procps/free.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini free implementation for busybox
   4  *
   5  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   6  *
   7  * Licensed under GPLv2, see file LICENSE in this source tree.
   8  */
   9 //config:config FREE
  10 //config:       bool "free (3.1 kb)"
  11 //config:       default y
  12 //config:       select PLATFORM_LINUX #sysinfo()
  13 //config:       help
  14 //config:       free displays the total amount of free and used physical and swap
  15 //config:       memory in the system, as well as the buffers used by the kernel.
  16 //config:       The shared memory column should be ignored; it is obsolete.
  17
  18 //applet:IF_FREE(APPLET_NOFORK(free, free, BB_DIR_USR_BIN, BB_SUID_DROP, free))
  19
  20 //kbuild:lib-$(CONFIG_FREE) += free.o
  21
  22 //usage:#define free_trivial_usage
  23 //usage:       "" IF_DESKTOP("[-b/k/m/g]")
  24 //usage:#define free_full_usage "\n\n"
  25 //usage:       "Display the amount of free and used system memory"
  26 //usage:
  27 //usage:#define free_example_usage
  28 //usage:       "$ free\n"
  29 //usage:       "              total         used         free       shared      buffers\n"
  30 //usage:       "  Mem:       257628       248724         8904        59644        93124\n"
  31 //usage:       " Swap:       128516         8404       120112\n"
  32 //usage:       "Total:       386144       257128       129016\n"
  33
  34 #include "libbb.h"
  35 #ifdef __linux__
  36 # include <sys/sysinfo.h>
  37 #endif
  38
  39 struct globals {
  40         unsigned mem_unit;
  41 #if ENABLE_DESKTOP
  42         uint8_t unit_steps;
  43 # define G_unit_steps g->unit_steps
  44 #else
  45 # define G_unit_steps 10
  46 #endif
  47         unsigned long cached_kb, available_kb, reclaimable_kb;
  48 };
  49 /* Because of NOFORK, "globals" are not in global data */
  50
  51 static unsigned long long scale(struct globals *g, unsigned long d)
  52 {
  53         return ((unsigned long long)d * g->mem_unit) >> G_unit_steps;
  54 }
  55
  56 /* NOINLINE reduces main() stack usage, which makes code smaller (on x86 at least) */
  57 static NOINLINE unsigned int parse_meminfo(struct globals *g)
  58 {
  59         char buf[60]; /* actual lines we expect are ~30 chars or less */
  60         FILE *fp;
  61         int seen_cached_and_available_and_reclaimable;
  62
  63         fp = xfopen_for_read("/proc/meminfo");
  64         g->cached_kb = g->available_kb = g->reclaimable_kb = 0;
  65         seen_cached_and_available_and_reclaimable = 3;
  66         while (fgets(buf, sizeof(buf), fp)) {
  67                 if (sscanf(buf, "Cached: %lu %*s\n", &g->cached_kb) == 1)
  68                         if (--seen_cached_and_available_and_reclaimable == 0)
  69                                 break;
  70                 if (sscanf(buf, "MemAvailable: %lu %*s\n", &g->available_kb) == 1)
  71                         if (--seen_cached_and_available_and_reclaimable == 0)
  72                                 break;
  73                 if (sscanf(buf, "SReclaimable: %lu %*s\n", &g->reclaimable_kb) == 1)
  74                         if (--seen_cached_and_available_and_reclaimable == 0)
  75                                 break;
  76         }
  77         /* Have to close because of NOFORK */
  78         fclose(fp);
  79
  80         return seen_cached_and_available_and_reclaimable == 0;
  81 }
  82
  83 int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  84 int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
  85 {
  86         struct globals G;
  87         struct sysinfo info;
  88         unsigned long long cached, cached_plus_free, available;
  89         int seen_available;
  90
  91 #if ENABLE_DESKTOP
  92         G.unit_steps = 10;
  93         if (argv[1] && argv[1][0] == '-') {
  94                 switch (argv[1][1]) {
  95                 case 'b':
  96                         G.unit_steps = 0;
  97                         break;
  98                 case 'k': /* 2^10 */
  99                         /* G.unit_steps = 10; - already is */
 100                         break;
 101                 case 'm': /* 2^(2*10) */
 102                         G.unit_steps = 20;
 103                         break;
 104                 case 'g': /* 2^(3*10) */
 105                         G.unit_steps = 30;
 106                         break;
 107                 default:
 108                         bb_show_usage();
 109                 }
 110         }
 111 #endif
 112         printf("       %12s%12s%12s%12s%12s%12s\n"
 113         "Mem:   ",
 114                 "total",
 115                 "used",
 116                 "free",
 117                 "shared", "buff/cache", "available" /* swap and total don't have these columns */
 118         );
 119
 120         sysinfo(&info);
 121         /* Kernels prior to 2.4.x will return info.mem_unit==0, so cope... */
 122         G.mem_unit = (info.mem_unit ? info.mem_unit : 1);
 123         /* Extract cached and memavailable from /proc/meminfo and convert to mem_units */
 124         seen_available = parse_meminfo(&G);
 125         available = ((unsigned long long) G.available_kb * 1024) / G.mem_unit;
 126         cached = ((unsigned long long) G.cached_kb * 1024) / G.mem_unit;
 127         cached += info.bufferram;
 128         cached += ((unsigned long long) G.reclaimable_kb * 1024) / G.mem_unit;
 129         cached_plus_free = cached + info.freeram;
 130
 131 #define FIELDS_6 "%12llu %11llu %11llu %11llu %11llu %11llu\n"
 132 #define FIELDS_3 (FIELDS_6 + 6 + 7 + 7)
 133 #define FIELDS_2 (FIELDS_6 + 6 + 7 + 7 + 7)
 134
 135         printf(FIELDS_6,
 136                 scale(&G, info.totalram),                //total
 137                 scale(&G, info.totalram - cached_plus_free), //used
 138                 scale(&G, info.freeram),                 //free
 139                 scale(&G, info.sharedram),               //shared
 140                 scale(&G, cached),                       //buff/cache
 141                 scale(&G, available)                     //available
 142         );
 143         /* On kernels < 3.14, MemAvailable is not provided.
 144          * Show alternate, more meaningful busy/free numbers by counting
 145          * buffer cache as free memory. */
 146         if (!seen_available) {
 147                 printf("-/+ buffers/cache: ");
 148                 printf(FIELDS_2,
 149                         scale(&G, info.totalram - cached_plus_free), //used
 150                         scale(&G, cached_plus_free)                  //free
 151                 );
 152         }
 153 #if BB_MMU
 154         printf("Swap:  ");
 155         printf(FIELDS_3,
 156                 scale(&G, info.totalswap),                 //total
 157                 scale(&G, info.totalswap - info.freeswap), //used
 158                 scale(&G, info.freeswap)                   //free
 159         );
 160 #endif
 161         return EXIT_SUCCESS;
 162 }