jvmAndroidMain.org.luaj.vm2.server.LuajClassLoader.kt Maven / Gradle / Ivy
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/*******************************************************************************
* Copyright (c) 2015 Luaj.org. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.luaj.vm2.server
import java.io.*
/**
* Class loader that can be used to launch a lua script in a Java VM that has a
* unique set of classes for org.luaj classes.
*
* *Note: This class is experimental and subject to change in future versions.*
*
* By using a custom class loader per script, it allows the script to have
* its own set of globals, including static values such as shared metatables
* that cannot access lua values from other scripts because their classes are
* loaded from different class loaders. Thus normally unsafe libraries such
* as luajava can be exposed to scripts in a server environment using these
* techniques.
*
* All classes in the package "org.luaj.vm2." are considered user classes, and
* loaded into this class loader from their bytes in the class path. Other
* classes are considered systemc classes and loaded via the system loader. This
* class set can be extended by overriding [.isUserClass].
*
* The [Launcher] interface is loaded as a system class by exception so
* that the caller may use it to launch lua scripts.
*
* By default [.NewLauncher] creates a subclass of [Launcher] of
* type [DefaultLauncher] which creates debug globals, runs the script,
* and prints the return values. This behavior can be changed by supplying a
* different implementation class to [.NewLauncher] which must
* extend [Launcher].
*
* @see Launcher
*
* @see .NewLauncher
* @see .NewLauncher
* @see DefaultLauncher
*
* @since luaj 3.0.1
*/
class LuajClassLoader : ClassLoader() {
/** Local cache of classes loaded by this loader. */
internal var classes: MutableMap> = HashMap()
override fun loadClass(classname: String): Class<*> {
if (classes.containsKey(classname))
return classes[classname]!!
return if (!isUserClass(classname)) super.findSystemClass(classname) else loadAsUserClass(classname)
}
private fun loadAsUserClass(classname: String): Class<*> {
val path = classname.replace('.', '/') + ".class"
val `is` = getResourceAsStream(path)
if (`is` != null) {
try {
val baos = ByteArrayOutputStream()
val b = ByteArray(1024)
var n = 0
while (run { n = `is`.read(b); n } >= 0) baos.write(b, 0, n)
val bytes = baos.toByteArray()
val result = super.defineClass(classname, bytes, 0, bytes.size)
classes[classname] = result
return result
} catch (e: IOException) {
throw ClassNotFoundException("Read failed: $classname: $e")
}
}
throw ClassNotFoundException("Not found: $classname")
}
companion object {
/** String describing the luaj packages to consider part of the user classes */
internal val luajPackageRoot = "org.luaj.vm2."
/** String describing the Launcher interface to be considered a system class */
internal val launcherInterfaceRoot = Launcher::class.java.name
/**
* Construct a [Launcher] instance that will load classes in
* its own [LuajClassLoader] using a user-supplied implementation class
* that implements [Launcher].
*
* The [Launcher] that is returned will be a pristine luaj vm
* whose classes are loaded into this loader including static variables
* such as shared metatables, and should not be able to directly access
* variables from other Launcher instances.
*
* @return instance of type 'launcher_class' that can be used to launch scripts.
* @com.soywiz.luak.compat.java.Throws InstantiationException
* @com.soywiz.luak.compat.java.Throws IllegalAccessException
* @com.soywiz.luak.compat.java.Throws ClassNotFoundException
*/
@JvmOverloads
fun NewLauncher(launcher_class: Class = DefaultLauncher::class.java): Launcher =
LuajClassLoader().loadAsUserClass(launcher_class.name).newInstance() as Launcher
/**
* Test if a class name should be considered a user class and loaded
* by this loader, or a system class and loaded by the system loader.
* @param classname Class name to test.
* @return true if this should be loaded into this class loader.
*/
fun isUserClass(classname: String): Boolean =
classname.startsWith(luajPackageRoot) && !classname.startsWith(launcherInterfaceRoot)
}
}
/**
* Construct a default [Launcher] instance that will load classes in
* its own [LuajClassLoader] using the default implementation class
* [DefaultLauncher].
*
* The [Launcher] that is returned will be a pristine luaj vm
* whose classes are loaded into this loader including static variables
* such as shared metatables, and should not be able to directly access
* variables from other Launcher instances.
*
* @return [Launcher] instance that can be used to launch scripts.
* @com.soywiz.luak.compat.java.Throws InstantiationException
* @com.soywiz.luak.compat.java.Throws IllegalAccessException
* @com.soywiz.luak.compat.java.Throws ClassNotFoundException
*/