debuggerd/handler/debuggerd_fallback.cpp

/*
 * Copyright (C) 2017 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stddef.h>
#include <sys/ucontext.h>
#include <unistd.h>

#include "tombstone.h"

extern "C" void __linker_use_fallback_allocator();

extern "C" bool debuggerd_fallback(ucontext_t* ucontext, siginfo_t* siginfo, void* abort_message) {
  // This is incredibly sketchy to do inside of a signal handler, especially when libbacktrace
  // uses the C++ standard library throughout, but this code runs in the linker, so we'll be using
  // the linker's malloc instead of the libc one. Switch it out for a replacement, just in case.
  //
  // This isn't the default method of dumping because it can fail in cases such as memory space
  // exhaustion.
  __linker_use_fallback_allocator();
  engrave_tombstone_ucontext(-1, getpid(), gettid(), reinterpret_cast<uintptr_t>(abort_message),
                             siginfo, ucontext);
  return true;
}