time zone matching: added debug and error logging

Previously, failures in VTIMEZONEtoTZEntry() were
ignored. VTIMEZONEtoInternal() then continued with incomplete
information, typically leading to wrong results.

This patch adds an error message and debug logging.  The error message
makes it obvious that something went wrong. The debug logging is
necessary to debug more subtle problems.

3 files changed, 33 insertions, 10 deletions

diff --git a/src/sysync/timezones.cpp b/src/sysync/timezones.cpp
index 39cf8bf..3ca5b73 100755
--- a/src/sysync/timezones.cpp
+++ b/src/sysync/timezones.cpp
@@ -109,7 +109,7 @@ bool GZones::initialize()
 }
 
 
-bool GZones::matchTZ(const tz_entry &aTZ, timecontext_t &aContext)
+bool GZones::matchTZ(const tz_entry &aTZ, TDebugLogger *aLogP, timecontext_t &aContext)
 {
   // keeps track of best match while iterating
   class comparison : public visitor {
@@ -128,16 +128,20 @@ bool GZones::matchTZ(const tz_entry &aTZ, timecontext_t &aContext)
     /** the last entry without dynYear, i.e., the main entry of a group */
     timecontext_t fLeadContext;
 
+    TDebugLogger *fLogP;
+
     /** time zones */
     GZones *fG;
 
+
   public:
-    comparison(const tz_entry &aTZ, GZones *g) :
+    comparison(const tz_entry &aTZ, TDebugLogger *aLogP, GZones *g) :
       fRuleMatch(false),
       fLocationMatch(false),
       fContext(TCTX_UNKNOWN),
       fTZID(aTZ.name),
       fLeadContext(TCTX_UNKNOWN),
+      fLogP(aLogP),
       fG(g)
     {
       // prepare information for tzcmp() and YearFit()
@@ -164,6 +168,8 @@ bool GZones::matchTZ(const tz_entry &aTZ, timecontext_t &aContext)
          !fTZ.name.empty() && // empty match is NOT better !!
           fTZ.name == aTZ.name) {
         // name AND rule match => best possible match, return early
+        PLOGDEBUGPRINTFX(fLogP, DBG_PARSE+DBG_EXOTIC,
+                         ("matchTZ: final rule and name match for %s", fTZ.name.c_str()));
         fContext = fLeadContext;
         return true;
       }
@@ -175,6 +181,10 @@ bool GZones::matchTZ(const tz_entry &aTZ, timecontext_t &aContext)
             (!fRuleMatch && rule_match)) {
           // previous match did not match location or
           // not the rules and we do, so this match is better
+          PLOGDEBUGPRINTFX(fLogP, DBG_PARSE+DBG_EXOTIC,
+                           ("matchTZ %s: location %s found, rules %s",
+                            aTZ.name.c_str(), aTZ.location.c_str(),
+                            rule_match ? "match" : "don't match"));
           fLocationMatch = true;
           fRuleMatch = rule_match;
           fContext = fLeadContext;
@@ -186,6 +196,8 @@ bool GZones::matchTZ(const tz_entry &aTZ, timecontext_t &aContext)
       if (!fLocationMatch &&
           rule_match &&
           !fRuleMatch) {
+          PLOGDEBUGPRINTFX(fLogP, DBG_PARSE+DBG_EXOTIC,
+                           ("matchTZ %s: rules match", aTZ.name.c_str()));
         fContext = fLeadContext;
         fRuleMatch = true;
       }
@@ -204,7 +216,7 @@ bool GZones::matchTZ(const tz_entry &aTZ, timecontext_t &aContext)
     } // result
   }
 
-  c(aTZ, this);
+  c(aTZ, aLogP, this);
 
   foreachTZ(c);
 
diff --git a/src/sysync/timezones.h b/src/sysync/timezones.h
index 095ead5..16e5071 100755
--- a/src/sysync/timezones.h
+++ b/src/sysync/timezones.h
@@ -251,7 +251,7 @@ class GZones {
      *                     refers to the tz_entry without a dynYear
      * @return true if match found
      */
-    bool matchTZ(const tz_entry &aTZ, timecontext_t &aContext);
+    bool matchTZ(const tz_entry &aTZ, TDebugLogger *aLogP, timecontext_t &aContext);
 
     class visitor {
     public:
diff --git a/src/sysync/vtimezone.cpp b/src/sysync/vtimezone.cpp
index 4eee4b5..f737379 100644
--- a/src/sysync/vtimezone.cpp
+++ b/src/sysync/vtimezone.cpp
@@ -258,6 +258,7 @@ static bool GetTZInfo( cAppCharP     aText,
   timecontext_t tctx;
   lineartime_t  dtstart, dtH= 0;
   string        a, st;
+  bool          success = true;
 
   if (aNth==-1) { // search for the last (in time)
     sInt32 i= 1;
@@ -286,9 +287,11 @@ static bool GetTZInfo( cAppCharP     aText,
     string             vvv;
     internalRToRRULE2( vvv, r, false, aLogP );
     Rtm_to_tChange        ( r, dtstart, c );
+  } else {
+    success = false;
   } // if
 
-  return true;
+  return success;
 } // GetTZInfo
 
 
@@ -397,13 +400,19 @@ bool VTIMEZONEtoTZEntry( const char*    aText, // VTIMEZONE string to be parsed
                          TDebugLogger*  aLogP)
 {
   short dBias; // the full bias for DST
+  bool success = true;
 
                                  t.name   = "";
                                  t.ident  = "";
                                  t.dynYear= "CUR";
                                  t.biasDST= 0;
-       GetTZInfo( aText,VTZ_STD, t.std, t.bias, aStdName, -1, aLogP );
-  if (!GetTZInfo( aText,VTZ_DST, t.dst,  dBias, aDstName, -1, aLogP )) dBias= t.bias;
+  if (!GetTZInfo( aText,VTZ_STD, t.std, t.bias, aStdName, -1, aLogP )) {
+    success = false;
+  }
+  if (!GetTZInfo( aText,VTZ_DST, t.dst,  dBias, aDstName, -1, aLogP )) {
+    dBias= t.bias;
+    success = false;
+  }
 
   if  (t.bias ==  dBias) ClrDST( t ); // no DST ?
   else t.biasDST= dBias - t.bias; // t.biasDST WILL be calculated here
@@ -411,7 +420,7 @@ bool VTIMEZONEtoTZEntry( const char*    aText, // VTIMEZONE string to be parsed
   // get TZID as found in VTIMEZONE
   t.name = VValue( aText, VTZ_ID );
 
-  return true;
+  return success;
 } // VTIMEZONEtoTZEntry
 
 
@@ -430,7 +439,9 @@ bool VTIMEZONEtoInternal( const char*    aText, // VTIMEZONE string to be parsed
                 lName;
   timecontext_t lContext;
 
-  VTIMEZONEtoTZEntry( aText, t, stdName, dstName, aLogP );
+  if (!VTIMEZONEtoTZEntry( aText, t, stdName, dstName, aLogP )) {
+    PLOGDEBUGPRINTFX(aLogP, DBG_PARSE+DBG_ERROR, ("parsing VTIMEZONE failed:\n%s", aText));
+  }
   if (aTzidP) *aTzidP = t.name; // return the original TZID as found, needed to match with TZID occurences in rest of vCalendar
 
   bool sC= !(stdName=="");
@@ -453,7 +464,7 @@ bool VTIMEZONEtoInternal( const char*    aText, // VTIMEZONE string to be parsed
   // find best match for VTIMEZONE: checks name and rules
   // allows multiple timezone, if last is ok !
   if (!g) return false; // avoid crashes with g==NULL
-  ok=  g->matchTZ(t, aContext);
+  ok=  g->matchTZ(t, aLogP, aContext);
 
   if (!ok && !okM) { // store it "as is" if both is not ok
     ClrDST( t );