MemoryMappedFile.CreateFromFile Method (FileStream, String, Int64, MemoryMappedFileAccess, MemoryMappedFileSecurity, HandleInheritability, Boolean)
Creates a memory-mapped file that has the specified name, capacity, access type, security permissions, inheritability, and disposal requirement from a file on disk.
Assembly: System.Core (in System.Core.dll)
'Declaration <SecurityPermissionAttribute(SecurityAction.Demand, Flags := SecurityPermissionFlag.UnmanagedCode)> _ Public Shared Function CreateFromFile ( _ fileStream As FileStream, _ mapName As String, _ capacity As Long, _ access As MemoryMappedFileAccess, _ memoryMappedFileSecurity As MemoryMappedFileSecurity, _ inheritability As HandleInheritability, _ leaveOpen As Boolean _ ) As MemoryMappedFile
- Type: System.IO.FileStream
The fileStream to the file to map.
- Type: System.String
A name to assign to the memory-mapped file.
- Type: System.Int64
The maximum size, in bytes, to allocate to the memory-mapped file. Specify 0 to set the capacity to the size of the file on disk.
- Type: System.IO.MemoryMappedFiles.MemoryMappedFileAccess
One of the enumeration values that specifies the type of access allowed to the memory-mapped file.
This parameter can’t be set to Write.
- Type: System.IO.MemoryMappedFiles.MemoryMappedFileSecurity
The permissions that can be granted for file access and operations on memory-mapped files.
This parameter can be Nothing.
- Type: System.IO.HandleInheritability
One of the enumeration values that specifies whether a handle to the memory-mapped file can be inherited by a child process. The default is None.
Return ValueType: System.IO.MemoryMappedFiles.MemoryMappedFile
A memory-mapped file that has the specified characteristics.
mapName is an empty string.
capacity and the length of the file are zero.
fileStream or mapname is Nothing.
capacity is less than zero.
capacity is less than the file size.
access is not a valid MemoryMappedFileAccess enumeration value.
inheritability is not a valid HandleInheritability enumeration value.
fileStream was closed.
mapName already exists.
If capacity is larger than the size of the file on disk, the file on disk is increased to match the specified capacity even if no data is written to the memory-mapped file. To prevent this from occurring, specify 0 (zero) for the default capacity, which will internally set capacity to the size of the file on disk.