C Pipe Write and Read never hit EOF - c

Question

I posted the issue with fork() and pipe(), but later I saw that the problem was only in pipe().
So I'm removing fork() code from here.
Problem: Writing in pipe(), and reading from pipe() but never reach the EOF condition in loops
Here is a simplification code of the problem:
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
int fd[2];
int main() {
if(pipe(fd) == 0) {
printf("Pipe is Open\n");
}
for(int i = 0; i < 5; i++) {
close(fd[1]);
write(fd[0], &i, sizeof(int));
close(fd[0]);
}
for(int i = 0; i < 5; i++) {
int value;
close(fd[0]);
read(fd[1], &value, sizeof(int));
close(fd[1]);
printf("%d\n", value);
}
return 0;
}
Output:
Pipe is Open
4
4
4
4
4

Answer 1

Despite wanting to read in a loop multiple times, you close the file descriptor immediately after the first read, so that subsequent reads must fail; in addition, you forget to check the reads' return value for error and so use the unchanged value from the previous loop cycle.

Answer 2

Had to use <fcntl.h> to work properly
<fcntl.h> is a file control removed the need to close the pipe off my hands in order for it to reach EOF
if (fcntl(fd[0], F_SETFL, O_NONBLOCK) < 0)
exit(-1);
Where fd[0] is the pipe created
Without the fcntl() the code never hit the EOF condition
The implementations below, unlike the previous code, the close() has been removed and the fcntl() has been added to handle this, giving the output as desired to read values ​​inside a pipe in a loop until reaching EOF.
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
int fd[2];
int main() {
if(pipe(fd) == 0) {
printf("Pipe is Open\n");
}
if (fcntl(fd[0], F_SETFL, O_NONBLOCK) < 0)
exit(-1);
for(int i = 0; i < 5; i++) {
write(fd[1], &i, sizeof(int));
}
int status;
while(1) {
int value;
status = read(fd[0], &value, sizeof(int));
printf("status: %d\n", status);
if(status > 0) {
printf("%d\n", value);
} else {
// END of FILE
printf("\nEOF\n");
break;
}
}
return 0;
}
OUTPUT:
Pipe is Open
status: 4
0
status: 4
1
status: 4
2
status: 4
3
status: 4
4
status: -1
EOF