lib/system_specific_process_info.c

   1 /*
   2  *
   3  *   Copyright (c) International Business Machines  Corp., 2009
   4  *
   5  *   This program is free software;  you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation; either version 2 of the License, or
   8  *   (at your option) any later version.
   9  *
  10  *   This program is distributed in the hope that it will be useful,
  11  *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  13  *   the GNU General Public License for more details.
  14  *
  15  *   You should have received a copy of the GNU General Public License
  16  *   along with this program;  if not, write to the Free Software
  17  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18  */
  19
  20 /*
  21  *   DESCRIPTION
  22  *      get_max_pids(): Return the maximum number of pids for this system by
  23  *                      reading /proc/sys/kernel/pid_max
  24  *
  25  *      get_free_pids(): Return number of free pids by subtracting the number
  26  *                       of pids currently used ('ps -eT') from max_pids
  27  */
  28
  29
  30 #include <fcntl.h>
  31 #include <limits.h>
  32 #include <sys/types.h>
  33 #include "test.h"
  34
  35 #define BUFSIZE 512
  36
  37 int get_max_pids(void)
  38 {
  39 #ifdef __linux__
  40
  41         FILE *f;
  42         char buf[BUFSIZE];
  43
  44         f = fopen("/proc/sys/kernel/pid_max", "r");
  45         if (!f) {
  46                 tst_resm(TBROK, "Could not open /proc/sys/kernel/pid_max");
  47                 return -1;
  48         }
  49         if (!fgets(buf, BUFSIZE, f)) {
  50                 fclose(f);
  51                 tst_resm(TBROK, "Could not read /proc/sys/kernel/pid_max");
  52                 return -1;
  53         }
  54         fclose(f);
  55         return atoi(buf);
  56 #else
  57         return SHRT_MAX;
  58 #endif
  59 }
  60
  61
  62 int get_free_pids(void)
  63 {
  64         FILE *f;
  65         int rc, used_pids, max_pids;
  66
  67         f = popen("ps -eT | wc -l", "r");
  68         if (!f) {
  69                 tst_resm(TBROK, "Could not run 'ps' to calculate used "
  70                                 "pids");
  71                 return -1;
  72         }
  73         rc = fscanf(f, "%i", &used_pids);
  74         pclose(f);
  75
  76         if (rc != 1 || used_pids < 0) {
  77                 tst_resm(TBROK, "Could not read output of 'ps' to "
  78                                 "calculate used pids");
  79                 return -1;
  80         }
  81
  82         max_pids = get_max_pids();
  83
  84         if (max_pids < 0)
  85                 return -1;
  86
  87         return max_pids - used_pids;
  88 }
  89