CreateOptions

pub const CreateOptions = struct {
    /// Size of the mapping, in bytes. If this is longer than the file size,
    /// `memory` beyond the file end will be filled with zeroes and it is
    /// unspecified whether, after calling `write`, the file length will be
    /// set to `len` or remain unchanged.
    ///
    /// This value has no minimum alignment requirement, but may gain
    /// efficiency benefits from being a multiple of `File.Stat.block_size`.
    len: usize,
    /// When this has read set to false, bytes that are not modified before a
    /// sync may have the original file contents, or may be set to zero.
    protection: std.process.MemoryProtection = .{ .read = true, .write = true },
    /// If set to `true`, allows bytes observed before calling `read` to be
    /// undefined, and bytes unwritten before calling `write` to write
    /// undefined memory to the file.
    undefined_contents: bool = false,
    /// Prefault the pages. If this option is unsupported, it is silently
    /// ignored. Aside from custom Io implementations, this option is only
    /// supported on Linux.
    populate: bool = true,
    /// Asserted to be a multiple of page size which can be obtained via
    /// `std.heap.pageSize`.
    offset: u64 = 0,
}