multi-pipe C program does not work - c

Question

I decided to write a simple, hard coded c program to better understand how pipes work.
The program has 3 commands:
find . -name '.' | sed 's/.*\.// | sort
And it works with 1 pipe (if i use only 2 commands) but it fails with 2 pipes(sort just does not get the information).
I think the error is in close or waitpid, but I have tried everything(i could think of) and it still does not work. What am I missing ?
information i used:
Is it possible to have pipe between two child processes created by same parent (LINUX, POSIX)
http://www.quora.com/Unix/How-can-I-write-a-code-for-PIPE-in-C-shell-script-python <--Sams example
Implementation of multiple pipes in C
EDIT:
the commands are written with no mistakes. The problem is definitely not in them (since they work if I only use 1 pipe)
My code:
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char* argv[]) {
pid_t test, test2, test3;
int old_pipe[2];
int new_pipe[2];
//test command
//char *argv1[] = {"ls", "-1", "-h", NULL};
char *argv1[] = {"find", ".", "-name", "*.*",NULL};
char *argv2[] = {"sed", "s/.*\\.//", NULL};
char *argv3[] = {"sort", NULL};
//creates a pipe
pipe(old_pipe);
pipe(new_pipe);
test = fork();
if(test == 0){
dup2(old_pipe[1], 1);
close(old_pipe[0]);
execvp(argv1[0], argv1);
perror("exec");
return 1;
}
test2 = fork();
if(test2 == 0){
dup2(old_pipe[0], 0);
close(old_pipe[1]);
dup2(new_pipe[1], 1);
close(new_pipe[0]);
execvp(argv2[0], argv2);
perror("exec");
return 1;
}
test3 = fork();
if(test3 == 0){
dup2(new_pipe[0], 0);
close(new_pipe[1]);
execvp(argv3[0], argv3);
perror("exec");
return 1;
}
close(old_pipe[0]);
close(old_pipe[1]);
close(new_pipe[0]);
close(new_pipe[1]);
waitpid(test);
waitpid(test2);
waitpid(test3);
return 0;
}

Answer 1

your 3rd exec (starting "sort") does not close old_pipe[1] and keeps it open. sed will not see the EOF and stays alive. You should call pipe(2) very late.
I suggest to look into /proc/<pid>/fd resp. use lsof to see which filedescriptors are open. E.g. after
dup2(old_pipe[1], 1);
close(old_pipe[0]);
you should close old_pipe[1] when it is not 1.
Some more explanations (as asked in comment): You program has
pipe(old_pipe);
pipe(new_pipe);
test = fork();
/* --> 'find'; writes into old_pipe[1] */
test2 = fork();
/* --> 'sed'; reads from old_pipe[0], writes into new_pipe[1] */
test3 = fork();
/* --> 'sort'; reads from new_pipe[0] */
The test2 program does not exit as long as its input (old_pipe[0]) is open. Because this pipe is alive for test3 (which waits for test2 to finish), it will deadlock.
Closing fds in child branches does not close them in the parent process.