date: add -ds, document +FORMAT escapes.

1 files changed, 108 insertions, 58 deletions

diff --git a/toys/posix/date.c b/toys/posix/date.c
index e1ba636d..f56c4804 100644
--- a/toys/posix/date.c
+++ b/toys/posix/date.c
@@ -7,21 +7,39 @@
  * 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))
+USE_DATE(NEWTOY(date, "d:s:r:u", TOYFLAG_BIN))
 
 config DATE
   bool "date"
   default y
   help
-    usage: date [-u] [-r FILE] [+FORMAT] | mmddhhmm[[cc]yy[.ss]]
+    usage: date [-u] [-r FILE] [-d DATE] [+DISPLAY_FORMAT] [-s SET_FORMAT] [SET]
 
-    Set/get the current date/time.
+    Set/get the current date/time. With no SET shows the current date.
 
-    Setting the date requires month, day, hour (0-23), and minute, each
-    two digits. It can optionally include year, century, and .seconds.
+    Default SET format is "MMDDhhmm[[CC]YY][.ss]", that's (2 digits each)
+    month, day, hour (0-23), and minute. Optionally century, year, and second.
 
-    -u	Use UTC timezone instead of current
-    -r	Use date from FILE instead of current date
+    -d	Show DATE instead of current time (convert date format)
+    -r	Use modification time of FILE instead of current date
+    -s	+FORMAT for SET or -d (instead of MMDDhhmm[[CC]YY][.ss])
+    -u	Use UTC instead of current timezone
+
+    +FORMAT specifies display format string using these escapes:
+
+    %% literal %             %n newline              %t tab
+    %S seconds (00-60)       %M minute (00-59)       %m month (01-12)
+    %H hour (0-23)           %I hour (01-12)         %p AM/PM
+    %y short year (00-99)    %Y year                 %C century
+    %a short weekday name    %A weekday name         %u day of week (1-7, 1=mon)
+    %b short month name      %B month name           %Z timezone name
+    %j day of year (001-366) %d day of month (01-31) %e day of month ( 1-31)
+
+    %U Week of year (0-53 start sunday)   %W Week of year (0-53 start monday)
+    %V Week of year (1-53 start monday, week < 4 days not part of this year) 
+
+    %D = "%m/%d/%y"    %r = "%I : %M : %S %p"   %T = "%H:%M:%S"   %h = "%b"
+    %x locale date     %X locale time           %c locale date/time
 */
 
 #define FOR_date
@@ -29,72 +47,98 @@ config DATE
 
 GLOBALS(
   char *file;
+  char *setfmt;
+  char *showdate;
 )
 
+// Handle default posix date format: mmddhhmm[[cc]yy]
+// returns 0 success, nonzero for error
+int parse_posixdate(char *str, struct tm *tm)
+{
+  int len;
+
+  len = 0;
+  sscanf(str, "%2u%2u%2u%2u%n", &tm->tm_mon, &tm->tm_mday, &tm->tm_hour,
+    &tm->tm_min, &len);
+  if (len != 8) return 1;
+  str += len;
+  tm->tm_mon--;
+
+  // If year specified, overwrite one we fetched earlier
+  if (*str && *str != '.') {
+    unsigned year, r1 = tm->tm_year % 100, r2 = (tm->tm_year + 50) % 100,
+      century = tm->tm_year - r1;
+
+    len = 0;
+    sscanf(str, "%u%n", &year, &len);
+    if (len == 4) year -= 1900;
+    else if (len != 2) return 1;
+    str += 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 (*str == '.') {
+    len = 0;
+    sscanf(str, ".%u%n", &tm->tm_sec, &len);
+    str += len;
+  }
+
+  return *str;
+}
+
 void date_main(void)
 {
-  const char *format_string = "%a %b %e %H:%M:%S %Z %Y";
+  char *setdate = *toys.optargs, *format_string = "%a %b %e %H:%M:%S %Z %Y",
+       *tz;
   time_t now = time(NULL);
   struct tm tm;
 
+  // We can't just pass a timezone to mktime because posix.
+  if (toys.optflags & FLAG_u) {
+    tz = CFG_TOYBOX_FREE ? getenv("TZ") : 0;
+    setenv("TZ", "UTC", 1);
+    tzset();
+  }
+
   if (TT.file) {
     struct stat st;
 
     xstat(TT.file, &st);
     now = st.st_mtim.tv_sec;
-  }
-  ((toys.optflags & FLAG_u) ? gmtime_r : localtime_r)(&now, &tm);
-
+  } else if (TT.showdate) {
+    setdate = TT.showdate;
+    if (TT.setfmt) {
+printf("TT.showdate=%s TT.setfmt=%s\n", TT.showdate, TT.setfmt);
+      char *s = strptime(TT.showdate, TT.setfmt+(*TT.setfmt=='+'), &tm);
+
+      if (!s || *s) goto bad_date;
+    } else if (parse_posixdate(TT.showdate, &tm)) goto bad_date;
+  } else localtime_r(&now, &tm);
+
+  setdate = *toys.optargs;
+  // Fall through if no arguments
+  if (!setdate);
   // 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)) goto bad_format;
-
-    puts(toybuf);
+  else if (*setdate == '+') {
+    format_string = toys.optargs[0]+1;
+    setdate = toys.optargs[1];
 
   // Set the date
-  } else {
+  } else if (setdate) {
     struct timeval tv;
-    char *s = *toys.optargs;
-    int len;
 
-    // Date format: mmddhhmm[[cc]yy]
-    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 (*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 (parse_posixdate(setdate, &tm)) goto bad_date;
 
     if (toys.optflags & FLAG_u) {
-      // Get the UTC version of a struct tm
       char *tz = CFG_TOYBOX_FREE ? getenv("TZ") : 0;
+
+      // We can't just pass a timezone to mktime because posix.
       setenv("TZ", "UTC", 1);
       tzset();
       tv.tv_sec = mktime(&tm);
@@ -107,15 +151,21 @@ void date_main(void)
     if (tv.tv_sec == (time_t)-1) goto bad_date;
 
     tv.tv_usec = 0;
-    if (!strftime(toybuf, sizeof(toybuf), format_string, &tm)) goto bad_format;
-    puts(toybuf);
     if (settimeofday(&tv, NULL) < 0) perror_msg("cannot set date");
   }
 
+  if (toys.optflags & FLAG_u) {
+    if (tz) setenv("TZ", tz, 1);
+    else unsetenv("TZ");
+    tzset();
+  }
+
+  if (!strftime(toybuf, sizeof(toybuf), format_string, &tm))
+    perror_exit("bad format '%s'", format_string);
+  puts(toybuf);
+
   return;
 
 bad_date:
-  error_exit("bad date '%s'", *toys.optargs);
-bad_format:
-  perror_msg("bad format '%s'", format_string);
+  error_exit("bad date '%s'", setdate);
 }