src/date.c

   1 /* date - print or set the system date and time
   2    Copyright (C) 1989-2024 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 "parse-datetime.h"
  30 #include "posixtm.h"
  31 #include "quote.h"
  32 #include "show-date.h"
  33 #include "stat-time.h"
  34
  35 /* The official name of this program (e.g., no 'g' prefix).  */
  36 #define PROGRAM_NAME "date"
  37
  38 #define AUTHORS proper_name ("David MacKenzie")
  39
  40 static bool show_date_helper (char const *, struct timespec, timezone_t);
  41
  42 enum Time_spec
  43 {
  44   /* Display only the date.  */
  45   TIME_SPEC_DATE,
  46   /* Display date, hours, minutes, and seconds.  */
  47   TIME_SPEC_SECONDS,
  48   /* Similar, but display nanoseconds. */
  49   TIME_SPEC_NS,
  50
  51   /* Put these last, since they aren't valid for --rfc-3339.  */
  52
  53   /* Display date and hour.  */
  54   TIME_SPEC_HOURS,
  55   /* Display date, hours, and minutes.  */
  56   TIME_SPEC_MINUTES
  57 };
  58
  59 static char const *const time_spec_string[] =
  60 {
  61   /* Put "hours" and "minutes" first, since they aren't valid for
  62      --rfc-3339.  */
  63   "hours", "minutes",
  64   "date", "seconds", "ns", nullptr
  65 };
  66 static enum Time_spec const time_spec[] =
  67 {
  68   TIME_SPEC_HOURS, TIME_SPEC_MINUTES,
  69   TIME_SPEC_DATE, TIME_SPEC_SECONDS, TIME_SPEC_NS
  70 };
  71 ARGMATCH_VERIFY (time_spec_string, time_spec);
  72
  73 /* A format suitable for Internet RFCs 5322, 2822, and 822.  */
  74 static char const rfc_email_format[] = "%a, %d %b %Y %H:%M:%S %z";
  75
  76 /* For long options that have no equivalent short option, use a
  77    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
  78 enum
  79 {
  80   DEBUG_DATE_PARSING_OPTION = CHAR_MAX + 1,
  81   RESOLUTION_OPTION,
  82   RFC_3339_OPTION
  83 };
  84
  85 static char const short_options[] = "d:f:I::r:Rs:u";
  86
  87 static struct option const long_options[] =
  88 {
  89   {"date", required_argument, nullptr, 'd'},
  90   {"debug", no_argument, nullptr, DEBUG_DATE_PARSING_OPTION},
  91   {"file", required_argument, nullptr, 'f'},
  92   {"iso-8601", optional_argument, nullptr, 'I'},
  93   {"reference", required_argument, nullptr, 'r'},
  94   {"resolution", no_argument, nullptr, RESOLUTION_OPTION},
  95   {"rfc-email", no_argument, nullptr, 'R'},
  96   {"rfc-822", no_argument, nullptr, 'R'},
  97   {"rfc-2822", no_argument, nullptr, 'R'},
  98   {"rfc-3339", required_argument, nullptr, RFC_3339_OPTION},
  99   {"set", required_argument, nullptr, 's'},
 100   {"uct", no_argument, nullptr, 'u'},
 101   {"utc", no_argument, nullptr, 'u'},
 102   {"universal", no_argument, nullptr, 'u'},
 103   {GETOPT_HELP_OPTION_DECL},
 104   {GETOPT_VERSION_OPTION_DECL},
 105   {nullptr, 0, nullptr, 0}
 106 };
 107
 108 /* flags for parse_datetime2 */
 109 static unsigned int parse_datetime_flags;
 110
 111 #if LOCALTIME_CACHE
 112 # define TZSET tzset ()
 113 #else
 114 # define TZSET /* empty */
 115 #endif
 116
 117 #ifdef _DATE_FMT
 118 # define DATE_FMT_LANGINFO() nl_langinfo (_DATE_FMT)
 119 #else
 120 # define DATE_FMT_LANGINFO() ""
 121 #endif
 122
 123 void
 124 usage (int status)
 125 {
 126   if (status != EXIT_SUCCESS)
 127     emit_try_help ();
 128   else
 129     {
 130       printf (_("\
 131 Usage: %s [OPTION]... [+FORMAT]\n\
 132   or:  %s [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]\n\
 133 "),
 134               program_name, program_name);
 135       fputs (_("\
 136 Display date and time in the given FORMAT.\n\
 137 With -s, or with [MMDDhhmm[[CC]YY][.ss]], set the date and time.\n\
 138 "), stdout);
 139
 140       emit_mandatory_arg_note ();
 141
 142       fputs (_("\
 143   -d, --date=STRING          display time described by STRING, not 'now'\n\
 144 "), stdout);
 145       fputs (_("\
 146       --debug                annotate the parsed date,\n\
 147                               and warn about questionable usage to stderr\n\
 148 "), stdout);
 149       fputs (_("\
 150   -f, --file=DATEFILE        like --date; once for each line of DATEFILE\n\
 151 "), stdout);
 152       fputs (_("\
 153   -I[FMT], --iso-8601[=FMT]  output date/time in ISO 8601 format.\n\
 154                                FMT='date' for date only (the default),\n\
 155                                'hours', 'minutes', 'seconds', or 'ns'\n\
 156                                for date and time to the indicated precision.\n\
 157                                Example: 2006-08-14T02:34:56-06:00\n\
 158 "), stdout);
 159       fputs (_("\
 160   --resolution               output the available resolution of timestamps\n\
 161                                Example: 0.000000001\n\
 162 "), stdout);
 163       fputs (_("\
 164   -R, --rfc-email            output date and time in RFC 5322 format.\n\
 165                                Example: Mon, 14 Aug 2006 02:34:56 -0600\n\
 166 "), stdout);
 167       fputs (_("\
 168       --rfc-3339=FMT         output date/time in RFC 3339 format.\n\
 169                                FMT='date', 'seconds', or 'ns'\n\
 170                                for date and time to the indicated precision.\n\
 171                                Example: 2006-08-14 02:34:56-06:00\n\
 172 "), stdout);
 173       fputs (_("\
 174   -r, --reference=FILE       display the last modification time of FILE\n\
 175 "), stdout);
 176       fputs (_("\
 177   -s, --set=STRING           set time described by STRING\n\
 178   -u, --utc, --universal     print or set Coordinated Universal Time (UTC)\n\
 179 "), stdout);
 180       fputs (HELP_OPTION_DESCRIPTION, stdout);
 181       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 182       fputs (_("\
 183 \n\
 184 All options that specify the date to display are mutually exclusive.\n\
 185 I.e.: --date, --file, --reference, --resolution.\n\
 186 "), stdout);
 187       fputs (_("\
 188 \n\
 189 FORMAT controls the output.  Interpreted sequences are:\n\
 190 \n\
 191   %%   a literal %\n\
 192   %a   locale's abbreviated weekday name (e.g., Sun)\n\
 193 "), stdout);
 194       fputs (_("\
 195   %A   locale's full weekday name (e.g., Sunday)\n\
 196   %b   locale's abbreviated month name (e.g., Jan)\n\
 197   %B   locale's full month name (e.g., January)\n\
 198   %c   locale's date and time (e.g., Thu Mar  3 23:05:25 2005)\n\
 199 "), stdout);
 200       fputs (_("\
 201   %C   century; like %Y, except omit last two digits (e.g., 20)\n\
 202   %d   day of month (e.g., 01)\n\
 203   %D   date; same as %m/%d/%y\n\
 204   %e   day of month, space padded; same as %_d\n\
 205 "), stdout);
 206       fputs (_("\
 207   %F   full date; like %+4Y-%m-%d\n\
 208   %g   last two digits of year of ISO week number (see %G)\n\
 209   %G   year of ISO week number (see %V); normally useful only with %V\n\
 210 "), stdout);
 211       fputs (_("\
 212   %h   same as %b\n\
 213   %H   hour (00..23)\n\
 214   %I   hour (01..12)\n\
 215   %j   day of year (001..366)\n\
 216 "), stdout);
 217       fputs (_("\
 218   %k   hour, space padded ( 0..23); same as %_H\n\
 219   %l   hour, space padded ( 1..12); same as %_I\n\
 220   %m   month (01..12)\n\
 221   %M   minute (00..59)\n\
 222 "), stdout);
 223       fputs (_("\
 224   %n   a newline\n\
 225   %N   nanoseconds (000000000..999999999)\n\
 226   %p   locale's equivalent of either AM or PM; blank if not known\n\
 227   %P   like %p, but lower case\n\
 228   %q   quarter of year (1..4)\n\
 229   %r   locale's 12-hour clock time (e.g., 11:11:04 PM)\n\
 230   %R   24-hour hour and minute; same as %H:%M\n\
 231   %s   seconds since the Epoch (1970-01-01 00:00 UTC)\n\
 232 "), stdout);
 233       fputs (_("\
 234   %S   second (00..60)\n\
 235   %t   a tab\n\
 236   %T   time; same as %H:%M:%S\n\
 237   %u   day of week (1..7); 1 is Monday\n\
 238 "), stdout);
 239       fputs (_("\
 240   %U   week number of year, with Sunday as first day of week (00..53)\n\
 241   %V   ISO week number, with Monday as first day of week (01..53)\n\
 242   %w   day of week (0..6); 0 is Sunday\n\
 243   %W   week number of year, with Monday as first day of week (00..53)\n\
 244 "), stdout);
 245       fputs (_("\
 246   %x   locale's date representation (e.g., 12/31/99)\n\
 247   %X   locale's time representation (e.g., 23:13:48)\n\
 248   %y   last two digits of year (00..99)\n\
 249   %Y   year\n\
 250 "), stdout);
 251       fputs (_("\
 252   %z   +hhmm numeric time zone (e.g., -0400)\n\
 253   %:z  +hh:mm numeric time zone (e.g., -04:00)\n\
 254   %::z  +hh:mm:ss numeric time zone (e.g., -04:00:00)\n\
 255   %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)\n\
 256   %Z   alphabetic time zone abbreviation (e.g., EDT)\n\
 257 \n\
 258 By default, date pads numeric fields with zeroes.\n\
 259 "), stdout);
 260       fputs (_("\
 261 The following optional flags may follow '%':\n\
 262 \n\
 263   -  (hyphen) do not pad the field\n\
 264   _  (underscore) pad with spaces\n\
 265   0  (zero) pad with zeros\n\
 266   +  pad with zeros, and put '+' before future years with >4 digits\n\
 267   ^  use upper case if possible\n\
 268   #  use opposite case if possible\n\
 269 "), stdout);
 270       fputs (_("\
 271 \n\
 272 After any flags comes an optional field width, as a decimal number;\n\
 273 then an optional modifier, which is either\n\
 274 E to use the locale's alternate representations if available, or\n\
 275 O to use the locale's alternate numeric symbols if available.\n\
 276 "), stdout);
 277       fputs (_("\
 278 \n\
 279 Examples:\n\
 280 Convert seconds since the Epoch (1970-01-01 UTC) to a date\n\
 281   $ date --date='@2147483647'\n\
 282 \n\
 283 Show the time on the west coast of the US (use tzselect(1) to find TZ)\n\
 284   $ TZ='America/Los_Angeles' date\n\
 285 \n\
 286 Show the local time for 9AM next Friday on the west coast of the US\n\
 287   $ date --date='TZ=\"America/Los_Angeles\" 09:00 next Fri'\n\
 288 "), stdout);
 289       emit_ancillary_info (PROGRAM_NAME);
 290     }
 291   exit (status);
 292 }
 293
 294 /* Yield the number of decimal digits needed to output a time with the
 295    nanosecond resolution RES, without losing information.  */
 296
 297 ATTRIBUTE_CONST
 298 static int
 299 res_width (long int res)
 300 {
 301   int i = 9;
 302   for (long long int r = 1; (r *= 10) <= res; )
 303     i--;
 304   return i;
 305 }
 306
 307 /* Return a newly allocated copy of FORMAT with each "%-N" adjusted to
 308    be "%9N", "%6N", or whatever other resolution is appropriate for
 309    the current platform.  If no "%-N" appears, return nullptr.  */
 310
 311 static char *
 312 adjust_resolution (char const *format)
 313 {
 314   char *copy = nullptr;
 315
 316   for (char const *f = format; *f; f++)
 317     if (f[0] == '%')
 318       {
 319         if (f[1] == '-' && f[2] == 'N')
 320           {
 321             if (!copy)
 322               copy = xstrdup (format);
 323             copy[f + 1 - format] = '0' + res_width (gettime_res ());
 324             f += 2;
 325           }
 326         else
 327           f += f[1] == '%';
 328       }
 329
 330   return copy;
 331 }
 332
 333 /* Parse each line in INPUT_FILENAME as with --date and display each
 334    resulting time and date.  If the file cannot be opened, tell why
 335    then exit.  Issue a diagnostic for any lines that cannot be parsed.
 336    Return true if successful.  */
 337
 338 static bool
 339 batch_convert (char const *input_filename, char const *format,
 340                timezone_t tz, char const *tzstring)
 341 {
 342   bool ok;
 343   FILE *in_stream;
 344   char *line;
 345   size_t buflen;
 346   struct timespec when;
 347
 348   if (STREQ (input_filename, "-"))
 349     {
 350       input_filename = _("standard input");
 351       in_stream = stdin;
 352     }
 353   else
 354     {
 355       in_stream = fopen (input_filename, "r");
 356       if (in_stream == nullptr)
 357         error (EXIT_FAILURE, errno, "%s", quotef (input_filename));
 358     }
 359
 360   line = nullptr;
 361   buflen = 0;
 362   ok = true;
 363   while (true)
 364     {
 365       ssize_t line_length = getline (&line, &buflen, in_stream);
 366       if (line_length < 0)
 367         {
 368           if (ferror (in_stream))
 369             error (EXIT_FAILURE, errno, _("%s: read error"),
 370                    quotef (input_filename));
 371           break;
 372         }
 373
 374       if (! parse_datetime2 (&when, line, nullptr,
 375                              parse_datetime_flags, tz, tzstring))
 376         {
 377           if (line[line_length - 1] == '\n')
 378             line[line_length - 1] = '\0';
 379           error (0, 0, _("invalid date %s"), quote (line));
 380           ok = false;
 381         }
 382       else
 383         {
 384           ok &= show_date_helper (format, when, tz);
 385         }
 386     }
 387
 388   if (fclose (in_stream) == EOF)
 389     error (EXIT_FAILURE, errno, "%s", quotef (input_filename));
 390
 391   free (line);
 392
 393   return ok;
 394 }
 395
 396 int
 397 main (int argc, char **argv)
 398 {
 399   int optc;
 400   char const *datestr = nullptr;
 401   char const *set_datestr = nullptr;
 402   struct timespec when;
 403   bool set_date = false;
 404   char const *format = nullptr;
 405   bool get_resolution = false;
 406   char *batch_file = nullptr;
 407   char *reference = nullptr;
 408   struct stat refstats;
 409   bool ok;
 410   bool discarded_datestr = false;
 411   bool discarded_set_datestr = false;
 412
 413   initialize_main (&argc, &argv);
 414   set_program_name (argv[0]);
 415   setlocale (LC_ALL, "");
 416   bindtextdomain (PACKAGE, LOCALEDIR);
 417   textdomain (PACKAGE);
 418
 419   atexit (close_stdout);
 420
 421   while ((optc = getopt_long (argc, argv, short_options, long_options, nullptr))
 422          != -1)
 423     {
 424       char const *new_format = nullptr;
 425
 426       switch (optc)
 427         {
 428         case 'd':
 429           if (datestr)
 430             discarded_datestr = true;
 431           datestr = optarg;
 432           break;
 433         case DEBUG_DATE_PARSING_OPTION:
 434           parse_datetime_flags |= PARSE_DATETIME_DEBUG;
 435           break;
 436         case 'f':
 437           batch_file = optarg;
 438           break;
 439         case RESOLUTION_OPTION:
 440           get_resolution = true;
 441           break;
 442         case RFC_3339_OPTION:
 443           {
 444             static char const rfc_3339_format[][32] =
 445               {
 446                 "%Y-%m-%d",
 447                 "%Y-%m-%d %H:%M:%S%:z",
 448                 "%Y-%m-%d %H:%M:%S.%N%:z"
 449               };
 450             enum Time_spec i =
 451               XARGMATCH ("--rfc-3339", optarg,
 452                          time_spec_string + 2, time_spec + 2);
 453             new_format = rfc_3339_format[i];
 454             break;
 455           }
 456         case 'I':
 457           {
 458             static char const iso_8601_format[][32] =
 459               {
 460                 "%Y-%m-%d",
 461                 "%Y-%m-%dT%H:%M:%S%:z",
 462                 "%Y-%m-%dT%H:%M:%S,%N%:z",
 463                 "%Y-%m-%dT%H%:z",
 464                 "%Y-%m-%dT%H:%M%:z"
 465               };
 466             enum Time_spec i =
 467               (optarg
 468                ? XARGMATCH ("--iso-8601", optarg, time_spec_string, time_spec)
 469                : TIME_SPEC_DATE);
 470             new_format = iso_8601_format[i];
 471             break;
 472           }
 473         case 'r':
 474           reference = optarg;
 475           break;
 476         case 'R':
 477           new_format = rfc_email_format;
 478           break;
 479         case 's':
 480           if (set_datestr)
 481             discarded_set_datestr = true;
 482           set_datestr = optarg;
 483           set_date = true;
 484           break;
 485         case 'u':
 486           /* POSIX says that 'date -u' is equivalent to setting the TZ
 487              environment variable, so this option should do nothing other
 488              than setting TZ.  */
 489           if (putenv (bad_cast ("TZ=UTC0")) != 0)
 490             xalloc_die ();
 491           TZSET;
 492           break;
 493         case_GETOPT_HELP_CHAR;
 494         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 495         default:
 496           usage (EXIT_FAILURE);
 497         }
 498
 499       if (new_format)
 500         {
 501           if (format)
 502             error (EXIT_FAILURE, 0, _("multiple output formats specified"));
 503           format = new_format;
 504         }
 505     }
 506
 507   int option_specified_date = (!!datestr + !!batch_file + !!reference
 508                                + get_resolution);
 509
 510   if (option_specified_date > 1)
 511     {
 512       error (0, 0,
 513         _("the options to specify dates for printing are mutually exclusive"));
 514       usage (EXIT_FAILURE);
 515     }
 516
 517   if (set_date && option_specified_date)
 518     {
 519       error (0, 0,
 520           _("the options to print and set the time may not be used together"));
 521       usage (EXIT_FAILURE);
 522     }
 523
 524   if (discarded_datestr && (parse_datetime_flags & PARSE_DATETIME_DEBUG))
 525     error (0, 0, _("only using last of multiple -d options"));
 526
 527   if (discarded_set_datestr && (parse_datetime_flags & PARSE_DATETIME_DEBUG))
 528     error (0, 0, _("only using last of multiple -s options"));
 529
 530   if (optind < argc)
 531     {
 532       if (optind + 1 < argc)
 533         {
 534           error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
 535           usage (EXIT_FAILURE);
 536         }
 537
 538       if (argv[optind][0] == '+')
 539         {
 540           if (format)
 541             error (EXIT_FAILURE, 0, _("multiple output formats specified"));
 542           format = argv[optind++] + 1;
 543         }
 544       else if (set_date || option_specified_date)
 545         {
 546           error (0, 0,
 547                  _("the argument %s lacks a leading '+';\n"
 548                    "when using an option to specify date(s), any non-option\n"
 549                    "argument must be a format string beginning with '+'"),
 550                  quote (argv[optind]));
 551           usage (EXIT_FAILURE);
 552         }
 553     }
 554
 555   if (!format)
 556     {
 557       if (get_resolution)
 558         format = "%s.%N";
 559       else
 560         {
 561           format = DATE_FMT_LANGINFO ();
 562
 563           /* Do not wrap the following literal format string with _(...).
 564              For example, suppose LC_ALL is unset, LC_TIME=POSIX,
 565              and LANG="ko_KR".  In that case, POSIX says that LC_TIME
 566              determines the format and contents of date and time strings
 567              written by date, which means "date" must generate output
 568              using the POSIX locale; but adding _() would cause "date"
 569              to use a Korean translation of the format.  */
 570           if (! *format)
 571             format = "%a %b %e %H:%M:%S %Z %Y";
 572         }
 573     }
 574
 575   char *format_copy = adjust_resolution (format);
 576   char const *format_res = format_copy ? format_copy : format;
 577   char const *tzstring = getenv ("TZ");
 578   timezone_t tz = tzalloc (tzstring);
 579
 580   if (batch_file != nullptr)
 581     ok = batch_convert (batch_file, format_res, tz, tzstring);
 582   else
 583     {
 584       bool valid_date = true;
 585       ok = true;
 586
 587       if (!option_specified_date && !set_date)
 588         {
 589           if (optind < argc)
 590             {
 591               /* Prepare to set system clock to the specified date/time
 592                  given in the POSIX-format.  */
 593               set_date = true;
 594               datestr = argv[optind];
 595               valid_date = posixtime (&when.tv_sec,
 596                                       datestr,
 597                                       (PDS_TRAILING_YEAR
 598                                        | PDS_CENTURY | PDS_SECONDS));
 599               when.tv_nsec = 0; /* FIXME: posixtime should set this.  */
 600             }
 601           else
 602             {
 603               /* Prepare to print the current date/time.  */
 604               gettime (&when);
 605             }
 606         }
 607       else
 608         {
 609           /* (option_specified_date || set_date) */
 610           if (reference != nullptr)
 611             {
 612               if (stat (reference, &refstats) != 0)
 613                 error (EXIT_FAILURE, errno, "%s", quotef (reference));
 614               when = get_stat_mtime (&refstats);
 615             }
 616           else if (get_resolution)
 617             {
 618               long int res = gettime_res ();
 619               when.tv_sec = res / TIMESPEC_HZ;
 620               when.tv_nsec = res % TIMESPEC_HZ;
 621             }
 622           else
 623             {
 624               if (set_datestr)
 625                 datestr = set_datestr;
 626               valid_date = parse_datetime2 (&when, datestr, nullptr,
 627                                             parse_datetime_flags,
 628                                             tz, tzstring);
 629             }
 630         }
 631
 632       if (! valid_date)
 633         error (EXIT_FAILURE, 0, _("invalid date %s"), quote (datestr));
 634
 635       if (set_date)
 636         {
 637           /* Set the system clock to the specified date, then regardless of
 638              the success of that operation, format and print that date.  */
 639           if (settime (&when) != 0)
 640             {
 641               error (0, errno, _("cannot set date"));
 642               ok = false;
 643             }
 644         }
 645
 646       ok &= show_date_helper (format_res, when, tz);
 647     }
 648
 649   main_exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 650 }
 651
 652 static bool
 653 show_date_helper (char const *format, struct timespec when, timezone_t tz)
 654 {
 655   if (parse_datetime_flags & PARSE_DATETIME_DEBUG)
 656     error (0, 0, _("output format: %s"), quote (format));
 657
 658   if (format == rfc_email_format)
 659     setlocale (LC_TIME, "C");
 660
 661   bool ok = show_date (format, when, tz);
 662
 663   if (format == rfc_email_format)
 664     setlocale (LC_TIME, "");
 665
 666   putchar ('\n');
 667   return ok;
 668 }