MPI and Socket programming - Notify if no process found the file searching - c

Question

I have an assignment to combine MPI and Socket programming for searching a file. MPI will be used to create processes which search into folders whereas sockets will be used for sending and receiving messages. My only problem right now is how I notify my master process if no file was found. Everything else is working fine.
Here is my code:
int main(int argc, char** argv)
{
int rank, size;
DIR *d;
FILE *fp;
struct dirent *dir;
if (argc < 2) {
error("Ju lutem jepni emrin e file.");
}
printf("Fillon kerkimi...\n\n");
// Initialize the MPI environment.
MPI_Init(&argc, &argv);
// Get the number of processes
MPI_Comm_size(MPI_COMM_WORLD, &size);
// Get the rank of the process
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (rank == 0) {
server();
} else {
char str[100];
sprintf(str, "./%d/%s", rank, argv[1]);
//if file is found
if ((fp = fopen(str, "r")) != NULL) {
char buffer[4096];
int i=0;
char c;
while((c = getc(fp)) != EOF)
{
buffer[i++] = c;
}
buffer[i]='\0';
client(buffer);
}
}
MPI_Finalize();
return 0;
}
The server() and client() functions are used for sending and receiving using sockets. Didn't post the code because it is working fine.
Any ideas?
EDIT:
Server code:
void server() {
int sockfd, newsockfd, clilen;
char buffer[MAX_LEN];
struct sockaddr_in serv_addr, cli_addr;
int n;
struct timeval timeout;
timeout.tv_sec = 3;
timeout.tv_usec = 0;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
{
error("ERROR opening socket");
}
//clear
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(PORTNO);
if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
{
error("ERROR on binding");
}
if (setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
sizeof(timeout)) < 0) {;
printf("File nuk u gjend!");
return;
}
listen(sockfd,5);;
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
{
error("ERROR on accept");
}
bzero(buffer, 256);
if (read(newsockfd, buffer, 255) < 0)
{
error("ERROR reading from socket");
}
close(newsockfd);
close(sockfd);
printf("File output: \n%s\n", buffer);
return;
}
Client code:
void client(char* msg[]) {
int sockfd, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
strcpy(buffer, msg);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
{
error("ERROR opening socket");
}
server = gethostbyname("localhost");
if (server == NULL)
{
fprintf(stderr, "ERROR no such host\n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy( (char *) server->h_addr,
(char *) &serv_addr.sin_addr.s_addr,
server->h_length
);
serv_addr.sin_port = htons(PORTNO);
while(1)
{
if (connect(sockfd, &serv_addr, sizeof(serv_addr)) >= 0)
break;
}
if (write(sockfd, buffer, strlen(buffer)) < 0)
{
error("ERROR writing to socket");
}
close(sockfd);
return;
}
Note: I'm using setsockopt() on the server function which seems to work well for a timeout and do the job, though it doesn't let me print my own message to the console.