Update //base to chromium 9659b08ea5a34f889dc4166217f438095ddc10d2

base/android/java/src/org/chromium/base/library_loader/LegacyLinker.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.base.library_loader;
+
+import android.os.Bundle;
+import android.os.Parcel;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.Log;
+import org.chromium.base.SysUtils;
+import org.chromium.base.ThreadUtils;
+
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+
+import javax.annotation.Nullable;
+
+/*
+ * For more, see Technical note, Security considerations, and the explanation
+ * of how this class is supposed to be used in Linker.java.
+ */
+
+/**
+ * Provides a concrete implementation of the Chromium Linker.
+ *
+ * This Linker implementation uses the crazy linker to map and then run Chrome
+ * for Android.
+ *
+ * For more on the operations performed by the Linker, see {@link Linker}.
+ */
+class LegacyLinker extends Linker {
+    // Log tag for this class.
+    private static final String TAG = "cr.library_loader";
+
+    // Name of the library that contains our JNI code.
+    private static final String LINKER_JNI_LIBRARY = "chromium_android_linker";
+
+    // Becomes true after linker initialization.
+    private boolean mInitialized = false;
+
+    // Set to true to indicate that the system supports safe sharing of RELRO sections.
+    private boolean mRelroSharingSupported = false;
+
+    // Set to true if this runs in the browser process. Disabled by initServiceProcess().
+    // TODO(petrcermak): This flag can be incorrectly set to false (even though this might run in
+    // the browser process) on low-memory devices.
+    private boolean mInBrowserProcess = true;
+
+    // Becomes true to indicate this process needs to wait for a shared RELRO in
+    // finishLibraryLoad().
+    private boolean mWaitForSharedRelros = false;
+
+    // Becomes true when initialization determines that the browser process can use the
+    // shared RELRO.
+    private boolean mBrowserUsesSharedRelro = false;
+
+    // The map of all RELRO sections either created or used in this process.
+    private Bundle mSharedRelros = null;
+
+    // Current common random base load address.
+    private long mBaseLoadAddress = 0;
+
+    // Current fixed-location load address for the next library called by loadLibrary().
+    private long mCurrentLoadAddress = 0;
+
+    // Becomes true once prepareLibraryLoad() has been called.
+    private boolean mPrepareLibraryLoadCalled = false;
+
+    // The map of libraries that are currently loaded in this process.
+    protected HashMap<String, LibInfo> mLoadedLibraries = null;
+
+    // Used internally to initialize the linker's static data. Assume lock is held.
+    private void ensureInitializedLocked() {
+        assert Thread.holdsLock(mLock);
+
+        if (mInitialized) {
+            return;
+        }
+
+        mRelroSharingSupported = false;
+        if (NativeLibraries.sUseLinker) {
+            if (DEBUG) {
+                Log.i(TAG, "Loading lib" + LINKER_JNI_LIBRARY + ".so");
+            }
+            try {
+                System.loadLibrary(LINKER_JNI_LIBRARY);
+            } catch (UnsatisfiedLinkError e) {
+                // In a component build, the ".cr" suffix is added to each library name.
+                Log.w(TAG, "Couldn't load lib" + LINKER_JNI_LIBRARY + ".so, "
+                                + "trying lib" + LINKER_JNI_LIBRARY + ".cr.so");
+                System.loadLibrary(LINKER_JNI_LIBRARY + ".cr");
+            }
+            mRelroSharingSupported = nativeCanUseSharedRelro();
+            if (!mRelroSharingSupported) {
+                Log.w(TAG, "This system cannot safely share RELRO sections");
+            } else {
+                if (DEBUG) {
+                    Log.i(TAG, "This system supports safe shared RELRO sections");
+                }
+            }
+
+            if (mMemoryDeviceConfig == MEMORY_DEVICE_CONFIG_INIT) {
+                if (SysUtils.isLowEndDevice()) {
+                    mMemoryDeviceConfig = MEMORY_DEVICE_CONFIG_LOW;
+                } else {
+                    mMemoryDeviceConfig = MEMORY_DEVICE_CONFIG_NORMAL;
+                }
+            }
+
+            switch (BROWSER_SHARED_RELRO_CONFIG) {
+                case BROWSER_SHARED_RELRO_CONFIG_NEVER:
+                    mBrowserUsesSharedRelro = false;
+                    break;
+                case BROWSER_SHARED_RELRO_CONFIG_LOW_RAM_ONLY:
+                    if (mMemoryDeviceConfig == MEMORY_DEVICE_CONFIG_LOW) {
+                        mBrowserUsesSharedRelro = true;
+                        Log.w(TAG, "Low-memory device: shared RELROs used in all processes");
+                    } else {
+                        mBrowserUsesSharedRelro = false;
+                    }
+                    break;
+                case BROWSER_SHARED_RELRO_CONFIG_ALWAYS:
+                    Log.w(TAG, "Beware: shared RELROs used in all processes!");
+                    mBrowserUsesSharedRelro = true;
+                    break;
+                default:
+                    assert false : "Unreached";
+                    break;
+            }
+        } else {
+            if (DEBUG) {
+                Log.i(TAG, "Linker disabled");
+            }
+        }
+
+        if (!mRelroSharingSupported) {
+            // Sanity.
+            mBrowserUsesSharedRelro = false;
+            mWaitForSharedRelros = false;
+        }
+
+        mInitialized = true;
+    }
+
+    /**
+     * Call this method to determine if this chromium project must
+     * use this linker. If not, System.loadLibrary() should be used to load
+     * libraries instead.
+     */
+    @Override
+    public boolean isUsed() {
+        // Only GYP targets that are APKs and have the 'use_chromium_linker' variable
+        // defined as 1 will use this linker. For all others (the default), the
+        // auto-generated NativeLibraries.sUseLinker variable will be false.
+        if (!NativeLibraries.sUseLinker) return false;
+
+        synchronized (mLock) {
+            ensureInitializedLocked();
+            // At the moment, there is also no point in using this linker if the
+            // system does not support RELRO sharing safely.
+            return mRelroSharingSupported;
+        }
+    }
+
+    /**
+     * Call this method to determine if the linker will try to use shared RELROs
+     * for the browser process.
+     */
+    @Override
+    public boolean isUsingBrowserSharedRelros() {
+        synchronized (mLock) {
+            ensureInitializedLocked();
+            return mBrowserUsesSharedRelro;
+        }
+    }
+
+    /**
+     * Call this method to determine if the chromium project must load
+     * the library directly from the zip file.
+     */
+    @Override
+    public boolean isInZipFile() {
+        return NativeLibraries.sUseLibraryInZipFile;
+    }
+
+    /**
+     * Call this method just before loading any native shared libraries in this process.
+     */
+    @Override
+    public void prepareLibraryLoad() {
+        if (DEBUG) {
+            Log.i(TAG, "prepareLibraryLoad() called");
+        }
+        synchronized (mLock) {
+            mPrepareLibraryLoadCalled = true;
+
+            if (mInBrowserProcess) {
+                // Force generation of random base load address, as well
+                // as creation of shared RELRO sections in this process.
+                setupBaseLoadAddressLocked();
+            }
+        }
+    }
+
+    /**
+     * Call this method just after loading all native shared libraries in this process.
+     * Note that when in a service process, this will block until the RELRO bundle is
+     * received, i.e. when another thread calls useSharedRelros().
+     */
+    @Override
+    public void finishLibraryLoad() {
+        if (DEBUG) {
+            Log.i(TAG, "finishLibraryLoad() called");
+        }
+        synchronized (mLock) {
+            if (DEBUG) {
+                Log.i(TAG,
+                        String.format(Locale.US,
+                                "mInBrowserProcess=%s mBrowserUsesSharedRelro=%s mWaitForSharedRelros=%s",
+                                mInBrowserProcess ? "true" : "false",
+                                mBrowserUsesSharedRelro ? "true" : "false",
+                                mWaitForSharedRelros ? "true" : "false"));
+            }
+
+            if (mLoadedLibraries == null) {
+                if (DEBUG) {
+                    Log.i(TAG, "No libraries loaded");
+                }
+            } else {
+                if (mInBrowserProcess) {
+                    // Create new Bundle containing RELRO section information
+                    // for all loaded libraries. Make it available to getSharedRelros().
+                    mSharedRelros = createBundleFromLibInfoMap(mLoadedLibraries);
+                    if (DEBUG) {
+                        Log.i(TAG, "Shared RELRO created");
+                        dumpBundle(mSharedRelros);
+                    }
+
+                    if (mBrowserUsesSharedRelro) {
+                        useSharedRelrosLocked(mSharedRelros);
+                    }
+                }
+
+                if (mWaitForSharedRelros) {
+                    assert !mInBrowserProcess;
+
+                    // Wait until the shared relro bundle is received from useSharedRelros().
+                    while (mSharedRelros == null) {
+                        try {
+                            mLock.wait();
+                        } catch (InterruptedException ie) {
+                            // no-op
+                        }
+                    }
+                    useSharedRelrosLocked(mSharedRelros);
+                    // Clear the Bundle to ensure its file descriptor references can't be reused.
+                    mSharedRelros.clear();
+                    mSharedRelros = null;
+                }
+            }
+
+            if (NativeLibraries.sEnableLinkerTests && mTestRunnerClassName != null) {
+                // The TestRunner implementation must be instantiated _after_
+                // all libraries are loaded to ensure that its native methods
+                // are properly registered.
+                if (DEBUG) {
+                    Log.i(TAG, "Instantiating " + mTestRunnerClassName);
+                }
+                TestRunner testRunner = null;
+                try {
+                    testRunner = (TestRunner) Class.forName(mTestRunnerClassName).newInstance();
+                } catch (Exception e) {
+                    Log.e(TAG, "Could not extract test runner class name", e);
+                    testRunner = null;
+                }
+                if (testRunner != null) {
+                    if (!testRunner.runChecks(mMemoryDeviceConfig, mInBrowserProcess)) {
+                        Log.wtf(TAG, "Linker runtime tests failed in this process!!");
+                        assert false;
+                    } else {
+                        Log.i(TAG, "All linker tests passed!");
+                    }
+                }
+            }
+        }
+        if (DEBUG) {
+            Log.i(TAG, "finishLibraryLoad() exiting");
+        }
+    }
+
+    /**
+     * Call this to send a Bundle containing the shared RELRO sections to be
+     * used in this process. If initServiceProcess() was previously called,
+     * finishLibraryLoad() will not exit until this method is called in another
+     * thread with a non-null value.
+     * @param bundle The Bundle instance containing a map of shared RELRO sections
+     * to use in this process.
+     */
+    @Override
+    public void useSharedRelros(Bundle bundle) {
+        // Ensure the bundle uses the application's class loader, not the framework
+        // one which doesn't know anything about LibInfo.
+        // Also, hold a fresh copy of it so the caller can't recycle it.
+        Bundle clonedBundle = null;
+        if (bundle != null) {
+            bundle.setClassLoader(LibInfo.class.getClassLoader());
+            clonedBundle = new Bundle(LibInfo.class.getClassLoader());
+            Parcel parcel = Parcel.obtain();
+            bundle.writeToParcel(parcel, 0);
+            parcel.setDataPosition(0);
+            clonedBundle.readFromParcel(parcel);
+            parcel.recycle();
+        }
+        if (DEBUG) {
+            Log.i(TAG, "useSharedRelros() called with " + bundle + ", cloned " + clonedBundle);
+        }
+        synchronized (mLock) {
+            // Note that in certain cases, this can be called before
+            // initServiceProcess() in service processes.
+            mSharedRelros = clonedBundle;
+            // Tell any listener blocked in finishLibraryLoad() about it.
+            mLock.notifyAll();
+        }
+    }
+
+    /**
+     * Call this to retrieve the shared RELRO sections created in this process,
+     * after loading all libraries.
+     * @return a new Bundle instance, or null if RELRO sharing is disabled on
+     * this system, or if initServiceProcess() was called previously.
+     */
+    @Override
+    public Bundle getSharedRelros() {
+        if (DEBUG) {
+            Log.i(TAG, "getSharedRelros() called");
+        }
+        synchronized (mLock) {
+            if (!mInBrowserProcess) {
+                if (DEBUG) {
+                    Log.i(TAG, "... returning null Bundle");
+                }
+                return null;
+            }
+
+            // Return the Bundle created in finishLibraryLoad().
+            if (DEBUG) {
+                Log.i(TAG, "... returning " + mSharedRelros);
+            }
+            return mSharedRelros;
+        }
+    }
+
+    /**
+     * Call this method before loading any libraries to indicate that this
+     * process shall neither create or reuse shared RELRO sections.
+     */
+    @Override
+    public void disableSharedRelros() {
+        if (DEBUG) {
+            Log.i(TAG, "disableSharedRelros() called");
+        }
+        synchronized (mLock) {
+            mInBrowserProcess = false;
+            mWaitForSharedRelros = false;
+            mBrowserUsesSharedRelro = false;
+        }
+    }
+
+    /**
+     * Call this method before loading any libraries to indicate that this
+     * process is ready to reuse shared RELRO sections from another one.
+     * Typically used when starting service processes.
+     * @param baseLoadAddress the base library load address to use.
+     */
+    @Override
+    public void initServiceProcess(long baseLoadAddress) {
+        if (DEBUG) {
+            Log.i(TAG,
+                    String.format(Locale.US, "initServiceProcess(0x%x) called", baseLoadAddress));
+        }
+        synchronized (mLock) {
+            ensureInitializedLocked();
+            mInBrowserProcess = false;
+            mBrowserUsesSharedRelro = false;
+            if (mRelroSharingSupported) {
+                mWaitForSharedRelros = true;
+                mBaseLoadAddress = baseLoadAddress;
+                mCurrentLoadAddress = baseLoadAddress;
+            }
+        }
+    }
+
+    /**
+     * Retrieve the base load address of all shared RELRO sections.
+     * This also enforces the creation of shared RELRO sections in
+     * prepareLibraryLoad(), which can later be retrieved with getSharedRelros().
+     * @return a common, random base load address, or 0 if RELRO sharing is
+     * disabled.
+     */
+    @Override
+    public long getBaseLoadAddress() {
+        synchronized (mLock) {
+            ensureInitializedLocked();
+            if (!mInBrowserProcess) {
+                Log.w(TAG, "Shared RELRO sections are disabled in this process!");
+                return 0;
+            }
+
+            setupBaseLoadAddressLocked();
+            if (DEBUG) {
+                Log.i(TAG, String.format(Locale.US, "getBaseLoadAddress() returns 0x%x",
+                                   mBaseLoadAddress));
+            }
+            return mBaseLoadAddress;
+        }
+    }
+
+    // Used internally to lazily setup the common random base load address.
+    private void setupBaseLoadAddressLocked() {
+        assert Thread.holdsLock(mLock);
+        if (mBaseLoadAddress == 0) {
+            long address = computeRandomBaseLoadAddress();
+            mBaseLoadAddress = address;
+            mCurrentLoadAddress = address;
+            if (address == 0) {
+                // If the computed address is 0, there are issues with finding enough
+                // free address space, so disable RELRO shared / fixed load addresses.
+                Log.w(TAG, "Disabling shared RELROs due address space pressure");
+                mBrowserUsesSharedRelro = false;
+                mWaitForSharedRelros = false;
+            }
+        }
+    }
+
+    /**
+     * Compute a random base load address at which to place loaded libraries.
+     * @return new base load address, or 0 if the system does not support
+     * RELRO sharing.
+     */
+    private long computeRandomBaseLoadAddress() {
+        // nativeGetRandomBaseLoadAddress() returns an address at which it has previously
+        // successfully mapped an area of the given size, on the basis that we will be
+        // able, with high probability, to map our library into it.
+        //
+        // One issue with this is that we do not yet know the size of the library that
+        // we will load is. So here we pass a value that we expect will always be larger
+        // than that needed. If it is smaller the library mapping may still succeed. The
+        // other issue is that although highly unlikely, there is no guarantee that
+        // something else does not map into the area we are going to use between here and
+        // when we try to map into it.
+        //
+        // The above notes mean that all of this is probablistic. It is however okay to do
+        // because if, worst case and unlikely, we get unlucky in our choice of address,
+        // the back-out and retry without the shared RELRO in the ChildProcessService will
+        // keep things running.
+        final long maxExpectedBytes = 192 * 1024 * 1024;
+        final long address = nativeGetRandomBaseLoadAddress(maxExpectedBytes);
+        if (DEBUG) {
+            Log.i(TAG, String.format(Locale.US, "Random native base load address: 0x%x", address));
+        }
+        return address;
+    }
+
+    // Used for debugging only.
+    private void dumpBundle(Bundle bundle) {
+        if (DEBUG) {
+            Log.i(TAG, "Bundle has " + bundle.size() + " items: " + bundle);
+        }
+    }
+
+    /**
+     * Use the shared RELRO section from a Bundle received form another process.
+     * Call this after calling setBaseLoadAddress() then loading all libraries
+     * with loadLibrary().
+     * @param bundle Bundle instance generated with createSharedRelroBundle() in
+     * another process.
+     */
+    private void useSharedRelrosLocked(Bundle bundle) {
+        assert Thread.holdsLock(mLock);
+
+        if (DEBUG) {
+            Log.i(TAG, "Linker.useSharedRelrosLocked() called");
+        }
+
+        if (bundle == null) {
+            if (DEBUG) {
+                Log.i(TAG, "null bundle!");
+            }
+            return;
+        }
+
+        if (!mRelroSharingSupported) {
+            if (DEBUG) {
+                Log.i(TAG, "System does not support RELRO sharing");
+            }
+            return;
+        }
+
+        if (mLoadedLibraries == null) {
+            if (DEBUG) {
+                Log.i(TAG, "No libraries loaded!");
+            }
+            return;
+        }
+
+        if (DEBUG) {
+            dumpBundle(bundle);
+        }
+        HashMap<String, LibInfo> relroMap = createLibInfoMapFromBundle(bundle);
+
+        // Apply the RELRO section to all libraries that were already loaded.
+        for (Map.Entry<String, LibInfo> entry : relroMap.entrySet()) {
+            String libName = entry.getKey();
+            LibInfo libInfo = entry.getValue();
+            if (!nativeUseSharedRelro(libName, libInfo)) {
+                Log.w(TAG, "Could not use shared RELRO section for " + libName);
+            } else {
+                if (DEBUG) {
+                    Log.i(TAG, "Using shared RELRO section for " + libName);
+                }
+            }
+        }
+
+        // In service processes, close all file descriptors from the map now.
+        if (!mInBrowserProcess) closeLibInfoMap(relroMap);
+
+        if (DEBUG) {
+            Log.i(TAG, "Linker.useSharedRelrosLocked() exiting");
+        }
+    }
+
+    /**
+     * Load a native shared library with the Chromium linker. If the zip file
+     * is not null, the shared library must be uncompressed and page aligned
+     * inside the zipfile. Note the crazy linker treats libraries and files as
+     * equivalent, so you can only open one library in a given zip file. The
+     * library must not be the Chromium linker library.
+     *
+     * @param zipFilePath The path of the zip file containing the library (or null).
+     * @param libFilePath The path of the library (possibly in the zip file).
+     */
+    @Override
+    public void loadLibrary(@Nullable String zipFilePath, String libFilePath) {
+        if (DEBUG) {
+            Log.i(TAG, "loadLibrary: " + zipFilePath + ", " + libFilePath);
+        }
+
+        synchronized (mLock) {
+            ensureInitializedLocked();
+
+            // Security: Ensure prepareLibraryLoad() was called before.
+            // In theory, this can be done lazily here, but it's more consistent
+            // to use a pair of functions (i.e. prepareLibraryLoad() + finishLibraryLoad())
+            // that wrap all calls to loadLibrary() in the library loader.
+            assert mPrepareLibraryLoadCalled;
+
+            if (mLoadedLibraries == null) {
+                mLoadedLibraries = new HashMap<String, LibInfo>();
+            }
+
+            if (mLoadedLibraries.containsKey(libFilePath)) {
+                if (DEBUG) {
+                    Log.i(TAG, "Not loading " + libFilePath + " twice");
+                }
+                return;
+            }
+
+            LibInfo libInfo = new LibInfo();
+            long loadAddress = 0;
+            if ((mInBrowserProcess && mBrowserUsesSharedRelro) || mWaitForSharedRelros) {
+                // Load the library at a fixed address.
+                loadAddress = mCurrentLoadAddress;
+            }
+
+            String sharedRelRoName = libFilePath;
+            if (zipFilePath != null) {
+                if (!nativeLoadLibraryInZipFile(zipFilePath, libFilePath, loadAddress, libInfo)) {
+                    String errorMessage =
+                            "Unable to load library: " + libFilePath + ", in: " + zipFilePath;
+                    Log.e(TAG, errorMessage);
+                    throw new UnsatisfiedLinkError(errorMessage);
+                }
+                sharedRelRoName = zipFilePath;
+            } else {
+                if (!nativeLoadLibrary(libFilePath, loadAddress, libInfo)) {
+                    String errorMessage = "Unable to load library: " + libFilePath;
+                    Log.e(TAG, errorMessage);
+                    throw new UnsatisfiedLinkError(errorMessage);
+                }
+            }
+
+            // Print the load address to the logcat when testing the linker. The format
+            // of the string is expected by the Python test_runner script as one of:
+            //    BROWSER_LIBRARY_ADDRESS: <library-name> <address>
+            //    RENDERER_LIBRARY_ADDRESS: <library-name> <address>
+            // Where <library-name> is the library name, and <address> is the hexadecimal load
+            // address.
+            if (NativeLibraries.sEnableLinkerTests) {
+                Log.i(TAG, String.format(Locale.US, "%s_LIBRARY_ADDRESS: %s %x",
+                                   mInBrowserProcess ? "BROWSER" : "RENDERER", libFilePath,
+                                   libInfo.mLoadAddress));
+            }
+
+            if (mInBrowserProcess) {
+                // Create a new shared RELRO section at the 'current' fixed load address.
+                if (!nativeCreateSharedRelro(sharedRelRoName, mCurrentLoadAddress, libInfo)) {
+                    Log.w(TAG,
+                            String.format(Locale.US, "Could not create shared RELRO for %s at %x",
+                                    libFilePath, mCurrentLoadAddress));
+                } else {
+                    if (DEBUG) {
+                        Log.i(TAG,
+                                String.format(Locale.US, "Created shared RELRO for %s at %x: %s",
+                                        sharedRelRoName, mCurrentLoadAddress, libInfo.toString()));
+                    }
+                }
+            }
+
+            if (mCurrentLoadAddress != 0) {
+                // Compute the next current load address. If mBaseLoadAddress
+                // is not 0, this is an explicit library load address. Otherwise,
+                // this is an explicit load address for relocated RELRO sections
+                // only.
+                mCurrentLoadAddress = libInfo.mLoadAddress + libInfo.mLoadSize;
+            }
+
+            mLoadedLibraries.put(sharedRelRoName, libInfo);
+            if (DEBUG) {
+                Log.i(TAG, "Library details " + libInfo.toString());
+            }
+        }
+    }
+
+    /**
+     * Determine whether a library is the linker library. Also deal with the
+     * component build that adds a .cr suffix to the name.
+     */
+    @Override
+    public boolean isChromiumLinkerLibrary(String library) {
+        return library.equals(LINKER_JNI_LIBRARY) || library.equals(LINKER_JNI_LIBRARY + ".cr");
+    }
+
+    /**
+     * Move activity from the native thread to the main UI thread.
+     * Called from native code on its own thread.  Posts a callback from
+     * the UI thread back to native code.
+     *
+     * @param opaque Opaque argument.
+     */
+    @CalledByNative
+    public static void postCallbackOnMainThread(final long opaque) {
+        ThreadUtils.postOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                nativeRunCallbackOnUiThread(opaque);
+            }
+        });
+    }
+
+    /**
+     * Native method to run callbacks on the main UI thread.
+     * Supplied by the crazy linker and called by postCallbackOnMainThread.
+     * @param opaque Opaque crazy linker arguments.
+     */
+    private static native void nativeRunCallbackOnUiThread(long opaque);
+
+    /**
+     * Native method used to load a library.
+     * @param library Platform specific library name (e.g. libfoo.so)
+     * @param loadAddress Explicit load address, or 0 for randomized one.
+     * @param libInfo If not null, the mLoadAddress and mLoadSize fields
+     * of this LibInfo instance will set on success.
+     * @return true for success, false otherwise.
+     */
+    private static native boolean nativeLoadLibrary(
+            String library, long loadAddress, LibInfo libInfo);
+
+    /**
+     * Native method used to load a library which is inside a zipfile.
+     * @param zipfileName Filename of the zip file containing the library.
+     * @param library Platform specific library name (e.g. libfoo.so)
+     * @param loadAddress Explicit load address, or 0 for randomized one.
+     * @param libInfo If not null, the mLoadAddress and mLoadSize fields
+     * of this LibInfo instance will set on success.
+     * @return true for success, false otherwise.
+     */
+    private static native boolean nativeLoadLibraryInZipFile(
+            String zipfileName, String libraryName, long loadAddress, LibInfo libInfo);
+
+    /**
+     * Native method used to create a shared RELRO section.
+     * If the library was already loaded at the same address using
+     * nativeLoadLibrary(), this creates the RELRO for it. Otherwise,
+     * this loads a new temporary library at the specified address,
+     * creates and extracts the RELRO section from it, then unloads it.
+     * @param library Library name.
+     * @param loadAddress load address, which can be different from the one
+     * used to load the library in the current process!
+     * @param libInfo libInfo instance. On success, the mRelroStart, mRelroSize
+     * and mRelroFd will be set.
+     * @return true on success, false otherwise.
+     */
+    private static native boolean nativeCreateSharedRelro(
+            String library, long loadAddress, LibInfo libInfo);
+
+    /**
+     * Native method used to use a shared RELRO section.
+     * @param library Library name.
+     * @param libInfo A LibInfo instance containing valid RELRO information
+     * @return true on success.
+     */
+    private static native boolean nativeUseSharedRelro(String library, LibInfo libInfo);
+
+    /**
+     * Checks that the system supports shared RELROs. Old Android kernels
+     * have a bug in the way they check Ashmem region protection flags, which
+     * makes using shared RELROs unsafe. This method performs a simple runtime
+     * check for this misfeature, even though nativeEnableSharedRelro() will
+     * always fail if this returns false.
+     */
+    private static native boolean nativeCanUseSharedRelro();
+
+    /**
+     * Return a random address that should be free to be mapped with the given size.
+     * Maps an area of size bytes, and if successful then unmaps it and returns
+     * the address of the area allocated by the system (with ASLR). The idea is
+     * that this area should remain free of other mappings until we map our library
+     * into it.
+     * @param sizeBytes Size of area in bytes to search for.
+     * @return address to pass to future mmap, or 0 on error.
+     */
+    private static native long nativeGetRandomBaseLoadAddress(long sizeBytes);
+}