#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>

int main(int argc, char ** argv) {
  int childstat;
  char ** lsargv;
  char ** lsenv;
  
  printf("Entry\n");
  pid_t pidreturn = fork();
  if (pidreturn == 0) {
    printf("hello from child\n");
    if (argc > 1) { // Exec /bin/ls -l ..
      // allocate and initialize argv needed for execve
      lsargv = (char **) malloc(4 * sizeof(char *));
      lsargv[0] = "/bin/ls";
      lsargv[1] = "-l";
      lsargv[2] = "..";
      lsargv[3] = NULL;
      
      //allocate and initialize env needed for execve
      lsenv = (char **) malloc(1 * sizeof(char *));
      lsenv[0] = NULL;

      execve(lsargv[0], lsargv, lsenv);
    } else {
      sleep(10);
    }
  } else {
    printf("hello from parent.  Child's pid is %d\n", pidreturn);
    waitpid(pidreturn, &childstat, 0);
    assert(WIFEXITED(childstat));
    printf("Child exit status: %d\n", WEXITSTATUS(childstat));
  }
  // on execve case, child should never get here
  printf("After conditional\n");
  if (pidreturn == 0) {
    return 1;
  } else {
    return 5;
  }
}