utils

date.c (1946B)

// Collection of Unix tools, comparable to coreutils
// SPDX-FileCopyrightText: 2017-2022 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include "../lib/iso_parse.h" /* iso_parse */
#include <errno.h>  /* errno */
#include <locale.h> /* setlocale() */
#include <stdio.h>  /* BUFSIZ, perror(), puts() */
#include <stdlib.h> /* exit(), strtol() */
#include <time.h>   /* time, localtime, tm, strftime */
#include <unistd.h> /* getopt(), optarg, optind */
void
usage()
{
	fprintf(stderr, "date [-uR][-d datetime] [+format]\n");
}
int
main(int argc, char *argv[])
{
	char outstr[BUFSIZ];
	struct tm *tm;
	time_t now;
	char *format = "%c";
	int uflag    = 0;
	int c;
	setlocale(LC_ALL, "");
	now = time(NULL);
	if(now == (time_t)-1)
	{
		perror("date: time");
		exit(EXIT_FAILURE);
	}
	while((c = getopt(argc, argv, ":d:uR")) != -1)
	{
		switch(c)
		{
		case 'd': /* Custom datetime */
			now = iso_parse(optarg).tv_sec;
			break;
		case 'u': /* UTC timezone */
			uflag++;
			break;
		case 'R': /* Email (RFC 5322) format */
			format = "%a, %d %b %Y %H:%M:%S %z";
			break;
		case ':':
			fprintf(stderr, "date: Error: Missing operand for option: '-%c'\n", optopt);
			usage();
			return 1;
		case '?':
			fprintf(stderr, "date: Error: Unrecognised option: '-%c'\n", optopt);
			usage();
			return 1;
		}
	}
	if(uflag)
	{
		tm = gmtime(&now);
		if(tm == NULL)
		{
			perror("date: gmtime");
			exit(EXIT_FAILURE);
		}
	}
	else
	{
		tm = localtime(&now);
		if(tm == NULL)
		{
			perror("date: localtime");
			exit(EXIT_FAILURE);
		}
	}
	argc -= optind;
	argv += optind;
	(void)argc;
	if(*argv && **argv == '+') format = *argv + 1;
	errno = 0;
	if(strftime(outstr, sizeof(outstr), format, tm) == 0 && errno != 0)
	{
		perror("date: strftime");
		exit(EXIT_FAILURE);
	}
	if(puts(outstr) < 0)
	{
		perror("date: puts");
		exit(EXIT_FAILURE);
	}
	return 0;
}