dup2 function not returning any value

Question

I'm trying to write nameless pipe program by using fork,pipe,dup2 and execvp. The program should take the first command ,from the command line, and fork a child process. the parent should do the command and pass the output to the child. the child should continue the to the next command (token is '-' instead of regular pipe sign '|') and do it on the input from the parent and so on, so the output of each parent is passed to is son until the last command that should execute at the main aand to the consule. for some reason the program seems to stop at dup2 before printing "parent2!". thanks in advance for all the help :)

#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h> // for open flags
#include <time.h> // for time measurement
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#define LINE_MAX 1024

char* buffer[LINE_MAX];


void np_exec(char* cmd, char** argv)
{
int i,len=0,ret_p,ret_c;
int mypipefd[2];

/* count how many args till NULL to know how much space to allocate */
for(i=0;argv[i]!=NULL;i++)
    len++;
if (len == 0)
{
    printf("ERROR_CMD\n");
    exit(EXIT_FAILURE);
}
char* par[len+1];
par[len] = NULL;

/* creat parameters array */
for(i=0;argv[i]!=NULL;i++)
    par[i] = argv[i];

/* creat pipe */
if (pipe(mypipefd)==-1)
{
    printf("ERROR_PIPE: %s\n", strerror(errno));
    exit(EXIT_FAILURE);
}
pid_t cpid;
cpid = fork();
if (cpid == -1)
{
    printf("FORK_ERROR: %s\n", strerror(errno));
    exit(EXIT_FAILURE);
}
/* child process */
else if (cpid==0)
{
    printf("child!\n");//TODO delete
    dup2(mypipefd[0], STDIN_FILENO);
    close(mypipefd[1]);
    if(read(STDIN_FILENO,buffer,LINE_MAX)<0) //read output from pipe.
    {
        printf("READ_ERROR: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
    printf("child2!\n");//TODO delete
}
/* parent process */
else
{
    printf("parent!\n");//TODO delete
    dup2(mypipefd[1], STDOUT_FILENO);
    printf("parent2!\n");//TODO delete
    close(mypipefd[0]); //Closes read side of pipe
    if (execvp(cmd,par) == -1)
    {
        printf("EXECVP_ERROR: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }
}
}

int main(int argc, char** argv)
{
/* last char is not '-' */
assert(strcmp(argv[argc-1], "-"));

/*The program then parses the arguments,
 * calling the function np_exec for each separate set of arguments except the last,
 *  i.e., list of arguments that end with a minus character.*/
int i;
for (i = 1; i < argc; ++i) {
    if (!strcmp(argv[i], "-")) {
        argv[i] = NULL;
        np_exec(argv[1], &argv[1]);
        /* support milti pipes */
        argv = &argv[i];
        argc -= i;
        i = 0;
    }
}

/* array for the final program in the arguments */
char* args[argc];
args[argc-1] = NULL;

/* let it start from index 0 */
for (i = 1; i < argc; ++i) {
    args[i-1] = argv[i];
}
printf("finish!!!\n");//TODO delete
/* execute the final program in the arguments using execvp */
if (execvp(args[0], args) == -1)
    perror("execvp failed");
return;

}