OS-Labs/lab2/src/part2_partitioner.cpp

#include <iostream>
#include <cstdlib>
#include <fstream>
#include <unistd.h>
#include <sys/wait.h>
#include <signal.h>
#include <string>
#include <cstring>

using namespace std;

int main(int argc, char **argv)
{
    if (argc != 6)
    {
        cout << "usage: ./partitioner.out <path-to-file> <pattern> <search-start-position> <search-end-position> <max-chunk-size>\nprovided arguments:\n";
        for (int i = 0; i < argc; i++)
            cout << argv[i] << "\n";
        return -1;
    }

    char *file_to_search_in = argv[1];
    char *pattern_to_search_for = argv[2];
    int search_start_position = atoi(argv[3]);
    int search_end_position = atoi(argv[4]);
    int max_chunk_size = atoi(argv[5]);

    pid_t my_pid = getpid();
    pid_t searcher_pid;
    pid_t children[2];

    cout << "[" << my_pid << "] start position = " << search_start_position << " ; end position = " << search_end_position << "\n";

    if (search_end_position - search_start_position >= max_chunk_size)
    {
        int mid = (search_start_position + search_end_position) / 2;

        children[0] = fork();

        if (children[0] == 0)
        {
            //Left Child
            char start_str[10], mid_str[10], chunk_size_str[10];

            string temp = to_string(search_start_position);
            strcpy(start_str, temp.c_str());

            temp = to_string(mid);
            strcpy(mid_str, temp.c_str());
            
            temp = to_string(max_chunk_size);
            strcpy(chunk_size_str, temp.c_str());

            char *args[] = { "./part2_partitioner.out",file_to_search_in , pattern_to_search_for, start_str, mid_str, chunk_size_str, NULL };
            execv("./part2_partitioner.out", args);
        }
        else
        {
            // Parent process
            cout << "[" << my_pid << "] forked left child " << children[0] << "\n";
        }

        children[1] = fork();
        if (children[1] == 0)
        {
            //Right Child
            char mid_next[10], end_str[10], chunk_size_str[10];

            string temp = to_string(mid+1);
            strcpy(mid_next, temp.c_str());

            temp = to_string(search_end_position);
            strcpy(end_str, temp.c_str());
            
            temp = to_string(max_chunk_size);
            strcpy(chunk_size_str, temp.c_str());

            char *args[] = { "./part2_partitioner.out", file_to_search_in, pattern_to_search_for, mid_next, end_str, chunk_size_str, NULL };
            execv("./part2_partitioner.out", args);
        }
        else
        {
            // Parent process
            cout << "[" << my_pid << "] forked right child " << children[1] << "\n";
        }

        for(int i = 0; i < 2; ++i) {
            pid_t returned_pid = wait(NULL);
            if(returned_pid == children[0]) {
                cout << "[" << my_pid << "] left child returned\n";
            }
            else {
                cout << "[" << my_pid << "] right child returned\n";
            }
        }
        
    }
    else
    {
        searcher_pid = fork();
        if (searcher_pid == 0)
        {
            // Child process
            char start_str[10], end_str[10];

            string temp = to_string(search_start_position);
            strcpy(start_str, temp.c_str());

            temp = to_string(search_end_position);
            strcpy(end_str, temp.c_str());
            
            char *args[] = { "./part2_searcher.out", file_to_search_in, pattern_to_search_for, start_str, end_str ,NULL};
            execv("./part2_searcher.out", args);
        }
        else
        {
            // Parent process
            cout << "[" << my_pid << "] forked searcher child " << searcher_pid << "\n";
        }

        waitpid(searcher_pid, NULL, 0);
        cout << "[" << my_pid << "] searcher child returned \n";
    }

    //TODO
	//cout << "[" << my_pid << "] start position = " << search_start_position << " ; end position = " << search_end_position << "\n";
	//cout << "[" << my_pid << "] forked left child " << my_children[0] << "\n";
	//cout << "[" << my_pid << "] forked right child " << my_children[1] << "\n";
	//cout << "[" << my_pid << "] left child returned\n";
	//cout << "[" << my_pid << "] right child returned\n";
	//cout << "[" << my_pid << "] left child returned\n";
	//cout << "[" << my_pid << "] right child returned\n";*/
	//cout << "[" << my_pid << "] forked searcher child " << searcher_pid << "\n";
	//cout << "[" << my_pid << "] searcher child returned \n";
	//cout << "[" << my_pid << "] received SIGTERM\n"; //applicable for Part III of the assignment

    return 0;
}