rpn2 test fails on non-glibc Linux

[awilfox]

Describe the bug
musl libc does not provide _NL_TIME_FIRST_WEEKDAY. This causes find_first_weekday to return 1 (Monday), and the rpn2 test requires the first weekday to be 0 (Sunday).

To Reproduce
Steps to reproduce the behavior:

1. Install a Linux distribution using musl libc.
2. Unpack rrdtool-1.7.2.
3. Build.
4. Run make check.

Expected behavior
Passing tests (which do occur if either rpn2 test is disabled, or hardcoded return value from find_first_weekday is 0 instead of 1).

Screenshots

Desktop (please complete the following information):

• OS: Adélie Linux 1.0-BETA3 on 64-bit PowerPC
• Browser: Firefox
• Version: 1.7.2, release tarball

Additional context
This is similar to #661 but it isn't the same thing, because _NL_TIME_FIRST_WEEKDAY really doesn't exist on musl libc.

[nirgal]

Out of curiosity, what does locale -ck LC_TIME yields? Here:

$ locale -ck LC_TIME
LC_TIME
abday="Sun;Mon;Tue;Wed;Thu;Fri;Sat"
day="Sunday;Monday;Tuesday;Wednesday;Thursday;Friday;Saturday"
abmon="Jan;Feb;Mar;Apr;May;Jun;Jul;Aug;Sep;Oct;Nov;Dec"
mon="January;February;March;April;May;June;July;August;September;October;November;December"
am_pm="am;pm"
d_t_fmt="%a %d %b %Y %T %Z"
d_fmt="%d/%m/%y"
t_fmt="%T"
t_fmt_ampm="%l:%M:%S %P %Z"
era=
era_year=""
era_d_fmt=""
alt_digits=
era_d_t_fmt=""
era_t_fmt=""
time-era-num-entries=0
time-era-entries="S"
week-ndays=7
week-1stday=19971130
week-1stweek=4
first_weekday=2
first_workday=2
cal_direction=1
timezone=""
date_fmt="%a %e %b %H:%M:%S %Z %Y"
time-codeset="UTF-8"

[awilfox]

musl doesn't have a locale command, unfortunately.

[nirgal]

Ouch, obviously this is an issue for weekly data, as its depends of the first day of the week (Monday or Sunday depending of local folklore).

We are assuming this is Monday when HAVE__NL_TIME_WEEK_1STDAY is undefined.

I can see rpn2 xport test runs with "LC_TIME=C" meaning that we expect the test to run with the first day of the week being Sunday.

Two options:

• Change the rpn2 test to run with a LC_TIME where weeks starts on Monday.
• Change the default values of firstday of the week from Monday to Sunday if HAVE__NL_TIME_WEEK_1STDAY is undefined (3 occurrences in the source).

Tobias: Any suggestion?

[oetiker]

I guess assuming sunday for the weekstart when HAVE__NL_TIME_WEEK_1STDAY is not present is the 'right thing' thing in the sense of least surprise ... after all this is all US centric and in the US sunday is the start of the week, so if the system has not bothered to support localization at that level we should keep it US-style.

[nirgal]

Then this should do the trick:

diff --git a/src/rrd_graph.c b/src/rrd_graph.c
index f5d2cdec..62c3e645 100644
--- a/src/rrd_graph.c
+++ b/src/rrd_graph.c
@@ -1568,7 +1568,7 @@ static int find_first_weekday(
         }
         first_weekday = (week_1stday + first_weekday - 1) % 7;
 #else
-        first_weekday = 1;
+        first_weekday = 0;
 #endif
     }
     return first_weekday;
diff --git a/src/rrd_rpncalc.c b/src/rrd_rpncalc.c
index 0f54c6be..84f69211 100644
--- a/src/rrd_rpncalc.c
+++ b/src/rrd_rpncalc.c
@@ -564,7 +564,7 @@ static int find_first_weekday(void){
         }
         first_weekday=(week_1stday + first_weekday - 1) % 7;
 #else
-        first_weekday = 1;
+        first_weekday = 0;
 #endif
     }
     return first_weekday;

[oetiker]

indeed :) can you make a PR ?