Can I create a file in Windows that only exists in memory - and if so, how?

_{This question is not a duplicate of any of these existing questions:}

• _{How can I store an object File that only exists in memory as a file inside of my storage system? - This question is not about Java's File API.}
• _{Temp file that exists only in RAM? - This is close to what I'm asking, except the OP isn't asking how to create files from memory for the purposes of sharing passing them to child-processes}
• _{I'm not asking about Win32's Memory-mapped File either - as they're essentially the opposite of what I'm after: a memory-mapped file is a file-on disk that's mapped to a process' virtual memory space - whereas what I want is a file that exists in the OS' filesystem (but not the disk's physical filesystem) like a mount-point and that file's data is mapped to an existing buffer in memory.}
  • _{I.e., with Memory Mapped Files, writing/writing to a byte at a particular buffer address and offset in memory will cause the byte at the same offset from the start of the file to be modified - but the file physically exists on-disk, which isn't what I want.}

To elaborate and to provide context:

• I have an ASP.NET Core server-side application that receives request streams sized between 1 and 10MB on a regular basis. This program will run only on Windows / Windows Server, so using Windows-specific functionality is fine.
• 75% of the time my application just reads through these streams by itself and that's it.

• But a minority of the time it needs to have a separate applications read the data which it starts using Process.Start and passing the file-name as a command-line argument.

  • It passes the data to these separate applications by saving the stream to a temporary file on-disk and passing the filename of that stream.
  • Unfortunately it can't write the content to the child-process's stdin because some of the those programs expect a file on-disk rather than reading from stdin.

• Additionally, while the machine it's running on has lots of RAM (so keeping the streams buffered in-memory is fine) it has slow spinning-rust HDDs, which is further reason to avoid temporary files on-disk.

• I'd like to avoid unnecessary buffering and copies - ideally I'd like to stream the entire 1-10MB request into a single in-memory buffer, and then expose that same buffer to other processes and use that same buffer as the backing for a temporary file.

• If I were on Linux, I could use tmpfs - it isn't perfect:

  • To my knowledge, an existing process can't instruct the OS to take an existing region of its virtual-memory and map a file in tmpfs to that memory region, instead tmpfs still requires that the file be populated by writing (i.e. copying) all of the data to its file-descriptor - which is counter to the aim of having a zero-copy system.

• Windows' built-in RAM-disk functionality is limited to providing the basis for a RAM-disk implementation via a third-party device-driver - I'm surprised that Microsoft never shipped Windows with a built-in RAM-disk GUI or API, especially given their relative simplicity.

  • The ImDisk program is an implementation of a RAM-disk using Microsoft's RAM-disk driver platform, but as far as I can tell while it's more like tmpfs in that it can create a file that exists only in-memory, it doesn't allow the file's data to be backed by a buffer directly accessible to a running process (or a shared-memory buffer).