09c2311b3a
From POSIX:
When no formatting operand is specified, the output in the POSIX
locale shall be equivalent to specifying:
date "+%a %b %e %H:%M:%S %Z %Y"
104 lines
1.8 KiB
C
104 lines
1.8 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <ctype.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include "util.h"
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static void
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usage(void)
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{
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eprintf("usage: %s [-u] [-d time] [+format | mmddHHMM[[CC]yy]]\n", argv0);
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}
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static int
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datefield(const char *s, size_t i)
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{
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if (!isdigit(s[i]) || !isdigit(s[i+1]))
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eprintf("invalid date format: %s\n", s);
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return (s[i] - '0') * 10 + (s[i+1] - '0');
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}
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static void
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setdate(const char *s, struct tm *now)
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{
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struct tm date;
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struct timespec ts;
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switch (strlen(s)) {
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case 8:
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date.tm_year = now->tm_year;
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break;
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case 10:
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date.tm_year = datefield(s, 8);
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if (date.tm_year < 69)
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date.tm_year += 100;
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break;
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case 12:
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date.tm_year = ((datefield(s, 8) - 19) * 100) + datefield(s, 10);
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break;
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default:
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eprintf("invalid date format: %s\n", s);
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break;
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}
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date.tm_mon = datefield(s, 0) - 1;
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date.tm_mday = datefield(s, 2);
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date.tm_hour = datefield(s, 4);
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date.tm_min = datefield(s, 6);
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date.tm_sec = 0;
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date.tm_isdst = -1;
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ts.tv_sec = mktime(&date);
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if (ts.tv_sec == -1)
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eprintf("mktime:");
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ts.tv_nsec = 0;
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if (clock_settime(CLOCK_REALTIME, &ts) == -1)
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eprintf("clock_settime:");
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}
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int
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main(int argc, char *argv[])
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{
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struct tm *now;
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time_t t;
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char buf[BUFSIZ], *fmt = "%a %b %e %H:%M:%S %Z %Y";
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t = time(NULL);
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if (t == -1)
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eprintf("time:");
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ARGBEGIN {
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case 'd':
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t = estrtonum(EARGF(usage()), 0, LLONG_MAX);
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break;
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case 'u':
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if (setenv("TZ", "UTC0", 1) < 0)
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eprintf("setenv:");
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break;
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default:
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usage();
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} ARGEND
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if (!(now = localtime(&t)))
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eprintf("localtime:");
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if (argc) {
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if (argc != 1)
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usage();
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if (argv[0][0] != '+') {
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setdate(argv[0], now);
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return 0;
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}
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fmt = &argv[0][1];
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}
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strftime(buf, sizeof(buf), fmt, now);
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puts(buf);
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return fshut(stdout, "<stdout>");
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}
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