/* Name Chris Jackey
 * Date 10/5/09
 * Class CPSC 410
 */

// FIRST - RENAME THIS FILE TO myps.c

#include <stdio.h>
#include <stdlib.h>
#include <procfs.h>
#include <sys/fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include <string.h>


int main (void) {

	DIR *directory; // pointer to the /proc directory.
	struct dirent *dirItem;  // each directory item in /proc, these are all named after a system process id.
	char fname[25]; // character array to hold the complete path to psinfo for each directory in /proc.
	int fd; //  reuseable file descriptor to reference the open psinfo file.
	struct psinfo ps; // a psinfo struct to hold the information read in from the psinfo file.


	// If the /proc file system can be opened capture a reference to it and continue
	// else exit cleanly.
	if(opendir("/proc") == NULL){
		exit(1);
	}
	else{
		directory = opendir("/proc");
	}

		// You don't need the . and .. directories so bypass them.

		// Pretty print out your headers for each required stat (PID, PPID, CPU, ISIZE, RSIZE, CMD)

	printf("PID     PPID    CPU     ISIZE   RSIZE   CMD\n");

		/* Using the correct loop type -- remember, for loops are for when you know the number of
		 * iterations and while loops are for when you don't know the number but do know the stop
		 * condition -- loop through the directory doing the following on each iteration:
		 *
		 * 1)	Set the fname to the complete path to psinfo [man sprintf].
		 * 2)	open [man open(2)] the fname O_RDONLY, make sure to deal with error conditions if the file
		 * 		cannot be opened.
		 * 3)	If the file is successfully opened, read [man read(2)] the file into the ps struct - note,
		 * 		this is the heavy lifter and the trickiest line in the program.
		 * 4)	Once you have captured the psinfo in the ps struct then print out the variables of interest
		 *		using the C accessor operator, aka, the dot operator (.).
		 *
		 *
		 * NOTE: the read function you are looking for is:
		 *
		 *		ssize_t read(int fildes, void *buf, size_t nbyte);
		 *
		 * filedes is the file descriptor you captured when the open was successful.
		 * void *buf is a pointer to the buffer to store the read data in.
		 * size_t nbyte is the number of bytes to read from the file...read up on the sizeof function
		 *
		 * Your read function should look something like this
		 * read(filedescriptor, an assignment to the address of your ps variable cast to a char *, the sizeof the struct psinfo)
		 *
		 */

	readdir(directory);
	readdir(directory);	

	while((dirItem = readdir(directory)) != NULL){
		sprintf(fname, "/proc/%s/psinfo", dirItem->d_name);
		fd = open(fname, O_RDONLY);

		if(fd != -1){
			read(fd, &ps, sizeof(struct psinfo));

			char isize[8];
			sprintf(isize, "%d", ps.pr_size);
			strcat(isize, "K");
		
			char rsize[8];
			sprintf(rsize, "%d", ps.pr_rssize);
			strcat(rsize, "K");

			char cpu[8];
			sprintf(cpu, "%.2f", (ps.pr_pctcpu / (float)0x800) * 100);
			strcat(cpu, "%");		

			printf("%-8u%-8u%-8s%-8s%-8s%s\n", ps.pr_pid, ps.pr_ppid, cpu,
				isize, rsize, ps.pr_psargs);
		
		}

		close(fd);
	}

	// Properly close the directory

	exit(1); //  and exit the program.
}