utils-std

date.c (6637B)

// utils-std: Collection of commonly available Unix tools
// SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _DEFAULT_SOURCE // tm_gmtoff/tm_zone
#define _POSIX_C_SOURCE 200809L
#define _XOPEN_SOURCE 700 // strptime is in XSI
#include "../lib/iso_parse.h" /* iso_parse */
#include <errno.h>
#include <locale.h> /* setlocale() */
#include <stdbool.h>
#include <stdio.h>  /* BUFSIZ, fprintf(), puts() */
#include <stdlib.h> /* exit(), strtol() */
#include <string.h> /* strerror */
#include <time.h>   /* time, localtime, tm, strftime, strptime, clock_settime */
#include <unistd.h> /* getopt(), optarg, optind */
const char *argv0 = "date";
static void
usage(void)
{
	fprintf(stderr, "\
Usage:\n\
	date [-jRu] [-d datetime | -r epoch] [+format]\n\
	date [-jRu] mmddHHMM[[CC]yy] [+format]\n\
	date [-jRu] -f now_format now [+format]\n\
");
}
int
main(int argc, char *argv[])
{
	char outstr[BUFSIZ];
	struct tm tm = {
	    .tm_year = 0,
	    .tm_mon = 0,
	    .tm_mday = 0,
	    .tm_hour = 0,
	    .tm_min = 0,
	    .tm_sec = 0,
	    .tm_isdst = -1, // unknown if DST is in effect
	    .tm_gmtoff = 0,
	    .tm_zone = NULL,
	};
	struct timespec tp = {
	    .tv_sec = 0,
	    .tv_nsec = 0,
	};
	const char *format = "%c";
	const char *input_format = NULL;
	int uflag = 0;
	int dflag = 0, rflag = 0;
	int c;
	bool jflag = false;
	bool settime = false;
	setlocale(LC_ALL, "");
	errno = 0;
	tp.tv_sec = time(NULL);
	if(tp.tv_sec == (time_t)-1)
	{
		fprintf(stderr, "%s: error: Failed getting current time: %s\n", argv0, strerror(errno));
		exit(EXIT_FAILURE);
	}
	while((c = getopt(argc, argv, ":d:f:jr:Ru")) != -1)
	{
		const char *errstr = NULL;
		switch(c)
		{
		case 'd': /* Custom datetime */
			if(input_format != NULL)
			{
				fprintf(stderr, "%s: error: Cannot both use '-d' and '-f'\n", argv0);
				exit(EXIT_FAILURE);
			}
			if(rflag == 1)
			{
				fprintf(stderr, "%s: error: Cannot both use '-d' and '-r'\n", argv0);
				exit(EXIT_FAILURE);
			}
			iso_parse(optarg, &tm, &tp.tv_nsec, &errstr);
			dflag = 1;
			if(errstr != NULL)
			{
				fprintf(stderr, "%s: error: iso_parse(\"%s\", …): %s\n", argv0, optarg, errstr);
				exit(EXIT_FAILURE);
			}
			tp.tv_sec = mktime_tz(&tm);
			if(tp.tv_sec == (time_t)-1)
			{
				fprintf(stderr, "%s: error: mktime: %s\n", argv0, strerror(errno));
				exit(EXIT_FAILURE);
			}
			errno = 0;
			break;
		case 'f': /* input datetime format */
			if(dflag == 1)
			{
				fprintf(stderr, "%s: error: Cannot both use '-d' and '-f'\n", argv0);
				exit(EXIT_FAILURE);
			}
			if(rflag == 1)
			{
				fprintf(stderr, "%s: error: Cannot both use '-f' and '-r'\n", argv0);
				exit(EXIT_FAILURE);
			}
			input_format = optarg;
			settime = true;
			break;
		case 'r': /* seconds relative to epoch */
		{
			if(input_format != NULL)
			{
				fprintf(stderr, "%s: error: Cannot both use '-f' and '-r'\n", argv0);
				exit(EXIT_FAILURE);
			}
			if(dflag == 1)
			{
				fprintf(stderr, "%s: error: Cannot both use '-d' and '-r'\n", argv0);
				exit(EXIT_FAILURE);
			}
			char *endptr = NULL;
			errno = 0;
			tp.tv_sec = strtol(optarg, &endptr, 10);
			if(errno != 0)
			{
				fprintf(stderr, "%s: error: Failed parsing '-r %s'\n", argv0, optarg);
				exit(EXIT_FAILURE);
			}
			if(!(endptr == NULL || *endptr == '\0'))
			{
				fprintf(stderr, "%s: error: Invalid characters in '-r %s': %s\n", argv0, optarg, endptr);
				exit(EXIT_FAILURE);
			}
			break;
		}
		case 'R': /* Email (RFC 5322) format */
			format = "%a, %d %b %Y %H:%M:%S %z";
			break;
		case 'u': /* UTC timezone */
			uflag++;
			setenv("TZ", "UTC", 1);
			tzset();
			break;
		case 'j':
			jflag = true;
			break;
		case ':':
			fprintf(stderr, "%s: error: Missing operand for option: '-%c'\n", argv0, optopt);
			usage();
			return 1;
		case '?':
			fprintf(stderr, "%s: error: Unrecognised option: '-%c'\n", argv0, optopt);
			usage();
			return 1;
		}
	}
	argc -= optind;
	argv += optind;
	if(uflag)
	{
		if(gmtime_r(&tp.tv_sec, &tm) == NULL)
		{
			fprintf(stderr, "%s: error: gmtime_r: %s\n", argv0, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}
	else
	{
		if(localtime_r(&tp.tv_sec, &tm) == NULL)
		{
			fprintf(stderr, "%s: error: localtime_r: %s\n", argv0, strerror(errno));
			exit(EXIT_FAILURE);
		}
	}
	if(argc > 0 && input_format != NULL)
	{
		char *res = strptime(argv[0], input_format, &tm);
		if(res == NULL)
		{
			fprintf(stderr,
			        "%s: error: strptime(\"%s\", \"%s\", …) as passed by '-f' option failed\n",
			        argv0,
			        argv[0],
			        input_format);
			exit(EXIT_FAILURE);
		}
		tp.tv_sec = mktime_tz(&tm);
		tp.tv_nsec = 0;
		if(tp.tv_sec == (time_t)-1)
		{
			fprintf(stderr, "%s: error: mktime: %s\n", argv0, strerror(errno));
			exit(EXIT_FAILURE);
		}
		errno = 0;
		argv++;
		argc--;
	}
	if(input_format == NULL && argc > 0 && *argv && **argv != '+')
	{
		const char *fmt = "%m%d%H%M";
		char *s = strptime(argv[0], fmt, &tm);
		if(s == NULL)
		{
			fprintf(stderr, "%s: error: strptime(\"%s\", \"%s\", …) returned NULL\n", argv0, *argv, fmt);
			exit(EXIT_FAILURE);
		}
		size_t rem = strlen(s);
		if(rem > 0)
		{
			switch(rem)
			{
			case 2:
				fmt = "%y";
				break;
			case 4:
				fmt = "%Y";
				break;
			default:
				fprintf(stderr,
				        "%s: error: Got %zu trailing characters after \"%s\" for mmddHHMM\n",
				        argv0,
				        rem,
				        fmt);
				exit(EXIT_FAILURE);
			}
			s = strptime(s, fmt, &tm);
			if(s == NULL)
			{
				fprintf(
				    stderr, "%s: error: strptime(\"%s\", \"%s\", …) returned NULL\n", argv0, *argv, fmt);
				exit(EXIT_FAILURE);
			}
		}
		tp.tv_sec = mktime(&tm);
		tp.tv_nsec = 0;
		if(tp.tv_sec == (time_t)-1)
		{
			fprintf(stderr, "%s: error: mktime: %s\n", argv0, strerror(errno));
			exit(EXIT_FAILURE);
		}
		errno = 0;
		argv++;
		argc--;
		settime = true;
	}
	if(settime && !jflag)
	{
		if(clock_settime(CLOCK_REALTIME, &tp) != 0)
		{
			fprintf(stderr,
			        "%s: error: clock_settime(CLOCK_REALTIME, {%ld, %ld}): %s\n",
			        argv0,
			        tp.tv_sec,
			        tp.tv_nsec,
			        strerror(errno));
			exit(EXIT_FAILURE);
		}
	}
	if(argc > 0 && *argv && **argv == '+')
	{
		format = *argv + 1;
		argv++;
		argc--;
	}
	errno = 0;
	if(strftime(outstr, sizeof(outstr), format, &tm) == 0 && errno != 0)
	{
		fprintf(stderr, "%s: error: Failed formatting time: %s\n", argv0, strerror(errno));
		exit(EXIT_FAILURE);
	}
	if(puts(outstr) < 0)
	{
		fprintf(stderr, "%s: error: Failed writing time: %s\n", argv0, strerror(errno));
		exit(EXIT_FAILURE);
	}
	return 0;
}