Fix DelegateReader: Close the delegate reader only if it has not been…

… created yet

This avoids swallowing exceptions in cases when the creation of the delegate reader will consume the entire contents of the inner reader, and close it. In that case a client of the delegate reader will call "close" which would trigger the creation of the delegate reader again, but the inner reader is already closed at that point, reporting IOException "stream closed" and hiding the original exception.

gradle-plugin-utils/src/main/kotlin/org/unbrokendome/gradle/pluginutils/io/DelegateReader.kt

@@ -8,12 +8,25 @@ import java.nio.CharBuffer
 /**
  * Implementation of [FilterReader] that delegates all [Reader] methods to another reader.
  */
+@Suppress("LeakingThis")
 abstract class DelegateReader(input: Reader) : FilterReader(input) {
 
+    /**
+     * Creates the delegate [Reader].
+     *
+     * @param input the input [Reader]
+     * @return the delegate [Reader]
+     */
+    protected abstract fun createDelegateReader(input: Reader): Reader
+
+    private val lazyDelegate = lazy(LazyThreadSafetyMode.NONE) {
+        createDelegateReader(`in`)
+    }
+
     /**
      * The delegate [Reader].
      */
-    protected abstract val delegate: Reader
+    private val delegate: Reader by lazyDelegate
 
 
     override fun read(): Int =
@@ -52,6 +65,11 @@ abstract class DelegateReader(input: Reader) : FilterReader(input) {
         delegate.reset()
 
 
-    override fun close() =
-        delegate.close()
+    override fun close() {
+        if (lazyDelegate.isInitialized()) {
+            delegate.close()
+        } else {
+            `in`.close()
+        }
+    }
 }

gradle-plugin-utils/src/main/kotlin/org/unbrokendome/gradle/pluginutils/io/SimpleTemplateEngineFilterReader.kt

@@ -3,9 +3,7 @@ package org.unbrokendome.gradle.pluginutils.io
 import groovy.text.SimpleTemplateEngine
 import org.gradle.api.file.ContentFilterable
 import org.unbrokendome.gradle.pluginutils.io.DelegateReader
-import java.io.Reader
-import java.io.StringReader
-import java.io.StringWriter
+import java.io.*
 
 
 /**
@@ -43,18 +41,17 @@ internal class SimpleTemplateEngineFilterReader(
     var properties: Map<String, *> = emptyMap<String, Any?>()
     var escapeBackslash: Boolean = false
 
+    override fun createDelegateReader(input: Reader): Reader {
 
-    override val delegate: Reader by lazy(LazyThreadSafetyMode.NONE) {
-
-        val template = `in`.use { input ->
+        val template = input.buffered().use {
             val engine = SimpleTemplateEngine()
             engine.isEscapeBackslash = escapeBackslash
-            engine.createTemplate(input)
+            engine.createTemplate(it)
         }
 
         val writer = StringWriter()
         template.make(properties).writeTo(writer)
 
-        StringReader(writer.toString())
+        return StringReader(writer.toString())
     }
 }