coreutils/nproc.c

   1 /*
   2  * Copyright (C) 2017 Denys Vlasenko <vda.linux@googlemail.com>
   3  *
   4  * Licensed under GPLv2, see LICENSE in this source tree
   5  */
   6 //config:config NPROC
   7 //config:       bool "nproc (248 bytes)"
   8 //config:       default y
   9 //config:       help
  10 //config:       Print number of CPUs
  11
  12 //applet:IF_NPROC(APPLET_NOFORK(nproc, nproc, BB_DIR_USR_BIN, BB_SUID_DROP, nproc))
  13
  14 //kbuild:lib-$(CONFIG_NPROC) += nproc.o
  15
  16 //usage:#define nproc_trivial_usage
  17 //usage:        ""IF_LONG_OPTS("--all --ignore=N")
  18 //usage:#define nproc_full_usage "\n\n"
  19 //usage:        "Print number of available CPUs"
  20 //usage:        IF_LONG_OPTS(
  21 //usage:     "\n"
  22 //usage:     "\n        --all           Number of installed CPUs"
  23 //usage:     "\n        --ignore=N      Exclude N CPUs"
  24 //usage:        )
  25
  26 #include <sched.h>
  27 #include "libbb.h"
  28
  29 int nproc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  30 int nproc_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
  31 {
  32         unsigned long mask[1024];
  33         int count = 0;
  34 #if ENABLE_LONG_OPTS
  35         int ignore = 0;
  36         int opts = getopt32long(argv, "\xfe:+",
  37                         "ignore\0" Required_argument "\xfe"
  38                         "all\0"    No_argument       "\xff"
  39                         , &ignore
  40         );
  41
  42         if (opts & (1 << 1)) {
  43                 DIR *cpusd = opendir("/sys/devices/system/cpu");
  44                 if (cpusd) {
  45                         struct dirent *de;
  46                         while (NULL != (de = readdir(cpusd))) {
  47                                 char *cpuid = strstr(de->d_name, "cpu");
  48                                 if (cpuid && isdigit(cpuid[strlen(cpuid) - 1]))
  49                                         count++;
  50                         }
  51                         closedir(cpusd);
  52                 }
  53         } else
  54 #endif
  55         if (sched_getaffinity(0, sizeof(mask), (void*)mask) == 0) {
  56                 int i;
  57                 for (i = 0; i < ARRAY_SIZE(mask); i++) {
  58                         unsigned long m = mask[i];
  59                         while (m) {
  60                                 if (m & 1)
  61                                         count++;
  62                                 m >>= 1;
  63                         }
  64                 }
  65         }
  66
  67         IF_LONG_OPTS(count -= ignore;)
  68         if (count <= 0)
  69                 count = 1;
  70
  71         printf("%u\n", count);
  72
  73         return 0;
  74 }