MemoryMappedFile.CreateFromFile Method (String, FileMode, String, Int64)
Creates a memory-mapped file that has the specified access mode, name, and capacity from a file on disk.
Assembly: System.Core (in System.Core.dll)
Public Shared Function CreateFromFile ( path As String, mode As FileMode, mapName As String, capacity As Long ) As MemoryMappedFile
The path to the file to map.
- Type: System.IO.FileMode
A name to assign to the memory-mapped file.
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.
Return ValueType: System.IO.MemoryMappedFiles.MemoryMappedFile
A memory-mapped file that has the specified characteristics.
path or mapName is null.
capacity is greater than the size of the logical address space.
capacity is less than zero.
capacity is less than the file size (but not zero).
capacity is zero, and the size of the file on disk is also zero.
An I/O error occurred.
path exceeds the maximum length defined by the operating system. In Windows, paths must contain fewer than 248 characters, and file names must contain fewer than 260 characters.
The caller does not have the required permissions for the file.
The mode parameter pertains to the source file on disk.
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.
Available since 4.0