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/*
* #%L
* Native library loader for extracting and loading native libraries from Java.
* %%
* Copyright (C) 2010 - 2015 Board of Regents of the University of
* Wisconsin-Madison and Glencoe Software, Inc.
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* #L%
*/
// This code is derived from Richard van der Hoff's mx-native-loader project:
// http://opensource.mxtelecom.com/maven/repo/com/wapmx/native/mx-native-loader/1.7/
// See NOTICE.txt for details.
// Copyright 2006 MX Telecom Ltd
package org.scijava.nativelib;
import java.io.IOException;
/**
* Provides a means of loading JNI libraries which are stored within a jar.
*
* The library is first extracted to a temporary file, and then loaded with
* System.load().
*
* The extractor implementation can be replaced, but the default implementation
* expects to find the library in META-INF/lib/, with its OS-dependent name. It
* extracts the library underneath a temporary directory, whose name is given by
* the System property "java.library.tmpdir", defaulting to "tmplib".
*
* This is complicated by Java's library and version management - specifically
* "The same JNI native library cannot be loaded into more than one class loader"
* . In practice this appears to mean
* "A JNI library on a given absolute path cannot be loaded by more than one classloader"
* . Native libraries that are loaded by the OS dynamic linker as dependencies
* of JNI libraries are not subject to this restriction.
*
* Native libraries that are loaded as dependencies must be extracted using the
* library identifier a.k.a. soname (which usually includes a major version
* number) instead of what was linked against (this can be found using ldd on
* linux or using otool on OS X). Because they are loaded by the OS dynamic
* linker and not by explicit invocation within Java, this extractor needs to be
* aware of them to extract them by alternate means. This is accomplished by
* listing the base filename in a META-INF/lib/AUTOEXTRACT.LIST classpath
* resource. This is useful for shipping libraries which are used by code which
* is not itself aware of the NativeLoader system. The application must call
* {@link #extractRegistered()} at some suitably early point in its
* initialization (before loading any JNI libraries which might require these
* dependencies), and ensure that JVM is launched with the LD_LIBRARY_PATH
* environment variable (or other OS-dependent equivalent) set to include the
* "tmplib" directory (or other directory as overridden by "java.library.tmpdir"
* as above).
*
* @author Richard van der Hoff ([email protected])
*/
public class NativeLoader {
private static JniExtractor jniExtractor = null;
static {
try {
/*
* We provide two implementations of JniExtractor
*
* The first will work with transitively, dynamically linked libraries with shared global variables
* (e.g. dynamically linked c++) but can only be used by one ClassLoader in the JVM.
*
* The second can be used by multiple ClassLoaders in the JVM but will only work if global variables
* are not shared between transitively, dynamically linked libraries.
*
* For convenience we assume that if the NativeLoader is loaded by the system ClassLoader then it should be
* use the first form, and that if it is loaded by a different ClassLoader then it should use the second.
*/
if (NativeLoader.class.getClassLoader() == ClassLoader
.getSystemClassLoader())
{
jniExtractor = new DefaultJniExtractor();
}
else {
jniExtractor = new WebappJniExtractor("Classloader");
}
}
catch (final IOException e) {
throw new ExceptionInInitializerError(e);
}
}
/**
* Extract the given library from a jar, and load it.
*
* The default jni extractor expects libraries to be in META-INF/lib/, with
* their platform-dependent name.
*
* @param libname platform-independent library name (as would be passed to
* System.loadLibrary)
* @throws IOException if there is a problem extracting the jni library
* @throws SecurityException if a security manager exists and its
* checkLink method doesn't allow loading of the
* specified dynamic library
*/
public static void loadLibrary(final String libname) throws IOException {
// TODO pass in library path or get rid of this method
System.load(jniExtractor.extractJni("", libname).getAbsolutePath());
}
/**
* Extract all libraries registered for auto-extraction by way of
* META-INF/lib/AUTOEXTRACT.LIST resources. The application must call
* {@link #extractRegistered()} at some suitably early point in its
* initialization if it is using libraries packaged in this way.
*
* @throws IOException if there is a problem extracting the libraries
*/
public static void extractRegistered() throws IOException {
jniExtractor.extractRegistered();
}
/**
* @return the JniExtractor implementation object.
*/
public static JniExtractor getJniExtractor() {
return jniExtractor;
}
/**
* @param jniExtractor JniExtractor implementation to use instead of the
* default.
*/
public static void setJniExtractor(final JniExtractor jniExtractor) {
NativeLoader.jniExtractor = jniExtractor;
}
}