nptl_db/td_thr_event_getmsg.c

   1 /* Retrieve event.
   2    Copyright (C) 1999-2022 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 "thread_dbP.h"
  20 #include <assert.h>
  21
  22
  23 td_err_e
  24 td_thr_event_getmsg (const td_thrhandle_t *th, td_event_msg_t *msg)
  25 {
  26   td_err_e err;
  27   psaddr_t eventbuf, eventnum, eventdata;
  28   psaddr_t thp, prevp;
  29   void *copy;
  30
  31   LOG ("td_thr_event_getmsg");
  32
  33   /* Copy the event message buffer in from the inferior.  */
  34   err = DB_GET_FIELD_ADDRESS (eventbuf, th->th_ta_p, th->th_unique, pthread,
  35                               eventbuf, 0);
  36   if (err == TD_OK)
  37     err = DB_GET_STRUCT (copy, th->th_ta_p, eventbuf, td_eventbuf_t);
  38   if (err != TD_OK)
  39     return err;
  40
  41   /* Check whether an event occurred.  */
  42   err = DB_GET_FIELD_LOCAL (eventnum, th->th_ta_p, copy,
  43                             td_eventbuf_t, eventnum, 0);
  44   if (err != TD_OK)
  45     return err;
  46   if ((int) (uintptr_t) eventnum == TD_EVENT_NONE)
  47     /* Nothing.  */
  48     return TD_NOMSG;
  49
  50   /* Fill the user's data structure.  */
  51   err = DB_GET_FIELD_LOCAL (eventdata, th->th_ta_p, copy,
  52                             td_eventbuf_t, eventdata, 0);
  53   if (err != TD_OK)
  54     return err;
  55
  56   msg->msg.data = (uintptr_t) eventdata;
  57   msg->event = (uintptr_t) eventnum;
  58   msg->th_p = th;
  59
  60   /* And clear the event message in the target.  */
  61   memset (copy, 0, th->th_ta_p->ta_sizeof_td_eventbuf_t);
  62   err = DB_PUT_STRUCT (th->th_ta_p, eventbuf, td_eventbuf_t, copy);
  63   if (err != TD_OK)
  64     return err;
  65
  66   /* Get the pointer to the thread descriptor with the last event.
  67      If it doesn't match TH, then walk down the list until we find it.
  68      We must splice it out of the list so that there is no dangling
  69      pointer to it later when it dies.  */
  70   err = DB_GET_SYMBOL (prevp, th->th_ta_p, __nptl_last_event);
  71   if (err != TD_OK)
  72     return err;
  73   err = DB_GET_VALUE (thp, th->th_ta_p, __nptl_last_event, 0);
  74   if (err != TD_OK)
  75     return err;
  76
  77   while (thp != 0)
  78     {
  79       psaddr_t next;
  80       err = DB_GET_FIELD (next, th->th_ta_p, th->th_unique, pthread,
  81                           nextevent, 0);
  82       if (err != TD_OK)
  83         return err;
  84
  85       if (next == thp)
  86         return TD_DBERR;
  87
  88       if (thp == th->th_unique)
  89         {
  90           /* PREVP points at this thread, splice it out.  */
  91           psaddr_t next_nextp;
  92           err = DB_GET_FIELD_ADDRESS (next_nextp, th->th_ta_p, next, pthread,
  93                                       nextevent, 0);
  94           assert (err == TD_OK); /* We used this field before.  */
  95           if (prevp == next_nextp)
  96             return TD_DBERR;
  97
  98           err = _td_store_value (th->th_ta_p,
  99                                  th->th_ta_p->ta_var___nptl_last_event, -1,
 100                                  0, prevp, next);
 101           if (err != TD_OK)
 102             return err;
 103
 104           /* Now clear this thread's own next pointer so it's not dangling
 105              when the thread resumes and then chains on for its next event.  */
 106           return DB_PUT_FIELD (th->th_ta_p, thp, pthread, nextevent, 0, 0);
 107         }
 108
 109       err = DB_GET_FIELD_ADDRESS (prevp, th->th_ta_p, thp, pthread,
 110                                   nextevent, 0);
 111       assert (err == TD_OK); /* We used this field before.  */
 112       thp = next;
 113     }
 114
 115   /* Ack!  This should not happen.  */
 116   return TD_DBERR;
 117 }