text: // Copyright (c) 2010, Google Inc.
  // 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.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // 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.
  //
  // Helper program for the linux_dumper class, which creates a bunch of
  // threads. The first word of each thread's stack is set to the thread
  // id.
  
  #include <pthread.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/syscall.h>
  #include <unistd.h>
  
  #include "common/scoped_ptr.h"
  #include "third_party/lss/linux_syscall_support.h"
  
  #if defined(__ARM_EABI__)
  #define TID_PTR_REGISTER "r3"
  #elif defined(__aarch64__)
  #define TID_PTR_REGISTER "x3"
  #elif defined(__i386)
  #define TID_PTR_REGISTER "ecx"
  #elif defined(__x86_64)
  #define TID_PTR_REGISTER "rcx"
  #elif defined(__mips__)
  #define TID_PTR_REGISTER "$1"
  #else
  #error This test has not been ported to this platform.
  #endif
  
  void *thread_function(void *data) {
    int pipefd = *static_cast<int *>(data);
    volatile pid_t* thread_id = new pid_t;
    *thread_id = syscall(__NR_gettid);
    // Signal parent that a thread has started.
    uint8_t byte = 1;
    if (write(pipefd, &byte, sizeof(byte)) != sizeof(byte)) {
      perror("ERROR: parent notification failed");
      return NULL;
    }
    volatile pid_t *thread_id_ptr asm(TID_PTR_REGISTER) = thread_id;
    while (true)
      asm volatile ("" : : "r" (thread_id_ptr));
    return NULL;
  }
  
  int main(int argc, char *argv[]) {
    if (argc < 3) {
      fprintf(stderr,
              "usage: linux_dumper_unittest_helper <pipe fd> <# of threads>\n");
      return 1;
    }
    int pipefd = atoi(argv[1]);
    int num_threads = atoi(argv[2]);
    if (num_threads < 1) {
      fprintf(stderr, "ERROR: number of threads is 0");
      return 1;
    }
    google_breakpad::scoped_array<pthread_t> threads(new pthread_t[num_threads]);
    pthread_attr_t thread_attributes;
    pthread_attr_init(&thread_attributes);
    pthread_attr_setdetachstate(&thread_attributes, PTHREAD_CREATE_DETACHED);
    for (int i = 1; i < num_threads; i++) {
      pthread_create(&threads[i], &thread_attributes, &thread_function, &pipefd);
    }
    thread_function(&pipefd);
    return 0;
  }
  