There should be a way to test the integrity of ZIP (and JAR, WAR, TAR) files in ant. Preferably, this would be done using a supported <condition>. As shown in bug #34893, the JVM is left holding corrupt zip files open after <unzip> is run. An integrity test could be used here as a work-around. And the test would be useful for general reporting and error recovery even after 34893 is fixed.