procps/proc/vmstat.c
Jim Warner 74beff80ff library: make reads & unref logic a little more robust
Since we are not using a higher level standard C fopen
all of the read requests were made signal sensitive as
that can result in a 'temporarily' failed i/o request.

Also, protection against some user calling the 'unref'
function on already free memory has been incorporated.
This will protect us from some nasty 'Abort' surprise.

Signed-off-by: Jim Warner <james.warner@comcast.net>
2015-06-29 21:30:48 +10:00

196 lines
4.4 KiB
C

#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;
}
for (;;) {
if ((size = read(info->vmstat_fd, buf, sizeof(buf)-1)) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
return -errno;
}
break;
}
if (size == 0)
return 0;
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 || info->refcount == 0)
return NULL;
info->refcount--;
if (info->refcount > 0)
return info;
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;
}
PROCPS_EXPORT int procps_vmstat_get_chain (
struct procps_vmstat *info,
struct vmstat_result *item)
{
if (item == NULL)
return -EINVAL;
do {
switch (item->item) {
case PROCPS_VMSTAT_PGPGIN:
item->result = info->data.pgpgin;
break;
case PROCPS_VMSTAT_PGPGOUT:
item->result = info->data.pgpgout;
break;
case PROCPS_VMSTAT_PSWPIN:
item->result = info->data.pswpin;
break;
case PROCPS_VMSTAT_PSWPOUT:
item->result = info->data.pswpout;
break;
default:
return -EINVAL;
}
item = item->next;
} while (item);
return 0;
}