feat: allow ignoring duplicate entries in Jar files

Add new member `duplicatesStrategy` to task signJars.

This member is unset by default, which is the same behavior as before.
Setting the value to `INCLUDE` would result in the same.

If the member is set to `EXCLUDE`, duplicate entries in jar files are
ignored and a debug message is printed to the log.

If it is `WARN`, a warning is printed to the log, but the build will fail
nonetheless, because the JarOutputStream will not allow duplicate entries.

If it is `FAIL`, the build will fail as well, but gracefully by throwing a
DuplicateFileCopyingException.

Closes: #37

gradle-jnlp-plugin/src/main/groovy/de/gliderpilot/gradle/jnlp/SignJarsTask.groovy

@@ -16,6 +16,9 @@
 package de.gliderpilot.gradle.jnlp
 
 import groovyx.gpars.GParsPool
+import org.gradle.api.file.DuplicateFileCopyingException
+import org.gradle.api.file.DuplicatesStrategy
+import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.TaskAction
 import org.gradle.api.tasks.incremental.IncrementalTaskInputs
 
@@ -24,9 +27,10 @@ import java.util.jar.JarFile
 import java.util.jar.JarOutputStream
 import java.util.jar.Manifest
 
-
 class SignJarsTask extends AbstractCopyJarsTask {
 
+    @Input
+    DuplicatesStrategy duplicatesStrategy = DuplicatesStrategy.INCLUDE
 
     @TaskAction
     void signJars(IncrementalTaskInputs inputs) {
@@ -64,6 +68,7 @@ class SignJarsTask extends AbstractCopyJarsTask {
 
     File copyUnsignAndAlterManifest(File input) {
         File output = new File(into, newName(input.name))
+        logger.info("Copying " + input + " to " + output)
         JarFile jarFile = new JarFile(input)
         Manifest manifest = jarFile.manifest ?: new Manifest()
         def removeManifestEntries = { pattern, attributes ->
@@ -86,8 +91,21 @@ class SignJarsTask extends AbstractCopyJarsTask {
             manifest.mainAttributes.putValue('Manifest-Version', '1.0')
 
         new JarOutputStream(output.newOutputStream(), manifest).withStream { os ->
+            def entries = [] as Set
             jarFile.entries().each { entry ->
-                if (entry.name != JarFile.MANIFEST_NAME && !(entry.name ==~ "(?i)META-INF/${project.jnlp.signJarFilteredMetaInfFiles}")) {
+                def duplicate = !entries.add(entry.name)
+                if (duplicate && duplicatesStrategy == DuplicatesStrategy.WARN) {
+                    logger.warn("Duplicate entry found in jar: " + output + " entry: " + entry.name)
+                }
+                if (duplicate && duplicatesStrategy == DuplicatesStrategy.FAIL) {
+                    throw new DuplicateFileCopyingException("Duplicate entry found in jar: " + output + " entry: " + entry.name)
+                }
+                if (duplicate && duplicatesStrategy == DuplicatesStrategy.EXCLUDE) {
+                    logger.debug("Ignoring duplicate entry in jar: " + output + " entry: " + entry.name)
+                } else if (entry.name == JarFile.MANIFEST_NAME || entry.name ==~ "(?i)META-INF/${project.jnlp.signJarFilteredMetaInfFiles}") {
+                    logger.debug("Ignoring entry jar: " + output + " entry: " + entry.name)
+                } else {
+                    logger.debug("copying jar: " + input.name + " entry: " + entry.name)
                     os.putNextEntry(new JarEntry(entry.name))
                     os << jarFile.getInputStream(entry)
                     os.closeEntry()

gradle-jnlp-plugin/src/test/groovy/de/gliderpilot/gradle/jnlp/SignJarsDuplicateEntriesSpec.groovy

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package de.gliderpilot.gradle.jnlp
+
+import org.gradle.api.file.DuplicatesStrategy
+import spock.lang.Issue
+
+@Issue("https://github.com/tschulte/gradle-jnlp-plugin/issues/37")
+class SignJarsDuplicateEntriesSpec extends AbstractJnlpIntegrationSpec {
+
+    def setup() {
+        writeHelloWorld('de.gliderpilot.jnlp.test')
+        file('src/main/resources/test')
+        file('src/test/resources/test')
+        buildFile << """\
+            apply plugin: 'java'
+            apply plugin: 'application'
+            jnlp {
+                usePack200 = false
+                signJarRemovedNamedManifestEntries = ".*"
+            }
+            mainClassName = 'de.gliderpilot.jnlp.test.HelloWorld'
+            jar {
+                from sourceSets.test.output
+            }
+            """.stripIndent()
+        enableJarSigner()
+    }
+
+    def 'cannot sign jar without DuplicatesStrategy'() {
+        expect:
+        runTasksWithFailure(':createWebstartDir')
+    }
+
+    def 'cannot sign jar with DuplicatesStrategy.INCLUDE'() {
+        given:
+        duplicatesStrategy = DuplicatesStrategy.INCLUDE
+
+        expect:
+        runTasksWithFailure(':createWebstartDir')
+    }
+
+    def 'cannot sign jar with DuplicatesStrategy.FAIL'() {
+        given:
+        duplicatesStrategy = DuplicatesStrategy.FAIL
+
+        expect:
+        runTasksWithFailure(':createWebstartDir')
+    }
+
+    def 'cannot sign jar with duplicatesStrategy.WARN'() {
+        given:
+        duplicatesStrategy = DuplicatesStrategy.WARN
+
+        expect:
+        runTasksWithFailure(':createWebstartDir')
+    }
+
+    def 'can sign jar with DuplicatesStrategy.EXCLUDE'() {
+        given:
+        duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+
+        expect:
+        runTasksSuccessfully(':createWebstartDir')
+    }
+
+    void setDuplicatesStrategy(DuplicatesStrategy duplicatesStrategy) {
+        buildFile << """\
+            tasks.signJars {
+                duplicatesStrategy = DuplicatesStrategy.${duplicatesStrategy}
+            }
+            """.stripIndent()
+    }
+
+}