/**
 * Simple program demonstrating shared memory in POSIX systems.
 *
 * This is the producer process that writes to the shared memory region.
 *
 * Figure 3.17
 *
 * @author Silberschatz, Galvin, and Gagne
 * Operating System Concepts  - Ninth Edition
 * Copyright John Wiley & Sons - 2013
 */


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>

int main(int argc, char **argv)
{
	const int SIZE = 4096;
	const char *name = "OS";
	const char *message0= "Studying ";
	const char *message1= "Operating Systems ";
	const char *message2= "Is Fun!";
	int BUFFER_SIZE = 0;
	int NUM_PRODUCERS = 0;
	int NUM_MESSAGES = 0;

	int shm_fd;
	void *ptr;

	checkArgs(argc,argv);
	/* create the shared memory segment */
	shm_fd = shm_open(name, O_CREAT | O_RDWR, 0666);

	/* configure the size of the shared memory segment */
	ftruncate(shm_fd,SIZE);

	/* now map the shared memory segment in the address space of the process */
	ptr = mmap(0,SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
	if (ptr == MAP_FAILED) {
		printf("Map failed\n");
		return -1;
	}

	/**
	 * Now write to the shared memory region.
 	 *
	 * Note we must increment the value of ptr after each write.
	 */
	sprintf(ptr,"%s",message0);
	ptr += strlen(message0);
	sprintf(ptr,"%s",message1);
	ptr += strlen(message1);
	sprintf(ptr,"%s",message2);
	ptr += strlen(message2);

	return 0;
}

void produce()
{

}

void checkArgs(int argc, char **argv)
{
	if(argc == 1){
		BUFFER_SIZE = 10;
		NUM_PRODUCERS = 5;
		NUM_MESSAGES = 100;
	}

	if(argc == 2 && (argv[0] == "-h")){
		displayHelp();
	}

	if(argc == 4 && (numCheck(argv[0])) && (numCheck(argv[1))
		&& (numCheck(argv[2]))){
		BUFFER_SIZE = argv[0];
		NUM_PRODUCERS = argv[1];
		NUM_MESSAGES = argv[2];
	}

	else {
		displayHelp();
	}
}

void displayHelp()
{
	printf("help");
}

int numCheck(int x)
{
	if((x >= 1) && (x <= 100)){
		return x;
	} else
	return 0;

}