src/date.c

   1 /* date - print or set the system date and time
   2    Copyright (C) 1989-2022 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.
  16
  17    David MacKenzie <djm@gnu.ai.mit.edu> */
  18
  19 #include <config.h>
  20 #include <stdio.h>
  21 #include <getopt.h>
  22 #include <sys/types.h>
  23 #if HAVE_LANGINFO_CODESET
  24 # include <langinfo.h>
  25 #endif
  26
  27 #include "system.h"
  28 #include "argmatch.h"
  29 #include "die.h"
  30 #include "error.h"
  31 #include "parse-datetime.h"
  32 #include "posixtm.h"
  33 #include "quote.h"
  34 #include "stat-time.h"
  35 #include "fprintftime.h"
  36
  37 /* The official name of this program (e.g., no 'g' prefix).  */
  38 #define PROGRAM_NAME "date"
  39
  40 #define AUTHORS proper_name ("David MacKenzie")
  41
  42 static bool show_date (char const *, struct timespec, timezone_t);
  43
  44 enum Time_spec
  45 {
  46   /* Display only the date.  */
  47   TIME_SPEC_DATE,
  48   /* Display date, hours, minutes, and seconds.  */
  49   TIME_SPEC_SECONDS,
  50   /* Similar, but display nanoseconds. */
  51   TIME_SPEC_NS,
  52
  53   /* Put these last, since they aren't valid for --rfc-3339.  */
  54
  55   /* Display date and hour.  */
  56   TIME_SPEC_HOURS,
  57   /* Display date, hours, and minutes.  */
  58   TIME_SPEC_MINUTES
  59 };
  60
  61 static char const *const time_spec_string[] =
  62 {
  63   /* Put "hours" and "minutes" first, since they aren't valid for
  64      --rfc-3339.  */
  65   "hours", "minutes",
  66   "date", "seconds", "ns", NULL
  67 };
  68 static enum Time_spec const time_spec[] =
  69 {
  70   TIME_SPEC_HOURS, TIME_SPEC_MINUTES,
  71   TIME_SPEC_DATE, TIME_SPEC_SECONDS, TIME_SPEC_NS
  72 };
  73 ARGMATCH_VERIFY (time_spec_string, time_spec);
  74
  75 /* A format suitable for Internet RFCs 5322, 2822, and 822.  */
  76 static char const rfc_email_format[] = "%a, %d %b %Y %H:%M:%S %z";
  77
  78 /* For long options that have no equivalent short option, use a
  79    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
  80 enum
  81 {
  82   DEBUG_DATE_PARSING_OPTION = CHAR_MAX + 1,
  83   RESOLUTION_OPTION,
  84   RFC_3339_OPTION
  85 };
  86
  87 static char const short_options[] = "d:f:I::r:Rs:u";
  88
  89 static struct option const long_options[] =
  90 {
  91   {"date", required_argument, NULL, 'd'},
  92   {"debug", no_argument, NULL, DEBUG_DATE_PARSING_OPTION},
  93   {"file", required_argument, NULL, 'f'},
  94   {"iso-8601", optional_argument, NULL, 'I'},
  95   {"reference", required_argument, NULL, 'r'},
  96   {"resolution", no_argument, NULL, RESOLUTION_OPTION},
  97   {"rfc-email", no_argument, NULL, 'R'},
  98   {"rfc-822", no_argument, NULL, 'R'},
  99   {"rfc-2822", no_argument, NULL, 'R'},
 100   {"rfc-3339", required_argument, NULL, RFC_3339_OPTION},
 101   {"set", required_argument, NULL, 's'},
 102   {"uct", no_argument, NULL, 'u'},
 103   {"utc", no_argument, NULL, 'u'},
 104   {"universal", no_argument, NULL, 'u'},
 105   {GETOPT_HELP_OPTION_DECL},
 106   {GETOPT_VERSION_OPTION_DECL},
 107   {NULL, 0, NULL, 0}
 108 };
 109
 110 /* flags for parse_datetime2 */
 111 static unsigned int parse_datetime_flags;
 112
 113 #if LOCALTIME_CACHE
 114 # define TZSET tzset ()
 115 #else
 116 # define TZSET /* empty */
 117 #endif
 118
 119 #ifdef _DATE_FMT
 120 # define DATE_FMT_LANGINFO() nl_langinfo (_DATE_FMT)
 121 #else
 122 # define DATE_FMT_LANGINFO() ""
 123 #endif
 124
 125 void
 126 usage (int status)
 127 {
 128   if (status != EXIT_SUCCESS)
 129     emit_try_help ();
 130   else
 131     {
 132       printf (_("\
 133 Usage: %s [OPTION]... [+FORMAT]\n\
 134   or:  %s [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]\n\
 135 "),
 136               program_name, program_name);
 137       fputs (_("\
 138 Display the current time in the given FORMAT, or set the system date.\n\
 139 "), stdout);
 140
 141       emit_mandatory_arg_note ();
 142
 143       fputs (_("\
 144   -d, --date=STRING          display time described by STRING, not 'now'\n\
 145 "), stdout);
 146       fputs (_("\
 147       --debug                annotate the parsed date,\n\
 148                               and warn about questionable usage to stderr\n\
 149 "), stdout);
 150       fputs (_("\
 151   -f, --file=DATEFILE        like --date; once for each line of DATEFILE\n\
 152 "), stdout);
 153       fputs (_("\
 154   -I[FMT], --iso-8601[=FMT]  output date/time in ISO 8601 format.\n\
 155                                FMT='date' for date only (the default),\n\
 156                                'hours', 'minutes', 'seconds', or 'ns'\n\
 157                                for date and time to the indicated precision.\n\
 158                                Example: 2006-08-14T02:34:56-06:00\n\
 159 "), stdout);
 160       fputs (_("\
 161   --resolution               output the available resolution of timestamps\n\
 162                                Example: 0.000000001\n\
 163 "), stdout);
 164       fputs (_("\
 165   -R, --rfc-email            output date and time in RFC 5322 format.\n\
 166                                Example: Mon, 14 Aug 2006 02:34:56 -0600\n\
 167 "), stdout);
 168       fputs (_("\
 169       --rfc-3339=FMT         output date/time in RFC 3339 format.\n\
 170                                FMT='date', 'seconds', or 'ns'\n\
 171                                for date and time to the indicated precision.\n\
 172                                Example: 2006-08-14 02:34:56-06:00\n\
 173 "), stdout);
 174       fputs (_("\
 175   -r, --reference=FILE       display the last modification time of FILE\n\
 176 "), stdout);
 177       fputs (_("\
 178   -s, --set=STRING           set time described by STRING\n\
 179   -u, --utc, --universal     print or set Coordinated Universal Time (UTC)\n\
 180 "), stdout);
 181       fputs (HELP_OPTION_DESCRIPTION, stdout);
 182       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 183       fputs (_("\
 184 \n\
 185 FORMAT controls the output.  Interpreted sequences are:\n\
 186 \n\
 187   %%   a literal %\n\
 188   %a   locale's abbreviated weekday name (e.g., Sun)\n\
 189 "), stdout);
 190       fputs (_("\
 191   %A   locale's full weekday name (e.g., Sunday)\n\
 192   %b   locale's abbreviated month name (e.g., Jan)\n\
 193   %B   locale's full month name (e.g., January)\n\
 194   %c   locale's date and time (e.g., Thu Mar  3 23:05:25 2005)\n\
 195 "), stdout);
 196       fputs (_("\
 197   %C   century; like %Y, except omit last two digits (e.g., 20)\n\
 198   %d   day of month (e.g., 01)\n\
 199   %D   date; same as %m/%d/%y\n\
 200   %e   day of month, space padded; same as %_d\n\
 201 "), stdout);
 202       fputs (_("\
 203   %F   full date; like %+4Y-%m-%d\n\
 204   %g   last two digits of year of ISO week number (see %G)\n\
 205   %G   year of ISO week number (see %V); normally useful only with %V\n\
 206 "), stdout);
 207       fputs (_("\
 208   %h   same as %b\n\
 209   %H   hour (00..23)\n\
 210   %I   hour (01..12)\n\
 211   %j   day of year (001..366)\n\
 212 "), stdout);
 213       fputs (_("\
 214   %k   hour, space padded ( 0..23); same as %_H\n\
 215   %l   hour, space padded ( 1..12); same as %_I\n\
 216   %m   month (01..12)\n\
 217   %M   minute (00..59)\n\
 218 "), stdout);
 219       fputs (_("\
 220   %n   a newline\n\
 221   %N   nanoseconds (000000000..999999999)\n\
 222   %p   locale's equivalent of either AM or PM; blank if not known\n\
 223   %P   like %p, but lower case\n\
 224   %q   quarter of year (1..4)\n\
 225   %r   locale's 12-hour clock time (e.g., 11:11:04 PM)\n\
 226   %R   24-hour hour and minute; same as %H:%M\n\
 227   %s   seconds since the Epoch (1970-01-01 00:00 UTC)\n\
 228 "), stdout);
 229       fputs (_("\
 230   %S   second (00..60)\n\
 231   %t   a tab\n\
 232   %T   time; same as %H:%M:%S\n\
 233   %u   day of week (1..7); 1 is Monday\n\
 234 "), stdout);
 235       fputs (_("\
 236   %U   week number of year, with Sunday as first day of week (00..53)\n\
 237   %V   ISO week number, with Monday as first day of week (01..53)\n\
 238   %w   day of week (0..6); 0 is Sunday\n\
 239   %W   week number of year, with Monday as first day of week (00..53)\n\
 240 "), stdout);
 241       fputs (_("\
 242   %x   locale's date representation (e.g., 12/31/99)\n\
 243   %X   locale's time representation (e.g., 23:13:48)\n\
 244   %y   last two digits of year (00..99)\n\
 245   %Y   year\n\
 246 "), stdout);
 247       fputs (_("\
 248   %z   +hhmm numeric time zone (e.g., -0400)\n\
 249   %:z  +hh:mm numeric time zone (e.g., -04:00)\n\
 250   %::z  +hh:mm:ss numeric time zone (e.g., -04:00:00)\n\
 251   %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)\n\
 252   %Z   alphabetic time zone abbreviation (e.g., EDT)\n\
 253 \n\
 254 By default, date pads numeric fields with zeroes.\n\
 255 "), stdout);
 256       fputs (_("\
 257 The following optional flags may follow '%':\n\
 258 \n\
 259   -  (hyphen) do not pad the field\n\
 260   _  (underscore) pad with spaces\n\
 261   0  (zero) pad with zeros\n\
 262   +  pad with zeros, and put '+' before future years with >4 digits\n\
 263   ^  use upper case if possible\n\
 264   #  use opposite case if possible\n\
 265 "), stdout);
 266       fputs (_("\
 267 \n\
 268 After any flags comes an optional field width, as a decimal number;\n\
 269 then an optional modifier, which is either\n\
 270 E to use the locale's alternate representations if available, or\n\
 271 O to use the locale's alternate numeric symbols if available.\n\
 272 "), stdout);
 273       fputs (_("\
 274 \n\
 275 Examples:\n\
 276 Convert seconds since the Epoch (1970-01-01 UTC) to a date\n\
 277   $ date --date='@2147483647'\n\
 278 \n\
 279 Show the time on the west coast of the US (use tzselect(1) to find TZ)\n\
 280   $ TZ='America/Los_Angeles' date\n\
 281 \n\
 282 Show the local time for 9AM next Friday on the west coast of the US\n\
 283   $ date --date='TZ=\"America/Los_Angeles\" 09:00 next Fri'\n\
 284 "), stdout);
 285       emit_ancillary_info (PROGRAM_NAME);
 286     }
 287   exit (status);
 288 }
 289
 290 /* Yield the number of decimal digits needed to output a time with the
 291    nanosecond resolution RES, without losing information.  */
 292
 293 static int
 294 res_width (long int res)
 295 {
 296   int i = 9;
 297   for (long long int r = 1; (r *= 10) <= res; )
 298     i--;
 299   return i;
 300 }
 301
 302 /* Return a newly allocated copy of FORMAT with each "%-N" adjusted to
 303    be "%9N", "%6N", or whatever other resolution is appropriate for
 304    the current platform.  If no "%-N" appears, return NULL.  */
 305
 306 static char *
 307 adjust_resolution (char const *format)
 308 {
 309   char *copy = NULL;
 310
 311   for (char const *f = format; *f; f++)
 312     if (f[0] == '%' && f[1] == '-' && f[2] == 'N')
 313       {
 314         if (!copy)
 315           copy = xstrdup (format);
 316         copy[f + 1 - format] = '0' + res_width (gettime_res ());
 317         f += 2;
 318       }
 319
 320   return copy;
 321 }
 322
 323 /* Parse each line in INPUT_FILENAME as with --date and display each
 324    resulting time and date.  If the file cannot be opened, tell why
 325    then exit.  Issue a diagnostic for any lines that cannot be parsed.
 326    Return true if successful.  */
 327
 328 static bool
 329 batch_convert (char const *input_filename, char const *format,
 330                timezone_t tz, char const *tzstring)
 331 {
 332   bool ok;
 333   FILE *in_stream;
 334   char *line;
 335   size_t buflen;
 336   struct timespec when;
 337
 338   if (STREQ (input_filename, "-"))
 339     {
 340       input_filename = _("standard input");
 341       in_stream = stdin;
 342     }
 343   else
 344     {
 345       in_stream = fopen (input_filename, "r");
 346       if (in_stream == NULL)
 347         {
 348           die (EXIT_FAILURE, errno, "%s", quotef (input_filename));
 349         }
 350     }
 351
 352   line = NULL;
 353   buflen = 0;
 354   ok = true;
 355   while (true)
 356     {
 357       ssize_t line_length = getline (&line, &buflen, in_stream);
 358       if (line_length < 0)
 359         {
 360           /* FIXME: detect/handle error here.  */
 361           break;
 362         }
 363
 364       if (! parse_datetime2 (&when, line, NULL,
 365                              parse_datetime_flags, tz, tzstring))
 366         {
 367           if (line[line_length - 1] == '\n')
 368             line[line_length - 1] = '\0';
 369           error (0, 0, _("invalid date %s"), quote (line));
 370           ok = false;
 371         }
 372       else
 373         {
 374           ok &= show_date (format, when, tz);
 375         }
 376     }
 377
 378   if (fclose (in_stream) == EOF)
 379     die (EXIT_FAILURE, errno, "%s", quotef (input_filename));
 380
 381   free (line);
 382
 383   return ok;
 384 }
 385
 386 int
 387 main (int argc, char **argv)
 388 {
 389   int optc;
 390   char const *datestr = NULL;
 391   char const *set_datestr = NULL;
 392   struct timespec when;
 393   bool set_date = false;
 394   char const *format = NULL;
 395   bool get_resolution = false;
 396   char *batch_file = NULL;
 397   char *reference = NULL;
 398   struct stat refstats;
 399   bool ok;
 400
 401   initialize_main (&argc, &argv);
 402   set_program_name (argv[0]);
 403   setlocale (LC_ALL, "");
 404   bindtextdomain (PACKAGE, LOCALEDIR);
 405   textdomain (PACKAGE);
 406
 407   atexit (close_stdout);
 408
 409   while ((optc = getopt_long (argc, argv, short_options, long_options, NULL))
 410          != -1)
 411     {
 412       char const *new_format = NULL;
 413
 414       switch (optc)
 415         {
 416         case 'd':
 417           datestr = optarg;
 418           break;
 419         case DEBUG_DATE_PARSING_OPTION:
 420           parse_datetime_flags |= PARSE_DATETIME_DEBUG;
 421           break;
 422         case 'f':
 423           batch_file = optarg;
 424           break;
 425         case RESOLUTION_OPTION:
 426           get_resolution = true;
 427           break;
 428         case RFC_3339_OPTION:
 429           {
 430             static char const rfc_3339_format[][32] =
 431               {
 432                 "%Y-%m-%d",
 433                 "%Y-%m-%d %H:%M:%S%:z",
 434                 "%Y-%m-%d %H:%M:%S.%N%:z"
 435               };
 436             enum Time_spec i =
 437               XARGMATCH ("--rfc-3339", optarg,
 438                          time_spec_string + 2, time_spec + 2);
 439             new_format = rfc_3339_format[i];
 440             break;
 441           }
 442         case 'I':
 443           {
 444             static char const iso_8601_format[][32] =
 445               {
 446                 "%Y-%m-%d",
 447                 "%Y-%m-%dT%H:%M:%S%:z",
 448                 "%Y-%m-%dT%H:%M:%S,%N%:z",
 449                 "%Y-%m-%dT%H%:z",
 450                 "%Y-%m-%dT%H:%M%:z"
 451               };
 452             enum Time_spec i =
 453               (optarg
 454                ? XARGMATCH ("--iso-8601", optarg, time_spec_string, time_spec)
 455                : TIME_SPEC_DATE);
 456             new_format = iso_8601_format[i];
 457             break;
 458           }
 459         case 'r':
 460           reference = optarg;
 461           break;
 462         case 'R':
 463           new_format = rfc_email_format;
 464           break;
 465         case 's':
 466           set_datestr = optarg;
 467           set_date = true;
 468           break;
 469         case 'u':
 470           /* POSIX says that 'date -u' is equivalent to setting the TZ
 471              environment variable, so this option should do nothing other
 472              than setting TZ.  */
 473           if (putenv (bad_cast ("TZ=UTC0")) != 0)
 474             xalloc_die ();
 475           TZSET;
 476           break;
 477         case_GETOPT_HELP_CHAR;
 478         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 479         default:
 480           usage (EXIT_FAILURE);
 481         }
 482
 483       if (new_format)
 484         {
 485           if (format)
 486             die (EXIT_FAILURE, 0, _("multiple output formats specified"));
 487           format = new_format;
 488         }
 489     }
 490
 491   int option_specified_date = (!!datestr + !!batch_file + !!reference
 492                                + get_resolution);
 493
 494   if (option_specified_date > 1)
 495     {
 496       error (0, 0,
 497         _("the options to specify dates for printing are mutually exclusive"));
 498       usage (EXIT_FAILURE);
 499     }
 500
 501   if (set_date && option_specified_date)
 502     {
 503       error (0, 0,
 504           _("the options to print and set the time may not be used together"));
 505       usage (EXIT_FAILURE);
 506     }
 507
 508   if (optind < argc)
 509     {
 510       if (optind + 1 < argc)
 511         {
 512           error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
 513           usage (EXIT_FAILURE);
 514         }
 515
 516       if (argv[optind][0] == '+')
 517         {
 518           if (format)
 519             die (EXIT_FAILURE, 0, _("multiple output formats specified"));
 520           format = argv[optind++] + 1;
 521         }
 522       else if (set_date || option_specified_date)
 523         {
 524           error (0, 0,
 525                  _("the argument %s lacks a leading '+';\n"
 526                    "when using an option to specify date(s), any non-option\n"
 527                    "argument must be a format string beginning with '+'"),
 528                  quote (argv[optind]));
 529           usage (EXIT_FAILURE);
 530         }
 531     }
 532
 533   if (!format)
 534     {
 535       if (get_resolution)
 536         format = "%s.%N";
 537       else
 538         {
 539           format = DATE_FMT_LANGINFO ();
 540
 541           /* Do not wrap the following literal format string with _(...).
 542              For example, suppose LC_ALL is unset, LC_TIME=POSIX,
 543              and LANG="ko_KR".  In that case, POSIX says that LC_TIME
 544              determines the format and contents of date and time strings
 545              written by date, which means "date" must generate output
 546              using the POSIX locale; but adding _() would cause "date"
 547              to use a Korean translation of the format.  */
 548           if (! *format)
 549             format = "%a %b %e %H:%M:%S %Z %Y";
 550         }
 551     }
 552
 553   char *format_copy = adjust_resolution (format);
 554   char const *format_res = format_copy ? format_copy : format;
 555   char const *tzstring = getenv ("TZ");
 556   timezone_t tz = tzalloc (tzstring);
 557
 558   if (batch_file != NULL)
 559     ok = batch_convert (batch_file, format_res, tz, tzstring);
 560   else
 561     {
 562       bool valid_date = true;
 563       ok = true;
 564
 565       if (!option_specified_date && !set_date)
 566         {
 567           if (optind < argc)
 568             {
 569               /* Prepare to set system clock to the specified date/time
 570                  given in the POSIX-format.  */
 571               set_date = true;
 572               datestr = argv[optind];
 573               valid_date = posixtime (&when.tv_sec,
 574                                       datestr,
 575                                       (PDS_TRAILING_YEAR
 576                                        | PDS_CENTURY | PDS_SECONDS));
 577               when.tv_nsec = 0; /* FIXME: posixtime should set this.  */
 578             }
 579           else
 580             {
 581               /* Prepare to print the current date/time.  */
 582               gettime (&when);
 583             }
 584         }
 585       else
 586         {
 587           /* (option_specified_date || set_date) */
 588           if (reference != NULL)
 589             {
 590               if (stat (reference, &refstats) != 0)
 591                 die (EXIT_FAILURE, errno, "%s", quotef (reference));
 592               when = get_stat_mtime (&refstats);
 593             }
 594           else if (get_resolution)
 595             {
 596               long int res = gettime_res ();
 597               when.tv_sec = res / TIMESPEC_HZ;
 598               when.tv_nsec = res % TIMESPEC_HZ;
 599             }
 600           else
 601             {
 602               if (set_datestr)
 603                 datestr = set_datestr;
 604               valid_date = parse_datetime2 (&when, datestr, NULL,
 605                                             parse_datetime_flags,
 606                                             tz, tzstring);
 607             }
 608         }
 609
 610       if (! valid_date)
 611         die (EXIT_FAILURE, 0, _("invalid date %s"), quote (datestr));
 612
 613       if (set_date)
 614         {
 615           /* Set the system clock to the specified date, then regardless of
 616              the success of that operation, format and print that date.  */
 617           if (settime (&when) != 0)
 618             {
 619               error (0, errno, _("cannot set date"));
 620               ok = false;
 621             }
 622         }
 623
 624       ok &= show_date (format_res, when, tz);
 625     }
 626
 627   IF_LINT (tzfree (tz));
 628   IF_LINT (free (format_copy));
 629
 630   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 631 }
 632
 633 /* Display the date and/or time in WHEN according to the format specified
 634    in FORMAT, followed by a newline.  Return true if successful.  */
 635
 636 static bool
 637 show_date (char const *format, struct timespec when, timezone_t tz)
 638 {
 639   struct tm tm;
 640
 641   if (parse_datetime_flags & PARSE_DATETIME_DEBUG)
 642     error (0, 0, _("output format: %s"), quote (format));
 643
 644   if (localtime_rz (tz, &when.tv_sec, &tm))
 645     {
 646       if (format == rfc_email_format)
 647         setlocale (LC_TIME, "C");
 648       fprintftime (stdout, format, &tm, tz, when.tv_nsec);
 649       if (format == rfc_email_format)
 650         setlocale (LC_TIME, "");
 651       fputc ('\n', stdout);
 652       return true;
 653     }
 654   else
 655     {
 656       char buf[INT_BUFSIZE_BOUND (intmax_t)];
 657       error (0, 0, _("time %s is out of range"),
 658              quote (timetostr (when.tv_sec, buf)));
 659       return false;
 660     }
 661 }