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 (2.4 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  16 //config:       The shared memory column should be ignored; it is obsolete.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 };
  48 /* Because of NOFORK, "globals" are not in global data */
  49
  50 static unsigned long long scale(struct globals *g, unsigned long d)
  51 {
  52         return ((unsigned long long)d * g->mem_unit) >> G_unit_steps;
  53 }
  54
  55 /* NOINLINE reduces main() stack usage, which makes code smaller (on x86 at least) */
  56 static NOINLINE unsigned long parse_cached_kb(void)
  57 {
  58         char buf[60]; /* actual lines we expect are ~30 chars or less */
  59         FILE *fp;
  60         unsigned long cached = 0;
  61
  62         fp = xfopen_for_read("/proc/meminfo");
  63         while (fgets(buf, sizeof(buf), fp) != NULL) {
  64                 if (sscanf(buf, "Cached: %lu %*s\n", &cached) == 1)
  65                         break;
  66         }
  67         /* Have to close because of NOFORK */
  68         fclose(fp);
  69
  70         return cached;
  71 }
  72
  73 int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  74 int free_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
  75 {
  76         struct globals G;
  77         struct sysinfo info;
  78         unsigned long long cached;
  79
  80 #if ENABLE_DESKTOP
  81         G.unit_steps = 10;
  82         if (argv[1] && argv[1][0] == '-') {
  83                 switch (argv[1][1]) {
  84                 case 'b':
  85                         G.unit_steps = 0;
  86                         break;
  87                 case 'k': /* 2^10 */
  88                         /* G.unit_steps = 10; - already is */
  89                         break;
  90                 case 'm': /* 2^(2*10) */
  91                         G.unit_steps = 20;
  92                         break;
  93                 case 'g': /* 2^(3*10) */
  94                         G.unit_steps = 30;
  95                         break;
  96                 default:
  97                         bb_show_usage();
  98                 }
  99         }
 100 #endif
 101         printf("       %11s%11s%11s%11s%11s%11s\n"
 102         "Mem:   ",
 103                 "total",
 104                 "used",
 105                 "free",
 106                 "shared", "buffers", "cached" /* swap and total don't have these columns */
 107         );
 108
 109         sysinfo(&info);
 110         /* Kernels prior to 2.4.x will return info.mem_unit==0, so cope... */
 111         G.mem_unit = (info.mem_unit ? info.mem_unit : 1);
 112         /* Extract cached from /proc/meminfo and convert to mem_units */
 113         cached = ((unsigned long long) parse_cached_kb() * 1024) / G.mem_unit;
 114
 115 #define FIELDS_6 "%11llu%11llu%11llu%11llu%11llu%11llu\n"
 116 #define FIELDS_3 (FIELDS_6 + 3*6)
 117 #define FIELDS_2 (FIELDS_6 + 4*6)
 118
 119         printf(FIELDS_6,
 120                 scale(&G, info.totalram),                //total
 121                 scale(&G, info.totalram - info.freeram), //used
 122                 scale(&G, info.freeram),                 //free
 123                 scale(&G, info.sharedram),               //shared
 124                 scale(&G, info.bufferram),               //buffers
 125                 scale(&G, cached)                        //cached
 126         );
 127         /* Show alternate, more meaningful busy/free numbers by counting
 128          * buffer cache as free memory. */
 129         printf("-/+ buffers/cache:");
 130         cached += info.freeram;
 131         cached += info.bufferram;
 132         printf(FIELDS_2,
 133                 scale(&G, info.totalram - cached), //used
 134                 scale(&G, cached)                  //free
 135         );
 136 #if BB_MMU
 137         printf("Swap:  ");
 138         printf(FIELDS_3,
 139                 scale(&G, info.totalswap),                 //total
 140                 scale(&G, info.totalswap - info.freeswap), //used
 141                 scale(&G, info.freeswap)                   //free
 142         );
 143 #endif
 144         return EXIT_SUCCESS;
 145 }