Robustness: wrap any calls to System.getProperty in case security is enabled.

Since calling System.getProperty may throw an exception on locked-down systems.

Note: this patch has the side-effect of making the 'guice_include_stack_traces'
setting static, rather than querying the system property each time a module is
installed. Making the setting static improves performance as System.getProperty
can be a bottleneck, at the cost of being able to change the setting
on-the-fly.

(This is a slightly modified version of the pull request from #872.)
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79427020

2 files changed, 81 insertions, 16 deletions

diff --git a/core/src/com/google/inject/internal/BytecodeGen.java b/core/src/com/google/inject/internal/BytecodeGen.java
index ad7764b7..ed01cd10 100644
--- a/core/src/com/google/inject/internal/BytecodeGen.java
+++ b/core/src/com/google/inject/internal/BytecodeGen.java
@@ -16,9 +16,12 @@
 
 package com.google.inject.internal;
 
+import static com.google.inject.internal.InternalFlags.getCustomClassLoadingOption;
+
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
+import com.google.inject.internal.InternalFlags.CustomClassLoadingOption;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Member;
@@ -116,10 +119,6 @@ public final class BytecodeGen {
   private static final String CGLIB_PACKAGE = " "; // any string that's illegal in a package name
   end[NO_AOP]*/
 
-  /** Use "-Dguice.custom.loader=false" to disable custom classloading. */
-  private static final boolean CUSTOM_LOADER_ENABLED
-      = Boolean.parseBoolean(System.getProperty("guice.custom.loader", "true"));
-
   /**
    * Weak cache of bridge class loaders that make the Guice implementation
    * classes visible to various code-generated proxies of client classes.
@@ -128,12 +127,12 @@ public final class BytecodeGen {
 
   static {
     CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().weakKeys().weakValues();
-    if (!CUSTOM_LOADER_ENABLED) {
+    if (getCustomClassLoadingOption() == CustomClassLoadingOption.OFF) {
       builder.maximumSize(0);
     }
     CLASS_LOADER_CACHE = builder.build(
         new CacheLoader<ClassLoader, ClassLoader>() {
-          public ClassLoader load(final ClassLoader typeClassLoader) {
+          @Override public ClassLoader load(final ClassLoader typeClassLoader) {
             logger.fine("Creating a bridge ClassLoader for " + typeClassLoader);
             return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
               public ClassLoader run() {
@@ -162,7 +161,7 @@ public final class BytecodeGen {
   private static ClassLoader getClassLoader(Class<?> type, ClassLoader delegate) {
 
     // simple case: do nothing!
-    if (!CUSTOM_LOADER_ENABLED) {
+    if (getCustomClassLoadingOption() == CustomClassLoadingOption.OFF) {
       return delegate;
     }
 
diff --git a/core/src/com/google/inject/internal/InternalFlags.java b/core/src/com/google/inject/internal/InternalFlags.java
index 2b3c3a61..74e0db23 100644
--- a/core/src/com/google/inject/internal/InternalFlags.java
+++ b/core/src/com/google/inject/internal/InternalFlags.java
@@ -16,13 +16,24 @@
 
 package com.google.inject.internal;
 
+
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.util.Arrays;
 import java.util.logging.Logger;
 /**
  * Contains flags for Guice.
  */
 public class InternalFlags {
-  private final static Logger logger = Logger.getLogger(InternalFlags.class.getName());
+  private static final Logger logger = Logger.getLogger(InternalFlags.class.getName());
+
+  private static final IncludeStackTraceOption INCLUDE_STACK_TRACES
+      = parseIncludeStackTraceOption();
+
+  private static final CustomClassLoadingOption CUSTOM_CLASS_LOADING
+      = parseCustomClassLoadingOption();
+
+
   /**
    * The options for Guice stack trace collection.
    */
@@ -35,18 +46,73 @@ public class InternalFlags {
     COMPLETE
   }
 
+  /**
+   * The options for Guice custom class loading.
+   */
+  public enum CustomClassLoadingOption {
+    /** No custom class loading */
+    OFF,
+    /** Automatically bridge between class loaders (Default) */
+    BRIDGE
+  }
 
   public static IncludeStackTraceOption getIncludeStackTraceOption() {
-    String flag = System.getProperty("guice_include_stack_traces");
+    return INCLUDE_STACK_TRACES;
+  }
+
+  public static CustomClassLoadingOption getCustomClassLoadingOption() {
+    return CUSTOM_CLASS_LOADING;
+  }
+
+  private static IncludeStackTraceOption parseIncludeStackTraceOption() {
+    return getSystemOption("guice_include_stack_traces",
+        IncludeStackTraceOption.ONLY_FOR_DECLARING_SOURCE);
+  }
+
+  private static CustomClassLoadingOption parseCustomClassLoadingOption() {
+    return getSystemOption("guice_custom_class_loading",
+        CustomClassLoadingOption.BRIDGE, CustomClassLoadingOption.OFF);
+  }
+
+  /**
+   * Gets the system option indicated by the specified key; runs as a privileged action.
+   *
+   * @param name of the system option
+   * @param defaultValue if the option is not set
+   *
+   * @return value of the option, defaultValue if not set
+   */
+  private static <T extends Enum<T>> T getSystemOption(final String name, T defaultValue) {
+    return getSystemOption(name, defaultValue, defaultValue);
+  }
+
+  /**
+   * Gets the system option indicated by the specified key; runs as a privileged action.
+   *
+   * @param name of the system option
+   * @param defaultValue if the option is not set
+   * @param secureValue if the security manager disallows access to the option
+   *
+   * @return value of the option, defaultValue if not set, secureValue if no access
+   */
+  private static <T extends Enum<T>> T getSystemOption(final String name, T defaultValue,
+      T secureValue) {
+    @SuppressWarnings("unchecked")
+    Class<T> enumType = defaultValue.getDeclaringClass();
+    String value = null;
     try {
-      return (flag == null || flag.length() == 0)
-          ? IncludeStackTraceOption.ONLY_FOR_DECLARING_SOURCE
-          : IncludeStackTraceOption.valueOf(flag);
+      value = AccessController.doPrivileged(new PrivilegedAction<String>() {
+        public String run() {
+          return System.getProperty(name);
+        }
+      });
+      return (value != null && value.length() > 0) ? Enum.valueOf(enumType, value) : defaultValue;
+    } catch (SecurityException e) {
+      return secureValue;
     } catch (IllegalArgumentException e) {
-      logger.warning(flag
-          + " is not a valid flag value for guice_include_stack_traces. "
-          + " Values must be one of " + Arrays.asList(IncludeStackTraceOption.values()));
-      return IncludeStackTraceOption.ONLY_FOR_DECLARING_SOURCE;
+      logger.warning(value + " is not a valid flag value for " + name + ". "
+          + " Values must be one of " + Arrays.asList(enumType.getEnumConstants()));
+      return defaultValue;
     }
   }
 }