Working with multiple pipes
main.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(int argc, char* argv[]) {
int fd[3][2];
int i;
for (i = 0; i < 3; i++) {
if (pipe(fd[i]) < 0) {
return 1;
}
}
int pid1 = fork();
if (pid1 < 0) {
return 2;
}
if (pid1 == 0) {
// Child process 1
close(fd[0][1]);
close(fd[1][0]);
close(fd[2][0]);
close(fd[2][1]);
int x = 0;
if (read(fd[0][0], &x, sizeof(int)) < 0) {
return 3;
}
x += 5;
if (write(fd[1][1], &x, sizeof(int)) < 0) {
return 4;
}
close(fd[0][0]);
close(fd[1][1]);
return;
}
int pid2 = fork();
if (pid2 < 0) {
return 5;
}
if (pid2 == 0) {
// Child process 2
close(fd[0][0]);
close(fd[0][1]);
close(fd[1][1]);
close(fd[2][0]);
int x = 0;
if (read(fd[1][0], &x, sizeof(int)) < 0) {
return 6;
}
x += 5;
if (write(fd[2][1], &x, sizeof(int)) < 0) {
return 7;
}
close(fd[1][0]);
close(fd[2][1]);
return;
}
// Parent process
close(fd[0][0]);
close(fd[1][0]);
close(fd[1][1]);
close(fd[2][1]);
int x = 0;
if (write(fd[0][1], &x, sizeof(int)) < 0) {
return 8;
}
if (read(fd[2][0], &x, sizeof(int)) < 0) {
return 9;
}
printf("Result is %d\n", x);
close(fd[0][1]);
close(fd[2][0]);
waitpid(pid1, NULL, 0);
waitpid(pid2, NULL, 0);
return 0;
}
Unix Processes in C
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