4. Develop a C program which demonstrates inter-process communication between a reader process and a writer process. Use mkfifo, open, read, write and close APIs in your program.
PROGRAM: We'll create two separate programs: writer.c and reader.c
writer.c This program will create a FIFO (if it doesn’t already exist) and write a message to it.
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#define FIFO_NAME "/tmp/myfifo"
#define BUFFER_SIZE 256
int main() {
int fd;
const char *message = "Hello from writer process!";
if (mkfifo(FIFO_NAME, 0666) == -1) {
perror("mkfifo");
exit(EXIT_FAILURE);
}
printf("Writer: FIFO created\n");
fd = open(FIFO_NAME, O_WRONLY);
if (fd == -1) {
perror("open");
exit(EXIT_FAILURE);
}
printf("Writer: FIFO opened for writing\n");
size_t message_length = strlen(message);
if (write(fd, message, message_length) == -1) {
perror("write");
close(fd);
exit(EXIT_FAILURE);
}
printf("Writer: Message written to FIFO\n");
close(fd);
return 0;
}reader.c This program will open the FIFO and read the message written by the writer process.
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#define FIFO_NAME "/tmp/myfifo"
#define BUFFER_SIZE 256
int main() {
int fd;
char buffer[BUFFER_SIZE];
ssize_t bytesRead;
fd = open(FIFO_NAME, O_RDONLY);
if (fd == -1) {
perror("open");
exit(EXIT_FAILURE);
}
bytesRead = read(fd, buffer, BUFFER_SIZE - 1);
if (bytesRead == -1) {
perror("read");
close(fd);
exit(EXIT_FAILURE);
}
buffer[bytesRead] = '\0';
printf("Reader: Message received: %s\n", buffer);
close(fd);
if (unlink(FIFO_NAME) == -1) {
perror("unlink");
exit(EXIT_FAILURE);
}
return 0;
}Compilation and Execution:
1. Compile the writer and reader programs one by one using below command:
braham@braham:~/Desktop/program$ gcc writer.c -o writer
braham@braham:~/Desktop/program$ gcc reader.c -o reader2. Open two terminals:
- In the first terminal, run the writer:
./writer- In the second terminal, run the reader:
./readerOUTPUT: Check the both terminal to see the output...
braham@braham:~/Desktop/program$ ./writer
Writer: FIFO created
Writer: FIFO opened for writing
Writer: Message written to FIFO
braham@braham:~/Desktop/program$ ./reader
Reader: Message received: Hello from writer process!