1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <pthread.h>
30
31#include <fcntl.h>
32#include <stdio.h> // For snprintf.
33#include <string.h>
34#include <sys/prctl.h>
35#include <sys/stat.h>
36#include <sys/types.h>
37#include <unistd.h>
38
39#include "private/ErrnoRestorer.h"
40#include "pthread_internal.h"
41
42// This value is not exported by kernel headers.
43#define MAX_TASK_COMM_LEN 16
44#define TASK_COMM_FMT "/proc/self/task/%d/comm"
45
46int pthread_setname_np(pthread_t t, const char* thread_name) {
47  ErrnoRestorer errno_restorer;
48
49  size_t thread_name_len = strlen(thread_name);
50  if (thread_name_len >= MAX_TASK_COMM_LEN) {
51    return ERANGE;
52  }
53
54  // Changing our own name is an easy special case.
55  if (t == pthread_self()) {
56    return prctl(PR_SET_NAME, thread_name) ? errno : 0;
57  }
58
59  // We have to change another thread's name.
60  pthread_internal_t* thread = __pthread_internal_find(t);
61  if (thread == NULL) {
62    return ENOENT;
63  }
64  pid_t tid = thread->tid;
65
66  char comm_name[sizeof(TASK_COMM_FMT) + 8];
67  snprintf(comm_name, sizeof(comm_name), TASK_COMM_FMT, tid);
68  int fd = open(comm_name, O_CLOEXEC | O_WRONLY);
69  if (fd == -1) {
70    return errno;
71  }
72  ssize_t n = TEMP_FAILURE_RETRY(write(fd, thread_name, thread_name_len));
73  close(fd);
74
75  if (n < 0) {
76    return errno;
77  } else if (n != static_cast<ssize_t>(thread_name_len)) {
78    return EIO;
79  }
80  return 0;
81}
82