close

fn close(ev: *Evented, fd: fd_t) void {
    var cancel_region: CancelRegion = .initBlocked();
    defer cancel_region.deinit();
    const thread = cancel_region.awaitIoUring() catch |err| switch (err) {
        error.Canceled => unreachable, // blocked
    };
    thread.enqueue().* = .{
        .opcode = .CLOSE,
        .flags = 0,
        .ioprio = 0,
        .fd = fd,
        .off = 0,
        .addr = 0,
        .len = 0,
        .rw_flags = 0,
        .user_data = @intFromPtr(cancel_region.fiber),
        .buf_index = 0,
        .personality = 0,
        .splice_fd_in = 0,
        .addr3 = 0,
        .resv = 0,
    };
    ev.yield(null, .nothing);
    switch (cancel_region.errno()) {
        .BADF => recoverableOsBugDetected(), // Always a race condition.
        .INTR => {}, // This is still a success. See https://github.com/ziglang/zig/issues/2425
        else => {},
    }
}