1/*
2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16// Test that /proc/thread-self gives correct TGID/PID.
17#undef NDEBUG
18#include <assert.h>
19#include <sched.h>
20#include <stdio.h>
21#include <unistd.h>
22#include <sys/mman.h>
23#include <sys/wait.h>
24
25#include "proc.h"
26
27int f(void *arg)
28{
29 char buf1[64], buf2[64];
30 pid_t pid, tid;
31 ssize_t rv;
32
33 pid = sys_getpid();
34 tid = sys_gettid();
35 snprintf(buf1, sizeof(buf1), "%u/task/%u", pid, tid);
36
37 rv = readlink("/proc/thread-self", buf2, sizeof(buf2));
38 assert(rv == strlen(buf1));
39 buf2[rv] = '\0';
40 assert(streq(buf1, buf2));
41
42 if (arg)
43 exit(0);
44 return 0;
45}
46
47int main(void)
48{
49 const int PAGE_SIZE = sysconf(_SC_PAGESIZE);
50 pid_t pid;
51 void *stack;
52
53 /* main thread */
54 f(arg: (void *)0);
55
56 stack = mmap(NULL, 2 * PAGE_SIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
57 assert(stack != MAP_FAILED);
58 /* side thread */
59 pid = clone(f, stack + PAGE_SIZE, CLONE_THREAD|CLONE_SIGHAND|CLONE_VM, (void *)1);
60 assert(pid > 0);
61 pause();
62
63 return 0;
64}
65

source code of linux/tools/testing/selftests/proc/thread-self.c