memfd

“memfd” (memory file descriptor) lets us open pseudo-“files” that are not actually stored in the “real” file system. This feature is only available on Linux.

Such a file is described as an “anonymous file”. It behaves like a regular file, and so can be modified, truncated, memory-mapped, and so on. However, unlike a regular file, it lives in RAM and has a volatile backing storage. Once all references to the file are dropped, it is automatically released.

The recommended way to import this library is:

import qualified Memfd

There is one central function:

create :: CreateOptions -> IO Fd

Fd stands for “file descriptor”. Here are some things you can do with a file descriptor:

• Set the file size
• Map the file into your process’s memory space
• Send the file descriptor over a Unix-domain socket to share the memory with another process
• Close the file and allow its contents to get garbage collected by the operating system