1  /* Retrieve event.
       2     Copyright (C) 1999-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <stddef.h>
      20  #include <string.h>
      21  
      22  #include "thread_dbP.h"
      23  
      24  
      25  td_err_e
      26  td_ta_event_getmsg (const td_thragent_t *ta_arg, td_event_msg_t *msg)
      27  {
      28    td_thragent_t *const ta = (td_thragent_t *) ta_arg;
      29    td_err_e err;
      30    psaddr_t eventbuf, eventnum, eventdata;
      31    psaddr_t thp, next;
      32    void *copy;
      33  
      34    /* XXX I cannot think of another way but using a static variable.  */
      35    /* XXX Use at least __thread once it is possible.  */
      36    static td_thrhandle_t th;
      37  
      38    LOG ("td_thr_event_getmsg");
      39  
      40    /* Test whether the TA parameter is ok.  */
      41    if (! ta_ok (ta))
      42      return TD_BADTA;
      43  
      44    /* Get the pointer to the thread descriptor with the last event.  */
      45    err = DB_GET_VALUE (thp, ta, __nptl_last_event, 0);
      46    if (err != TD_OK)
      47      return err;
      48  
      49    if (thp == 0)
      50      /* Nothing waiting.  */
      51      return TD_NOMSG;
      52  
      53    /* Copy the event message buffer in from the inferior.  */
      54    err = DB_GET_FIELD_ADDRESS (eventbuf, ta, thp, pthread, eventbuf, 0);
      55    if (err == TD_OK)
      56      err = DB_GET_STRUCT (copy, ta, eventbuf, td_eventbuf_t);
      57    if (err != TD_OK)
      58      return err;
      59  
      60    /* Read the event details from the target thread.  */
      61    err = DB_GET_FIELD_LOCAL (eventnum, ta, copy, td_eventbuf_t, eventnum, 0);
      62    if (err != TD_OK)
      63      return err;
      64    /* If the structure is on the list there better be an event recorded.  */
      65    if ((int) (uintptr_t) eventnum == TD_EVENT_NONE)
      66      return TD_DBERR;
      67  
      68    /* Fill the user's data structure.  */
      69    err = DB_GET_FIELD_LOCAL (eventdata, ta, copy, td_eventbuf_t, eventdata, 0);
      70    if (err != TD_OK)
      71      return err;
      72  
      73    /* Generate the thread descriptor.  */
      74    th.th_ta_p = (td_thragent_t *) ta;
      75    th.th_unique = thp;
      76  
      77    /* Fill the user's data structure.  */
      78    msg->msg.data = (uintptr_t) eventdata;
      79    msg->event = (uintptr_t) eventnum;
      80    msg->th_p = &th;
      81  
      82    /* And clear the event message in the target.  */
      83    memset (copy, 0, ta->ta_sizeof_td_eventbuf_t);
      84    err = DB_PUT_STRUCT (ta, eventbuf, td_eventbuf_t, copy);
      85    if (err != TD_OK)
      86      return err;
      87  
      88    /* Get the pointer to the next descriptor with an event.  */
      89    err = DB_GET_FIELD (next, ta, thp, pthread, nextevent, 0);
      90    if (err != TD_OK)
      91      return err;
      92  
      93    /* Store the pointer in the list head variable.  */
      94    err = DB_PUT_VALUE (ta, __nptl_last_event, 0, next);
      95    if (err != TD_OK)
      96      return err;
      97  
      98    if (next != 0)
      99      /* Clear the next pointer in the current descriptor.  */
     100      err = DB_PUT_FIELD (ta, thp, pthread, nextevent, 0, 0);
     101  
     102    return err;
     103  }