text: /*
   * Copyright (C) 2014 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 <sys/sysinfo.h>
  
  #include <dirent.h>
  #include <limits.h>
  #include <stdio.h>
  #include <string.h>
  
  #include "private/ScopedReaddir.h"
  
  static bool __matches_cpuN(const char* s) {
    // The %c trick is to ensure that we have the anchored match "^cpu[0-9]+$".
    unsigned cpu;
    char dummy;
    return (sscanf(s, "cpu%u%c", &cpu, &dummy) == 1);
  }
  
  int get_nprocs_conf() {
    // On x86 kernels you can use /proc/cpuinfo for this, but on ARM kernels offline CPUs disappear
    // from there. This method works on both.
    ScopedReaddir reader("/sys/devices/system/cpu");
    if (reader.IsBad()) {
      return 1;
    }
  
    int result = 0;
    dirent* entry;
    while ((entry = reader.ReadEntry()) != NULL) {
      if (entry->d_type == DT_DIR && __matches_cpuN(entry->d_name)) {
        ++result;
      }
    }
    return result;
  }
  
  int get_nprocs() {
    FILE* fp = fopen("/proc/stat", "re");
    if (fp == NULL) {
      return 1;
    }
  
    int result = 0;
    char buf[256];
    while (fgets(buf, sizeof(buf), fp) != NULL) {
      // Extract just the first word from the line.
      // 'cpu0 7976751 1364388 3116842 469770388 8629405 0 49047 0 0 0'
      char* p = strchr(buf, ' ');
      if (p != NULL) {
        *p = 0;
      }
      if (__matches_cpuN(buf)) {
        ++result;
      }
    }
    fclose(fp);
    return result;
  }
  
  static int __get_meminfo_page_count(const char* pattern) {
    FILE* fp = fopen("/proc/meminfo", "re");
    if (fp == NULL) {
      return -1;
    }
  
    int page_count = -1;
    char buf[256];
    while (fgets(buf, sizeof(buf), fp) != NULL) {
      long total;
      if (sscanf(buf, pattern, &total) == 1) {
        page_count = static_cast<int>(total / (PAGE_SIZE / 1024));
        break;
      }
    }
    fclose(fp);
    return page_count;
  }
  
  long get_phys_pages() {
    return __get_meminfo_page_count("MemTotal: %ld kB");
  }
  
  long get_avphys_pages() {
    return __get_meminfo_page_count("MemFree: %ld kB");
  }
  