const std = @import("std");

const Self = @This();

size: usize = 0,
name: [24]u8 = undefined,
fd: std.posix.fd_t = undefined,

pub fn init_random() !Self {
    var buf: [8]u8 = undefined;
    try std.posix.getrandom(&buf);

    var self: Self = .{};

    const name = std.fmt.bufPrint(&self.name, "/wl.shm.{x}{x}{x}{x}{x}{x}{x}{x}", .{
        buf[0],
        buf[1],
        buf[2],
        buf[3],
        buf[4],
        buf[5],
        buf[6],
        buf[7],
    }) catch unreachable;

    self.fd = try std.posix.memfd_create(name, 0);

    return self;
}

pub fn truncate(self: *Self, size: usize) !void {
    try std.posix.ftruncate(self.fd, size);
    self.size = size;
}

pub fn mmap(self: *Self) ![]u8 {
    return std.posix.mmap(
        null,
        self.size,
        std.os.linux.PROT.READ | std.os.linux.PROT.WRITE,
        .{
            .TYPE = .SHARED,
            .ANONYMOUS = true,
        },
        self.fd,
        0,
    );
}

pub fn close(self: *Self) void {
    std.posix.close(self.fd);
    self.* = undefined;
}