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      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_internal.h"
     30 
     31 #include <errno.h>
     32 #include <stdlib.h>
     33 #include <string.h>
     34 #include <sys/mman.h>
     35 
     36 #include "private/bionic_futex.h"
     37 #include "private/bionic_sdk_version.h"
     38 #include "private/bionic_tls.h"
     39 #include "private/libc_logging.h"
     40 
     41 static pthread_internal_t* g_thread_list = nullptr;
     42 static pthread_rwlock_t g_thread_list_lock = PTHREAD_RWLOCK_INITIALIZER;
     43 
     44 template <bool write> class ScopedRWLock {
     45  public:
     46   ScopedRWLock(pthread_rwlock_t* rwlock) : rwlock_(rwlock) {
     47     (write ? pthread_rwlock_wrlock : pthread_rwlock_rdlock)(rwlock_);
     48   }
     49 
     50   ~ScopedRWLock() {
     51     pthread_rwlock_unlock(rwlock_);
     52   }
     53 
     54  private:
     55   pthread_rwlock_t* rwlock_;
     56   DISALLOW_IMPLICIT_CONSTRUCTORS(ScopedRWLock);
     57 };
     58 
     59 typedef ScopedRWLock<true> ScopedWriteLock;
     60 typedef ScopedRWLock<false> ScopedReadLock;
     61 
     62 pthread_t __pthread_internal_add(pthread_internal_t* thread) {
     63   ScopedWriteLock locker(&g_thread_list_lock);
     64 
     65   // We insert at the head.
     66   thread->next = g_thread_list;
     67   thread->prev = nullptr;
     68   if (thread->next != nullptr) {
     69     thread->next->prev = thread;
     70   }
     71   g_thread_list = thread;
     72   return reinterpret_cast<pthread_t>(thread);
     73 }
     74 
     75 void __pthread_internal_remove(pthread_internal_t* thread) {
     76   ScopedWriteLock locker(&g_thread_list_lock);
     77 
     78   if (thread->next != nullptr) {
     79     thread->next->prev = thread->prev;
     80   }
     81   if (thread->prev != nullptr) {
     82     thread->prev->next = thread->next;
     83   } else {
     84     g_thread_list = thread->next;
     85   }
     86 }
     87 
     88 static void __pthread_internal_free(pthread_internal_t* thread) {
     89   if (thread->mmap_size != 0) {
     90     // Free mapped space, including thread stack and pthread_internal_t.
     91     munmap(thread->attr.stack_base, thread->mmap_size);
     92   }
     93 }
     94 
     95 void __pthread_internal_remove_and_free(pthread_internal_t* thread) {
     96   __pthread_internal_remove(thread);
     97   __pthread_internal_free(thread);
     98 }
     99 
    100 pthread_internal_t* __pthread_internal_find(pthread_t thread_id) {
    101   pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(thread_id);
    102 
    103   // Check if we're looking for ourselves before acquiring the lock.
    104   if (thread == __get_thread()) return thread;
    105 
    106   ScopedReadLock locker(&g_thread_list_lock);
    107   for (pthread_internal_t* t = g_thread_list; t != nullptr; t = t->next) {
    108     if (t == thread) return thread;
    109   }
    110 
    111   // Historically we'd return null, but
    112   if (bionic_get_application_target_sdk_version() >= __ANDROID_API_O__) {
    113     if (thread == nullptr) {
    114       // This seems to be a common mistake, and it's relatively harmless because
    115       // there will never be a valid thread at address 0, whereas other invalid
    116       // addresses might sometimes contain threads or things that look enough like
    117       // threads for us to do some real damage by continuing.
    118       // TODO: try getting rid of this when Treble lets us keep vendor blobs on an old API level.
    119       __libc_format_log(ANDROID_LOG_WARN, "libc", "invalid pthread_t (0) passed to libc");
    120     } else {
    121       __libc_fatal("invalid pthread_t %p passed to libc", thread);
    122     }
    123   }
    124   return nullptr;
    125 }
    126