Bug 751984 - Use UTC timezone when displaying QDateTimes parsed from SOURCE_DATE_EPOCH

According to the SOURCE_DATE_EPOCH spec [1], "Formatting MUST be deferred until runtime if an end user should observe the value in their own locale or timezone."

However setTime_t uses localtime, so the output is in the timezone of the build machine running doxygen, and not the timezone of the reader consuming the final output.

To adhere to the spec, the easiest option is to add a setTimeUtc_t function that is the same as setTime_t, but only uses gmtime instead of first trying localtime.

[1] https://reproducible-builds.org/specs/source-date-epoch/

2 files changed, 24 insertions, 0 deletions

diff --git a/qtools/qdatetime.cpp b/qtools/qdatetime.cpp
index d0cc36e..88569f8 100644
--- a/qtools/qdatetime.cpp
+++ b/qtools/qdatetime.cpp
@@ -1158,6 +1158,29 @@ void QDateTime::setTime_t( uint secsSince1Jan1970UTC )
 
 
 /*!
+  Sets the UTC date and time given the number of seconds that have passed
+  since 00:00:00 on January 1, 1970, Coordinated Universal Time (UTC).
+
+  Note that Microsoft Windows supports only a limited range of values for
+  \a secsSince1Jan1970UTC.
+*/
+
+void QDateTime::setTimeUtc_t( uint secsSince1Jan1970UTC )
+{
+    time_t tmp = (time_t) secsSince1Jan1970UTC;
+    tm *tM = gmtime( &tmp );
+    if ( !tM ) {
+	    d.jd = QDate::greg2jul( 1970, 1, 1 );
+	    t.ds = 0;
+	    return;
+    }
+    d.jd = QDate::greg2jul( tM->tm_year + 1900, tM->tm_mon + 1, tM->tm_mday );
+    t.ds = MSECS_PER_HOUR*tM->tm_hour + MSECS_PER_MIN*tM->tm_min +
+	    1000*tM->tm_sec;
+}
+
+
+/*!
   Returns the datetime as a string.
 
   The string format is "Sat May 20 03:40:13 1998".
diff --git a/qtools/qdatetime.h b/qtools/qdatetime.h
index 2d5869c..010ae73 100644
--- a/qtools/qdatetime.h
+++ b/qtools/qdatetime.h
@@ -173,6 +173,7 @@ public:
     void   setDate( const QDate &date ) { d=date; }
     void   setTime( const QTime &time ) { t=time; }
     void   setTime_t( uint secsSince1Jan1970UTC );
+    void   setTimeUtc_t( uint secsSince1Jan1970UTC );
 
     QString toString()	const;