1/* Retrieve event.
2 Copyright (C) 1999-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include "thread_dbP.h"
21#include <assert.h>
22
23
24td_err_e
25td_thr_event_getmsg (const td_thrhandle_t *th, td_event_msg_t *msg)
26{
27 td_err_e err;
28 psaddr_t eventbuf, eventnum, eventdata;
29 psaddr_t thp, prevp;
30 void *copy;
31
32 LOG ("td_thr_event_getmsg");
33
34 /* Copy the event message buffer in from the inferior. */
35 err = DB_GET_FIELD_ADDRESS (eventbuf, th->th_ta_p, th->th_unique, pthread,
36 eventbuf, 0);
37 if (err == TD_OK)
38 err = DB_GET_STRUCT (copy, th->th_ta_p, eventbuf, td_eventbuf_t);
39 if (err != TD_OK)
40 return err;
41
42 /* Check whether an event occurred. */
43 err = DB_GET_FIELD_LOCAL (eventnum, th->th_ta_p, copy,
44 td_eventbuf_t, eventnum, 0);
45 if (err != TD_OK)
46 return err;
47 if ((int) (uintptr_t) eventnum == TD_EVENT_NONE)
48 /* Nothing. */
49 return TD_NOMSG;
50
51 /* Fill the user's data structure. */
52 err = DB_GET_FIELD_LOCAL (eventdata, th->th_ta_p, copy,
53 td_eventbuf_t, eventdata, 0);
54 if (err != TD_OK)
55 return err;
56
57 msg->msg.data = (uintptr_t) eventdata;
58 msg->event = (uintptr_t) eventnum;
59 msg->th_p = th;
60
61 /* And clear the event message in the target. */
62 memset (copy, 0, th->th_ta_p->ta_sizeof_td_eventbuf_t);
63 err = DB_PUT_STRUCT (th->th_ta_p, eventbuf, td_eventbuf_t, copy);
64 if (err != TD_OK)
65 return err;
66
67 /* Get the pointer to the thread descriptor with the last event.
68 If it doesn't match TH, then walk down the list until we find it.
69 We must splice it out of the list so that there is no dangling
70 pointer to it later when it dies. */
71 err = DB_GET_SYMBOL (prevp, th->th_ta_p, __nptl_last_event);
72 if (err != TD_OK)
73 return err;
74 err = DB_GET_VALUE (thp, th->th_ta_p, __nptl_last_event, 0);
75 if (err != TD_OK)
76 return err;
77
78 while (thp != 0)
79 {
80 psaddr_t next;
81 err = DB_GET_FIELD (next, th->th_ta_p, th->th_unique, pthread,
82 nextevent, 0);
83 if (err != TD_OK)
84 return err;
85
86 if (next == thp)
87 return TD_DBERR;
88
89 if (thp == th->th_unique)
90 {
91 /* PREVP points at this thread, splice it out. */
92 psaddr_t next_nextp;
93 err = DB_GET_FIELD_ADDRESS (next_nextp, th->th_ta_p, next, pthread,
94 nextevent, 0);
95 assert (err == TD_OK); /* We used this field before. */
96 if (prevp == next_nextp)
97 return TD_DBERR;
98
99 err = _td_store_value (th->th_ta_p,
100 th->th_ta_p->ta_var___nptl_last_event, -1,
101 0, prevp, next);
102 if (err != TD_OK)
103 return err;
104
105 /* Now clear this thread's own next pointer so it's not dangling
106 when the thread resumes and then chains on for its next event. */
107 return DB_PUT_FIELD (th->th_ta_p, thp, pthread, nextevent, 0, 0);
108 }
109
110 err = DB_GET_FIELD_ADDRESS (prevp, th->th_ta_p, thp, pthread,
111 nextevent, 0);
112 assert (err == TD_OK); /* We used this field before. */
113 thp = next;
114 }
115
116 /* Ack! This should not happen. */
117 return TD_DBERR;
118}
119