/// <summary>
/// 创建文件映射。
/// </summary>
/// <param name="mappingName">文件映射对象的名称。</param>
/// <param name="pageAccessRights">页面访问权限。</param>
/// <param name="mappingAccessRights">文件映射的访问权限。</param>
/// <param name="mappingOffset">文件映射的偏移量(起始位置)。</param>
/// <param name="viewSize">文件映射的视图大小。</param>
/// <exception cref="System.ComponentModel.Win32Exception">创建文件映射失败时。</exception>
protected virtual SafeFileMappingHandle CreateMapping(string mappingName, WIN32_API.PageAccess pageAccessRights,
WIN32_API.FileMappingAccess mappingAccessRights, ulong mappingOffset, ref uint viewSize)
{
SafeFileMappingHandle result = null;
result = WIN32_API.CreateFileMapping(new SafeFileHandle(WIN32_API.InvalidHandleValue, true),
IntPtr.Zero,
pageAccessRights,
0,
viewSize,
mappingName);
if (result.IsInvalid)
{
throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
}
return(result);
}
/// <summary>
/// 创建文件映射。
/// </summary>
/// <param name="mappingName">文件映射对象的名称。</param>
/// <param name="pageAccessRights">页面访问权限。</param>
/// <param name="mappingAccessRights">文件映射的访问权限。</param>
/// <param name="mappingOffset">文件映射的偏移量(起始位置)。</param>
/// <param name="viewSize">[in, out]文件映射的视图大小，等于0时表示按文件实际大小取值。</param>
/// <exception cref="System.ComponentModel.Win32Exception">创建文件映射失败时。</exception>
protected override SafeFileMappingHandle CreateMapping(string mappingName, WIN32_API.PageAccess pageAccessRights,
WIN32_API.FileMappingAccess mappingAccessRights, ulong mappingOffset, ref uint viewSize)
{
SafeFileMappingHandle result = null;
WIN32_API.GenericRight genericRights = 0;
if ((m_accessRights & FileAccess.Read) == FileAccess.Read)
{
genericRights |= WIN32_API.GenericRight.GENERIC_READ;
}
if ((m_accessRights & FileAccess.Write) == FileAccess.Write)
{
genericRights |= WIN32_API.GenericRight.GENERIC_WRITE;
}
SafeFileHandle handle = null;
try
{
Debug.Assert(!String.IsNullOrEmpty(m_filePath));
handle = WIN32_API.CreateFile(m_filePath, genericRights, m_shareMode, IntPtr.Zero, m_creationMode, FileAttributes.Normal, IntPtr.Zero);
if (handle.IsInvalid)
{
throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
}
ulong actualFileSize = 0;
{
uint fileSizeHigh = 0;
uint fileSizeLow = WIN32_API.GetFileSize(handle, out fileSizeHigh);
if (fileSizeLow == uint.MaxValue)
{
throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
}
actualFileSize = (((ulong)fileSizeHigh) << 32) + fileSizeLow;
}
ulong expectedFileSize = 0;
if (viewSize == 0)
{
if (actualFileSize == 0)
{
throw new ArgumentException("The actual file size is zero, Can't set the value of MappingSize.");
}
if (actualFileSize <= mappingOffset)
{
throw new ArgumentOutOfRangeException("MappingOffset is greater than the actual file size, Can't set the value of MappingSize.");
}
if ((actualFileSize - mappingOffset) > uint.MaxValue)
{
throw new ArgumentException("The actual file size is too large to set the value of MappingSize.");
}
viewSize = (uint)(actualFileSize - mappingOffset);
expectedFileSize = actualFileSize;
}
else
{
Debug.Assert(ulong.MaxValue - mappingOffset >= viewSize);
expectedFileSize = mappingOffset + viewSize;
}
// 不需处理，创建FileMapping时，会自动扩大
//if (expectedFileSize < actualFileSize)
//{
// // Resize File
//}
result = WIN32_API.CreateFileMapping(handle,
IntPtr.Zero,
pageAccessRights,
(uint)(expectedFileSize >> 32),
(uint)expectedFileSize,
mappingName);
if (result.IsInvalid)
{
throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
}
}
catch (Exception)
{
if (handle != null && !handle.IsInvalid)
{
handle.Dispose();
handle = null;
}
throw;
}
Debug.Assert(m_fileHandle == null);
m_fileHandle = handle;
return(result);
}