtr address,
	IntPtr size,
	MemoryAllocationType allocationType,
	MemoryProtectionOptions protection
)

<DllImportAttribute("Kernel32.dll", ExactSpelling := true, SetLastError := true>]
Public Shared Function VirtualAlloc ( 
	address As IntPtr,
	size As IntPtr,
	allocationType As MemoryAllocationType,
	protection As MemoryProtectionOptions
) As IntPtr

Dim address As IntPtr
Dim size As IntPtr
Dim allocationType As MemoryAllocationType
Dim protection As MemoryProtectionOptions

Dim returnValue As IntPtr

returnValue = Kernel32.VirtualAlloc(address, 
	size, allocationType, protection)

public:
[DllImportAttribute(L"Kernel32.dll", ExactSpelling = true, SetLastError = true)]
static IntPtr VirtualAlloc(
	IntPtr address, 
	IntPtr size, 
	MemoryAllocationType allocationType, 
	MemoryProtectionOptions protection
)

[<DllImportAttribute("Kernel32.dll", ExactSpelling = true, SetLastError = true)>]
static member VirtualAlloc : 
        address : IntPtr * 
        size : IntPtr * 
        allocationType : MemoryAllocationType * 
        protection : MemoryProtectionOptions -> IntPtr 

No code example is currently available or this language may not be supported.

Parameters

address  IntPtr

The starting address of the region to allocate.

If the memory is being reserved, the specified address is rounded down to the nearest multiple of the allocation granularity.

If the memory is already reserved and is being committed, the address is rounded down to the next page boundary.

To determine the size of a page and the allocation granularity on the host computer, use the GetSystemInfo function.

If this parameter is Zero, the system determines where to allocate the region.

If this address is within an enclave that you have not initialized by calling InitializeEnclave, VirtualAlloc(IntPtr, IntPtr, MemoryAllocationType, MemoryProtectionOptions) allocates a page of zeros for the enclave at that address.

The page must be previously uncommitted, and will not be measured with the EEXTEND instruction of the Intel Software Guard Extensions programming model.

If the address in within an enclave that you initialized, then the allocation operation fails with the ERROR_INVALID_ADDRESS error.

size  IntPtr

The size of the region, in bytes.

If the address parameter is Zero, this value is rounded up to the next page boundary. Otherwise, the allocated pages include all pages containing one or more bytes in the range from address to address+size.

This means that a 2-byte range straddling a page boundary causes both pages to be included in the allocated region.

allocationType  MemoryAllocationType

The type of memory allocation.

protection  MemoryProtectionOptions

The memory protection for the region of pages to be allocated.

If address parameter specifies an address within an enclave, protection cannot be any of the following values:

NoAccess, Guard, NoCache, WriteCombine

Return Value

If the function fails, the return value is Zero.

To get extended error information, call GetLastWin32Error.

Reference