procps/proc/vmstat.c

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#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <proc/vmstat.h>
#include "procps-private.h"
#define VMSTAT_FILE "/proc/vmstat"
#define ROW_NAME_LEN 32
struct vmstat_data {
unsigned long pgpgin;
unsigned long pgpgout;
unsigned long pswpin;
unsigned long pswpout;
};
struct mem_table_struct {
const char *name;
unsigned long *slot;
};
struct procps_vmstat {
int refcount;
int vmstat_fd;
struct vmstat_data data;
};
/*
* procps_vmstat_new:
*
* Create a new container to hold the vmstat information
*
* The initial refcount is 1, and needs to be decremented
* to release the resources of the structure.
*
* Returns: a new procps_vmstat container
*/
PROCPS_EXPORT int procps_vmstat_new(struct procps_vmstat **info)
{
struct procps_vmstat *v;
v = calloc(1, sizeof(struct procps_vmstat));
if (!v)
return -ENOMEM;
v->refcount = 1;
v->vmstat_fd = -1;
*info = v;
return 0;
}
/*
* procps_vmstat_read:
*
* Read the data out of /proc/vmstat putting the information
* into the supplied info structure
*
* Returns: 0 on success, negative on error
*/
PROCPS_EXPORT int procps_vmstat_read(struct procps_vmstat *info)
{
char buf[8192];
char *head, *tail;
int size;
unsigned long *valptr;
if (info == NULL)
return -1;
memset(&(info->data), 0, sizeof(struct vmstat_data));
/* read in the data */
if (-1 == info->vmstat_fd && (info->vmstat_fd = open(VMSTAT_FILE, O_RDONLY)) == -1) {
return -errno;
}
if (lseek(info->vmstat_fd, 0L, SEEK_SET) == -1) {
return -errno;
}
if ((size = read(info->vmstat_fd, buf, sizeof(buf)-1)) < 0) {
return -1;
}
buf[size] = '\0';
/* Scan the file */
head = buf;
do {
tail = strchr(head, ' ');
if (!tail)
break;
*tail = '\0';
valptr = NULL;
if (0 == strcmp(head, "pgpgin")) {
valptr = &(info->data.pgpgin);
}else if (0 == strcmp(head, "pgpgout")) {
valptr = &(info->data.pgpgout);
}else if (0 == strcmp(head, "pswpin")) {
valptr = &(info->data.pswpin);
}else if (0 == strcmp(head, "pswpout")) {
valptr = &(info->data.pswpout);
}
head = tail+1;
if (valptr) {
*valptr = strtoul(head, &tail, 10);
}
tail = strchr(head, '\n');
if (!tail)
break;
head = tail + 1;
} while(tail);
return 0;
}
PROCPS_EXPORT struct procps_vmstat *procps_vmstat_ref(struct procps_vmstat *info)
{
if (info == NULL)
return NULL;
info->refcount++;
return info;
}
PROCPS_EXPORT struct procps_vmstat *procps_vmstat_unref(struct procps_vmstat *info)
{
if (info == NULL)
return NULL;
info->refcount--;
if (info->refcount > 0)
return NULL;
free(info);
return NULL;
}
/* Accessor functions */
PROCPS_EXPORT unsigned long procps_vmstat_get(
struct procps_vmstat *info,
enum vmstat_item item)
{
switch(item) {
case PROCPS_VMSTAT_PGPGIN:
return info->data.pgpgin;
case PROCPS_VMSTAT_PGPGOUT:
return info->data.pgpgout;
case PROCPS_VMSTAT_PSWPIN:
return info->data.pswpin;
case PROCPS_VMSTAT_PSWPOUT:
return info->data.pswpout;
}
return 0;
}