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Rework service lookup to allow absolute paths. Fixes #2336.
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@headius
headius committed Dec 19, 2014
1 parent 91444d1 commit a0624ee
Showing 1 changed file with 112 additions and 28 deletions.
140 changes: 112 additions & 28 deletions core/src/main/java/org/jruby/runtime/load/ClassExtensionLibrary.java
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Expand Up @@ -27,8 +27,11 @@
***** END LICENSE BLOCK *****/
package org.jruby.runtime.load;

import jnr.posix.JavaSecuredFile;
import org.jruby.Ruby;

import java.net.URL;

/**
* The ClassExtensionLibrary wraps a class which implements BasicLibraryService,
* and when asked to load the service, does a basicLoad of the BasicLibraryService.
Expand All @@ -41,40 +44,121 @@ public class ClassExtensionLibrary implements Library {
private final Class theClass;
private final String name;

/**
* Try to locate an extension service in the current classloader resources. This happens
* after the jar has been added to JRuby's URLClassLoader (JRubyClassLoader) and is how
* extensions can magically load.
*
* The basic logic is to use the require name (@param searchName) to build the name of
* a class ending in "Service", and then invoke that class to boot the extension.
*
* The looping logic here was in response to a RubyGems change that started absolutizing
* the path to the extension jar under some circumstances, leading to an incorrect
* package/class name for the service contained therein. The new logic will try
* successively more trailing elements until one of them is not a valid package
* name or all elements have been exhausted.
*
* @param runtime the current JRuby runtime
* @param searchName the name passed to `require`
* @return a ClassExtensionLibrary that will boot the ext, or null if none was found
*/
static ClassExtensionLibrary tryFind(Ruby runtime, String searchName) {
// Create package name, by splitting on / and joining all but the last elements with a ".", and downcasing them.
String[] all = searchName.split("/");

StringBuilder finName = new StringBuilder();
for(int i=0, j=(all.length-1); i<j; i++) {
finName.append(all[i].toLowerCase()).append(".");
}

try {
// Make the class name look nice, by splitting on _ and capitalize each segment, then joining
// the, together without anything separating them, and last put on "Service" at the end.
String[] last = all[all.length-1].split("_");
for(int i=0, j=last.length; i<j; i++) {
if ("".equals(last[i])) break;
finName.append(Character.toUpperCase(last[i].charAt(0))).append(last[i].substring(1));
// Create package name, by splitting on / and successively accumulating elements to form a class name
String[] elts = searchName.split("/");

boolean isAbsolute = new JavaSecuredFile(searchName).isAbsolute();

String simpleName = buildSimpleName(elts[elts.length - 1]);

int firstElement = isAbsolute ? elts.length - 1 : 0;
for (; firstElement >= 0; firstElement--) {
String className = buildClassName(elts, firstElement, elts.length - 1, simpleName);
ClassExtensionLibrary library = tryServiceLoad(runtime, className);

if (library != null) return library;
}

return null;
}

/**
* Build the "simple" part of a service class name from the given require path element
* by splitting on "_" and concatenating as CamelCase, plus "Service" suffix.
*
* @param element the element from which to build a simple service class name
* @return the resulting simple service class name
*/
private static String buildSimpleName(String element) {
StringBuilder nameBuilder = new StringBuilder(element.length() + "Service".length());

String[] last = element.split("_");
for (String part : last) {
if (part.isEmpty()) break;

nameBuilder
.append(Character.toUpperCase(part.charAt(0)))
.append(part, 1, part.length());
}
nameBuilder.append("Service");

return nameBuilder.toString();
}

/**
* Build the full class name for a service by joining the specified package elements
* with '.' and appending the given simple class name.
*
* @param elts the array from which to retrieve the package elements
* @param firstElement the first element to use
* @param end the end index at which to stop building the package name
* @param simpleName the simple class name for the service
* @return the full class name for the service
*/
private static String buildClassName(String[] elts, int firstElement, int end, String simpleName) {
StringBuilder nameBuilder = new StringBuilder();
for (int offset = firstElement; offset < end; offset++) {
// avoid blank elements from leading or double slashes
if (elts[offset].isEmpty()) continue;

nameBuilder
.append(elts[offset].toLowerCase())
.append('.');
}
finName.append("Service");

// We don't want a package name beginning with dots, so we remove them
String className = finName.toString().replaceAll("^\\.*","");
nameBuilder.append(simpleName);

// quietly try to load the class
Class theClass = runtime.getJavaSupport().loadJavaClass(className);
return new ClassExtensionLibrary(className + ".java", theClass);
} catch (ClassNotFoundException cnfe) {
if (runtime.isDebug()) cnfe.printStackTrace();
return nameBuilder.toString();
}

/**
* Try loading the given service class. Rather than raise ClassNotFoundException for
* jars that do not contain any service class, we require that the service class be a
* "normal" .class file accessible as a classloader resource. If it can be found
* using ClassLoader.getResource, we proceed to attempt to load it as a class.
*
* @param runtime the Ruby runtime into which the extension service will load
* @param className the class name of the service class
* @return a ClassExtensionLibrary if the service class was found; null otherwise.
*/
private static ClassExtensionLibrary tryServiceLoad(Ruby runtime, String className) {
String classFile = className.replaceAll("\\.", "/") + ".class";

try {
// quietly try to load the class, which must be reachable as a .class resource
URL resource = runtime.getJRubyClassLoader().getResource(classFile);
if (resource != null) {
Class theClass = runtime.getJavaSupport().loadJavaClass(className);
return new ClassExtensionLibrary(className + ".java", theClass);
}
} catch (ClassNotFoundException cnfe) {
if (runtime.isDebug()) cnfe.printStackTrace();
} catch (UnsupportedClassVersionError ucve) {
if (runtime.isDebug()) ucve.printStackTrace();
throw runtime.newLoadError("JRuby ext built for wrong Java version in `" + className + "': " + ucve, className);
}

// So apparently the class doesn't exist
// The class doesn't exist
return null;
} catch (UnsupportedClassVersionError ucve) {
if (runtime.isDebug()) ucve.printStackTrace();
throw runtime.newLoadError("JRuby ext built for wrong Java version in `" + finName + "': " + ucve, finName.toString());
}
}

public ClassExtensionLibrary(String name, Class extension) {
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