date.c

#include "internal.h"
#include <stdlib.h>
#include <errno.h>
#include <sys/time.h>
#include <unistd.h>
#include <time.h>
#include <stdio.h>
#include <getopt.h>


/* This 'date' command supports only 2 time setting formats, 
   all the GNU strftime stuff (its in libc, lets use it),
   setting time using UTC and displaying int, as well as
   an RFC 822 complient date output for shell scripting
   mail commands */

const char	date_usage[] = "date [-uR] [+FORMAT|+%f] [ [-s|-d] MMDDhhmm[[CC]YY]\n"
"| [[[[CCYY.]MM.DD-]hh:mm[:ss]]]] ]";

//static const char date_usage[] = "Usage: date [OPTION]... [+FORMAT]\n"
//"or:  date [OPTION] [MMDDhhmm[[CC]YY][.ss]]\n"
//"Display the current time in the given FORMAT, or set the system date.\n";


static struct option const long_options[] =
{
  {"date", required_argument, NULL, 'd'},
  /*  {"rfc-822", no_argument, NULL, 'R'},
  {"set", required_argument, NULL, 's'},
  {"uct", no_argument, NULL, 'u'},
  {"utc", no_argument, NULL, 'u'},
  {"universal", no_argument, NULL, 'u'}, */
  {NULL, 0, NULL, 0}
};
  


/* Input parsing code is always bulky - used heavy duty libc stuff as
   much as possible, missed out a lot of bounds checking */

/* Default input handling to save suprising some people */

struct tm *
date_conv_time(struct tm *tm_time, const char *t_string) {
  int nr;

  nr = sscanf(t_string, "%2d%2d%2d%2d%d", 
	     &(tm_time->tm_mon),
	     &(tm_time->tm_mday),
	     &(tm_time->tm_hour),
	     &(tm_time->tm_min),
	     &(tm_time->tm_year));

  if(nr < 4 || nr > 5) {
    fprintf(stderr, "date: invalid date `%s'\n", t_string);
    exit(1);
  }

  /* correct for century  - minor Y2K problem here? */
  if(tm_time->tm_year >= 1900)
    tm_time->tm_year -= 1900;
  /* adjust date */
  tm_time->tm_mon -= 1;
	     
  return(tm_time);

}


/* The new stuff for LRP */

struct tm *
date_conv_ftime(struct tm *tm_time, const char *t_string) {
  struct tm itm_time, jtm_time, ktm_time, \
    ltm_time, mtm_time, ntm_time;
  
  itm_time = *tm_time;
  jtm_time = *tm_time;
  ktm_time = *tm_time;
  ltm_time = *tm_time;
  mtm_time = *tm_time;
  ntm_time = *tm_time;

  /* Parse input and assign appropriately to tm_time */
  
  if(sscanf(t_string, "%d:%d:%d",
	    &itm_time.tm_hour, 
	    &itm_time.tm_min, 
	    &itm_time.tm_sec) == 3 ) {

    *tm_time = itm_time;
    return(tm_time);

  } else if (sscanf(t_string, "%d:%d", 
		    &jtm_time.tm_hour, 
		    &jtm_time.tm_min) == 2) {

    *tm_time = jtm_time;
    return(tm_time);

  } else if (sscanf(t_string, "%d.%d-%d:%d:%d",
		    &ktm_time.tm_mon, 
		    &ktm_time.tm_mday, 
		    &ktm_time.tm_hour,
		    &ktm_time.tm_min,
		    &ktm_time.tm_sec) == 5) {

    ktm_time.tm_mon -= 1; /* Adjust dates from 1-12 to 0-11 */
    *tm_time = ktm_time;
    return(tm_time);

  } else if (sscanf(t_string, "%d.%d-%d:%d",
		    &ltm_time.tm_mon, 
		    &ltm_time.tm_mday, 
		    &ltm_time.tm_hour,
		    &ltm_time.tm_min) == 4) {

    ltm_time.tm_mon -= 1; /* Adjust dates from 1-12 to 0-11 */
    *tm_time = ltm_time;
    return(tm_time);

  } else if (sscanf(t_string, "%d.%d.%d-%d:%d:%d",
		    &mtm_time.tm_year,
		    &mtm_time.tm_mon, 
		    &mtm_time.tm_mday, 
		    &mtm_time.tm_hour,
		    &mtm_time.tm_min,
		    &mtm_time.tm_sec) == 6) {

    mtm_time.tm_year -= 1900; /* Adjust years */
    mtm_time.tm_mon -= 1; /* Adjust dates from 1-12 to 0-11 */
    *tm_time = mtm_time;
    return(tm_time);

  } else if (sscanf(t_string, "%d.%d.%d-%d:%d",
		    &ntm_time.tm_year,
		    &ntm_time.tm_mon, 
		    &ntm_time.tm_mday, 
		    &ntm_time.tm_hour,
		    &ntm_time.tm_min) == 5) { 
    ntm_time.tm_year -= 1900; /* Adjust years */
    ntm_time.tm_mon -= 1; /* Adjust dates from 1-12 to 0-11 */
    *tm_time = ntm_time;
    return(tm_time);

  }

  fprintf(stderr, "date: invalid date `%s'\n", t_string);

  exit(1);

}


void
date_err(void) {
  fprintf(stderr, "date: only one date argument can be given at a time.\n");
  exit(1);
}

int
date_main(int argc, char * * argv)
{
  char *date_str = NULL;
  char *date_fmt = NULL;
  char *t_buff;
  int set_time = 0;
  int rfc822 = 0;
  int utc = 0;
  int use_arg = 0;
  int n_args;
  time_t tm; 
  struct tm tm_time;
  char optc;
  
  /* Interpret command line args */
	

  while ((optc = getopt_long (argc, argv, "d:Rs:u", long_options, NULL))
         != EOF) {
    switch (optc) {
    case 0:
      break;    

    case 'R':
      rfc822 = 1;
      break;

    case 's':
      set_time = 1;
      if(date_str != NULL) date_err();
      date_str = optarg;
      break;

    case 'u':
      utc = 1;
      if (putenv ("TZ=UTC0") != 0) {
	fprintf(stderr,"date: memory exhausted\n");
	return(1);
      }
#if LOCALTIME_CACHE
      tzset ();
#endif                                                                                break;

    case 'd':
      use_arg = 1;
      if(date_str != NULL) date_err();
      date_str = optarg;
      break;

    default:
      fprintf(stderr, "Usage: %s", date_usage);
      break;
    }
  }


  n_args = argc - optind; 

  while (n_args--){
    switch(argv[optind][0]) {
      case '+':
      /* Date format strings */
      if(date_fmt != NULL) {
	fprintf(stderr, "date: only one date format can be given.\n");
	return(1);
      }
      date_fmt = &argv[optind][1];
      break;

      case '\0':
      break;

      default:
      /* Anything left over must be a date string to set the time */
      set_time = 1;
      if(date_str != NULL) date_err();
      date_str = argv[optind];
      break;
    }
    optind++;
  }


  /* Now we have parsed all the information except the date format
   which depends on whether the clock is being set or read */

  time(&tm);
  memcpy(&tm_time, localtime(&tm), sizeof(tm_time));
  /* Zero out fields - take her back to midnight!*/
  if(date_str != NULL) {
    tm_time.tm_sec = 0;
    tm_time.tm_min = 0;
    tm_time.tm_hour = 0;
  }

  /* Process any date input to UNIX time since 1 Jan 1970 */
  if(date_str != NULL) {

    if(strchr(date_str, ':') != NULL) {
      date_conv_ftime(&tm_time, date_str);
    } else {
      date_conv_time(&tm_time, date_str);
    }

    /* Correct any day of week and day of year etc fields */
    tm = mktime(&tm_time);
    if (tm < 0 ) {
      fprintf(stderr, "date: invalid date `%s'\n", date_str);
      exit(1);
    }

    /* if setting time, set it */
    if(set_time) {
      if( stime(&tm) < 0) {
	fprintf(stderr, "date: can't set date.\n");
	exit(1);
      }
    }
  }
  
  /* Display output */

  /* Deal with format string */
  if(date_fmt == NULL) {
    date_fmt = (rfc822
                ? (utc
                   ? "%a, %_d %b %Y %H:%M:%S GMT"
                   : "%a, %_d %b %Y %H:%M:%S %z")
                : "%a %b %e %H:%M:%S %Z %Y");

  } else if ( *date_fmt == '\0' ) {
    /* Imitate what GNU 'date' does with NO format string! */
    printf ("\n");
    return(0);
  }

  /* Handle special conversions */

  if( strncmp( date_fmt, "%f", 2) == 0 ) {
    date_fmt = "%Y.%m.%d-%H:%M:%S";
  }

  /* Print OUTPUT (after ALL that!) */
  t_buff = malloc(201);
  strftime(t_buff, 200, date_fmt, &tm_time);
  printf("%s\n", t_buff);

  return(0);

}