/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dalvik.system;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.security.ProtectionDomain;
import java.util.Enumeration;
/**
* Manipulates DEX files. The class is similar in principle to
* {@link java.util.zip.ZipFile}. It is used primarily by class loaders.
* <p>
* Note we don't directly open and read the DEX file here. They're memory-mapped
* read-only by the VM.
*
* @since Android 1.0
*/
public final class DexFile {
private final int mCookie;
private String mFileName;
/**
* Opens a DEX file from a given File object. This will usually be a ZIP/JAR
* file with a "classes.dex" inside. The method should not be used for files
* inside the Dalvik cache.
*
* @cts What will happen if we refer to the Dalvik cache? Should be either
* specified or throw an exception...
*
* @param file
* the File object referencing the actual DEX file
*
* @throws IOException
* if an I/O error occurs, such as the file not being found or
* access rights missing for opening it
*/
public DexFile(File file) throws IOException {
this(file.getPath());
}
/**
* Opens a DEX file from a given filename. This will usually be a ZIP/JAR
* file with a "classes.dex" inside. The method should not be used for files
* inside the Dalvik cache.
*
* @cts What will happen if we refer to the Dalvik cache? Should be either
* specified or throw an exception...
*
* @param fileName
* the filename of the DEX file
*
* @throws IOException
* if an I/O error occurs, such as the file not being found or
* access rights missing for opening it
*/
public DexFile(String fileName) throws IOException {
String wantDex = System.getProperty("android.vm.dexfile", "false");
if (!wantDex.equals("true"))
throw new UnsupportedOperationException("No dex in this VM");
mCookie = openDexFile(fileName, null, 0);
mFileName = fileName;
//System.out.println("DEX FILE cookie is " + mCookie);
}
/**
* Opens a DEX file from a given filename, using a specified file
* to hold the optimized data.
*
* @param sourceName
* Jar or APK file with "classes.dex".
* @param outputName
* File that will hold the optimized form of the DEX data.
* @param flags
* Enable optional features.
*/
private DexFile(String sourceName, String outputName, int flags)
throws IOException {
String wantDex = System.getProperty("android.vm.dexfile", "false");
if (!wantDex.equals("true"))
throw new UnsupportedOperationException("No dex in this VM");
mCookie = openDexFile(sourceName, outputName, flags);
mFileName = sourceName;
//System.out.println("DEX FILE cookie is " + mCookie);
}
/**
* Open a DEX file, specifying the file in which the optimized DEX
* data should be written. If the optimized form exists and appears
* to be current, it will be used; if not, the VM will attempt to
* regenerate it.
*
* This is intended for use by applications that wish to download
* and execute DEX files outside the usual application installation
* mechanism. This function should not be called directly by an
* application; instead, use a class loader such as
* dalvik.system.DexClassLoader.
*
* @param sourcePathName
* Jar or APK file with "classes.dex". (May expand this to include
* "raw DEX" in the future.)
* @param outputPathName
* File that will hold the optimized form of the DEX data.
* @param flags
* Enable optional features. (Currently none defined.)
* @return
* A new or previously-opened DexFile.
* @throws IOException
* If unable to open the source or output file.
*/
static public DexFile loadDex(String sourcePathName, String outputPathName,
int flags) throws IOException {
/*
* TODO: we may want to cache previously-opened DexFile objects.
* The cache would be synchronized with close(). This would help
* us avoid mapping the same DEX more than once when an app
* decided to open it multiple times. In practice this may not
* be a real issue.
*/
return new DexFile(sourcePathName, outputPathName, flags);
}
/**
* Gets the name of the (already opened) DEX file.
*
* @return the file name
*/
public String getName() {
return mFileName;
}
/**
* Closes the DEX file.
* <p>
* This may not be able to release any resources. If classes have been
* loaded, the underlying storage can't be discarded.
*
* @throws IOException
* if an I/O error occurs during closing the file, which
* normally should not happen
*
* @cts Second sentence is a bit cryptic.
*/
public void close() throws IOException {
closeDexFile(mCookie);
}
/**
* Loads a class. Returns the class on success, or a {@code null} reference
* on failure.
* <p>
* If you are not calling this from a class loader, this is most likely not
* going to do what you want. Use {@link Class#forName(String)} instead.
* <p>
* The method does not throw {@link ClassNotFoundException} if the class
* isn't found because it isn't feasible to throw exceptions wildly every
* time a class is not found in the first DEX file we look at. It will
* throw exceptions for other failures, though.
*
* @param name
* the class name, which should look like "java/lang/String"
*
* @param loader
* the class loader that tries to load the class (in most cases
* the caller of the method
*
* @return the {@link Class} object representing the class, or {@code null}
* if the class cannot be loaded
*
* @cts Exception comment is a bit cryptic. What exception will be thrown?
*/
public Class loadClass(String name, ClassLoader loader) {
return defineClass(name, loader, mCookie,
null);
//new ProtectionDomain(name) /*DEBUG ONLY*/);
}
native private static Class defineClass(String name, ClassLoader loader,
int cookie, ProtectionDomain pd);
/**
* Enumerate the names of the classes in this DEX file.
*
* @return an enumeration of names of classes contained in the DEX file, in
* the usual internal form (like "java/lang/String").
*/
public Enumeration<String> entries() {
return new DFEnum(this);
}
/*
* Helper class.
*/
private class DFEnum implements Enumeration<String> {
private int mIndex;
private String[] mNameList;
DFEnum(DexFile df) {
mIndex = 0;
mNameList = getClassNameList(mCookie);
}
public boolean hasMoreElements() {
return (mIndex < mNameList.length);
}
public String nextElement() {
return mNameList[mIndex++];
}
}
/* return a String array with class names */
native private static String[] getClassNameList(int cookie);
/**
* Called when the class is finalized. Makes sure the DEX file is closed.
*
* @throws IOException
* if an I/O error occurs during closing the file, which
* normally should not happen
*/
protected void finalize() throws IOException {
close();
}
/*
* Open a DEX file. The value returned is a magic VM cookie. On
* failure, an IOException is thrown.
*/
native private static int openDexFile(String sourceName, String outputName,
int flags) throws IOException;
/*
* Close DEX file.
*/
native private static void closeDexFile(int cookie);
/**
* Returns true if the VM believes that the apk/jar file is out of date
* and should be passed through "dexopt" again.
*
* @param fileName the absolute path to the apk/jar file to examine.
* @return true if dexopt should be called on the file, false otherwise.
* @throws java.io.FileNotFoundException if fileName is not readable,
* not a file, or not present.
* @throws java.io.IOException if fileName is not a valid apk/jar file or
* if problems occur while parsing it.
* @throws java.lang.NullPointerException if fileName is null.
* @throws dalvik.system.StaleDexCacheError if the optimized dex file
* is stale but exists on a read-only partition.
*/
native public static boolean isDexOptNeeded(String fileName)
throws FileNotFoundException, IOException;
}
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