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      1 /*
      2  * Copyright (C) 2017 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 <android/set_abort_message.h>
     30 
     31 #include <pthread.h>
     32 #include <string.h>
     33 #include <sys/mman.h>
     34 
     35 #include "private/bionic_defs.h"
     36 #include "private/ScopedPthreadMutexLocker.h"
     37 
     38 static pthread_mutex_t g_abort_msg_lock = PTHREAD_MUTEX_INITIALIZER;
     39 
     40 struct abort_msg_t {
     41   size_t size;
     42   char msg[0];
     43 };
     44 
     45 abort_msg_t** __abort_message_ptr; // Accessible to __libc_init_common.
     46 
     47 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
     48 void android_set_abort_message(const char* msg) {
     49   ScopedPthreadMutexLocker locker(&g_abort_msg_lock);
     50 
     51   if (__abort_message_ptr == nullptr) {
     52     // We must have crashed _very_ early.
     53     return;
     54   }
     55 
     56   if (*__abort_message_ptr != nullptr) {
     57     // We already have an abort message.
     58     // Assume that the first crash is the one most worth reporting.
     59     return;
     60   }
     61 
     62   size_t size = sizeof(abort_msg_t) + strlen(msg) + 1;
     63   void* map = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
     64   if (map == MAP_FAILED) {
     65     return;
     66   }
     67 
     68   abort_msg_t* new_abort_message = reinterpret_cast<abort_msg_t*>(map);
     69   new_abort_message->size = size;
     70   strcpy(new_abort_message->msg, msg);
     71   *__abort_message_ptr = new_abort_message;
     72 }
     73