fix(jardiff): handle cases where jardiff can not be packed

pack200 is a lossy compression algorithm. Sometimes packing a jardiff
alters the class files. This was not handled correctly.

Now in that case the fallback is to only gzip the jardiff (using
`pack200 --effort=0`).

Closes #48

gradle-jnlp-plugin/src/main/groovy/de/gliderpilot/gradle/jnlp/war/JarDiffTask.groovy

@@ -93,34 +93,49 @@ class JarDiffTask extends DefaultTask {
             File diffJarPacked = new File("${diffJar}.pack.gz")
             logger.info("packing $diffJar.name with pack200")
             try {
-                JavaHomeAware.exec(project, "pack200", "--repack", diffJar)
-                JavaHomeAware.exec(project, "pack200", diffJarPacked, diffJar)
-                project.delete(diffJar)
-                if (diffJarPacked.size() >= newVersion.file.size()) {
-                    // only keep jardiff.pack.gz if smaller than the full file
-                    logger.info("jardiff.pack.gz $diffJarPacked.name is not smaller than $newFile.name")
-                    project.delete(diffJarPacked)
-                }
-                return
+                // do the repack on a tmp file, because this might go wrong and we are stuck with a scrambled file
+                File tmpJar = tmpFile(diffJar)
+                // first repack
+                JavaHomeAware.exec(project, "pack200", "--repack", tmpJar)
+                // because the repacking might have altered the class files, resulting in a security exception
+                // when packing again
+                JavaHomeAware.exec(project, "pack200", diffJarPacked, tmpJar)
             } catch (e) {
+                // there was most probably a security exceptionls
                 // the file may be created and have size 0 -- delete
                 project.delete(diffJarPacked)
-                logger.warn("failed to pack $diffJar.name", e)
+                logger.info("failed to pack $diffJar.name using default params -- retrying with param --effort=0")
+                // use the unaltered diffJar as source, using --effort=0 is save, because it does not alter the class files
+                JavaHomeAware.exec(project, "pack200", "--effort=0", diffJarPacked, diffJar)
             }
+            project.delete(diffJar)
+            if (diffJarPacked.size() >= newVersion.file.size()) {
+                // only keep jardiff.pack.gz if smaller than the full file
+                logger.info("$diffJarPacked.name is not smaller than $newVersion.file.name")
+                project.delete(diffJarPacked)
+            }
+            return
         }
         if (diffJar.size() >= newVersion.file.size()) {
             // only keep jardiff if smaller than the full file
-            logger.info("jardiff $diffJar.name is not smaller than $newFile.name")
+            logger.info("$diffJar.name is not smaller than $newVersion.file.name")
             project.delete(diffJar)
         }
     }
 
     File getJar(File file) {
         if (file.name.endsWith('.jar'))
             return file
-        File jar = new File("$project.buildDir/tmp/jardiff", file.name - '.pack.gz')
+        File jar = new File(into.parentFile, file.name - '.pack.gz')
         JavaHomeAware.exec(project, "unpack200", file, jar)
         return jar
     }
 
+    File tmpFile(File file) {
+        project.copy {
+            from file
+            into into.parentFile
+        }
+        return new File(into.parentFile, file.name)
+    }
 }

gradle-jnlp-plugin/src/test/groovy/de/gliderpilot/gradle/jnlp/war/GradleJnlpWarPluginIntegrationSpec.groovy

@@ -327,7 +327,7 @@ class GradleJnlpWarPluginIntegrationSpec extends AbstractJnlpIntegrationSpec {
     }
 
     @Unroll
-    def '[gradle #gv] jardiffs are created'() {
+    def '[gradle #gv] jardiffs with pack200 are created'() {
         given:
         gradleVersion = gv
 
@@ -348,12 +348,49 @@ class GradleJnlpWarPluginIntegrationSpec extends AbstractJnlpIntegrationSpec {
                 }
             }
             '''
-        runTasksSuccessfully("build")
+        def result = runTasksSuccessfully("build")
 
         then:
+        !result.standardOutput.contains("failed to pack")
         fileExists("war/build/libs/war-1.1.war")
         fileExists("war/build/tmp/warContent/launch.jnlp")
         fileExists("war/build/tmp/warContent/lib/${moduleName}__V1.0-myalias__V1.1-myalias.diff.jar.pack.gz")
+        // but no diff.jar
+        !fileExists("war/build/tmp/warContent/lib/${moduleName}__V1.0-myalias__V1.1-myalias.diff.jar")
+
+        where:
+        gv << gradleVersions
+    }
+
+    @Unroll
+    def '[gradle #gv] jardiffs without pack200 are created'() {
+        given:
+        gradleVersion = gv
+
+        when:
+        buildFile << "jnlp.usePack200 = false\n"
+        runTasksSuccessfully('build', 'publish')
+        version = '1.1'
+        warBuildFile.text = '''\
+            jnlpWar {
+                versions {
+                    "1.0" "$rootProject.group:$rootProject.name:1.0:webstart@zip"
+                }
+                launchers {
+                    "1.1" {
+                        jardiff {
+                            from "1.0"
+                        }
+                    }
+                }
+            }
+            '''
+        runTasksSuccessfully("build")
+
+        then:
+        fileExists("war/build/libs/war-1.1.war")
+        fileExists("war/build/tmp/warContent/launch.jnlp")
+        fileExists("war/build/tmp/warContent/lib/${moduleName}__V1.0-myalias__V1.1-myalias.diff.jar")
 
         where:
         gv << gradleVersions
@@ -454,14 +491,20 @@ class GradleJnlpWarPluginIntegrationSpec extends AbstractJnlpIntegrationSpec {
                 }
             }
             '''
-        runTasksSuccessfully("build")
+        def result = runTasksSuccessfully("build")
 
         then:
         fileExists("war/build/libs/war-1.1.war")
         fileExists("war/build/tmp/warContent/launch.jnlp")
-        // somehow xalan does not work, no pack.gz is created
+        // somehow pack200 of the xalan jardiff does not work with default params
+        // does not even work with java 7
+        System.getProperty("java.specification.version") == "1.7" &&
+            result.standardOutput.contains("failed to create xalan__V2.7.1-myalias__V2.7.2-myalias.diff.jar") ||
+            result.standardOutput.contains("failed to pack xalan__V2.7.1-myalias__V2.7.2-myalias.diff.jar using default params -- retrying with param --effort=0") &&
+            // but the pack200.gz file using --effort=0 is not smaller than the new version .pack.gz
+            result.standardOutput.contains("xalan__V2.7.1-myalias__V2.7.2-myalias.diff.jar.pack.gz is not smaller than xalan__V2.7.2-myalias.jar.pack.gz")
+        // therefore we don't have the diff.jar.pack.gz nor the diff.jar
         !fileExists("war/build/tmp/warContent/lib/xalan__V2.7.1-myalias__V2.7.2-myalias.diff.jar.pack.gz")
-        // but the diff.jar is bigger than the v2.7.2.jar.pack.gz, therefore no diff
         !fileExists("war/build/tmp/warContent/lib/xalan__V2.7.1-myalias__V2.7.2-myalias.diff.jar")
 
         where: