Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / IO / MemoryMappedFiles / MemoryMappedView.cs / 1305376 / MemoryMappedView.cs
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: MemoryMappedView
**
** Purpose: Internal class representing MemoryMappedFile view
**
** Date: February 7, 2007
**
===========================================================*/
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;
namespace System.IO.MemoryMappedFiles {
internal class MemoryMappedView : IDisposable {
private SafeMemoryMappedViewHandle m_viewHandle;
private Int64 m_pointerOffset;
private Int64 m_size;
private MemoryMappedFileAccess m_access;
//
//
[System.Security.SecurityCritical]
private unsafe MemoryMappedView(SafeMemoryMappedViewHandle viewHandle, Int64 pointerOffset,
Int64 size, MemoryMappedFileAccess access) {
m_viewHandle = viewHandle;
m_pointerOffset = pointerOffset;
m_size = size;
m_access = access;
}
internal SafeMemoryMappedViewHandle ViewHandle {
//
//
[System.Security.SecurityCritical]
get {
return m_viewHandle;
}
}
internal Int64 PointerOffset {
get {
return m_pointerOffset;
}
}
internal Int64 Size {
get {
return m_size;
}
}
internal MemoryMappedFileAccess Access {
get {
return m_access;
}
}
// Callers must demand unmanaged code first
//
//
[System.Security.SecurityCritical]
internal unsafe static MemoryMappedView CreateView(SafeMemoryMappedFileHandle memMappedFileHandle,
MemoryMappedFileAccess access, Int64 offset, Int64 size) {
// MapViewOfFile can only create views that start at a multiple of the system memory allocation
// granularity. We decided to hide this restriction form the user by creating larger views than the
// user requested and hiding the parts that the user did not request. extraMemNeeded is the amount of
// extra memory we allocate before the start of the requested view. MapViewOfFile will also round the
// capacity of the view to the nearest multiple of the system page size. Once again, we hide this
// from the user by preventing them from writing to any memory that they did not request.
ulong extraMemNeeded = (ulong)offset % (ulong)MemoryMappedFile.GetSystemPageAllocationGranularity();
// newOffset takes into account the fact that we have some extra memory allocated before the requested view
ulong newOffset = (ulong)offset - extraMemNeeded;
Debug.Assert(newOffset >= 0, "newOffset = (offset - extraMemNeeded) < 0");
// determine size to pass to MapViewOfFile
ulong nativeSize;
if (size != MemoryMappedFile.DefaultSize) {
nativeSize = (ulong)size + (ulong)extraMemNeeded;
}
else {
nativeSize = 0;
}
if (IntPtr.Size == 4 && nativeSize > UInt32.MaxValue) {
throw new ArgumentOutOfRangeException("size", SR.GetString(SR.ArgumentOutOfRange_CapacityLargerThanLogicalAddressSpaceNotAllowed));
}
// if request is >= than total virtual, then MapViewOfFile will fail with meaningless error message
// "the parameter is incorrect"; this provides better error message in advance
UnsafeNativeMethods.MEMORYSTATUSEX memStatus = new UnsafeNativeMethods.MEMORYSTATUSEX();
bool result = UnsafeNativeMethods.GlobalMemoryStatusEx(memStatus);
ulong totalVirtual = memStatus.ullTotalVirtual;
if (nativeSize >= totalVirtual) {
throw new IOException(SR.GetString(SR.IO_NotEnoughMemory));
}
// split the Int64 into two ints
uint offsetLow = (uint)(newOffset & 0x00000000FFFFFFFFL);
uint offsetHigh = (uint)(newOffset >> 32);
// create the view
SafeMemoryMappedViewHandle viewHandle = UnsafeNativeMethods.MapViewOfFile(memMappedFileHandle,
MemoryMappedFile.GetFileMapAccess(access), offsetHigh, offsetLow, new UIntPtr(nativeSize));
if (viewHandle.IsInvalid) {
__Error.WinIOError(Marshal.GetLastWin32Error(), String.Empty);
}
// Query the view for its size and allocation type
UnsafeNativeMethods.MEMORY_BASIC_INFORMATION viewInfo = new UnsafeNativeMethods.MEMORY_BASIC_INFORMATION();
UnsafeNativeMethods.VirtualQuery(viewHandle, ref viewInfo, (IntPtr)Marshal.SizeOf(viewInfo));
ulong viewSize = (ulong)viewInfo.RegionSize;
// allocate the pages if we were using the MemoryMappedFileOptions.DelayAllocatePages option
if ((viewInfo.State & UnsafeNativeMethods.MEM_RESERVE) != 0) {
IntPtr tempHandle = UnsafeNativeMethods.VirtualAlloc(viewHandle, (UIntPtr)viewSize, UnsafeNativeMethods.MEM_COMMIT,
MemoryMappedFile.GetPageAccess(access));
int lastError = Marshal.GetLastWin32Error();
if (viewHandle.IsInvalid) {
__Error.WinIOError(lastError, String.Empty);
}
}
// if the user specified DefaultSize as the size, we need to get the actual size
if (size == MemoryMappedFile.DefaultSize) {
size = (Int64)(viewSize - extraMemNeeded);
}
else {
Debug.Assert(viewSize >= (ulong)size, "viewSize < size");
}
viewHandle.Initialize((ulong)size + extraMemNeeded);
MemoryMappedView mmv = new MemoryMappedView(viewHandle, (long)extraMemNeeded, size, access);
return mmv;
}
// Flushes the changes such that they are in [....] with the FileStream bits (ones obtained
// with the win32 ReadFile and WriteFile functions). Need to call FileStream's Flush to
// flush to the disk.
// NOTE: This will flush all bytes before and after the view up until an offset that is a multiple
// of SystemPageSize.
//
//
[System.Security.SecurityCritical]
public void Flush(IntPtr capacity) {
if (m_viewHandle != null) {
unsafe {
byte* firstPagePtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
m_viewHandle.AcquirePointer(ref firstPagePtr);
if (!UnsafeNativeMethods.FlushViewOfFile(firstPagePtr, capacity)) {
__Error.WinIOError(Marshal.GetLastWin32Error(), String.Empty);
}
}
finally {
if (firstPagePtr != null) {
m_viewHandle.ReleasePointer();
}
}
}
}
}
//
//
[System.Security.SecurityCritical]
protected virtual void Dispose(bool disposing) {
if (m_viewHandle != null && !m_viewHandle.IsClosed) {
m_viewHandle.Dispose();
}
}
//
//
[System.Security.SecurityCritical]
public void Dispose() {
Dispose(true);
GC.SuppressFinalize(this);
}
internal bool IsClosed {
get {
return (m_viewHandle == null || m_viewHandle.IsClosed);
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: MemoryMappedView
**
** Purpose: Internal class representing MemoryMappedFile view
**
** Date: February 7, 2007
**
===========================================================*/
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;
namespace System.IO.MemoryMappedFiles {
internal class MemoryMappedView : IDisposable {
private SafeMemoryMappedViewHandle m_viewHandle;
private Int64 m_pointerOffset;
private Int64 m_size;
private MemoryMappedFileAccess m_access;
//
//
[System.Security.SecurityCritical]
private unsafe MemoryMappedView(SafeMemoryMappedViewHandle viewHandle, Int64 pointerOffset,
Int64 size, MemoryMappedFileAccess access) {
m_viewHandle = viewHandle;
m_pointerOffset = pointerOffset;
m_size = size;
m_access = access;
}
internal SafeMemoryMappedViewHandle ViewHandle {
//
//
[System.Security.SecurityCritical]
get {
return m_viewHandle;
}
}
internal Int64 PointerOffset {
get {
return m_pointerOffset;
}
}
internal Int64 Size {
get {
return m_size;
}
}
internal MemoryMappedFileAccess Access {
get {
return m_access;
}
}
// Callers must demand unmanaged code first
//
//
[System.Security.SecurityCritical]
internal unsafe static MemoryMappedView CreateView(SafeMemoryMappedFileHandle memMappedFileHandle,
MemoryMappedFileAccess access, Int64 offset, Int64 size) {
// MapViewOfFile can only create views that start at a multiple of the system memory allocation
// granularity. We decided to hide this restriction form the user by creating larger views than the
// user requested and hiding the parts that the user did not request. extraMemNeeded is the amount of
// extra memory we allocate before the start of the requested view. MapViewOfFile will also round the
// capacity of the view to the nearest multiple of the system page size. Once again, we hide this
// from the user by preventing them from writing to any memory that they did not request.
ulong extraMemNeeded = (ulong)offset % (ulong)MemoryMappedFile.GetSystemPageAllocationGranularity();
// newOffset takes into account the fact that we have some extra memory allocated before the requested view
ulong newOffset = (ulong)offset - extraMemNeeded;
Debug.Assert(newOffset >= 0, "newOffset = (offset - extraMemNeeded) < 0");
// determine size to pass to MapViewOfFile
ulong nativeSize;
if (size != MemoryMappedFile.DefaultSize) {
nativeSize = (ulong)size + (ulong)extraMemNeeded;
}
else {
nativeSize = 0;
}
if (IntPtr.Size == 4 && nativeSize > UInt32.MaxValue) {
throw new ArgumentOutOfRangeException("size", SR.GetString(SR.ArgumentOutOfRange_CapacityLargerThanLogicalAddressSpaceNotAllowed));
}
// if request is >= than total virtual, then MapViewOfFile will fail with meaningless error message
// "the parameter is incorrect"; this provides better error message in advance
UnsafeNativeMethods.MEMORYSTATUSEX memStatus = new UnsafeNativeMethods.MEMORYSTATUSEX();
bool result = UnsafeNativeMethods.GlobalMemoryStatusEx(memStatus);
ulong totalVirtual = memStatus.ullTotalVirtual;
if (nativeSize >= totalVirtual) {
throw new IOException(SR.GetString(SR.IO_NotEnoughMemory));
}
// split the Int64 into two ints
uint offsetLow = (uint)(newOffset & 0x00000000FFFFFFFFL);
uint offsetHigh = (uint)(newOffset >> 32);
// create the view
SafeMemoryMappedViewHandle viewHandle = UnsafeNativeMethods.MapViewOfFile(memMappedFileHandle,
MemoryMappedFile.GetFileMapAccess(access), offsetHigh, offsetLow, new UIntPtr(nativeSize));
if (viewHandle.IsInvalid) {
__Error.WinIOError(Marshal.GetLastWin32Error(), String.Empty);
}
// Query the view for its size and allocation type
UnsafeNativeMethods.MEMORY_BASIC_INFORMATION viewInfo = new UnsafeNativeMethods.MEMORY_BASIC_INFORMATION();
UnsafeNativeMethods.VirtualQuery(viewHandle, ref viewInfo, (IntPtr)Marshal.SizeOf(viewInfo));
ulong viewSize = (ulong)viewInfo.RegionSize;
// allocate the pages if we were using the MemoryMappedFileOptions.DelayAllocatePages option
if ((viewInfo.State & UnsafeNativeMethods.MEM_RESERVE) != 0) {
IntPtr tempHandle = UnsafeNativeMethods.VirtualAlloc(viewHandle, (UIntPtr)viewSize, UnsafeNativeMethods.MEM_COMMIT,
MemoryMappedFile.GetPageAccess(access));
int lastError = Marshal.GetLastWin32Error();
if (viewHandle.IsInvalid) {
__Error.WinIOError(lastError, String.Empty);
}
}
// if the user specified DefaultSize as the size, we need to get the actual size
if (size == MemoryMappedFile.DefaultSize) {
size = (Int64)(viewSize - extraMemNeeded);
}
else {
Debug.Assert(viewSize >= (ulong)size, "viewSize < size");
}
viewHandle.Initialize((ulong)size + extraMemNeeded);
MemoryMappedView mmv = new MemoryMappedView(viewHandle, (long)extraMemNeeded, size, access);
return mmv;
}
// Flushes the changes such that they are in [....] with the FileStream bits (ones obtained
// with the win32 ReadFile and WriteFile functions). Need to call FileStream's Flush to
// flush to the disk.
// NOTE: This will flush all bytes before and after the view up until an offset that is a multiple
// of SystemPageSize.
//
//
[System.Security.SecurityCritical]
public void Flush(IntPtr capacity) {
if (m_viewHandle != null) {
unsafe {
byte* firstPagePtr = null;
RuntimeHelpers.PrepareConstrainedRegions();
try {
m_viewHandle.AcquirePointer(ref firstPagePtr);
if (!UnsafeNativeMethods.FlushViewOfFile(firstPagePtr, capacity)) {
__Error.WinIOError(Marshal.GetLastWin32Error(), String.Empty);
}
}
finally {
if (firstPagePtr != null) {
m_viewHandle.ReleasePointer();
}
}
}
}
}
//
//
[System.Security.SecurityCritical]
protected virtual void Dispose(bool disposing) {
if (m_viewHandle != null && !m_viewHandle.IsClosed) {
m_viewHandle.Dispose();
}
}
//
//
[System.Security.SecurityCritical]
public void Dispose() {
Dispose(true);
GC.SuppressFinalize(this);
}
internal bool IsClosed {
get {
return (m_viewHandle == null || m_viewHandle.IsClosed);
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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