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new 0e632f0f3d Fix Android-related issues in Log4j Core (#3071)
0e632f0f3d is described below
commit 0e632f0f3d55054342febd060632777ef4bd6958
Author: Piotr P. Karwasz <[email protected]>
AuthorDate: Thu Oct 10 13:46:23 2024 +0200
Fix Android-related issues in Log4j Core (#3071)
This fixes three issues encountered in the
[`log4j-samples-android`](https://github.com/apache/logging-log4j-samples/tree/main/log4j-samples-android)
test project:
1. Disables the `jvmrunargs` lookup on Android and fixes it on the other
platforms. Previously, the lookup always returned `null`.
2. Switches the default context selector to `BasicContextSelector` on
Android. `StackLocator` is broken on Android: it cannot use our JDK 8 code
(missing `sun.reflect` classes), but also it cannot use our JDK 11+ code
(missing multi-release JAR support). This causes `ClassLoaderContextSelector`
to use two different logger contexts for the same classloader.
3. Fixes a `ParserConfigurationException` caused by the lack of XInclude
capabilities in Android's XML parser. The fix to
[LOG4J2-3531](https://issues.apache.org/jira/browse/LOG4J2-3531) didn't cover
all the cases.
Closes #3056.
Part of #2832.
---
.../log4j/core/config/xml/XmlConfiguration.java | 12 ++---
.../logging/log4j/core/impl/CoreDefaultBundle.java | 6 ++-
.../lookup/JmxRuntimeInputArgumentsLookup.java | 27 ++++++-----
.../log4j/core/util/internal/SystemUtils.java | 40 +++++++++++++++++
src/changelog/.3.x.x/3056_android_support.xml | 8 ++++
src/site/antora/modules/ROOT/pages/faq.adoc | 52 ++++++++++++++++++++++
.../properties-logger-context.adoc | 6 ++-
7 files changed, 134 insertions(+), 17 deletions(-)
diff --git
a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
index eb0a97a0b4..daed5864f1 100644
---
a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
+++
b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
@@ -218,14 +218,16 @@ public class XmlConfiguration extends
AbstractConfiguration implements Reconfigu
*/
private static void enableXInclude(final DocumentBuilderFactory factory) {
try {
- // Alternative: We set if a system property on the command line is
set, for example:
- // -DLog4j.XInclude=true
factory.setXIncludeAware(true);
// LOG4J2-3531: Xerces only checks if the feature is supported
when creating a factory. To reproduce:
//
-Dorg.apache.xerces.xni.parser.XMLParserConfiguration=org.apache.xerces.parsers.XML11NonValidatingConfiguration
- factory.newDocumentBuilder();
- } catch (final UnsupportedOperationException |
ParserConfigurationException e) {
- factory.setXIncludeAware(false);
+ try {
+ factory.newDocumentBuilder();
+ } catch (final ParserConfigurationException e) {
+ factory.setXIncludeAware(false);
+ LOGGER.warn("The DocumentBuilderFactory [{}] does not support
XInclude: {}", factory, e);
+ }
+ } catch (final UnsupportedOperationException e) {
LOGGER.warn("The DocumentBuilderFactory [{}] does not support
XInclude: {}", factory, e);
} catch (final AbstractMethodError | NoSuchMethodError err) {
LOGGER.warn(
diff --git
a/log4j-core/src/main/java/org/apache/logging/log4j/core/impl/CoreDefaultBundle.java
b/log4j-core/src/main/java/org/apache/logging/log4j/core/impl/CoreDefaultBundle.java
index 9b686e6a95..9d9c2fc427 100644
---
a/log4j-core/src/main/java/org/apache/logging/log4j/core/impl/CoreDefaultBundle.java
+++
b/log4j-core/src/main/java/org/apache/logging/log4j/core/impl/CoreDefaultBundle.java
@@ -40,6 +40,7 @@ import
org.apache.logging.log4j.core.lookup.InterpolatorFactory;
import org.apache.logging.log4j.core.lookup.RuntimeStrSubstitutor;
import org.apache.logging.log4j.core.lookup.StrLookup;
import org.apache.logging.log4j.core.lookup.StrSubstitutor;
+import org.apache.logging.log4j.core.selector.BasicContextSelector;
import org.apache.logging.log4j.core.selector.ClassLoaderContextSelector;
import org.apache.logging.log4j.core.selector.ContextSelector;
import org.apache.logging.log4j.core.time.Clock;
@@ -47,6 +48,7 @@ import org.apache.logging.log4j.core.time.NanoClock;
import org.apache.logging.log4j.core.time.internal.DummyNanoClock;
import org.apache.logging.log4j.core.util.DefaultShutdownCallbackRegistry;
import org.apache.logging.log4j.core.util.ShutdownCallbackRegistry;
+import org.apache.logging.log4j.core.util.internal.SystemUtils;
import org.apache.logging.log4j.kit.env.PropertyEnvironment;
import org.apache.logging.log4j.kit.recycler.RecyclerFactory;
import org.apache.logging.log4j.kit.recycler.RecyclerFactoryProvider;
@@ -157,7 +159,9 @@ public final class CoreDefaultBundle {
@SingletonFactory
@ConditionalOnMissingBinding
public ContextSelector defaultContextSelector(final
ConfigurableInstanceFactory instanceFactory) {
- return new ClassLoaderContextSelector(instanceFactory);
+ return SystemUtils.isOsAndroid()
+ ? new BasicContextSelector(instanceFactory)
+ : new ClassLoaderContextSelector(instanceFactory);
}
@SingletonFactory
diff --git
a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup.java
b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup.java
index c05133b123..d14499f1dd 100644
---
a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup.java
+++
b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup.java
@@ -17,11 +17,13 @@
package org.apache.logging.log4j.core.lookup;
import java.lang.management.ManagementFactory;
-import java.util.List;
import java.util.Map;
+import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.util.internal.SystemUtils;
import org.apache.logging.log4j.plugins.Plugin;
import org.apache.logging.log4j.plugins.PluginFactory;
+import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.Lazy;
/**
@@ -34,9 +36,10 @@ import org.apache.logging.log4j.util.Lazy;
@Plugin("jvmrunargs")
public class JmxRuntimeInputArgumentsLookup extends MapLookup {
+ private static final Logger LOGGER = StatusLogger.getLogger();
+
private static final Lazy<JmxRuntimeInputArgumentsLookup> INSTANCE =
Lazy.lazy(() -> {
- final List<String> argsList =
ManagementFactory.getRuntimeMXBean().getInputArguments();
- return new JmxRuntimeInputArgumentsLookup(MapLookup.toMap(argsList));
+ return new JmxRuntimeInputArgumentsLookup(getMapFromJmx());
});
@PluginFactory
@@ -44,13 +47,6 @@ public class JmxRuntimeInputArgumentsLookup extends
MapLookup {
return INSTANCE.get();
}
- /**
- * Constructor when used directly as a plugin.
- */
- public JmxRuntimeInputArgumentsLookup() {
- super();
- }
-
public JmxRuntimeInputArgumentsLookup(final Map<String, String> map) {
super(map);
}
@@ -63,4 +59,15 @@ public class JmxRuntimeInputArgumentsLookup extends
MapLookup {
final Map<String, String> map = getMap();
return map == null ? null : map.get(key);
}
+
+ private static Map<String, String> getMapFromJmx() {
+ if (!SystemUtils.isOsAndroid()) {
+ try {
+ return
MapLookup.toMap(ManagementFactory.getRuntimeMXBean().getInputArguments());
+ } catch (LinkageError e) {
+ LOGGER.warn("Failed to get JMX arguments from JVM.", e);
+ }
+ }
+ return Map.of();
+ }
}
diff --git
a/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/SystemUtils.java
b/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/SystemUtils.java
new file mode 100644
index 0000000000..b7b3d9cbb4
--- /dev/null
+++
b/log4j-core/src/main/java/org/apache/logging/log4j/core/util/internal/SystemUtils.java
@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you 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 org.apache.logging.log4j.core.util.internal;
+
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.status.StatusLogger;
+
+public final class SystemUtils {
+
+ private static final Logger LOGGER = StatusLogger.getLogger();
+
+ private static String getJavaVendor() {
+ try {
+ return System.getProperty("java.vendor");
+ } catch (final SecurityException e) {
+ LOGGER.warn("Unable to determine Java vendor.", e);
+ }
+ return "Unknown";
+ }
+
+ public static boolean isOsAndroid() {
+ return getJavaVendor().contains("Android");
+ }
+
+ private SystemUtils() {}
+}
diff --git a/src/changelog/.3.x.x/3056_android_support.xml
b/src/changelog/.3.x.x/3056_android_support.xml
new file mode 100644
index 0000000000..764cb7f826
--- /dev/null
+++ b/src/changelog/.3.x.x/3056_android_support.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+ xmlns="https://logging.apache.org/xml/ns";
+ xsi:schemaLocation="https://logging.apache.org/xml/ns
https://logging.apache.org/xml/ns/log4j-changelog-0.xsd";
+ type="fixed">
+ <issue id="3056"
link="https://github.com/apache/logging-log4j2/issues/3056"/>
+ <description format="asciidoc">Fix Android-related issues in Log4j
Core.</description>
+</entry>
diff --git a/src/site/antora/modules/ROOT/pages/faq.adoc
b/src/site/antora/modules/ROOT/pages/faq.adoc
index c50d10b234..67916b0c0c 100644
--- a/src/site/antora/modules/ROOT/pages/faq.adoc
+++ b/src/site/antora/modules/ROOT/pages/faq.adoc
@@ -214,3 +214,55 @@ When you are using Log4j with ProGuard/R8 enabled, you
need to add the following
----
-keep,allowoptimization class org.apache.logging.log4j.** { *; }
----
+
+[#android]
+== Can I use Log4j with Android?
+
+Of course, you can!
+Since version `2.25.0` both the Log4j API and our three Log4j API
implementations are tested for compatibility with the Android platform.
+
+If you use
+xref:manual/api.adoc[Log4j API]
+in an Android project, you have four choices for the Log4j API implementation:
+
+[#android-log4j-core]
+Log4j Core::
++
+Our
+xref:manual/implementation.adoc[reference Log4j API implementation]
+works on Android out-of-the-box.
+However, due to the limitations of the Android platform, the following
features will not work:
++
+* The
+xref:manual/configuration.adoc#xinclude[XInclude feature]
+for XML configuration files will not work if you are using the standard
Android XML parser.
+You might need to add the
+https://xerces.apache.org/[Xerces parser]
+to use the feature.
+* Due to the lack of Android support for multi-release JARs, some
location-based features like the no-arg
+{log4j2-url}/javadoc/log4j-api/org/apache/logging/log4j/LogManager.html#getLogger()[`LogManager.getLogger()`]
+method or
+xref:manual/systemproperties.adoc#log4j.loggerContext.selector[`ClassLoaderContextSelector`]
+(default on JRE) are not available.
+You should use `BasicContextSelector` (default on Android) or
`BasicAsyncLoggerContextSelector` instead.
+
+[#android-jul]
+JUL::
+[#android-logback]
+Logback::
++
+Both our
+xref:manual/installation.adoc#impl-jul[Log4j API-to-JUL]
+and
+xref:manual/installation.adoc#impl-logback[Log4j API-to-SLF4J]
+bridges are tested for compatibility with Android.
+
+[#android-native]
+Log4j API-to-Android logging API bridge::
++
+If you wish to bridge Log4j API to
+https://developer.android.com/reference/android/util/Log[Android's native
logging API]
+directly, you can use the **third-party** `com.celeral:log4j2-android`
artifact.
+See the
+https://github.com/Celeral/log4j2-android[`log4j2-android` project website]
+for more information.
\ No newline at end of file
diff --git
a/src/site/antora/modules/ROOT/partials/manual/systemproperties/properties-logger-context.adoc
b/src/site/antora/modules/ROOT/partials/manual/systemproperties/properties-logger-context.adoc
index 1a34f7dc27..9b37090ccb 100644
---
a/src/site/antora/modules/ROOT/partials/manual/systemproperties/properties-logger-context.adoc
+++
b/src/site/antora/modules/ROOT/partials/manual/systemproperties/properties-logger-context.adoc
@@ -26,7 +26,11 @@
|
link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ContextSelector.html[`Class<?
extends ContextSelector>`]
| Default value
-|
link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector.html[`ClassLoaderContextSelector`]
+|
+link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector.html[`ClassLoaderContextSelector`]
+
+(on Android)
+link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/BasicContextSelector.html[`BasicContextSelector`]
|===
Specifies the fully qualified class name of the
