netAcceptPosix

fn netAcceptPosix(userdata: ?*anyopaque, listen_fd: net.Socket.Handle, options: net.Server.AcceptOptions) net.Server.AcceptError!net.Socket {
    if (!have_networking) return error.NetworkDown;
    const t: *Threaded = @ptrCast(@alignCast(userdata));
    _ = t;
    options;
    var storage: PosixAddress = undefined;
    var addr_len: posix.socklen_t = @sizeOf(PosixAddress);
    const syscall: Syscall = try .start();
    const fd = while (true) {
        const rc = if (have_accept4)
            posix.system.accept4(listen_fd, &storage.any, &addr_len, posix.SOCK.CLOEXEC)
        else
            posix.system.accept(listen_fd, &storage.any, &addr_len);
        switch (posix.errno(rc)) {
            .SUCCESS => {
                syscall.finish();
                const fd: posix.fd_t = @intCast(rc);
                errdefer closeFd(fd);
                if (!have_accept4) try setCloexec(fd);
                break fd;
            },
            .INTR => {
                try syscall.checkCancel();
                continue;
            },
            else => |e| {
                syscall.finish();
                switch (e) {
                    .AGAIN => |err| return errnoBug(err),
                    .BADF => |err| return errnoBug(err), // File descriptor used after closed.
                    .CONNABORTED => return error.ConnectionAborted,
                    .FAULT => |err| return errnoBug(err),
                    .INVAL => return error.SocketNotListening,
                    .NOTSOCK => |err| return errnoBug(err),
                    .MFILE => return error.ProcessFdQuotaExceeded,
                    .NFILE => return error.SystemFdQuotaExceeded,
                    .NOBUFS => return error.SystemResources,
                    .NOMEM => return error.SystemResources,
                    .OPNOTSUPP => |err| return errnoBug(err),
                    .PROTO => return error.ProtocolFailure,
                    .PERM => return error.BlockedByFirewall,
                    else => |err| return posix.unexpectedErrno(err),
                }
            },
        }
    };
    return .{ .handle = fd, .address = addressFromPosix(&storage) };
}