PROCESS INFO

[Killer B]

Hi I am trying to read the resource usage of each process in the
system . 
	The structure for each process has a pointer to a resource
structure.After getting process information, when I try to print
its resource usage, I am getting some garbage. Infact the contents 
of the pointer to resource structure , is 0, or in other words this
pointer is pointing to location 0.

Could you suggest some method, and also if I want to print for all the
processes ,should I check for EOF of file 'kmem'. Thanx in advance

Incidentally this is the second time I am posting this article, could
somebody guide me.

Pratap.


Here is the source code for your reference:

/*-------------------------------------------------------------------*/
#include <stdio.h>
#include <types.h>
#include <nlist.h>
#include <time.h>
#include <sys/resource.h>
#include <sys/proc.h>
#include <sys/fcntl.h>
#include <sys/file.h>

#define	MAX 10 
#define	ZERO 0 
#define	ERROR -1 
#define	NOERROR 0 
#define	VMUNIX "/vmunix" 
#define	KMEM "/dev/kmem" 
#define	PTR_KMEM "_proc" 

int	fileDes ;

main(argc,argv)
int argc ;
char *argv[] ;
{
	int	ret_cd ;

/* Position in Kmem file */
	if((ret_cd = posKmem()) == ERROR) {
		printf("Error in handling Kmem file \n") ;
		exit(0) ;
	}

/* process Kmem file */
	if((ret_cd = proKmem()) == ERROR) {
		printf("Error in processing Kmem file \n") ;
		exit(0) ;
	}

/* Close all open files */
	close(fileDes) ;
}

int posKmem()
{
	int ret_cd ;
	struct 	nlist nl[2] ;
	unsigned long proOff ;

/* Get _proc address from  'vmunix file in read mode' */
	nl[0].n_name = PTR_KMEM ;
	nl[0].n_type = N_DATA ;
	nl[1].n_name = (char *) NULL ;
	
	if((ret_cd = nlist(VMUNIX,nl)) < ZERO) {
		perror("Nlist failed") ;
		return(ERROR) ;
	}

/* Open file 'kmem' in read mode */
	if((fileDes = open(KMEM,O_RDONLY)) < ZERO) {
		perror("Kmem  open failed") ;
		return(ERROR) ;
	}

/* Seek to the offset returned by nlist */
	if((ret_cd = lseek(fileDes,nl[0].n_value,L_SET)) < nl[0].n_value) {
		perror("Lseek  failed") ;
		return(ERROR) ;
	}
	if((ret_cd = read(fileDes,(char *) &proOff,sizeof(long))) < 
						ZERO) {
		perror("Read  failed") ;
		return(ERROR) ;
	}

/* Seek to the offset returned by read */
	if((ret_cd = lseek(fileDes,proOff,L_SET)) < proOff) {
		perror("Lseek  failed") ;
		return(ERROR) ;
	}
	return(NOERROR) ;
}

int proKmem()
{
	char	*malloc() ;
	int 	ret_cd, ix ;
	struct  proc  *ptrProc ;

/* Get storage for proc structure */
	if((ptrProc = (struct proc *) malloc(sizeof(struct proc))) ==
				(struct proc *) NULL)  {
		perror("Malloc  failed") ;
		return(ERROR) ;
	}

/* Read  process structures */
	for (ix = 0 ; ix < MAX ; ix++ )  {
		if((ret_cd = read(fileDes,(char *) ptrProc,
				sizeof(struct proc))) < sizeof(struct proc)) {
			perror("Read  failed") ;
			return(ERROR) ;
		}
		disPinfo(ptrProc) ;
	}
	return(NOERROR) ;
}

int disPinfo(ps)
struct proc *ps ;
{
struct	rusage *ru ;

	ru = ps->p_ru ;

/* ps->p_ru is pointing to location 0 , and I dont know why */
		
/* Print process info and then the resource usage */
	printf("Process Information of process: %d\n" ,ps->p_pid) ;
	printf("----------------------------------------------------------\n") ;
	printf("PPID\tP_UID\tP_CPU\tP_GRP\n") ;
	printf("%hd\t\t%d\t\t%c\t\t%hd\n",ps->p_ppid,ps->p_uid,ps->p_cpu,
								ps->p_pgrp) ;
	printf("----------------------------------------------------------\n") ;
	printf("Resource Information of process: %d\n" ,ps->p_pid) ;
	printf("----------------------------------------------------------\n") ;
	printf("Page reclaims\tPage faults\tMessages received\tSignals\n") ;
	printf("%ld\t\t%ld\t\t%ld\t\t%ld\n\n\n ", ru->ru_minflt, ru->ru_majflt,
			ru->ru_msgrcv,ru->ru_nsignals);
	return(NOERROR) ;
}
/*--------------------E N D  O F  D A Y ' S  P L A Y--------------------------*/