Reading from a pipe even after the write end is closed - c

Question

Can you please explain me why is the child process able to read even after the parent closes its write end?
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
int main()
{
int fd[2];
char buffer[20];
pipe(fd);
if ( fork() == 0 ) //child
{
close(fd[0]); //As it is writing close the read end
strcpy(buffer, "Hello World");
write(fd[1], buffer, sizeof(buffer));
close(fd[1]);
}
else //parent
{
close(fd[1]); //As it is reading closing the write end
while(1)
{
read(fd[0], buffer, sizeof(buffer));
printf("Buffer:%s\n", buffer);
sleep(1);
}
close(fd[0]);
}
}
O/P: Child continuously prints:
Buffer:Hello World
Why is the child able to receive even when the parent terminates? Shouldn't read get EOF?

Answer 1

Why is the child able to receive even when the parent terminates? Shouldn't read get EOF?
At that point the parent process is basically reading nothing (i.e.: read() is returning 0) and printing over and over what it had read in a previous call to read().
You have to look at the value returned by the read() system call. That value is of type int, and basically :
-1: error, something went wrong.
0: nothing else remaining to read, i.e.: EOF (what you were looking for).
Otherwise: the number of bytes read by read() that were stored into buffer.
You can rewrite the parent's while-loop accordingly:
while(1) {
int count = read(fd[0], buffer, sizeof(buffer));
switch (count) {
case 0: // EOF
break;
case -1: // read() error
// ... error handling ...
break;
default: // fine
// count contains the number of bytes read
buffer[count] = '\0'; // NUL character, to indicate the end of string
printf("Buffer:%s\n", buffer);
sleep(1);
}
}