frank's homepage

I was working on the build system today and came across this Ant macro I wrote a while ago. It unsigns a JAR by removing all signatures from the manifest and re-jar'ing it. This is useful if you want to deploy your application via Webstart and want to include all JARs inside one JNLP file, instead of using JNLP extensions for JARs with different signatures. Simply unsign all JARs and then re-sign them with your own signature.

Since there is no straight-forward way to do this in Ant I had to write my own macro. This might come in useful to other people, so I decided to post it:

<macrodef name="unsignjar">
	
    <attribute name="jar"/>
    	
    <sequential>
	<!-- Remove any existing signatures from a JAR file. -->
	<tempfile prefix="usignjar-" destdir="${java.io.tmpdir}" property="temp.file"/>
        <echo message="Removing signatures from JAR: @{jar}"/>
        <mkdir dir="${temp.file}"/>
	        
        <unjar src="@{jar}" dest="${temp.file}">
            <patternset>
                <include name="**"/>
                <exclude name="META-INF/*.SF"/>
                <exclude name="META-INF/*.DSA"/>
                <exclude name="META-INF/*.RSA"/>
            </patternset>
        </unjar>
	        
        <delete file="@{jar}" failonerror="true"/>
	        
        <!-- Touch it in case the file didn't have a manifest.
             Otherwise the JAR task below will fail if the manifest 
	     file doesn't exist. -->
        <mkdir dir="${temp.file}/META-INF"/>
        <touch file="${temp.file}/META-INF/MANIFEST.MF"/>
	        
        <jar destfile="@{jar}" 
            basedir="${temp.file}" 
            includes="**" 
            manifest="${temp.file}/META-INF/MANIFEST.MF"/>
	        
        <delete dir="${temp.file}" failonerror="true"/>
    </sequential>
</macrodef>

To use the macro:

  <unsignjar jar="/some/location/file.jar"/>