xref: /l4re-core-master/l4sys/include/factory

// vi:set ft=cpp: -*- Mode: C++ -*-
/**
 * \file
 * Common factory related definitions.
 */
/*
 * (c) 2008-2009 Adam Lackorzynski <adam@os.inf.tu-dresden.de>,
 *               Alexander Warg <warg@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU General Public License 2.
 * Please see the COPYING-GPL-2 file for details.
 *
 * As a special exception, you may use this file as part of a free software
 * library without restriction.  Specifically, if other files instantiate
 * templates or use macros or inline functions from this file, or you compile
 * this file and link it with other files to produce an executable, this
 * file does not by itself cause the resulting executable to be covered by
 * the GNU General Public License.  This exception does not however
 * invalidate any other reasons why the executable file might be covered by
 * the GNU General Public License.
 */

#pragma once

#include <l4/sys/factory.h>
#include <l4/sys/capability>
#include <l4/sys/cxx/ipc_iface>
#include <l4/sys/cxx/ipc_varg>

namespace L4 {

/**
 * C++ %Factory interface.
 *
 * Factories provide an interface to create objects which are accessed via
 * capabilities.
 *
 * For additional information about which objects can be created via this
 * interface, see server-specific information in
 * \ref l4re_concepts_kernel_factory and \ref l4re_servers.
 *
 * \includefile{l4/sys/factory}
 *
 * For the C interface refer to \ref l4_factory_api.
 */
class Factory : public Kobject_t<Factory, Kobject, L4_PROTO_FACTORY>
{
public:

  typedef l4_mword_t Proto;

  /**
   * Special type to add a void argument into the factory create stream.
   */
  struct Nil {};

  /**
   * Special type to add a pascal string into the factory create stream.
   *
   * This encapsulates a string that has an explicit length.
   */
  struct Lstr
  {
    /**
     * The character buffer.
     */
    char const *s;

    /**
     * The number of characters in the buffer.
     */
    unsigned len;

    /**
     * \param s    Pointer to the c-style string.
     * \param len  Length in number of characters of the string s.
     */
    Lstr(char const *s, unsigned len) noexcept : s(s), len(len) {}
  };

  /**
   * Stream class for the create() argument stream.
   *
   * This stream allows a variable number of arguments to be
   * added to a create() call.
   */
  class S
  {
  private:
    l4_utcb_t *u;
    l4_msgtag_t t;
    l4_cap_idx_t f;

    template<typename T>
    static T &&_move(T &c) { return static_cast<T &&>(c); }

  public:
    S(S const &) = delete;
    S &operator = (S const &) & = delete;

    /**
     * Move ...
     *
     * \param o  Instance of S to move.
     */
    S(S &&o) noexcept
    : u(o.u), t(o.t), f(o.f)
    { o.t.raw = 0; }

    S &operator = (S &&o) & noexcept
    {
      u = o.u;
      t = o.t;
      f = o.f;
      o.t.raw = 0;
      return *this;
    }

    /**
     * Create a stream for a specific create() call.
     *
     * \param      f       The capability for the factory object (L4::Factory).
     * \param      obj     The protocol ID to describe the type of the object
     *                     that shall be created.
     * \param[out] target  The capability selector for the new object. The
     *                     caller must allocate the capability slot. The kernel
     *                     stores the new object's capability into this slot.
     * \param      utcb    The UTCB to use for the operation.
     */
    S(l4_cap_idx_t f, long obj, L4::Cap<void> target,
      l4_utcb_t *utcb) noexcept
    : u(utcb), t(l4_factory_create_start_u(obj, target.cap(), u)), f(f)
    {}

    /**
     * Commit the operation in the destructor to have a cool syntax for
     * create().
     */
    ~S() noexcept
    {
      if (t.raw)
	l4_factory_create_commit_u(f, t, u);
    }

    /**
     * Explicitly commits the operation and returns the result.
     *
     * \return The result of the create() operation.
     */
    operator l4_msgtag_t () noexcept
    {
      l4_msgtag_t r = l4_factory_create_commit_u(f, t, u);
      t.raw = 0;
      return r;
    }

    /**
     * Put a single l4_mword_t as next argument.
     *
     * \param i  The value to add as next argument.
     *
     * \return  Reference to this stream.
     */
    void put(l4_mword_t i) noexcept
    {
      l4_factory_create_add_int_u(i, &t, u);
    }

    /**
     * Put a single l4_umword_t as next argument.
     *
     * \param i  The value to add as next argument.
     *
     * \return  Reference to this stream.
     */
    void put(l4_umword_t i) noexcept
    {
      l4_factory_create_add_uint_u(i, &t, u);
    }

    /**
     * Add a zero-terminated string as next argument.
     *
     * \param s  The string to add as next argument.
     *
     * \return  Reference to this stream.
     *
     * The string will be added with the zero-terminator.
     */
    void put(char const *s) & noexcept
    {
      l4_factory_create_add_str_u(s, &t, u);
    }

    /**
     * Add a pascal string as next argument.
     *
     * \param s  The string to add as next argument.
     *
     * \return  Reference to this stream.
     *
     * The string will be added with the exact length given. It is the
     * responsibility of the caller to make sure that the string is zero-
     * terminated when that is required by the server.
     */
    void put(Lstr const &s) & noexcept
    {
      l4_factory_create_add_lstr_u(s.s, s.len, &t, u);
    }

    /**
     * Add an empty argument.
     *
     * \return  Reference to this stream.
     */
    void put(Nil) & noexcept
    {
      l4_factory_create_add_nil_u(&t, u);
    }

    /**
     * Add a flex page as next argument.
     *
     * \param d  The flex page to add (there will be no map operation).
     *
     * \return  Reference to this stream.
     */
    void put(l4_fpage_t d) & noexcept
    {
      l4_factory_create_add_fpage_u(d, &t, u);
    }

    template<typename T>
    S &operator << (T const &d) & noexcept
    {
      put(d);
      return *this;
    }

    template<typename T>
    S &&operator << (T const &d) && noexcept
    {
      put(d);
      return _move(*this);
    }
  };


public:

  /**
   * Generic create call to the factory.
   *
   * \param[out] target  Capability selector for the new object. The caller
   *                     must allocate the capability slot. The kernel stores
   *                     the new objects's capability into this slot.
   * \param      obj     The protocol ID that specifies which kind of object
   *                     shall be created.
   * \param      utcb    The UTCB to use for the operation.
   *
   * \return A create stream that allows additional arguments to be passed to
   *         the create() call via the left-shift (<<) operator.
   *
   * This method does not directly invoke the factory. The factory is invoked
   * when the create stream returned by this method is converted to an
   * `l4_msgtag_t`, or otherwise when the stream goes out of scope.
   *
   * \note The create stream uses the UTCB to store parameters for the service
   *       call. During the lifetime of a create stream or, until it is
   *       converted to a `l4_msgtag_t`, other UTCB-using operations must not
   *       be used.
   *
   * \see create(Cap<OBJ>, l4_utcb_t *)
   */
  S create(Cap<void> target, long obj, l4_utcb_t *utcb = l4_utcb()) noexcept
  {
    return S(cap(), obj, target, utcb);
  }

  /**
   * Create call for typed capabilities.
   *
   * \tparam      OBJ     Capability type of the object to be created.
   * \param[out]  target  Capability of type OBJ.
   * \param       utcb    UTCB to use.
   *
   * \return A create stream that allows additional arguments to be passed to
   *         the create() call via the left-shift (<<) operator.
   *
   * This method does not directly invoke the factory. The factory is invoked
   * when the create stream returned by this method is converted to an
   * `l4_msgtag_t`, or otherwise when the stream goes out of scope.
   *
   * \note The create stream uses the UTCB to store parameters for the service
   *       call. During the lifetime of a create stream or, until it is
   *       converted to a `l4_msgtag_t`, other UTCB-using operations must not
   *       be used.
   *
   * Usage:
   * ~~~
   * L4::Cap<L4Re::Dataspace> ds = L4Re::Util::cap_alloc.alloc<L4Re::Dataspace>();
   * factory->create(ds) << l4_mword_t(size_in_bytes);
   * ~~~
   */
  template<typename OBJ>
  S create(Cap<OBJ> target, l4_utcb_t *utcb = l4_utcb()) noexcept
  {
    return S(cap(), OBJ::Protocol, target, utcb);
  }

  L4_INLINE_RPC_NF(
      l4_msgtag_t, create, (L4::Ipc::Out<L4::Cap<void> > target, l4_mword_t obj,
                            L4::Ipc::Varg const *args),
      L4::Ipc::Call_t<L4_CAP_FPAGE_S>);

  /**
   * Create a new task.
   *
   * \param[out] target_cap  The kernel stores the new task's capability into
   *                         this slot.
   * \param      utcb_area   Flexpage that describes an area in the address
   *                         space of the new task, where the kernel should
   *                         map the kernel-allocated kernel-user memory to.
   *                         The kernel uses the kernel-user memory to store
   *                         UTCBs and vCPU state-save-areas of the new task.
   * \param      utcb        The UTCB to use for the operation.
   *
   * \return Syscall return tag
   *
   * \note The size of the UTCB area specifies indirectly the number
   *       of UTCBs available for this task. Refer to L4::Task::add_ku_mem
   *       / l4_task_add_ku_mem() for adding more of this type of memory.
   *
   * \note This method is only guaranteed to work with the
   *       \ref l4re_concepts_kernel_factory.
   *
   * \see L4::Task
   */
  l4_msgtag_t create_task(Cap<Task> const & target_cap,
                          l4_fpage_t const &utcb_area,
                          l4_utcb_t *utcb = l4_utcb()) noexcept
  { return l4_factory_create_task_u(cap(), target_cap.cap(), utcb_area, utcb); }

  /**
   * Create a new factory.
   *
   * \param[out] target_cap  The kernel stores the new factory's capability into
   *                         this slot.
   * \param      limit       Limit for the new factory in bytes.
   * \param      utcb        The UTCB to use for the operation.
   *
   * \return Syscall return tag
   *
   * \note In addition to memory needed for internal data structures, the
   *       `limit` (quota) of the new factory is counted towards the quota of
   *       the creating factory. The `limit` must be within
   *       `1 ≤ limit ≤ 2^(8 * sizeof(l4_umword_t) − 1) − 2` otherwise the
   *       behavior is undefined.
   *
   * \note This method is only guaranteed to work with the
   *       \ref l4re_concepts_kernel_factory. For other services, use the
   *       generic create() method and consult the service documentation for
   *       information on the arguments that need to be passed to the create
   *       stream.
   */
  l4_msgtag_t create_factory(Cap<Factory> const &target_cap,
                             unsigned long limit,
                             l4_utcb_t *utcb = l4_utcb()) noexcept
  { return l4_factory_create_factory_u(cap(), target_cap.cap(), limit, utcb); }

  /**
   * Create a new IPC gate.
   *
   * \param[out] target_cap  The kernel stores the new IPC gate's capability
   *                         into this slot.
   * \param      thread_cap  Optional capability selector of the thread to
   *                         bind the gate to. Use #L4_INVALID_CAP to create
   *                         an unbound IPC gate.
   * \param      label       Optional label of the gate (is used if
   *                         `thread_cap` is valid).
   * \param      utcb        The UTCB to use for the operation.
   *
   * \return Syscall return tag containing one of the following return codes.
   *
   * \retval L4_EOK      No error occurred.
   * \retval -L4_ENOMEM  Out-of-memory during allocation of the Ipc_gate object.
   * \retval -L4_ENOENT  `thread_cap` is void or points to something that is not
   *                     a thread.
   * \retval -L4_EPERM   No #L4_CAP_FPAGE_S rights on `thread_cap`.
   *
   * An unbound IPC gate can be bound to a thread using
   * L4::Ipc_gate::bind_thread().
   *
   * \note This method is only guaranteed to work with the
   *       \ref l4re_concepts_kernel_factory.
   *
   * \see L4::Ipc_gate
   */
  l4_msgtag_t create_gate(Cap<void> const &target_cap,
                          Cap<Thread> const &thread_cap, l4_umword_t label,
                          l4_utcb_t *utcb = l4_utcb()) noexcept
  { return l4_factory_create_gate_u(cap(), target_cap.cap(), thread_cap.cap(), label, utcb); }

  typedef L4::Typeid::Rpc_nocode<create_t> Rpcs;
};

}