/*
 * mem_linux.c - module to get memory/swap usages, for GNU/Linxu
 *
 * Copyright(C) 2001,2002  Seiichi SATO <ssato@sh.rim.or.jp>
 * Copyright(C) 2001       John McCutchan <ttb@tentacle.dhs.org>
 *
 * licensed under the GPL
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

#if defined(HAVE_STRING_H)
#include <string.h>
#elif defined(HAVE_STRINGS_H)
#include <strings.h>
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#include <sys/utsname.h>
#include "mem.h"

static int isnewformat = 0; /* for kernel 2.5.1 or later */

#ifdef DEBUG
#  define INLINE_STATIC static
#else
#  define INLINE_STATIC inline static
#endif

/* initialize function */
void mem_init(void)
{
   struct utsname un;
   int version, patchlevel, sublevel;

   /* get kernel version */
   if (uname(&un) == -1)
      perror ("uname()");
   sscanf (un.release, "%d.%d.%d", &version, &patchlevel, &sublevel);

   /* new format ? (kernel >= 2.5.1pre?) */
   /* see linux/fs/proc/proc_misc.c */
   if (version >= 2 && patchlevel >= 5 && sublevel >= 1 || \
       version >= 2 && patchlevel >= 6 && sublevel >= 0)
      isnewformat = 1;
}


INLINE_STATIC char * skip_line (const char *p)
{
   while (*p != '\n') p++;
   return (char *) ++p;
}

INLINE_STATIC char * skip_token (const char *p)
{
   while (isspace(*p)) p++;
   while (*p && !isspace(*p)) p++;
   return (char *)p;
}

INLINE_STATIC char * skip_multiple_token (const char *p, int count)
{
   int i;
   for (i = 0; i < count; i++) p = skip_token (p);
   return (char *)p;
}

/* return mem/swap usage in percent 0 to 100 */
void mem_getusage(int *per_mem, int *per_swap, const struct mem_options *opts)
{
   char buffer[BUFSIZ], *p;
   int fd, len, i;
   u_int64_t mtotal, mused, mfree, mbuffer, mcached;
   u_int64_t stotal, sused, sfree, scached = 0;

   /* read /proc/meminfo */
   fd = open("/proc/meminfo", O_RDONLY);
   if (fd < 0) {
      perror("can't open /proc/meminfo");
      exit(1);
   }
   len = read(fd, buffer, BUFSIZ - 1);
   if (len < 0) {
      perror("can't read /proc/meminfo");
      exit(1);
   }
   close(fd);

   buffer[len] = '\0';
   p = buffer;

   if (!isnewformat) {
      /* skip 3 lines */
      for (i = 0; i < 3; i++)
         p = skip_line(p);
      p = skip_token(p);
      /* examine each line of file */
      mtotal  = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      mfree   = strtoul(p, &p, 0); p = skip_multiple_token(p, 5);
      mbuffer = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      mcached = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      scached = strtoul(p, &p, 0);
   }
   else {
      p = skip_token(p);
      /* examine each line of file */
      mtotal  = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      mfree   = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      mbuffer = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      mcached = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
      scached = strtoul(p, &p, 0);
   }


   /* skip N lines and examine info about swap */
   /* kernel-2.4.2:N=8  2.4.16:N=7  */
   while (isprint(p[0])) {
      p = skip_line(p);
      if (strncmp(p, "SwapTotal", 9) == 0) break;
   }

   p = skip_token(p);
   stotal = strtoul(p, &p, 0); p = skip_multiple_token(p, 2);
   sfree  = strtoul(p, &p, 0);

   /* calculate memory usage in percent */
   mused = mtotal - mfree;
   if (opts->ignore_buffers)
      mused -= mbuffer;
   if (opts->ignore_cached)
      mused -= mcached;
   *per_mem = 100 * (double) mused / (double) mtotal;

   /* calculate swap usage in percent */
   sused = stotal - sfree;
   if(opts->ignore_cached)
      sused -= scached;
   if (!stotal) {
      *per_swap = 0;
   } else {
      *per_swap = 100 * (double) sused / (double) stotal;
   }

#if DEBUG
   printf("-----------------------\n");
   printf("MemTotal:  %12ld\n", (unsigned long)mtotal);
   printf("MemFree:   %12ld\n", (unsigned long)mfree);
   printf("Buffers:   %12ld\n", (unsigned long)mbuffer);
   printf("Cached:    %12ld\n", (unsigned long)mcached);
   printf("SwapTotal: %12ld\n", (unsigned long)stotal);
   printf("SwapFree:  %12ld\n", (unsigned long)sfree);
   printf("SwapCached:%12ld\n", (unsigned long)scached);
   printf("-----------------------\n\n");
#endif

}