Move to kernel style SPDX license identifiers

[lttng-ust.git] / liblttng-ust-java-agent / java / lttng-ust-agent-common / org / lttng / ust / agent / context / ContextInfoManager.java

diff --git a/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java b/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java
index c3999b5d83883637be881352e9359a898b7fbcee..22efe022e794c3b1930570f560df5b408567ea2a 100644 (file)
--- a/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java
+++ b/liblttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/context/ContextInfoManager.java
@@ -1,18 +1,8 @@
 /*
- * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>
+ * SPDX-License-Identifier: LGPL-2.1-only
  *
- * This library is free software; you can redistribute it and/or modify it
- * under the terms of the GNU Lesser General Public License, version 2.1 only,
- * as published by the Free Software Foundation.
- *
- * This library is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
- * for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this library; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ * Copyright (C) 2015 EfficiOS Inc.
+ * Copyright (C) 2015 Alexandre Montplaisir <alexmonthy@efficios.com>
  */
 
 package org.lttng.ust.agent.context;
@@ -21,6 +11,8 @@ import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * The singleton manager of {@link IContextInfoRetriever} objects.
@@ -31,11 +23,17 @@ public final class ContextInfoManager {
 
        private static final String SHARED_LIBRARY_NAME = "lttng-ust-context-jni";
 
+       private static final Pattern VALID_CONTEXT_NAME_PATTERN = Pattern.compile("^[a-zA-Z0-9_\\.]+$");
+
        private static ContextInfoManager instance;
 
        private final Map<String, IContextInfoRetriever> contextInfoRetrievers = new ConcurrentHashMap<String, IContextInfoRetriever>();
        private final Map<String, Long> contextInforRetrieverRefs = new HashMap<String, Long>();
 
+       /**
+        * Lock used to keep the two maps above in sync when retrievers are
+        * registered or unregistered.
+        */
        private final Object retrieverLock = new Object();
 
        /** Singleton class, constructor should not be accessed directly */
@@ -95,6 +93,10 @@ public final class ContextInfoManager {
         */
        public boolean registerContextInfoRetriever(String retrieverName, IContextInfoRetriever contextInfoRetriever) {
                synchronized (retrieverLock) {
+                       if (!validateRetrieverName(retrieverName)) {
+                               return false;
+                       }
+
                        if (contextInfoRetrievers.containsKey(retrieverName)) {
                                /*
                                 * There is already a retriever registered with that name,
@@ -155,6 +157,33 @@ public final class ContextInfoManager {
         *         was none
         */
        public IContextInfoRetriever getContextInfoRetriever(String retrieverName) {
+               /*
+                * Note that this method does not take the retrieverLock, it lets
+                * concurrent threads access the ConcurrentHashMap directly.
+                *
+                * It's fine for a get() to happen during a registration or
+                * unregistration, it's first-come-first-serve.
+                */
                return contextInfoRetrievers.get(retrieverName);
        }
+
+       /**
+        * Validate that the given retriever name contains only the allowed
+        * characters, which are alphanumerical characters, period "." and
+        * underscore "_". The name must also not start with a number.
+        */
+       private static boolean validateRetrieverName(String contextName) {
+               if (contextName.isEmpty()) {
+                       return false;
+               }
+
+               /* First character must not be a number */
+               if (Character.isDigit(contextName.charAt(0))) {
+                       return false;
+               }
+
+               /* Validate the other characters of the string */
+               Matcher matcher = VALID_CONTEXT_NAME_PATTERN.matcher(contextName);
+               return matcher.matches();
+       }
 }