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
__open_task_comm_fd(pthread_t t,int flags,const char * caller)45 static int __open_task_comm_fd(pthread_t t, int flags, const char* caller) {
46 char comm_name[64];
47 snprintf(comm_name, sizeof(comm_name), "/proc/self/task/%d/comm",
48 __pthread_internal_gettid(t, caller));
49 return open(comm_name, O_CLOEXEC | flags);
50 }
51
pthread_getname_np(pthread_t t,char * buf,size_t buf_size)52 int pthread_getname_np(pthread_t t, char* buf, size_t buf_size) {
53 ErrnoRestorer errno_restorer;
54
55 if (buf_size < MAX_TASK_COMM_LEN) return ERANGE;
56
57 // Getting our own name is an easy special case.
58 if (t == pthread_self()) {
59 return prctl(PR_GET_NAME, buf) ? errno : 0;
60 }
61
62 // We have to get another thread's name.
63 int fd = __open_task_comm_fd(t, O_RDONLY, "pthread_getname_np");
64 if (fd == -1) return errno;
65
66 ssize_t n = TEMP_FAILURE_RETRY(read(fd, buf, buf_size));
67 close(fd);
68
69 if (n == -1) return errno;
70
71 // The kernel adds a trailing '\n' to the /proc file,
72 // so this is actually the normal case for short names.
73 if (n > 0 && buf[n - 1] == '\n') {
74 buf[n - 1] = '\0';
75 return 0;
76 }
77
78 if (n == static_cast<ssize_t>(buf_size)) return ERANGE;
79 buf[n] = '\0';
80 return 0;
81 }
82
pthread_setname_np(pthread_t t,const char * thread_name)83 int pthread_setname_np(pthread_t t, const char* thread_name) {
84 ErrnoRestorer errno_restorer;
85
86 size_t thread_name_len = strlen(thread_name);
87 if (thread_name_len >= MAX_TASK_COMM_LEN) return ERANGE;
88
89 // Setting our own name is an easy special case.
90 if (t == pthread_self()) {
91 return prctl(PR_SET_NAME, thread_name) ? errno : 0;
92 }
93
94 // We have to set another thread's name.
95 int fd = __open_task_comm_fd(t, O_WRONLY, "pthread_setname_np");
96 if (fd == -1) return errno;
97
98 ssize_t n = TEMP_FAILURE_RETRY(write(fd, thread_name, thread_name_len));
99 close(fd);
100
101 if (n == -1) return errno;
102 if (n != static_cast<ssize_t>(thread_name_len)) return EIO;
103 return 0;
104 }
105