Home | History | Annotate | Download | only in bionic 
      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 <sys/prctl.h>
     34 #include <sys/stat.h>
     35 #include <sys/types.h>
     36 #include <unistd.h>
     37 
     38 #include "pthread_accessor.h"
     39 #include "pthread_internal.h"
     40 #include "private/ErrnoRestorer.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 
     46 int 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   pid_t tid = 0;
     61   {
     62     pthread_accessor thread(t);
     63     if (thread.get() == NULL) {
     64       return ESRCH;
     65     }
     66     tid = thread->tid;
     67   }
     68   char comm_name[sizeof(TASK_COMM_FMT) + 8];
     69   snprintf(comm_name, sizeof(comm_name), TASK_COMM_FMT, tid);
     70   int fd = open(comm_name, O_WRONLY);
     71   if (fd == -1) {
     72     return errno;
     73   }
     74   ssize_t n = TEMP_FAILURE_RETRY(write(fd, thread_name, thread_name_len));
     75   close(fd);
     76 
     77   if (n < 0) {
     78     return errno;
     79   } else if (n != static_cast<ssize_t>(thread_name_len)) {
     80     return EIO;
     81   }
     82   return 0;
     83 }
     84