procps/proc/meminfo.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/meminfo.h>
#include "procps-private.h"
#define MEMINFO_FILE "/proc/meminfo"
struct meminfo_data {
unsigned long active;
unsigned long inactive;
unsigned long high_free;
unsigned long high_total;
unsigned long low_free;
unsigned long low_total;
unsigned long main_available;
unsigned long main_buffers;
unsigned long main_cached;
unsigned long main_free;
unsigned long main_shared;
unsigned long main_total;
unsigned long main_used;
unsigned long swap_free;
unsigned long swap_total;
unsigned long swap_used;
};
struct procps_meminfo {
int refcount;
int meminfo_fd;
struct meminfo_data data;
};
/*
* procps_meminfo_new:
*
* Create a new container to hold the meminfo information
*
* The initial refcount is 1, and needs to be decremented
* to release the resources of the structure.
*
* Returns: a new meminfo info container
*/
PROCPS_EXPORT int procps_meminfo_new(struct procps_meminfo **info)
{
struct procps_meminfo *m;
m = calloc(1, sizeof(struct procps_meminfo));
if (!m)
return -ENOMEM;
m->refcount = 1;
m->meminfo_fd = -1;
*info = m;
return 0;
}
/*
* procps_meminfo_read:
*
* Read the data out of /proc/meminfo putting the information
* into the supplied info structure
*/
PROCPS_EXPORT int procps_meminfo_read(struct procps_meminfo *info)
{
char buf[8192];
char *head, *tail;
int size;
unsigned long *valptr;
if (info == NULL)
return -1;
memset(&(info->data), 0, sizeof(struct meminfo_data));
/* read in the data */
if (-1 == info->meminfo_fd && (info->meminfo_fd = open(MEMINFO_FILE, O_RDONLY)) == -1) {
return -errno;
}
if (lseek(info->meminfo_fd, 0L, SEEK_SET) == -1) {
return -errno;
}
if ((size = read(info->meminfo_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, "Active:")) {
valptr = &(info->data.active);
} else if (0 == strcmp(head, "Inactive:")) {
valptr = &(info->data.inactive);
} else if (0 == strcmp(head, "HighFree:")) {
valptr = &(info->data.high_free);
} else if (0 == strcmp(head, "HighTotal:")) {
valptr = &(info->data.high_total);
} else if (0 == strcmp(head, "LowFree:")) {
valptr = &(info->data.low_free);
} else if (0 == strcmp(head, "LowTotal:")) {
valptr = &(info->data.low_total);
} else if (0 == strcmp(head, "MemAvailable:")) {
valptr = &(info->data.main_available);
} else if (0 == strcmp(head, "Buffers:")) {
valptr = &(info->data.main_buffers);
} else if (0 == strcmp(head, "Cached:")) {
valptr = &(info->data.main_cached);
} else if (0 == strcmp(head, "MemFree:")) {
valptr = &(info->data.main_free);
} else if (0 == strcmp(head, "Shmem:")) {
valptr = &(info->data.main_shared);
} else if (0 == strcmp(head, "MemTotal:")) {
valptr = &(info->data.main_total);
} else if (0 == strcmp(head, "SwapFree:")) {
valptr = &(info->data.swap_free);
} else if (0 == strcmp(head, "SwapTotal:")) {
valptr = &(info->data.swap_total);
}
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_meminfo *procps_meminfo_ref(struct procps_meminfo *info)
{
if (info == NULL)
return NULL;
info->refcount++;
return info;
}
PROCPS_EXPORT struct procps_meminfo *procps_meminfo_unref(struct procps_meminfo *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_meminfo_get(
struct procps_meminfo *info,
enum meminfo_item item)
{
switch(item) {
case PROCPS_MEMINFO_ACTIVE:
return info->data.active;
case PROCPS_MEMINFO_SWAP_USED:
if (info->data.swap_free > info->data.swap_total)
return 0;
return info->data.swap_total - info->data.swap_free;
}
return 0;
}