Initial commit

buildSrc/src/main/kotlin/ExecutableJar.kt

@@ -0,0 +1,47 @@
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.provider.ListProperty
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+import org.gradle.kotlin.dsl.listProperty
+
+/**
+ * Builds a self-contained Pkl CLI Jar that is directly executable on *nix
+ * and executable with `java -jar` on Windows.
+ *
+ * For direct execution, the `java` command must be on the PATH.
+ *
+ * https://skife.org/java/unix/2011/06/20/really_executable_jars.html
+ */
+open class ExecutableJar : DefaultTask() {
+  @get:InputFile
+  val inJar: RegularFileProperty = project.objects.fileProperty()
+
+  @get:OutputFile
+  val outJar: RegularFileProperty = project.objects.fileProperty()
+
+  @get:Input
+  val jvmArgs: ListProperty<String> = project.objects.listProperty()
+
+  @TaskAction
+  fun buildJar() {
+    val inFile = inJar.get().asFile
+    val outFile = outJar.get().asFile
+    val escapedJvmArgs = jvmArgs.get().joinToString(separator = " ") { "\"$it\"" }
+
+    val startScript = """
+      #!/bin/sh
+      exec java $escapedJvmArgs -jar $0 "$@"
+    """.trim().trimMargin() + "\n\n\n"
+
+    outFile.outputStream().use { outStream ->
+      startScript.byteInputStream().use { it.copyTo(outStream) }
+      inFile.inputStream().use { it.copyTo(outStream) }
+    }
+
+    // chmod a+x
+    outFile.setExecutable(true, false)
+  }
+}