read and write with the same process using two different pipes c++ - c++

Question

I am trying to create a child that calls some program or process. The parent write and read some data from child through a two pipes. My code compiles and runs, but there is no text on input. What am I doing wrong? Am I not closing the pipes correctly, writing the pipes or outputting the data correctly?
#include <iostream>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>
int main(){
int pipedes1[2],pipedes2[2];
char buff[256];
string text = "Hello";
pid_t pid;
pipe(pipedes1);
pipe(pipedes2);
pid = fork();
if(pid > 0){
close(pipedes1[1]);
close(pipedes2[0]);
dup2(pipedes2[1], STDOUT_FILENO);
dup2(pipedes1[0], STDIN_FILENO);
execve("/home/pi/Test", NULL, NULL);
} else {
close(pipedes1[1]);
close(pipedes2[1]);
write(pipedes1[0], text.c_str(), text.length());
while((len = read(pipedes2[0], buff, 256)) != 0){
cout << buff << endl;
}
close(pipedes2[0]);
close(pipedes1[0]);
}
return 0;
}
And there is my "chield" program:
int main(){
string str;
cin >> str;
str = "echo " + str + " >> /home/pi/1";
cout << str << endl;
return 0;
}
Output of prog:
echo << /home/pi/1
Im found a problem write() returns -1.
But i dont know why?

Answer 1

write(pipedes1[0], text.c_str(), text.length());
You are writing to the reading end of the pipe.
Except for this, your application is endangered by deadlock. What if you are attempting to write so much that the pipe buffer fills up, and the child produces so much data that its pipe buffer fills up as well? Then both processes are waiting for the other to drain the buffer, but they are each blocked in write!