Fix date setting, and fluff out help text a bit.

1 files changed, 50 insertions, 18 deletions

diff --git a/toys/posix/date.c b/toys/posix/date.c
index 68751043..e1ba636d 100644
--- a/toys/posix/date.c
+++ b/toys/posix/date.c
@@ -3,6 +3,9 @@
  * Copyright 2012 Andre Renaud <andre@bluewatersys.com>
  *
  * See http://opengroup.org/onlinepubs/9699919799/utilities/date.html
+ *
+ * Note: setting a 2 year date is 50 years back/forward from today,
+ * not posix's hardwired magic dates.
 
 USE_DATE(NEWTOY(date, "r:u", TOYFLAG_BIN))
 
@@ -10,9 +13,15 @@ config DATE
   bool "date"
   default y
   help
-    usage: date [-u] [-r file] [+format] | mmddhhmm[[cc]yy]
+    usage: date [-u] [-r FILE] [+FORMAT] | mmddhhmm[[cc]yy[.ss]]
+
+    Set/get the current date/time.
 
-    Set/get the current date/time
+    Setting the date requires month, day, hour (0-23), and minute, each
+    two digits. It can optionally include year, century, and .seconds.
+
+    -u	Use UTC timezone instead of current
+    -r	Use date from FILE instead of current date
 */
 
 #define FOR_date
@@ -39,8 +48,7 @@ void date_main(void)
   // Display the date?
   if (!toys.optargs[0] || toys.optargs[0][0] == '+') {
     if (toys.optargs[0]) format_string = toys.optargs[0]+1;
-    if (!strftime(toybuf, sizeof(toybuf), format_string, &tm))
-      perror_msg("bad format `%s'", format_string);
+    if (!strftime(toybuf, sizeof(toybuf), format_string, &tm)) goto bad_format;
 
     puts(toybuf);
 
@@ -48,23 +56,41 @@ void date_main(void)
   } else {
     struct timeval tv;
     char *s = *toys.optargs;
-    int len = strlen(s);
-
-    if (len < 8 || len > 12 || (len & 1)) error_msg("bad date `%s'", s);
+    int len;
 
     // Date format: mmddhhmm[[cc]yy]
-    memset(&tm, 0, sizeof(tm));
-    len = sscanf(s, "%2u%2u%2u%2u", &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
-      &tm.tm_min);
+    len = 0;
+    sscanf(s, "%2u%2u%2u%2u%n", &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
+      &tm.tm_min, &len);
+    if (len != 8) goto bad_date;
+    s += len;
     tm.tm_mon--;
 
     // If year specified, overwrite one we fetched earlier
-    if (len > 8) {
-      sscanf(s, "%u", &tm.tm_year);
-      if (len == 12) tm.tm_year -= 1900;
-      /* 69-99 = 1969-1999, 0 - 68 = 2000-2068 */
-      else if (tm.tm_year < 69) tm.tm_year += 100;
+    if (*s && *s != '.') {
+      unsigned year, r1 = tm.tm_year % 100, r2 = (tm.tm_year + 50) % 100,
+        century = tm.tm_year - r1;
+
+      len = 0;
+      sscanf(s, "%u%n", &year, &len);
+      if (len == 4) year -= 1900;
+      else if (len != 2) goto bad_date;
+      s += len;
+
+      // 2 digit years, next 50 years are "future", last 50 years are "past".
+      // A "future" date in past is a century ahead.
+      // A non-future date in the future is a century behind.
+      if ((r1 < r2) ? (r1 < year && year < r2) : (year < r1 || year > r2)) {
+        if (year < r1) year += 100;
+      } else if (year > r1) year -= 100;
+      tm.tm_year = year + century;
     }
+    if (*s == '.') {
+      len = 0;
+      sscanf(s, ".%u%n", &tm.tm_sec, &len);
+      s += len;
+    }
+    if (*s) goto bad_date;
 
     if (toys.optflags & FLAG_u) {
       // Get the UTC version of a struct tm
@@ -78,12 +104,18 @@ void date_main(void)
         tzset();
       }
     } else tv.tv_sec = mktime(&tm);
+    if (tv.tv_sec == (time_t)-1) goto bad_date;
 
-    if (tv.tv_sec == (time_t)-1) error_msg("bad `%s'", toys.optargs[0]);
     tv.tv_usec = 0;
-    if (!strftime(toybuf, sizeof(toybuf), format_string, &tm))
-      perror_msg("bad format `%s'", format_string);
+    if (!strftime(toybuf, sizeof(toybuf), format_string, &tm)) goto bad_format;
     puts(toybuf);
     if (settimeofday(&tv, NULL) < 0) perror_msg("cannot set date");
   }
+
+  return;
+
+bad_date:
+  error_exit("bad date '%s'", *toys.optargs);
+bad_format:
+  perror_msg("bad format '%s'", format_string);
 }