On Thu, 29 Dec 2016 12:11:33 +0100
Hiltjo Posthuma <hil...@codemadness.org> wrote:
> Nitpicks:
> - Check if digit in date_field().
> - Style: don't declare variables in the inner scope, just use the
> function scope for struct tm date; and struct timespec ts;
>
> Kind regards,
> Hiltjo
>
Thanks for your input.
-- >8 --
date.1 | 46 ++++++++++++++++++++++++++++++++++++++--
date.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 112 insertions(+), 9 deletions(-)
diff --git a/date.1 b/date.1
index 29081a5..0171936 100644
--- a/date.1
+++ b/date.1
@@ -3,12 +3,15 @@
.Os sbase
.Sh NAME
.Nm date
-.Nd print date and time
+.Nd print or set date and time
.Sh SYNOPSIS
.Nm
.Op Fl d Ar time
.Op Fl u
.Op Cm + Ns Ar format
+.Sm off
+.Op Ar mmddHHMM Oo Oo Ar CC Oc Ar yy Oc
+.Sm on
.Sh DESCRIPTION
.Nm
prints the date and time according to
@@ -16,7 +19,8 @@ prints the date and time according to
or
.Ar format
using
-.Xr strftime 3 .
+.Xr strftime 3
+or sets the date.
.Sh OPTIONS
.Bl -tag -width Ds
.It Fl d Ar time
@@ -27,6 +31,44 @@ Unix epoch 1970-01-01T00:00:00Z.
.It Fl u
Print UTC time instead of local time.
.El
+.Pp
+An operand with a leading plus
+.Pq Cm +
+sign signals a user-defined format string using
+.Xr strftime 3
+conversion specifications.
+.Pp
+An operand without a leading plus sign is
+interpreted a value for setting the systems current date and time.
+The canonical representation for setting the date and time is:
+.Pp
+.Bl -tag -width Ds -compact -offset indent
+.It Ar mm
+The month of the year, from 01 to 12.
+.It Ar dd
+The day of the month, from 01 to 31.
+.It Ar HH
+The hour of the day, from 00 to 23.
+.It Ar MM
+The minute of the hour, from 00 to 59.
+.It Ar CC
+The first two digits of the year (the century).
+.It Ar yy
+The second two digits of the year.
+If
+.Ar yy
+is specified, but
+.Ar CC
+is not, a value for
+.Ar yy
+between 69 and 99 results in a
+.Ar CC
+value of 19. Otherwise, a
+.Ar CC
+value of 20 is used.
+.El
+.Pp
+The century and year are optional. The default is the current year.
.Sh STANDARDS
The
.Nm
diff --git a/date.c b/date.c
index 1671e1f..bf377c7 100644
--- a/date.c
+++ b/date.c
@@ -1,6 +1,9 @@
/* See LICENSE file for copyright and license details. */
#include <stdio.h>
#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include <errno.h>
#include <time.h>
#include "util.h"
@@ -8,7 +11,15 @@
static void
usage(void)
{
- eprintf("usage: %s [-u] [-d time] [+format]\n", argv0);
+ eprintf("usage: %s [-u] [-d time] [+format] [mmddHHMM[[CC]yy]]\n",
argv0);
+}
+
+static int
+date_field(const char *s, size_t i)
+{
+ if (isdigit(s[i]) && isdigit(s[i+1]))
+ return (s[i] - '0') * 10 + (s[i+1] - '0');
+ return -1;
}
int
@@ -16,11 +27,12 @@ main(int argc, char *argv[])
{
struct tm *now;
struct tm *(*tztime)(const time_t *) = localtime;
+ struct tm date;
+ struct timespec ts;
time_t t;
+ int century, year;
char buf[BUFSIZ], *fmt = "%c", *tz = "local";
- t = time(NULL);
-
ARGBEGIN {
case 'd':
t = estrtonum(EARGF(usage()), 0, LLONG_MAX);
@@ -33,14 +45,63 @@ main(int argc, char *argv[])
usage();
} ARGEND
+ t = time(NULL);
+ if (t == (time_t)-1)
+ eprintf("time failed:");
+
+ if (!(now = tztime(&t)))
+ eprintf("%stime failed\n", tz);
+
if (argc) {
- if (argc != 1 || argv[0][0] != '+')
+ if (argc != 1) {
usage();
- else
+ } else if (argv[0][0] == '+') {
fmt = &argv[0][1];
+ } else {
+ switch (strlen(argv[0])) {
+ case 8:
+ date.tm_year = now->tm_year;
+ break;
+ case 10:
+ date.tm_year = date_field(argv[0], 8);
+ if ((date.tm_year >= 0) && (date.tm_year < 69))
+ date.tm_year += 100;
+ break;
+ case 12:
+ century = date_field(argv[0], 8);
+ year = date_field(argv[0], 10);
+ if ((century >= 0) && (year >= 0)) {
+ date.tm_year = ((century - 19) * 100) +
year;
+ break;
+ }
+ /* fallthrough */
+ default:
+ date.tm_year = -1;
+ break;
+ }
+
+ if ((date.tm_year < 0) ||
+ ((date.tm_mon = date_field(argv[0], 0)) < 0) ||
+ ((date.tm_mday = date_field(argv[0], 2)) < 0) ||
+ ((date.tm_hour = date_field(argv[0], 4)) < 0) ||
+ ((date.tm_min = date_field(argv[0], 6)) < 0))
+ eprintf("invalid date format: %s\n", argv[0]);
+
+ date.tm_mon--;
+
+ t = mktime(&date);
+ if (t == (time_t)-1)
+ eprintf("mktime failed: bad calender date/time:
%s\n", argv[0]);
+
+ ts.tv_sec = t;
+ ts.tv_nsec = 0;
+
+ if (clock_settime(CLOCK_REALTIME, &ts) == -1)
+ eprintf("clock_settime failed:");
+
+ return 0;
+ }
}
- if (!(now = tztime(&t)))
- eprintf("%stime failed\n", tz);
strftime(buf, sizeof(buf), fmt, now);
puts(buf);
