Communicate two child fork processes with FIFO - c

Question

I made this program with pipes to communicate two processes with PIPES. Now what I have to do is the same but with FIFO.
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <wait.h>
#include <string.h>
int main()
{
int e, p[20], hijo1, hijo2, nbytes, readbytes;
char texto[200], readbuffer[100];
printf("Write the message to send to the other process\n");
fgets(texto, 100, stdin);
pipe(p);
if ((hijo1 = fork()) == -1)
{
printf("ERROR FORK\n");
exit(EXIT_FAILURE);
}
if (hijo1 == 0)
{
printf("Im %d and Im child 1\n", getpid());
close(p[0]);
write(p[1], texto, strlen(texto + 1));
close(p[1]);
exit(0);
}
if ((hijo2 = fork()) == -1)
{
printf("ERROR FORK\n");
exit(EXIT_FAILURE);
}
if (hijo2 == 0)
{
printf("Im %d And Im child 2 \n", getpid());
close(p[1]);
write(1, "message received: ", 24);
while ((nbytes = read(p[0], readbuffer, 8)) == 8)
{
write(1, readbuffer, nbytes);
}
write(1, readbuffer, nbytes);
printf("\n");
close(p[0]);
exit(0);
}
printf("Im %d and Im the father\n", getpid());
waitpid(hijo1, &e, 0);
waitpid(hijo2, &e, 0);
exit(EXIT_SUCCESS);
}
This is what I tried to do but with FIFO
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <wait.h>
#include <string.h>
int main()
{
char texto[200], buf[200];
int fd, fd2, hijo1, hijo2, nbytes;
printf("Ingrese el mensaje para enviar al FIFO\n");
fgets(texto, 100, stdin);
printf("soy %d y soy el padre \n", getpid());
mkfifo("/tmp/mi_fifo", 0666);
if ((hijo1 = fork()) == -1)
{
printf("ERROR FORK\n");
exit(EXIT_FAILURE);
}
if (hijo1 == 0)
{
printf("soy %d y soy el hijo 1 \n", getpid());
fd = open("/tmp/mi_fifo", O_WRONLY);
write(fd, texto, sizeof(texto + 1));
close(fd);
exit(0);
}
if ((hijo2 = fork()) == -1)
{
printf("ERROR FORK\n");
exit(EXIT_FAILURE);
}
if (hijo2 == 0)
{
printf("soy %d y soy el hijo 2 \n", getpid());
fd2 = open("/tmp/mi_fifo", O_RDONLY);
write(1, "el mensaje recibido es: \n", 24);
while (nbytes = read(fd2, buf, 8) == 8)
{
write(1, buf, nbytes);
}
write(1, buf, nbytes);
close(fd2);
exit(0);
}
return 0;
}
This Fifo program is not receiving the Message from the other child process. When I print the buf variable with Write() It shows only one letter. It should show the whole message that's why it is in a while loop. How can I do that? I haven't found any information about fork processes and FIfOs I hope you can help me.

Answer 1

At least two problems:
sizeof(texto + 1) needs to be strlen(texto)+1 to ensure the right size for the string in the buffer.
while (nbytes = read(fd2, buf, 8) == 8) needs to be while ((nbytes = read(fd2, buf, 8)) == 8). Because == has higher precedence than =. What you have assigns either 1 or 0 (boolean result) to nbytes.