Error value returned in pipe

They ask me to do a function that first ls the current directory and store it in a file (tmp) and then read that file, grep -c and return the value in the return. I can not get the correct value back to me correctly in int, yes as char.

int do_nfiles (char *pattern)
    {
      t_string s;
      int fd[2],fd2[2];
      char buf[100];
      int val = 10;

      delay ();
      pipe(fd);
      int pid = fork();

       /*Proceso hijo*/
      if(pid == 0){

          fd[0] = open("tmp", O_WRONLY|O_CREAT, 0666);
          dup2(fd[0],STDOUT_FILENO);
          close(fd[0]);
          execlp("ls","ls", NULL);
      }
      else{
          pipe(fd2);
          pid = fork();

          if(pid == 0){
            fd2[0] = open("tmp", O_RDONLY);
            dup2(fd2[0],STDIN_FILENO);
            dup2(fd2[1],STDOUT_FILENO);
            close(fd2[0]);
            execlp("grep","grep","-c",pattern, NULL);
          }

          read(fd2[0], &val, sizeof(val));
          sprintf (s, "[%d] num %d\n", getpid (), val);

        return (val);
      }

      return 0;
    }

If I modify the function and put this:

read(fd2[0],buf,3);

It returns the correct value in char, not int.