1/* Validate a thread handle.
2 Copyright (C) 1999-2016 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 <http://www.gnu.org/licenses/>. */
19
20#include "thread_dbP.h"
21#include <stdbool.h>
22
23static td_err_e
24check_thread_list (const td_thrhandle_t *th, psaddr_t head, bool *uninit)
25{
26 td_err_e err;
27 psaddr_t next, ofs;
28
29 err = DB_GET_FIELD (next, th->th_ta_p, head, list_t, next, 0);
30 if (err == TD_OK)
31 {
32 if (next == 0)
33 {
34 *uninit = true;
35 return TD_NOTHR;
36 }
37 err = DB_GET_FIELD_ADDRESS (ofs, th->th_ta_p, 0, pthread, list, 0);
38 }
39
40 while (err == TD_OK)
41 {
42 if (next == head)
43 return TD_NOTHR;
44
45 if (next - (ofs - (psaddr_t) 0) == th->th_unique)
46 return TD_OK;
47
48 err = DB_GET_FIELD (next, th->th_ta_p, next, list_t, next, 0);
49 }
50
51 return err;
52}
53
54
55td_err_e
56td_thr_validate (const td_thrhandle_t *th)
57{
58 td_err_e err;
59 psaddr_t list;
60
61 LOG ("td_thr_validate");
62
63 /* First check the list with threads using user allocated stacks. */
64 bool uninit = false;
65 err = DB_GET_SYMBOL (list, th->th_ta_p, __stack_user);
66 if (err == TD_OK)
67 err = check_thread_list (th, list, &uninit);
68
69 /* If our thread is not on this list search the list with stack
70 using implementation allocated stacks. */
71 if (err == TD_NOTHR)
72 {
73 err = DB_GET_SYMBOL (list, th->th_ta_p, stack_used);
74 if (err == TD_OK)
75 err = check_thread_list (th, list, &uninit);
76
77 if (err == TD_NOTHR && uninit && th->th_unique == 0)
78 /* __pthread_initialize_minimal has not run yet.
79 There is only the special case thread handle. */
80 err = TD_OK;
81 }
82
83 if (err == TD_OK)
84 {
85 /* Verify that this is not a stale element in a fork child. */
86 pid_t match_pid = ps_getpid (th->th_ta_p->ph);
87 psaddr_t pid;
88 err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique, pthread, pid, 0);
89 if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
90 {
91 /* This was a thread that was about to fork, or it is the new sole
92 thread in a fork child. In the latter case, its tid was stored
93 via CLONE_CHILD_SETTID and so is already the proper child PID. */
94 if (-(pid_t) (uintptr_t) pid == match_pid)
95 /* It is about to do a fork, but is really still the parent PID. */
96 pid = (psaddr_t) (uintptr_t) match_pid;
97 else
98 /* It must be a fork child, whose new PID is in the tid field. */
99 err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique,
100 pthread, tid, 0);
101 }
102 if (err == TD_OK && (pid_t) (uintptr_t) pid != match_pid)
103 err = TD_NOTHR;
104 }
105
106 return err;
107}
108