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coreutils/src/date.c
Pádraig Brady 71ea30a742 maint: prefer NULL to nullptr 
NULL is best for C as discussed at:
https://bugs.gnu.org/66221#53

* bootstrap.conf: Remove dependency on nullptr.
* s/nullptr/NULL/.
2026-01-18 15:55:38 +00:00

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/* date - print or set the system date and time
Copyright (C) 1989-2026 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
David MacKenzie <djm@gnu.ai.mit.edu> */
#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
#if HAVE_LANGINFO_CODESET
# include <langinfo.h>
#endif
#include "system.h"
#include "argmatch.h"
#include "parse-datetime.h"
#include "posixtm.h"
#include "quote.h"
#include "show-date.h"
#include "stat-time.h"
#include "xsetenv.h"
/* The official name of this program (e.g., no 'g' prefix). */
#define PROGRAM_NAME "date"
#define AUTHORS proper_name ("David MacKenzie")
enum Time_spec
{
/* Display only the date. */
TIME_SPEC_DATE,
/* Display date, hours, minutes, and seconds. */
TIME_SPEC_SECONDS,
/* Similar, but display nanoseconds. */
TIME_SPEC_NS,
/* Put these last, since they aren't valid for --rfc-3339. */
/* Display date and hour. */
TIME_SPEC_HOURS,
/* Display date, hours, and minutes. */
TIME_SPEC_MINUTES
};
static char const *const time_spec_string[] =
{
/* Put "hours" and "minutes" first, since they aren't valid for
--rfc-3339. */
"hours", "minutes",
"date", "seconds", "ns", NULL
};
static enum Time_spec const time_spec[] =
{
TIME_SPEC_HOURS, TIME_SPEC_MINUTES,
TIME_SPEC_DATE, TIME_SPEC_SECONDS, TIME_SPEC_NS
};
ARGMATCH_VERIFY (time_spec_string, time_spec);
/* A format suitable for Internet RFCs 5322, 2822, and 822. */
static char const rfc_email_format[] = "%a, %d %b %Y %H:%M:%S %z";
/* For long options that have no equivalent short option, use a
non-character as a pseudo short option, starting with CHAR_MAX + 1. */
enum
{
DEBUG_DATE_PARSING_OPTION = CHAR_MAX + 1,
RESOLUTION_OPTION,
RFC_3339_OPTION
};
static char const short_options[] = "d:f:I::r:Rs:u";
static struct option const long_options[] =
{
{"date", required_argument, NULL, 'd'},
{"debug", no_argument, NULL, DEBUG_DATE_PARSING_OPTION},
{"file", required_argument, NULL, 'f'},
{"iso-8601", optional_argument, NULL, 'I'},
{"reference", required_argument, NULL, 'r'},
{"resolution", no_argument, NULL, RESOLUTION_OPTION},
{"rfc-email", no_argument, NULL, 'R'},
{"rfc-822", no_argument, NULL, 'R'}, /* Deprecated. */
{"rfc-2822", no_argument, NULL, 'R'}, /* Deprecated. */
{"rfc-3339", required_argument, NULL, RFC_3339_OPTION},
{"set", required_argument, NULL, 's'},
{"uct", no_argument, NULL, 'u'}, /* Deprecated. */
{"utc", no_argument, NULL, 'u'},
{"universal", no_argument, NULL, 'u'},
{GETOPT_HELP_OPTION_DECL},
{GETOPT_VERSION_OPTION_DECL},
{NULL, 0, NULL, 0}
};
/* flags for parse_datetime2 */
static unsigned int parse_datetime_flags;
#if LOCALTIME_CACHE
# define TZSET tzset ()
#else
# define TZSET /* empty */
#endif
#ifdef _DATE_FMT
# define DATE_FMT_LANGINFO() nl_langinfo (_DATE_FMT)
#else
# define DATE_FMT_LANGINFO() ""
#endif
void
usage (int status)
{
if (status != EXIT_SUCCESS)
emit_try_help ();
else
{
printf (_("\
Usage: %s [OPTION]... [+FORMAT]\n\
or: %s [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]\n\
"),
program_name, program_name);
fputs (_("\
Display date and time in the given FORMAT.\n\
With -s, or with [MMDDhhmm[[CC]YY][.ss]], set the date and time.\n\
"), stdout);
emit_mandatory_arg_note ();
fputs (_("\
-d, --date=STRING display time described by STRING, not 'now'\n\
"), stdout);
fputs (_("\
--debug annotate the parsed date, and\n\
warn about questionable usage to standard error\n\
"), stdout);
fputs (_("\
-f, --file=DATEFILE like --date; once for each line of DATEFILE;\n\
If DATEFILE is -, read names from standard input\
\n\
"), stdout);
fputs (_("\
-I[FMT], --iso-8601[=FMT] output date/time in ISO 8601 format.\n\
FMT='date' for date only (the default),\n\
'hours', 'minutes', 'seconds', or 'ns'\n\
for date and time to the indicated precision.\n\
Example: 2006-08-14T02:34:56-06:00\n\
"), stdout);
fputs (_("\
--resolution output the available resolution of timestamps\n\
Example: 0.000000001\n\
"), stdout);
fputs (_("\
-R, --rfc-email output date and time in RFC 5322 format.\n\
Example: Mon, 14 Aug 2006 02:34:56 -0600\n\
"), stdout);
fputs (_("\
--rfc-3339=FMT output date/time in RFC 3339 format.\n\
FMT='date', 'seconds', or 'ns'\n\
for date and time to the indicated precision.\n\
Example: 2006-08-14 02:34:56-06:00\n\
"), stdout);
fputs (_("\
-r, --reference=FILE display the last modification time of FILE\n\
"), stdout);
fputs (_("\
-s, --set=STRING set time described by STRING\n\
-u, --utc, --universal print or set Coordinated Universal Time (UTC)\n\
"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
fputs (_("\
\n\
All options that specify the date to display are mutually exclusive.\n\
I.e.: --date, --file, --reference, --resolution.\n\
"), stdout);
fputs (_("\
\n\
FORMAT controls the output. Interpreted sequences are:\n\
\n\
%% a literal %\n\
%a locale's abbreviated weekday name (e.g., Sun)\n\
"), stdout);
fputs (_("\
%A locale's full weekday name (e.g., Sunday)\n\
%b locale's abbreviated month name (e.g., Jan)\n\
%B locale's full month name (e.g., January)\n\
%c locale's date and time (e.g., Thu Mar 3 23:05:25 2005)\n\
"), stdout);
fputs (_("\
%C century; like %Y, except omit last two digits (e.g., 20)\n\
%d day of month (e.g., 01)\n\
%D date (ambiguous); same as %m/%d/%y\n\
%e day of month, space padded; same as %_d\n\
"), stdout);
fputs (_("\
%F full date; like %+4Y-%m-%d\n\
%g last two digits of year of ISO week number (ambiguous; 00-99); see %G\n\
%G year of ISO week number; normally useful only with %V\n\
"), stdout);
fputs (_("\
%h same as %b\n\
%H hour (00..23)\n\
%I hour (01..12)\n\
%j day of year (001..366)\n\
"), stdout);
fputs (_("\
%k hour, space padded ( 0..23); same as %_H\n\
%l hour, space padded ( 1..12); same as %_I\n\
%m month (01..12)\n\
%M minute (00..59)\n\
"), stdout);
fputs (_("\
%n a newline\n\
%N nanoseconds (000000000..999999999)\n\
%p locale's equivalent of either AM or PM; blank if not known\n\
%P like %p, but lower case\n\
%q quarter of year (1..4)\n\
%r locale's 12-hour clock time (e.g., 11:11:04 PM)\n\
%R 24-hour hour and minute; same as %H:%M\n\
%s seconds since the Epoch (1970-01-01 00:00 UTC)\n\
"), stdout);
fputs (_("\
%S second (00..60)\n\
%t a tab\n\
%T time; same as %H:%M:%S\n\
%u day of week (1..7); 1 is Monday\n\
"), stdout);
fputs (_("\
%U week number of year, with Sunday as first day of week (00..53)\n\
%V ISO week number, with Monday as first day of week (01..53)\n\
%w day of week (0..6); 0 is Sunday\n\
%W week number of year, with Monday as first day of week (00..53)\n\
"), stdout);
fputs (_("\
%x locale's date (can be ambiguous; e.g., 12/31/99)\n\
%X locale's time representation (e.g., 23:13:48)\n\
%y last two digits of year (ambiguous; 00..99)\n\
%Y year\n\
"), stdout);
fputs (_("\
%z +hhmm numeric time zone (e.g., -0400)\n\
%:z +hh:mm numeric time zone (e.g., -04:00)\n\
%::z +hh:mm:ss numeric time zone (e.g., -04:00:00)\n\
%:::z numeric time zone with : to necessary precision (e.g., -04, +05:30)\n\
%Z alphabetic time zone abbreviation (e.g., EDT)\n\
\n\
By default, date pads numeric fields with zeroes.\n\
"), stdout);
fputs (_("\
The following optional flags may follow '%':\n\
\n\
- (hyphen) do not pad the field\n\
_ (underscore) pad with spaces\n\
0 (zero) pad with zeros\n\
+ pad with zeros, and put '+' before future years with >4 digits\n\
^ use upper case if possible\n\
# use opposite case if possible\n\
"), stdout);
fputs (_("\
\n\
After any flags comes an optional field width, as a decimal number;\n\
then an optional modifier, which is either\n\
E to use the locale's alternate representations if available, or\n\
O to use the locale's alternate numeric symbols if available.\n\
"), stdout);
fputs (_("\
\n\
Examples:\n\
Convert seconds since the Epoch (1970-01-01 UTC) to a date\n\
$ date --date='@2147483647'\n\
\n\
Show the time on the west coast of the US (use tzselect(1) to find TZ)\n\
$ TZ='America/Los_Angeles' date\n\
\n\
Show the local time for 9AM next Friday on the west coast of the US\n\
$ date --date='TZ=\"America/Los_Angeles\" 09:00 next Fri'\n\
"), stdout);
emit_ancillary_info (PROGRAM_NAME);
}
exit (status);
}
/* Yield the number of decimal digits needed to output a time with the
nanosecond resolution RES, without losing information. */
ATTRIBUTE_CONST
static int
res_width (long int res)
{
int i = 9;
for (long long int r = 1; (r *= 10) <= res; )
i--;
return i;
}
/* Return a newly allocated copy of FORMAT with each "%-N" adjusted to
be "%9N", "%6N", or whatever other resolution is appropriate for
the current platform. If no "%-N" appears, return NULL. */
static char *
adjust_resolution (char const *format)
{
char *copy = NULL;
for (char const *f = format; *f; f++)
if (f[0] == '%')
{
if (f[1] == '-' && f[2] == 'N')
{
if (!copy)
copy = xstrdup (format);
copy[f + 1 - format] = '0' + res_width (gettime_res ());
f += 2;
}
else
f += f[1] == '%';
}
return copy;
}
/* Set the LC_TIME category of the current locale.
Return the previous value of the LC_TIME category, as a freshly allocated
string or null. */
static char *
set_LC_TIME (char const *locale)
{
/* It is not sufficient to do
setlocale (LC_TIME, locale);
because show_date relies on fprintftime, that uses the Gnulib module
'localename-unsafe', that looks at the values of the environment variables
(in order to distinguish the default locale from the C locale on platforms
like macOS). */
char const *all = getenv ("LC_ALL");
if (all != NULL && *all != '\0')
{
/* Setting LC_TIME when LC_ALL is set would have no effect. Therefore we
have to unset LC_ALL and sets its value to all locale categories that
are relevant for this program. */
xsetenv ("LC_CTYPE", all, 1); /* definitely needed */
xsetenv ("LC_TIME", all, 1); /* definitely needed */
xsetenv ("LC_MESSAGES", all, 1); /* definitely needed */
xsetenv ("LC_NUMERIC", all, 1); /* possibly needed */
/* xsetenv ("LC_COLLATE", all, 1); */ /* not needed */
/* xsetenv ("LC_MONETARY", all, 1); */ /* not needed */
unsetenv ("LC_ALL");
}
/* Set LC_TIME as an environment variable. */
char const *value = getenv ("LC_TIME");
char *ret = (value == NULL || *value == '\0' ? NULL : xstrdup (value));
if (locale != NULL)
xsetenv ("LC_TIME", locale, 1);
else
unsetenv ("LC_TIME");
/* Update the current locale accordingly. */
setlocale (LC_TIME, "");
return ret;
}
static bool
show_date_helper (char const *format, bool use_c_locale,
struct timespec when, timezone_t tz)
{
if (parse_datetime_flags & PARSE_DATETIME_DEBUG)
error (0, 0, _("output format: %s"), quote (format));
bool ok;
if (use_c_locale)
{
char *old_locale_category = set_LC_TIME ("C");
ok = show_date (format, when, tz);
char *new_locale_category = set_LC_TIME (old_locale_category);
free (new_locale_category);
free (old_locale_category);
}
else
ok = show_date (format, when, tz);
putchar ('\n');
return ok;
}
/* Parse each line in INPUT_FILENAME as with --date and display each
resulting time and date. If the file cannot be opened, tell why
then exit. Issue a diagnostic for any lines that cannot be parsed.
Return true if successful. */
static bool
batch_convert (char const *input_filename,
char const *format, bool format_in_c_locale,
timezone_t tz, char const *tzstring)
{
FILE *in_stream;
if (streq (input_filename, "-"))
{
input_filename = _("standard input");
in_stream = stdin;
}
else
{
in_stream = fopen (input_filename, "r");
if (in_stream == NULL)
error (EXIT_FAILURE, errno, "%s", quotef (input_filename));
}
char *line = NULL;
size_t buflen = 0;
bool ok = true;
while (true)
{
ssize_t line_length = getline (&line, &buflen, in_stream);
if (line_length < 0)
{
if (ferror (in_stream))
error (EXIT_FAILURE, errno, _("%s: read error"),
quotef (input_filename));
break;
}
struct timespec when;
if (! parse_datetime2 (&when, line, NULL,
parse_datetime_flags, tz, tzstring))
{
if (line[line_length - 1] == '\n')
line[line_length - 1] = '\0';
error (0, 0, _("invalid date %s"), quote (line));
ok = false;
}
else
{
ok &= show_date_helper (format, format_in_c_locale, when, tz);
}
if (ferror (stdout))
write_error ();
}
if (fclose (in_stream) == EOF)
error (EXIT_FAILURE, errno, "%s", quotef (input_filename));
free (line);
return ok;
}
int
main (int argc, char **argv)
{
char const *datestr = NULL;
char const *set_datestr = NULL;
bool set_date = false;
char const *format = NULL;
bool format_in_c_locale = false;
bool get_resolution = false;
char *batch_file = NULL;
char *reference = NULL;
bool discarded_datestr = false;
bool discarded_set_datestr = false;
initialize_main (&argc, &argv);
set_program_name (argv[0]);
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
atexit (close_stdout);
int optc;
while ((optc = getopt_long (argc, argv, short_options, long_options, NULL))
!= -1)
{
switch (optc)
{
case 'd':
if (datestr)
discarded_datestr = true;
datestr = optarg;
break;
case DEBUG_DATE_PARSING_OPTION:
parse_datetime_flags |= PARSE_DATETIME_DEBUG;
break;
case 'f':
batch_file = optarg;
break;
case RESOLUTION_OPTION:
get_resolution = true;
break;
case RFC_3339_OPTION:
{
static char const rfc_3339_format[][32] =
{
"%Y-%m-%d",
"%Y-%m-%d %H:%M:%S%:z",
"%Y-%m-%d %H:%M:%S.%N%:z"
};
enum Time_spec i =
XARGMATCH ("--rfc-3339", optarg,
time_spec_string + 2, time_spec + 2);
format = rfc_3339_format[i];
format_in_c_locale = true;
break;
}
case 'I':
{
static char const iso_8601_format[][32] =
{
"%Y-%m-%d",
"%Y-%m-%dT%H:%M:%S%:z",
"%Y-%m-%dT%H:%M:%S,%N%:z",
"%Y-%m-%dT%H%:z",
"%Y-%m-%dT%H:%M%:z"
};
enum Time_spec i =
(optarg
? XARGMATCH ("--iso-8601", optarg, time_spec_string, time_spec)
: TIME_SPEC_DATE);
format = iso_8601_format[i];
format_in_c_locale = true;
break;
}
case 'r':
reference = optarg;
break;
case 'R':
format = rfc_email_format;
format_in_c_locale = true;
break;
case 's':
if (set_datestr)
discarded_set_datestr = true;
set_datestr = optarg;
set_date = true;
break;
case 'u':
/* POSIX says that 'date -u' is equivalent to setting the TZ
environment variable, so this option should do nothing other
than setting TZ. */
if (putenv (bad_cast ("TZ=UTC0")) != 0)
xalloc_die ();
TZSET;
break;
case_GETOPT_HELP_CHAR;
case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
default:
usage (EXIT_FAILURE);
}
}
int option_specified_date = (!!datestr + !!batch_file + !!reference
+ get_resolution);
if (option_specified_date > 1)
{
error (0, 0,
_("the options to specify dates for printing are mutually exclusive"));
usage (EXIT_FAILURE);
}
if (set_date && option_specified_date)
{
error (0, 0,
_("the options to print and set the time may not be used together"));
usage (EXIT_FAILURE);
}
if (discarded_datestr && (parse_datetime_flags & PARSE_DATETIME_DEBUG))
error (0, 0, _("only using last of multiple -d options"));
if (discarded_set_datestr && (parse_datetime_flags & PARSE_DATETIME_DEBUG))
error (0, 0, _("only using last of multiple -s options"));
if (optind < argc)
{
if (optind + 1 < argc)
{
error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
usage (EXIT_FAILURE);
}
if (argv[optind][0] == '+')
{
if (format)
error (EXIT_FAILURE, 0, _("multiple output formats specified"));
format = argv[optind++] + 1;
}
else if (set_date || option_specified_date)
{
error (0, 0,
_("the argument %s lacks a leading '+';\n"
"when using an option to specify date(s), any non-option\n"
"argument must be a format string beginning with '+'"),
quote (argv[optind]));
usage (EXIT_FAILURE);
}
}
if (!format)
{
if (get_resolution)
format = "%s.%N";
else
{
format = DATE_FMT_LANGINFO ();
/* Do not wrap the following literal format string with _(...).
For example, suppose LC_ALL is unset, LC_TIME=POSIX,
and LANG="ko_KR". In that case, POSIX says that LC_TIME
determines the format and contents of date and time strings
written by date, which means "date" must generate output
using the POSIX locale; but adding _() would cause "date"
to use a Korean translation of the format. */
if (! *format)
format = "%a %b %e %H:%M:%S %Z %Y";
}
}
char *format_copy = adjust_resolution (format);
char const *format_res = format_copy ? format_copy : format;
char const *tzstring = getenv ("TZ");
timezone_t tz = tzalloc (tzstring);
bool ok = true;
if (batch_file != NULL)
ok = batch_convert (batch_file, format_res, format_in_c_locale,
tz, tzstring);
else
{
bool valid_date = true;
struct timespec when;
if (!option_specified_date && !set_date)
{
if (optind < argc)
{
/* Prepare to set system clock to the specified date/time
given in the POSIX-format. */
set_date = true;
datestr = argv[optind];
valid_date = posixtime (&when.tv_sec,
datestr,
(PDS_TRAILING_YEAR
| PDS_CENTURY | PDS_SECONDS));
when.tv_nsec = 0; /* FIXME: posixtime should set this. */
}
else
{
/* Prepare to print the current date/time. */
gettime (&when);
}
}
else
{
/* (option_specified_date || set_date) */
if (reference != NULL)
{
struct stat refstats;
if (stat (reference, &refstats) != 0)
error (EXIT_FAILURE, errno, "%s", quotef (reference));
when = get_stat_mtime (&refstats);
}
else if (get_resolution)
{
long int res = gettime_res ();
when.tv_sec = res / TIMESPEC_HZ;
when.tv_nsec = res % TIMESPEC_HZ;
}
else
{
if (set_datestr)
datestr = set_datestr;
valid_date = parse_datetime2 (&when, datestr, NULL,
parse_datetime_flags,
tz, tzstring);
}
}
if (! valid_date)
error (EXIT_FAILURE, 0, _("invalid date %s"), quote (datestr));
if (set_date)
{
/* Set the system clock to the specified date, then regardless of
the success of that operation, format and print that date. */
if (settime (&when) != 0)
{
error (0, errno, _("cannot set date"));
ok = false;
}
}
ok &= show_date_helper (format_res, format_in_c_locale, when, tz);
}
main_exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}
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