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      1 /*
      2  * Copyright (C) 2014 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 <sys/sysinfo.h>
     30 
     31 #include <dirent.h>
     32 #include <limits.h>
     33 #include <stdio.h>
     34 #include <string.h>
     35 
     36 #include "private/ScopedReaddir.h"
     37 
     38 static bool __matches_cpuN(const char* s) {
     39   // The %c trick is to ensure that we have the anchored match "^cpu[0-9]+$".
     40   unsigned cpu;
     41   char dummy;
     42   return (sscanf(s, "cpu%u%c", &cpu, &dummy) == 1);
     43 }
     44 
     45 int get_nprocs_conf() {
     46   // On x86 kernels you can use /proc/cpuinfo for this, but on ARM kernels offline CPUs disappear
     47   // from there. This method works on both.
     48   ScopedReaddir reader("/sys/devices/system/cpu");
     49   if (reader.IsBad()) {
     50     return 1;
     51   }
     52 
     53   int result = 0;
     54   dirent* entry;
     55   while ((entry = reader.ReadEntry()) != NULL) {
     56     if (entry->d_type == DT_DIR && __matches_cpuN(entry->d_name)) {
     57       ++result;
     58     }
     59   }
     60   return result;
     61 }
     62 
     63 int get_nprocs() {
     64   FILE* fp = fopen("/proc/stat", "re");
     65   if (fp == NULL) {
     66     return 1;
     67   }
     68 
     69   int result = 0;
     70   char buf[256];
     71   while (fgets(buf, sizeof(buf), fp) != NULL) {
     72     // Extract just the first word from the line.
     73     // 'cpu0 7976751 1364388 3116842 469770388 8629405 0 49047 0 0 0'
     74     char* p = strchr(buf, ' ');
     75     if (p != NULL) {
     76       *p = 0;
     77     }
     78     if (__matches_cpuN(buf)) {
     79       ++result;
     80     }
     81   }
     82   fclose(fp);
     83   return result;
     84 }
     85 
     86 static int __get_meminfo_page_count(const char* pattern) {
     87   FILE* fp = fopen("/proc/meminfo", "re");
     88   if (fp == NULL) {
     89     return -1;
     90   }
     91 
     92   int page_count = -1;
     93   char buf[256];
     94   while (fgets(buf, sizeof(buf), fp) != NULL) {
     95     long total;
     96     if (sscanf(buf, pattern, &total) == 1) {
     97       page_count = static_cast<int>(total / (PAGE_SIZE / 1024));
     98       break;
     99     }
    100   }
    101   fclose(fp);
    102   return page_count;
    103 }
    104 
    105 long get_phys_pages() {
    106   return __get_meminfo_page_count("MemTotal: %ld kB");
    107 }
    108 
    109 long get_avphys_pages() {
    110   return __get_meminfo_page_count("MemFree: %ld kB");
    111 }
    112