Index: maven-core/src/main/java/org/apache/maven/DefaultMaven.java
===================================================================
--- maven-core/src/main/java/org/apache/maven/DefaultMaven.java	(revision 416005)
+++ maven-core/src/main/java/org/apache/maven/DefaultMaven.java	(working copy)
@@ -552,7 +552,11 @@
     {
         if ( pom.exists() )
         {
-            if ( pom.length() == 0 )
+            // If 'pom' is a regular file, ensure that it is not empty ('pom'
+            // may not be a regular file; it may be a unix named pipe or some
+            // other platform-specific device from which the size is not
+            // available before reading).
+            if ( pom.isFile() && pom.length() == 0 )
             {
                 throw new ProjectBuildingException( "unknown", "The file " + pom.getAbsolutePath() +
                     " you specified has zero length." );