add iso8601-format date string handling utility function

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@3542 57a11ea4-9604-0410-9ed3-97b8803252fd

src/engine/date.c

@@ -373,6 +373,42 @@ gnc_iso8601_to_timespec(const char *str)
   return ts;
 }
 
+/********************************************************************\
+\********************************************************************/
+
+char * 
+gnc_timespec_to_iso8601_buff (Timespec ts, char * buff)
+{
+  int len;
+  int tz_hour, tz_min;
+  char cyn;
+  time_t tmp;
+  struct tm parsed;
+
+  tmp = ts.tv_sec;
+  localtime_r(&tmp, &parsed);
+
+  tz_hour = timezone/3600;
+  tz_min = (timezone - 3600*tz_hour)/60;
+  if (0>tz_min) { tz_min +=60; tz_hour --; }
+
+  /* we also have to print the sign by hand, to work around a bug
+   * in the glibc 2.1.3 printf (where %+02d fails to zero-pad)
+   */
+  cyn = '+';
+  if (0>tz_hour) { cyn = '-'; tz_hour = -tz_hour; }
+
+  len = sprintf (buff, "%4d-%02d-%02d %02d:%02d:%02d.%06ld %c%02d%02d",
+       parsed.tm_year+1900, parsed.tm_mon+1, parsed.tm_mday,
+       parsed.tm_hour, parsed.tm_min, parsed.tm_sec,
+       ts.tv_nsec/1000, cyn, tz_hour, tz_min);
+
+  /* return pointer to end of string */
+  buff += len;
+  return buff;
+}
+
+
 /********************************************************************\
 \********************************************************************/
 /* hack alert -- this routine returns incorrect values for 

src/engine/date.h

@@ -148,11 +148,18 @@ Timespec gnc_dmy2timespec (int day, int month, int year);
 /* Same as gnc_dmy2timespec, but last second of the day */
 Timespec gnc_dmy2timespec_end (int day, int month, int year);
 
-/* The gnc_iso8601_to_timespec() routine
+/* The gnc_iso8601_to_timespec() routine converts an ISO-8601 style 
- * converts an ISO-8601 style date/time string to Timespec.
+ *    date/time string to Timespec.
  *    For example: 1998-07-17 11:00:00.68-05 
  *    is 680 milliseconds after 11 o'clock, central daylight time 
+ *
+ * The gnc_timespec_to_iso8601_buff() routine prints a Timespec
+ *    as an ISO-8601 style string.  The buffer must be long enough
+ *    to contain the string.  The string is null-terminated. This
+ *    routine returns a pointer to the null terminator (and can 
+ *    thus be used in the 'stpcpy' metaphor of string concatenation).
  */
 Timespec gnc_iso8601_to_timespec(const char *);
+char * gnc_timespec_to_iso8601_buff (Timespec ts, char * buff);
 
 #endif /* __XACC_DATE_H__ */