list.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <dirent.h>
#include <string.h>
#include "list.h"

//Global Variables
const static int BUFFER = 500;
const int uidNum = 8;
char *proc = "/proc/";
char *statusDIR = "/status";

//Stores each pid into a array of integers
int *generateProcessList()
{
	DIR * dir;
	struct dirent * file;
	int *processList = (int*) malloc(sizeof(int) *BUFFER);

	//Tests if directory can be opened, error if it can't
	if (NULL == (dir = opendir(proc)))
	{
		printf("\n Cannot Open Directory\n");
		exit(1);
	}

	int i = 0;
	while ((file = readdir(dir)))
	{
		if (atoi(file->d_name) != 0)
		{
			if (testOwnership(file->d_name) == 1)
			{
				processList[i] = atoi(file->d_name);
				i++;
			}
		}
	}
	return processList;
}

//Scans status files for pid and compares to
//owner's pid. If true return 1, if false 0
int testOwnership(char *processName)
{
	char buff[BUFFER];
	char fileLocation[BUFFER];
	strcpy(fileLocation, proc);
	strcat(fileLocation, processName);
	strcat(fileLocation, statusDIR);
	FILE * fp;
	fp = fopen(fileLocation, "r");
	if (fp != NULL)
	{
		for (int i = 0; i < 9; i++)
		{
			fgets(buff, BUFFER, fp);
			if (i == uidNum)
			{
				fscanf(fp, "%s", buff);
				fscanf(fp, "%s", buff);

				if (atoi(buff) == getuid())
				{
					return 1;
				}
			}
		}
		fclose(fp);
	}
	return 0;
}