/*
 * Filename: md5_words.c
 *
 * File Created: 22.10.2017
 * Last Modified: Mon 23 Oct 2017 02:46:23 PM MDT
 * Description: 
 * Compute and print the MD5 checksum of each
 * word in the system dictionary. We can use
 * "/usr/bin/md5sum" to compute one checksum.
 */

#include "csapp.h"

int main()
{
  FILE *f;
  char word[256];
  size_t len;

  f = fopen("/usr/share/dict/words", "r");
  while (fgets(word, sizeof(word), f))
  {
    len = strlen(word);
    if (len && word[len-1] == '\n')
      word[--len] = 0;

    /* We want to print the 32-character MD5 sum
     *        after each word and on the same line as the
     *               word:
     */

    char pipe[2];

    int cpid = Fork();

    Dup2(pipe[0], 0);

    write(pipe[1], word, sizeof(word));

    if (cpid == 0)
    {
      Dup2(pipe[1], 1);
      close(pipe[0]);

      char** arguments = {"/usr/bin/md5sum", NULL};

      execv("/usr/bin/md5sum", arguments);
      return 0;
    }

    close(pipe[1]);
    close(pipe[0]);
  }

  return 0;
}