sysinfo.c

linux下获取一些环境信息的代码

/***********************************************************************/
void loadavg(double *restrict av1, double *restrict av5, double *restrict av15) {
    double avg_1=0, avg_5=0, avg_15=0;
    char *restrict savelocale;
    
    FILE_TO_BUF(LOADAVG_FILE,loadavg_fd);
    savelocale = setlocale(LC_NUMERIC, NULL);
    setlocale(LC_NUMERIC, "C");
    if (sscanf(buf, "%lf %lf %lf", &avg_1, &avg_5, &avg_15) < 3) {
	fputs("bad data in " LOADAVG_FILE "\n", stderr);
	exit(1);
    }
    setlocale(LC_NUMERIC, savelocale);
    SET_IF_DESIRED(av1,  avg_1);
    SET_IF_DESIRED(av5,  avg_5);
    SET_IF_DESIRED(av15, avg_15);
}

  static char buff[BUFFSIZE]; /* used in the procedures */
/***********************************************************************/

static void crash(const char *filename) {
    perror(filename);
    exit(EXIT_FAILURE);
}

/***********************************************************************/

static void getrunners(unsigned int *restrict running, unsigned int *restrict blocked) {
  struct direct *ent;
  DIR *proc;

  *running=0;
  *blocked=0;

  if((proc=opendir("/proc"))==NULL) crash("/proc");

  while(( ent=readdir(proc) )) {
    char tbuf[32];
    char *cp;
    int fd;
    char c;

    if (!isdigit(ent->d_name[0])) continue;
    sprintf(tbuf, "/proc/%s/stat", ent->d_name);

    fd = open(tbuf, O_RDONLY, 0);
    if (fd == -1) continue;
    memset(tbuf, '\0', sizeof tbuf); // didn't feel like checking read()
    read(fd, tbuf, sizeof tbuf - 1); // need 32 byte buffer at most
    close(fd);

    cp = strrchr(tbuf, ')');
    if(!cp) continue;
    c = cp[2];

    if (c=='R') {
      (*running)++;
      continue;
    }
    if (c=='D') {
      (*blocked)++;
      continue;
    }
  }
  closedir(proc);
}

/***********************************************************************/

void getstat(jiff *restrict cuse, jiff *restrict cice, jiff *restrict csys, jiff *restrict cide, jiff *restrict ciow, jiff *restrict cxxx, jiff *restrict cyyy, jiff *restrict czzz,
	     unsigned long *restrict pin, unsigned long *restrict pout, unsigned long *restrict s_in, unsigned long *restrict sout,
	     unsigned *restrict intr, unsigned *restrict ctxt,
	     unsigned int *restrict running, unsigned int *restrict blocked,
	     unsigned int *restrict btime, unsigned int *restrict processes) {
  static int fd;
  unsigned long long llbuf = 0;
  int need_vmstat_file = 0;
  int need_proc_scan = 0;
  const char* b;
  buff[BUFFSIZE-1] = 0;  /* ensure null termination in buffer */

  if(fd){
    lseek(fd, 0L, SEEK_SET);
  }else{
    fd = open("/proc/stat", O_RDONLY, 0);
    if(fd == -1) crash("/proc/stat");
  }
  read(fd,buff,BUFFSIZE-1);
  *intr = 0; 
  *ciow = 0;  /* not separated out until the 2.5.41 kernel */
  *cxxx = 0;  /* not separated out until the 2.6.0-test4 kernel */
  *cyyy = 0;  /* not separated out until the 2.6.0-test4 kernel */
  *czzz = 0;  /* not separated out until the 2.6.11 kernel */

  b = strstr(buff, "cpu ");
  if(b) sscanf(b,  "cpu  %Lu %Lu %Lu %Lu %Lu %Lu %Lu %Lu", cuse, cice, csys, cide, ciow, cxxx, cyyy, czzz);

  b = strstr(buff, "page ");
  if(b) sscanf(b,  "page %lu %lu", pin, pout);
  else need_vmstat_file = 1;

  b = strstr(buff, "swap ");
  if(b) sscanf(b,  "swap %lu %lu", s_in, sout);
  else need_vmstat_file = 1;

  b = strstr(buff, "intr ");
  if(b) sscanf(b,  "intr %Lu", &llbuf);
  *intr = llbuf;

  b = strstr(buff, "ctxt ");
  if(b) sscanf(b,  "ctxt %Lu", &llbuf);
  *ctxt = llbuf;

  b = strstr(buff, "btime ");
  if(b) sscanf(b,  "btime %u", btime);

  b = strstr(buff, "processes ");
  if(b) sscanf(b,  "processes %u", processes);

  b = strstr(buff, "procs_running ");
  if(b) sscanf(b,  "procs_running %u", running);
  else need_proc_scan = 1;

  b = strstr(buff, "procs_blocked ");
  if(b) sscanf(b,  "procs_blocked %u", blocked);
  else need_proc_scan = 1;

  if(need_proc_scan){   /* Linux 2.5.46 (approximately) and below */
    getrunners(running, blocked);
  }

  (*running)--;   // exclude vmstat itself

  if(need_vmstat_file){  /* Linux 2.5.40-bk4 and above */
    vminfo();
    *pin  = vm_pgpgin;
    *pout = vm_pgpgout;
    *s_in = vm_pswpin;
    *sout = vm_pswpout;
  }
}

/***********************************************************************/
/*
 * Copyright 1999 by Albert Cahalan; all rights reserved.
 * This file may be used subject to the terms and conditions of the
 * GNU Library General Public License Version 2, or any later version
 * at your option, as published by the Free Software Foundation.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Library General Public License for more details.
 */

typedef struct mem_table_struct {
  const char *name;     /* memory type name */
  unsigned long *slot; /* slot in return struct */
} mem_table_struct;

static int compare_mem_table_structs(const void *a, const void *b){
  return strcmp(((const mem_table_struct*)a)->name,((const mem_table_struct*)b)->name);
}

/* example data, following junk, with comments added:
 *
 * MemTotal:        61768 kB    old
 * MemFree:          1436 kB    old
 * MemShared:           0 kB    old (now always zero; not calculated)
 * Buffers:          1312 kB    old
 * Cached:          20932 kB    old
 * Active:          12464 kB    new
 * Inact_dirty:      7772 kB    new
 * Inact_clean:      2008 kB    new
 * Inact_target:        0 kB    new
 * Inact_laundry:       0 kB    new, and might be missing too
 * HighTotal:           0 kB
 * HighFree:            0 kB
 * LowTotal:        61768 kB
 * LowFree:          1436 kB
 * SwapTotal:      122580 kB    old
 * SwapFree:        60352 kB    old
 * Inactive:        20420 kB    2.5.41+
 * Dirty:               0 kB    2.5.41+
 * Writeback:           0 kB    2.5.41+
 * Mapped:           9792 kB    2.5.41+
 * Slab:             4564 kB    2.5.41+
 * Committed_AS:     8440 kB    2.5.41+
 * PageTables:        304 kB    2.5.41+
 * ReverseMaps:      5738       2.5.41+
 * SwapCached:          0 kB    2.5.??+
 * HugePages_Total:   220       2.5.??+
 * HugePages_Free:    138       2.5.??+
 * Hugepagesize:     4096 kB    2.5.??+
 */

/* obsolete */
unsigned long kb_main_shared;
/* old but still kicking -- the important stuff */
unsigned long kb_main_buffers;
unsigned long kb_main_cached;
unsigned long kb_main_free;
unsigned long kb_main_total;
unsigned long kb_swap_free;
unsigned long kb_swap_total;
/* recently introduced */
unsigned long kb_high_free;
unsigned long kb_high_total;
unsigned long kb_low_free;
unsigned long kb_low_total;
/* 2.4.xx era */
unsigned long kb_active;
unsigned long kb_inact_laundry;
unsigned long kb_inact_dirty;
unsigned long kb_inact_clean;
unsigned long kb_inact_target;
unsigned long kb_swap_cached;  /* late 2.4 and 2.6+ only */
/* derived values */
unsigned long kb_swap_used;
unsigned long kb_main_used;
/* 2.5.41+ */
unsigned long kb_writeback;
unsigned long kb_slab;
unsigned long nr_reversemaps;
unsigned long kb_committed_as;
unsigned long kb_dirty;
unsigned long kb_inactive;
unsigned long kb_mapped;
unsigned long kb_pagetables;
// seen on a 2.6.x kernel:
static unsigned long kb_vmalloc_chunk;
static unsigned long kb_vmalloc_total;
static unsigned long kb_vmalloc_used;

void meminfo(void){
  char namebuf[16]; /* big enough to hold any row name */
  mem_table_struct findme = { namebuf, NULL};
  mem_table_struct *found;
  char *head;
  char *tail;
  static const mem_table_struct mem_table[] = {
  {"Active",       &kb_active},       // important
  {"Buffers",      &kb_main_buffers}, // important
  {"Cached",       &kb_main_cached},  // important
  {"Committed_AS", &kb_committed_as},
  {"Dirty",        &kb_dirty},        // kB version of vmstat nr_dirty
  {"HighFree",     &kb_high_free},
  {"HighTotal",    &kb_high_total},
  {"Inact_clean",  &kb_inact_clean},
  {"Inact_dirty",  &kb_inact_dirty},
  {"Inact_laundry",&kb_inact_laundry},
  {"Inact_target", &kb_inact_target},
  {"Inactive",     &kb_inactive},     // important
  {"LowFree",      &kb_low_free},
  {"LowTotal",     &kb_low_total},
  {"Mapped",       &kb_mapped},       // kB version of vmstat nr_mapped
  {"MemFree",      &kb_main_free},    // important
  {"MemShared",    &kb_main_shared},  // important, but now gone!
  {"MemTotal",     &kb_main_total},   // important
  {"PageTables",   &kb_pagetables},   // kB version of vmstat nr_page_table_pages
  {"ReverseMaps",  &nr_reversemaps},  // same as vmstat nr_page_table_pages
  {"Slab",         &kb_slab},         // kB version of vmstat nr_slab
  {"SwapCached",   &kb_swap_cached},
  {"SwapFree",     &kb_swap_free},    // important
  {"SwapTotal",    &kb_swap_total},   // important
  {"VmallocChunk", &kb_vmalloc_chunk},
  {"VmallocTotal", &kb_vmalloc_total},
  {"VmallocUsed",  &kb_vmalloc_used},
  {"Writeback",    &kb_writeback},    // kB version of vmstat nr_writeback
  };
  const int mem_table_count = sizeof(mem_table)/sizeof(mem_table_struct);

  FILE_TO_BUF(MEMINFO_FILE,meminfo_fd);

  kb_inactive = ~0UL;

  head = buf;
  for(;;){
    tail = strchr(head, ':');
    if(!tail) break;
    *tail = '\0';
    if(strlen(head) >= sizeof(namebuf)){
      head = tail+1;
      goto nextline;
    }
    strcpy(namebuf,head);
    found = bsearch(&findme, mem_table, mem_table_count,
        sizeof(mem_table_struct), compare_mem_table_structs
    );
    head = tail+1;
    if(!found) goto nextline;
    *(found->slot) = strtoul(head,&tail,10);
nextline:
    tail = strchr(head, '\n');
    if(!tail) break;
    head = tail+1;
  }
  if(!kb_low_total){  /* low==main except with large-memory support */
    kb_low_total = kb_main_total;