Backport from xs.

xs_time.h

@@ -12,6 +12,7 @@ xs_str *xs_str_time(time_t t, const char *fmt, int local);
 time_t xs_parse_time(const char *str, const char *fmt, int local);
 #define xs_parse_localtime(str, fmt) xs_parse_time(str, fmt, 1)
 #define xs_parse_utctime(str, fmt) xs_parse_time(str, fmt, 0)
+xs_str *xs_str_time_diff(time_t time_diff);
 
 #ifdef XS_IMPLEMENTATION
 
@@ -37,6 +38,18 @@ xs_str *xs_str_time(time_t t, const char *fmt, int local)
 }
 
 
+xs_str *xs_str_time_diff(time_t time_diff)
+/* returns time_diff in seconds to 'human' units (d:hh:mm:ss) */
+{
+    int secs  = time_diff % 60;
+    int mins  = (time_diff /= 60) % 60;
+    int hours = (time_diff /= 60) % 24;
+    int days  = (time_diff /= 24);
+
+    return xs_fmt("%d:%02d:%02d:%02d", days, hours, mins, secs);
+}
+
+
 char *strptime(const char *s, const char *format, struct tm *tm);
 
 time_t xs_parse_time(const char *str, const char *fmt, int local)

xs_version.h

@@ -1 +1 @@
-/* dfdd729248d7169b80cb6a7462fe6c0ba6efeb16 */
+/* b4f118990f3b8327a033a28bd9ca687c75b23dee */