1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
/* This testcase is part of GDB, the GNU debugger.
Copyright 2023-2024 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#define _GNU_SOURCE
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <pthread.h>
#include <stdlib.h>
#include <errno.h>
int fds[2];
_Atomic pid_t bg_tid = 0;
pthread_barrier_t barrier;
#define FIVE_MINUTES (5 * 60)
/* One thread of the child process. This is traced by the parent
process. */
void *
block (void *ignore)
{
bg_tid = gettid ();
pthread_barrier_wait (&barrier);
sleep (FIVE_MINUTES);
return 0;
}
/* The parent process blocks in this function. */
void
parent_stop (pid_t child_thread_pid)
{
sleep (FIVE_MINUTES);
}
int
main ()
{
int result;
pthread_barrier_init (&barrier, NULL, 2);
result = pipe (fds);
assert (result != -1);
pid_t child = fork ();
if (child != 0)
{
/* Parent. */
close (fds[1]);
pid_t the_tid;
result = read (fds[0], &the_tid, sizeof (the_tid));
assert (result == sizeof (the_tid));
/* Trace a single, non-main thread of the child. This should
prevent gdb from attaching to the child at all. The bug here
was that gdb would get into an infinite loop repeatedly
trying to attach to this thread. */
result = ptrace (PTRACE_SEIZE, the_tid, (void *) 0, (void *) 0);
if (result == -1)
perror ("ptrace");
parent_stop (child);
}
else
{
/* Child. */
close (fds[0]);
pthread_t thr;
result = pthread_create (&thr, 0, block, 0);
assert (result == 0);
/* Wait until the TID has been assigned. */
pthread_barrier_wait (&barrier);
assert (bg_tid != 0);
result = write (fds[1], &bg_tid, sizeof (bg_tid));
assert (result == sizeof (bg_tid));
sleep (FIVE_MINUTES);
}
exit (0);
}
|
