Signal Repetition

#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<unistd.h>
#include<signal.h>
#include<fcntl.h>
#include<sys/wait.h>

int counter = 0;
int fd;
const char* filename;
int j = 0;
int no_of_children;
int* cpid;

//User define signal handler
static void sig_usr1(int);
static void sig_usr2(int);

static void sig_usr1(int signo)
{
    //Now the child process waits for reading the Filename

    //Block SIGUSR1 until it's complete
    signal(SIGUSR1, SIG_IGN);
    printf("Blocked now.\n");
    printf("Child no %d is reading now.\n\n",getpid());
    fd = open(filename, O_RDONLY | O_CREAT);

    char buf = 'a';
    int k=0;
    char* op = (char*) malloc (255*sizeof(char));

    while(read (fd, &buf, 1))
    {
        if (buf == '\n')
        {
            op[k] = '\0';
            break;
        }

        else
        {
            op[k++] = buf;
        }
    }

    //Now wait for a second and then send a signal
    sleep(1);
    //Print the contents of the buffer via op
    printf("Output: %s\n\n", op);


    //Now unblock the signal
    kill(getppid(), SIGUSR2);
    signal(SIGUSR1, sig_usr1);
    printf("Unblocked now\n");
}

static void sig_usr2(int signo)
{
    if (signo == SIGUSR2)
    {
        printf("Parent Received SIGUSR2. Child Process with PID %d is now free\n", cpid[j]);
        kill (cpid[j++], SIGUSR1);
        if (j == no_of_children)
        {
            j = 0;
        }

    }
}

int main(int argc, char* argv[])
{
    //Filename is the first argument
    filename = argv[1];

    //Number of Child Processes to be spawned
    no_of_children = atoi(argv[2]);

    cpid = (int*) malloc (no_of_children*sizeof(int));

    signal(SIGUSR2, sig_usr2);
    //Create no_of_children children
    for(int i=0; i<no_of_children; i++)
    {
        cpid[i] = fork();
        if (cpid[i] == 0)
        {
            //Inside a child
            printf("Created %dth child process", i);
            printf(" with Process ID = %d\n", getpid());

            signal(SIGUSR1, sig_usr1);

            while(1)
            {
                pause();
            }

            //Every child process must exit so control goes back to the parent
            exit(0);
        }
    }

    //Returns to the parent process
    while(1)
    {
        int fpid = cpid[j];
        //Send the signal to the free child process
        //printf("Sending to PID %d\n", fpid);
        kill(fpid, SIGUSR1);
        //j = (j < no_of_children - 1) ? j + 1 : 0;
    }

    return 0;
}