/* The kernel call implemented in this file:
 *   m_type:	SYS_UPDATE
 *
 * The parameters for this kernel call are:
 *    m2_i1:	SYS_UPD_SRC_ENDPT 	(source process endpoint)
 *    m2_i2:	SYS_UPD_DST_ENDPT	(destination process endpoint)
 */

#include "kernel/system.h"
#include "kernel/ipc.h"
#include <string.h>

#if USE_UPDATE

#define DEBUG 0

#define proc_is_updatable(p) \
    (RTS_ISSET(p, RTS_NO_PRIV) || RTS_ISSET(p, RTS_SIG_PENDING) \
    || (RTS_ISSET(p, RTS_RECEIVING) && !RTS_ISSET(p, RTS_SENDING)))

FORWARD _PROTOTYPE(void adjust_proc_slot, (struct proc *rp,
    struct proc *from_rp));
FORWARD _PROTOTYPE(void adjust_priv_slot, (struct priv *privp,
    struct priv *from_privp));
FORWARD _PROTOTYPE(void swap_proc_slot_pointer, (struct proc **rpp,
    struct proc *src_rp, struct proc *dst_rp));

/*===========================================================================*
 *				do_update				     *
 *===========================================================================*/
PUBLIC int do_update(struct proc * caller, message * m_ptr)
{
/* Handle sys_update(). Update a process into another by swapping their process
 * slots.
 */
  endpoint_t src_e, dst_e;
  int src_p, dst_p;
  struct proc *src_rp, *dst_rp;
  struct priv *src_privp, *dst_privp;
  struct proc orig_src_proc;
  struct proc orig_dst_proc;
  struct priv orig_src_priv;
  struct priv orig_dst_priv;

  /* Lookup slots for source and destination process. */
  src_e = m_ptr->SYS_UPD_SRC_ENDPT;
  if(!isokendpt(src_e, &src_p)) {
      return EINVAL;
  }
  src_rp = proc_addr(src_p);
  src_privp = priv(src_rp);
  if(!(src_privp->s_flags & SYS_PROC)) {
      return EPERM;
  }

  dst_e = m_ptr->SYS_UPD_DST_ENDPT;
  if(!isokendpt(dst_e, &dst_p)) {
      return EINVAL;
  }
  dst_rp = proc_addr(dst_p);
  dst_privp = priv(dst_rp);
  if(!(dst_privp->s_flags & SYS_PROC)) {
      return EPERM;
  }

  /* Check if processes are updatable. */
  if(!proc_is_updatable(src_rp) || !proc_is_updatable(dst_rp)) {
      return EBUSY;
  }

#if DEBUG
  printf("do_update: updating %d (%s, %d, %d) into %d (%s, %d, %d)\n",
      src_rp->p_endpoint, src_rp->p_name, src_rp->p_nr, priv(src_rp)->s_proc_nr,
      dst_rp->p_endpoint, dst_rp->p_name, dst_rp->p_nr, priv(dst_rp)->s_proc_nr);

  proc_stacktrace(src_rp);
  proc_stacktrace(dst_rp);
  printf("do_update: curr ptproc %d\n", ptproc->p_endpoint);
#endif

  /* Save existing data. */
  orig_src_proc = *src_rp;
  orig_src_priv = *(priv(src_rp));
  orig_dst_proc = *dst_rp;
  orig_dst_priv = *(priv(dst_rp));

  /* Swap slots. */
  *src_rp = orig_dst_proc;
  *src_privp = orig_dst_priv;
  *dst_rp = orig_src_proc;
  *dst_privp = orig_src_priv;

  /* Adjust process slots. */
  adjust_proc_slot(src_rp, &orig_src_proc);
  adjust_proc_slot(dst_rp, &orig_dst_proc);

  /* Adjust privilege slots. */
  adjust_priv_slot(priv(src_rp), &orig_src_priv);
  adjust_priv_slot(priv(dst_rp), &orig_dst_priv);

  /* Swap global process slot addresses. */
  swap_proc_slot_pointer(&ptproc, src_rp, dst_rp);

  /* Fix segments. */
  alloc_segments(src_rp);
  alloc_segments(dst_rp);
  prot_init();

#if DEBUG
  printf("do_update: updated %d (%s, %d, %d) into %d (%s, %d, %d)\n",
      src_rp->p_endpoint, src_rp->p_name, src_rp->p_nr, priv(src_rp)->s_proc_nr,
      dst_rp->p_endpoint, dst_rp->p_name, dst_rp->p_nr, priv(dst_rp)->s_proc_nr);

  proc_stacktrace(src_rp);
  proc_stacktrace(dst_rp);
  printf("do_update: curr ptproc %d\n", ptproc->p_endpoint);
#endif

  return OK;
}

/*===========================================================================*
 *			     adjust_proc_slot				     *
 *===========================================================================*/
PRIVATE void adjust_proc_slot(struct proc *rp, struct proc *from_rp)
{
  /* Preserve endpoints, slot numbers, priv structure. */
  rp->p_endpoint = from_rp->p_endpoint;
  rp->p_nr = from_rp->p_nr;
  rp->p_priv = from_rp->p_priv;
  priv(rp)->s_proc_nr = from_rp->p_nr;
}

/*===========================================================================*
 *			     adjust_priv_slot				     *
 *===========================================================================*/
PRIVATE void adjust_priv_slot(struct priv *privp, struct priv *from_privp)
{
  /* Preserve privilege ids and non-privilege stuff in the priv structure. */
  privp->s_id = from_privp->s_id;
  privp->s_notify_pending = from_privp->s_notify_pending;
  privp->s_int_pending = from_privp->s_int_pending;
  privp->s_sig_pending = from_privp->s_sig_pending;
  privp->s_alarm_timer = from_privp->s_alarm_timer;
  memcpy(privp->s_farmem, from_privp->s_farmem, sizeof(privp->s_farmem));
}

/*===========================================================================*
 *			   swap_proc_slot_pointer			     *
 *===========================================================================*/
PRIVATE void swap_proc_slot_pointer(struct proc **rpp, struct proc *src_rp,
    struct proc *dst_rp)
{
  if(*rpp == src_rp) {
      *rpp = dst_rp;
  }
  else if(*rpp == dst_rp) {
      *rpp = src_rp;
  }
}

#endif /* USE_UPDATE */