#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

/* 
 * truncate: truncate a file
 *
 * By Nelson Castillo ( http://geocities.com/arhuaco )
 *
 * What a program! :)
 *
 * TODO: Allow file_name to be specified with  "k", "M", "G", "ik", "iM", "iG".
 * 
 */

#define PROGRAM_NAME "truncate"

int main(int argc, char *argv[])
{
  char *num_str;
  char *file_name;
  long int new_size;
  char *end_ptr;
  
  if (argc != 3)
  {
    fprintf(stderr, "usage: %s file new-size-in-bytes\n", PROGRAM_NAME);
    exit(EXIT_FAILURE);
  }

  num_str   = argv[2]; 
  file_name = argv[1];
  
  new_size = strtol(num_str, &end_ptr, 10);

  if (!*num_str || *end_ptr)
  {	  
    fprintf(stderr, "'%s' is not a valid file size\n", num_str);
    exit(EXIT_FAILURE);
  }

  if(truncate(file_name, new_size))
  {
    fprintf(stderr, "%s\n", strerror(errno));
    exit(EXIT_FAILURE);
  }

  exit(EXIT_SUCCESS);
}