reproducible-build-timestamp.patch

Description: Set the maven.build.timestamp variable to the date defined by
 the SOURCE_DATE_EPOCH environment variable to make the Maven builds reproducible.
Author: Emmanuel Bourg <ebourg@apache.org>
Forwarded: no
--- a/maven-compat/src/main/java/org/apache/maven/project/interpolation/BuildTimestampValueSource.java
+++ b/maven-compat/src/main/java/org/apache/maven/project/interpolation/BuildTimestampValueSource.java
@@ -44,7 +44,15 @@
     public Object getValue(String expression) {
         if ("build.timestamp".equals(expression) || "maven.build.timestamp".equals(expression)) {
             if (formattedDate == null && startTime != null) {
-                formattedDate = new SimpleDateFormat(format).format(startTime);
+                if ( System.getenv( "SOURCE_DATE_EPOCH" ) == null ) {
+                    formattedDate = new SimpleDateFormat( format ).format( startTime );
+                } else {
+                    // Use the SOURCE_DATE_EPOCH timestamp and make the format locale insensitive
+                    SimpleDateFormat fmt = new SimpleDateFormat( format, java.util.Locale.ENGLISH );
+                    fmt.setTimeZone( java.util.TimeZone.getTimeZone( "UTC" ) );
+                    Date date = new Date( 1000 * Long.parseLong( System.getenv( "SOURCE_DATE_EPOCH" ) ) );
+                    formattedDate = fmt.format( date );
+                }
             }
 
             return formattedDate;
--- a/maven-model-builder/src/main/java/org/apache/maven/model/interpolation/MavenBuildTimestamp.java
+++ b/maven-model-builder/src/main/java/org/apache/maven/model/interpolation/MavenBuildTimestamp.java
@@ -21,6 +21,7 @@
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.GregorianCalendar;
+import java.util.Locale;
 import java.util.Properties;
 import java.util.TimeZone;
 
@@ -56,7 +57,15 @@
         if (time == null) {
             time = new Date();
         }
-        SimpleDateFormat dateFormat = new SimpleDateFormat(timestampFormat);
+
+        Locale locale = Locale.getDefault();
+        if ( System.getenv( "SOURCE_DATE_EPOCH" ) != null )
+        {
+            time = new Date( 1000 * Long.parseLong( System.getenv( "SOURCE_DATE_EPOCH" ) ) );
+            locale = Locale.ENGLISH;
+        }
+
+        SimpleDateFormat dateFormat = new SimpleDateFormat( timestampFormat, locale );
         dateFormat.setCalendar(new GregorianCalendar());
         dateFormat.setTimeZone(DEFAULT_BUILD_TIME_ZONE);
         formattedTimestamp = dateFormat.format(time);