/**
* Call this method to determine if this chromium project must use this linker. If not,
* System.loadLibrary() should be used to load libraries instead.
*/
public static 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.USE_LINKER variable will be false.
if (!NativeLibraries.USE_LINKER) return false;
synchronized (Linker.class) {
ensureInitializedLocked();
// At the moment, there is also no point in using this linker if the
// system does not support RELRO sharing safely.
return sRelroSharingSupported;
}
}
/**
* 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.
*/
public static long getBaseLoadAddress() {
synchronized (Linker.class) {
ensureInitializedLocked();
if (!sInBrowserProcess) {
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", sBaseLoadAddress));
return sBaseLoadAddress;
}
}
/**
* 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.
*/
public static void initServiceProcess(long baseLoadAddress) {
if (DEBUG) {
Log.i(TAG, String.format(Locale.US, "initServiceProcess(0x%x) called", baseLoadAddress));
}
synchronized (Linker.class) {
ensureInitializedLocked();
sInBrowserProcess = false;
sBrowserUsesSharedRelro = false;
if (sRelroSharingSupported) {
sWaitForSharedRelros = true;
sBaseLoadAddress = baseLoadAddress;
sCurrentLoadAddress = baseLoadAddress;
}
}
}
/**
* Load a native shared library with the Chromium linker. If neither initSharedRelro() or
* readFromBundle() were called previously, this uses the standard linker (i.e.
* System.loadLibrary()).
*
* @param library The library's base name.
*/
public static void loadLibrary(String library) {
if (DEBUG) Log.i(TAG, "loadLibrary: " + library);
// Don't self-load the linker. This is because the build system is
// not clever enough to understand that all the libraries packaged
// in the final .apk don't need to be explicitly loaded.
// Also deal with the component build that adds a .cr suffix to the name.
if (library.equals(TAG) || library.equals(TAG + ".cr")) {
if (DEBUG) Log.i(TAG, "ignoring self-linker load");
return;
}
synchronized (Linker.class) {
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 sPrepareLibraryLoadCalled;
String libName = System.mapLibraryName(library);
if (sLoadedLibraries == null) sLoadedLibraries = new HashMap<String, LibInfo>();
if (sLoadedLibraries.containsKey(libName)) {
if (DEBUG) Log.i(TAG, "Not loading " + libName + " twice");
return;
}
LibInfo libInfo = new LibInfo();
long loadAddress = 0;
if ((sInBrowserProcess && sBrowserUsesSharedRelro) || sWaitForSharedRelros) {
// Load the library at a fixed address.
loadAddress = sCurrentLoadAddress;
}
if (!nativeLoadLibrary(libName, loadAddress, libInfo)) {
String errorMessage = "Unable to load library: " + libName;
Log.e(TAG, errorMessage);
throw new UnsatisfiedLinkError(errorMessage);
}
// Keep track whether the library has been loaded at the expected load address.
if (loadAddress != 0 && loadAddress != libInfo.mLoadAddress) sLoadAtFixedAddressFailed = true;
// 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.ENABLE_LINKER_TESTS) {
Log.i(
TAG,
String.format(
Locale.US,
"%s_LIBRARY_ADDRESS: %s %x",
sInBrowserProcess ? "BROWSER" : "RENDERER",
libName,
libInfo.mLoadAddress));
}
if (sInBrowserProcess) {
// Create a new shared RELRO section at the 'current' fixed load address.
if (!nativeCreateSharedRelro(libName, sCurrentLoadAddress, libInfo)) {
Log.w(
TAG,
String.format(
Locale.US,
"Could not create shared RELRO for %s at %x",
libName,
sCurrentLoadAddress));
} else {
if (DEBUG)
Log.i(
TAG,
String.format(
Locale.US,
"Created shared RELRO for %s at %x: %s",
libName,
sCurrentLoadAddress,
libInfo.toString()));
}
}
if (sCurrentLoadAddress != 0) {
// Compute the next current load address. If sBaseLoadAddress
// is not 0, this is an explicit library load address. Otherwise,
// this is an explicit load address for relocated RELRO sections
// only.
sCurrentLoadAddress = libInfo.mLoadAddress + libInfo.mLoadSize;
}
sLoadedLibraries.put(libName, libInfo);
if (DEBUG) Log.i(TAG, "Library details " + libInfo.toString());
}
}