Allow the year to be specified with an optional century.

PR:	14472
Reported by:	j_guojun@lbl.gov (Jin Guojun)

2 files changed, 14 insertions, 4 deletions

diff --git a/bin/date/date.1 b/bin/date/date.1
index 8cf4246..f044471 100644
--- a/bin/date/date.1
+++ b/bin/date/date.1
@@ -49,7 +49,7 @@
 .Op Fl t Ar minutes_west
 .Op Fl v Ns Ar [+|-]val Ns Op ymwdHMS
 .Ar ...
-.Op Fl f Ar fmt Ar date | [[[[yy]mm]dd]HH]MM[\&.ss]
+.Op Fl f Ar fmt Ar date | [[[[[cc]yy]mm]dd]HH]MM[\&.ss]
 .Op Cm + Ns Ar format
 .Sh DESCRIPTION
 .Nm Date
@@ -74,7 +74,7 @@ Use
 .Ar fmt
 as the format string to parse the date provided rather than using
 the default
-.Ar [[[[yy]mm]dd]HH]MM[.ss]
+.Ar [[[[[cc]yy]mm]dd]HH]MM[.ss]
 format.  Parsing is done using
 .Xr strptime 3 .
 .It Fl j
@@ -168,6 +168,8 @@ a value for setting the system's notion of the current date and time.
 The canonical representation for setting the date and time is:
 .Pp
 .Bl -tag -width Ds -compact -offset indent
+.It Ar cc
+Century (either 19 or 20) prepended to the abbreviated year.
 .It Ar yy
 Year in abbreviated form (e.g. 89 for 1989, 06 for 2006).
 .It Ar mm
diff --git a/bin/date/date.c b/bin/date/date.c
index d699755..4d4c9cd 100644
--- a/bin/date/date.c
+++ b/bin/date/date.c
@@ -175,6 +175,8 @@ main(argc, argv)
 }
 
 #define	ATOI2(ar)	((ar)[0] - '0') * 10 + ((ar)[1] - '0'); (ar) += 2;
+#define	ATOI4(ar)	((ar)[0] - '0') * 1000 + ((ar)[1] - '0') * 100 + \
+			    ((ar)[2] - '0') * 10 + ((ar)[3] - '0'); (ar) += 4;
 void
 setthetime(fmt, p, jflag, nflag)
 	const char *fmt;
@@ -221,11 +223,16 @@ setthetime(fmt, p, jflag, nflag)
 
 		/* if p has a ".ss" field then let's pretend it's not there */
 		switch (strlen(p) - ((dot != NULL) ? 3 : 0)) {
+		case 12:				/* cc */
+			lt->tm_year = -1900 + ATOI4(p);
+			if (lt->tm_year < 0)
+				badformat();
+			goto year_done;
 		case 10:				/* yy */
 			lt->tm_year = ATOI2(p);
 			if (lt->tm_year < 69)		/* hack for 2000 ;-} */
 				lt->tm_year += 100;
-			/* FALLTHROUGH */
+year_done:		/* FALLTHROUGH */
 		case 8:					/* mm */
 			lt->tm_mon = ATOI2(p);
 			if (lt->tm_mon > 12)
@@ -286,6 +293,7 @@ usage()
 	(void)fprintf(stderr, "%s\n%s\n",
 	    "usage: date [-nu] [-d dst] [-r seconds] [-t west] "
 	    "[-v[+|-]val[ymwdHMS]] ... ",
-	    "            [-f fmt date | [[[[yy]mm]dd]HH]MM[.ss]] [+format]");
+	    "            "
+	    "[-f fmt date | [[[[[cc]yy]mm]dd]HH]MM[.ss]] [+format]");
 	exit(1);
 }