The cfg_print_duration() checks added previously in the 'duration_test'
unit test uncovered a bug in cfg_print_duration().
When calculating the current 'str' pointer of the generated text in the
buffer 'buf', it erroneously adds 1 byte to compensate for that part's
indicator character. For example, to add 12 minutes, it needs to add
2 + 1 = 3 characters, where 2 is the length of "12", and 1 is the length
of "M" (for minute). The mistake was that the length of the indicator
is already included in 'durationlen[i]', so there is no need to
calculate it again.
In the result of this mistake the current pointer can advance further
than needed and end up after the zero-byte instead of right on it, which
essentially cuts off any further generated text. For example, for a
5 minutes and 30 seconds duration, instead of having this:
'P', 'T', '5', 'M', '3', '0', 'S', '\0'
The function generates this:
'P', 'T', '5', 'M', '\0', '3', '0', 'S', '\0'
Fix the bug by adding to 'str' just 'durationlen[i]' instead of
'durationlen[i] + 1'.
(cherry picked from commit dc55f1ebb9)
e3fa77f577