Fix strptime bug with %a conversions (#1533)

* fix strptime bug with %a conversions.

* workaround time zone issues with strptime.

our strptime ignores %z results because tm_gmtoff is non-standard
until POSIX.1-2024.

Author: tsteven4

reference/strptime.csv

@@ -0,0 +1 @@
+Fri Nov 19 19:52:39Z 2021, 50.917162998, 11.573497706

reference/strptime.gpx

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<gpx version="1.0" creator="GPSBabel - https://www.gpsbabel.org" xmlns="http://www.topografix.com/GPX/1/0">
+  <time>1970-01-01T00:00:00Z</time>
+  <bounds minlat="50.917162998" minlon="11.573497706" maxlat="50.917162998" maxlon="11.573497706"/>
+  <wpt lat="50.917162998" lon="11.573497706">
+    <time>2021-11-19T19:52:39Z</time>
+    <name>WPT001</name>
+    <cmt>WPT001</cmt>
+    <desc>WPT001</desc>
+  </wpt>
+</gpx>

strptime/README.GPSBabel

@@ -11,3 +11,6 @@ README
 
 The modified files from glibc.git are:
 strptime_l.c
+
+strptime_l.c.patch is a patch for our standalone version of strptime.
+bug33858.patch is for a strptime bug reported but not fixed in glibc.  see https://sourceware.org/bugzilla/show_bug.cgi?id=33853

strptime/bug33853.patch

@@ -0,0 +1,13 @@
+diff --git a/strptime/strptime_l.c b/strptime/strptime_l.c
+index 1a647079..5d2e6b21 100644
+--- a/strptime/strptime_l.c
++++ b/strptime/strptime_l.c
+@@ -382,7 +382,7 @@ __strptime_internal (const char *rp, const char *fmt, struct tm *tmp,
+ 	      if (s.decided != loc
+ 		  && (((trp = rp, match_string (weekday_name[cnt], trp))
+ 		       && trp > rp_longest)
+-		      || ((trp = rp, match_string (ab_weekday_name[cnt], rp))
++		      || ((trp = rp, match_string (ab_weekday_name[cnt], trp))
+ 			  && trp > rp_longest)))
+ 		{
+ 		  rp_longest = trp;

strptime/strptime_l.c

@@ -382,7 +382,7 @@ __strptime_internal (const char *rp, const char *fmt, struct tm *tmp,
 	      if (s.decided != loc
 		  && (((trp = rp, match_string (weekday_name[cnt], trp))
 		       && trp > rp_longest)
-		      || ((trp = rp, match_string (ab_weekday_name[cnt], rp))
+		      || ((trp = rp, match_string (ab_weekday_name[cnt], trp))
 			  && trp > rp_longest)))
 		{
 		  rp_longest = trp;

testo.d/xcsv.test

@@ -426,3 +426,11 @@ if command -v tzselect >/dev/null 2>&1 ; then
 
   unset -v TZ
 fi
+
+# test for strptime bug https://sourceware.org/bugzilla/show_bug.cgi?id=33853
+echo 'FIELD_DELIMITER    COMMA' > ${TMPDIR}/strptime.style
+echo 'IFIELD GMT_TIME,"","%a %b %d %H:%M:%S%z %Y"' >> ${TMPDIR}/strptime.style
+echo 'IFIELD LAT_DECIMAL,"","%f"' >> ${TMPDIR}/strptime.style
+echo 'IFIELD LON_DECIMAL,"","%f"' >> ${TMPDIR}/strptime.style
+gpsbabel -i xcsv,style=${TMPDIR}/strptime.style -f ${REFERENCE}/strptime.csv -o gpx -F ${TMPDIR}/strptime.gpx
+compare ${REFERENCE}/strptime.gpx ${TMPDIR}/strptime.gpx