Common files for reporting and symbol server

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@5 4c0a9323-5329-0410-9bdc-e9ce6186880e

16 files changed, 1693 insertions, 0 deletions

diff --git a/java/common/build.xml b/java/common/build.xml
new file mode 100644
index 00000000..6dd2a885
--- /dev/null
+++ b/java/common/build.xml
@@ -0,0 +1,47 @@
+<project name="AirbagShared" default="compile" basedir=".">
+  <property name="src.home"  value="${basedir}/src"/>
+  <property name="lib.home"  value="${basedir}/../third-party"/>
+  <property name="dist.home" value="${basedir}/dist"/>
+  <property name="app.name"  value="airbag-common"/>
+  <property name="doc.home"  value="${basedir}/docs"/>
+  <property name="build.home" value="${basedir}/build"/>
+  
+  <property name="compile.debug" value="true"/>
+  <property name="compile.deprecation" value="true"/>
+  <property name="compile.optimize" value="false"/>
+
+  <path id="compile.classpath">
+    <pathelement location="${lib.home}/servlet-api.jar"/>
+  </path>
+
+	<target name="compile" 
+	        description="Compile Java sources">
+    <mkdir    dir="${build.home}"/>
+    <javac srcdir="${src.home}"
+		      destdir="${build.home}"
+            debug="${compile.debug}"
+      deprecation="${compile.deprecation}"
+         optimize="${compile.optimize}">
+         <classpath refid="compile.classpath"/>
+    </javac>
+  </target>
+
+  <target name="javadoc" depends="compile"
+    description="Create Javadoc API documentation">
+    <mkdir   dir="${dist.home}/docs"/>
+    <javadoc sourcepath="${src.home}"
+              destdir="${dist.home}/docs"
+              packagenames="*">
+          <classpath refid="compile.classpath"/>
+     </javadoc>
+  </target>
+
+  <target name="dist" depends="compile,javadoc"
+    description="Create binary distribution">
+    <mkdir dir="${dist.home}/docs"/>
+
+    <!-- Create JAR file -->
+    <jar jarfile="${dist.home}/${app.name}.jar"
+         basedir="${build.home}"/>
+  </target>
+</project>
diff --git a/java/common/src/com/google/airbag/common/AbstractMinidumpServlet.java b/java/common/src/com/google/airbag/common/AbstractMinidumpServlet.java
new file mode 100644
index 00000000..27fae88c
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/AbstractMinidumpServlet.java
@@ -0,0 +1,135 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.text.NumberFormat;
+import java.util.Calendar;
+import java.util.Random;
+import java.util.SortedMap;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Common part of uploading a file with parameters. A subclass needs to 
+ * provide a ReportStorage implementation.
+ *
+ * An upload file is saved in the file storage with parsed parameters from
+ * the URL.
+ *
+ * A separate processor will access the file storage and process these
+ * reports.
+ */
+@SuppressWarnings("serial")
+public class AbstractMinidumpServlet extends HttpServlet {
+  // Minidump storage to be instantiated by subclasses in init() method.
+  protected ReportStorage minidumpStorage;
+
+  // Random number generator
+  private final Random random = new Random();
+  
+  /**
+   * Always return success to a GET, to keep out nosy people who go
+   * directly to the URL.
+   */
+  public void doGet(HttpServletRequest req, HttpServletResponse res) {
+    res.setStatus(HttpServletResponse.SC_OK);
+  }
+
+  /**
+   * Takes the file POSTed to the server and writes it to a file storage.
+   * Parameters in URL are saved as attributes of the file.
+   *
+   * @param req a wrapped HttpServletRequest that represents a multipart 
+   *            request
+   * @return unique ID for this report, can be used to get parameters and
+   *         uploaded file contents from a file storage. If these is a 
+   *         collation, returns null.
+   *         
+   * @throws ServletException
+   * @throws IOException
+   */
+  protected String saveFile(MultipartRequest req)
+      throws ServletException, IOException {
+    // parse mutilpart request 
+    SortedMap<String, String> params = req.getParameters();
+
+    //TODO(fqian): verify required fields of a report
+    InputStream inputs = req.getInputStream();
+
+    /* It is possible that two or more clients report crashes at the same
+     * time with same parameters. To reduce the chance of collation, we
+     * add two internal parameters:
+     * 1. reporting time, a time string in the form of YYMMDD-HHMMSS;
+     * 2. a random number;
+     *
+     * In theory, there is still a chance to collate, but it is very low.
+     * When collation happens, the one coming later is dropped.
+     */
+    // 1. add a timestamp to parameters
+    params.put(NameConstants.REPORTTIME_PNAME, currentTimeString());
+    
+    // 2. get a random number to make the change of collation very small
+    int r;
+    synchronized (this.random) {
+      r = this.random.nextInt();
+    }
+    params.put(NameConstants.RANDOMNUM_PNAME, Integer.toString(r));
+    
+    String fid = this.minidumpStorage.getUniqueId(params);
+    
+    assert fid != null;
+    
+    if (this.minidumpStorage.reportExists(fid)) {
+      // collation happens 
+      return null;
+    }
+    
+    this.minidumpStorage.saveAttributes(fid, params);
+    // save uploaded contents to the storage
+    this.minidumpStorage.writeStreamToReport(fid, inputs, 0);
+    
+    return fid;
+  }
+
+  /* Gets a string representing the current time using the format: 
+   * YYMMDD-HHMMSS.
+   */
+  private String currentTimeString() {
+    NumberFormat formatter = NumberFormat.getInstance();
+    formatter.setGroupingUsed(false);
+    formatter.setMinimumIntegerDigits(2);  // 2 digits per date component
+
+    // All servers are in Pacific time
+    Calendar cal = Calendar.getInstance();
+
+    StringBuffer tstring = new StringBuffer();
+    tstring.append(formatter.format(cal.get(Calendar.YEAR)));
+    // We want January = 1.
+    tstring.append(formatter.format((cal.get(Calendar.MONTH) + 1)));
+    tstring.append(formatter.format(cal.get(Calendar.DAY_OF_MONTH)));
+    tstring.append("-");
+    tstring.append(formatter.format(cal.get(Calendar.HOUR_OF_DAY)));
+    tstring.append(formatter.format(cal.get(Calendar.MINUTE)));
+    tstring.append(formatter.format(cal.get(Calendar.SECOND)));
+    
+    return new String(tstring);
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/CrashUtils.java b/java/common/src/com/google/airbag/common/CrashUtils.java
new file mode 100644
index 00000000..a010c526
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/CrashUtils.java
@@ -0,0 +1,188 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+/** A utility class used by crash reporting server. */
+
+public class CrashUtils {
+  // A map from numbers to hexadecimal characters.
+  private static final char[] maps = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+    'A', 'B', 'C', 'D', 'E', 'F',
+  };
+  
+  private static final String MD_ALGORITHM = "MD5";
+
+  // delimiter between record
+  private static final String RECORD_DELIMITER = ";";
+  private static final String FIELD_DELIMITER = " ";
+  private static final int BUFFER_SIZE = 1024;
+  
+  /**
+   * Given a byte array, returns a string of its hex representation.
+   * Each byte is represented by two characters for its high and low
+   * parts. For example, if the input is [0x3F, 0x01], this method
+   * returns 3F01.
+   * 
+   * @param bs a byte array
+   * @return a string of hexadecimal characters
+   */
+  public static String bytesToHexString(byte[] bs) {
+    StringBuffer sb = new StringBuffer();
+    for (byte b : bs) {
+      int high = (b >> 4) & 0x0F;
+      int low = b & 0x0F;
+      sb.append(maps[high]);
+      sb.append(maps[low]);
+    }
+    return sb.toString();
+  }
+  
+  /**
+   * Given a byte array, computes its message digest using one-way hash 
+   * functions. 
+   * 
+   * @param data a byte array 
+   * @return a string as its signature, or null if no message digest 
+   *         algorithm
+   * supported by the system.
+   */
+  public static String dataSignature(byte[] data) {
+    try {
+      MessageDigest md = MessageDigest.getInstance(MD_ALGORITHM);
+      return bytesToHexString(md.digest(data));
+    } catch (NoSuchAlgorithmException e) {
+      return null;
+    }
+  }
+  
+  /** 
+   * Compute the signature of a file by calling dataSignature on file
+   * contents.
+   * 
+   * @param file a file name which signature to be computed
+   * @return the method signature of the file, or null if failed to 
+   * read file contents, or message digest algorithm is not supported
+   */
+  public static String fileSignature(File file) {
+    try {
+      FileInputStream fis = new FileInputStream(file);
+      byte[] buf = new byte[BUFFER_SIZE];
+      MessageDigest md = MessageDigest.getInstance(MD_ALGORITHM);
+      while (true) {
+        int bytesRead = fis.read(buf, 0, BUFFER_SIZE);
+        if (bytesRead == -1)
+          break;
+        md.update(buf, 0, bytesRead);
+      }
+      return bytesToHexString(md.digest());
+      
+    } catch (NoSuchAlgorithmException e) {
+      return null;
+    } catch (IOException e) {
+      return null;
+    }
+  }
+  
+  /**
+   * Encodes an attribute map to a string. Encoded string format:
+   * name value1[ value2];name value1[ value2]
+   * Names and values should be escaped so that there are no
+   * RECORD_DELIMITER and VALUE_DELIMITER in strings.
+   * 
+   * @param attributes a maps of attributes name and value to be encoded
+   * @return a string of encoded attributes
+   */
+  public static 
+  String attributesToString(SortedMap<String, String> attributes) {
+    StringBuffer res = new StringBuffer();
+    for (Map.Entry<String, String> e : attributes.entrySet()) {
+      String name = e.getKey();
+      String value = e.getValue();
+
+      assert name.indexOf(RECORD_DELIMITER) == -1;
+      assert name.indexOf(FIELD_DELIMITER) == -1;
+      res.append(name).append(FIELD_DELIMITER);
+
+      assert value.indexOf(RECORD_DELIMITER) == -1;
+      assert value.indexOf(FIELD_DELIMITER) == -1;
+      res.append(value).append(RECORD_DELIMITER);
+    }
+    return new String(res);
+  }
+
+  /**
+   *  Decodes a string to a map of attributes. 
+   */
+  public static SortedMap<String, String> stringToAttributes(String s) {
+    SortedMap<String, String> map = 
+      new TreeMap<String, String>();
+    String[] records = s.split(RECORD_DELIMITER);
+    for (String r : records) {
+      String[] fields = r.trim().split(FIELD_DELIMITER);
+      if (fields.length != 2) // discard records that has no values
+        continue;
+      String name = fields[0].trim();
+      String value = fields[1].trim();
+      map.put(name, value);
+    }
+    return map;
+  }
+  
+  /**
+   * Copies bytes from an input stream to an output stream, with max bytes.
+   * 
+   * @param ins an input stream to read
+   * @param outs an output stream to write
+   * @param max the maximum number of bytes to copy. If max <= 0, copy bytes 
+   *        until the end of input stream
+   * @return the number of bytes copied
+   * @throws IOException 
+   */
+  public static int copyStream(InputStream ins, OutputStream outs, int max) 
+    throws IOException {
+    byte[] buf = new byte[BUFFER_SIZE];
+    int bytesWritten = 0;
+
+    while (true) {
+      int bytesToRead = BUFFER_SIZE;
+      if (max > 0)
+        bytesToRead = Math.min(BUFFER_SIZE, max - bytesWritten);
+
+      if (bytesToRead <= 0)
+        break;
+
+      int bytesRead = ins.read(buf, 0, bytesToRead);
+      if (bytesRead == -1) // end of input stream
+        break;
+      outs.write(buf, 0, bytesRead);
+      bytesWritten += bytesRead;
+    }
+    
+    return bytesWritten;
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/MultipartRequest.java b/java/common/src/com/google/airbag/common/MultipartRequest.java
new file mode 100644
index 00000000..bd737bfb
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/MultipartRequest.java
@@ -0,0 +1,36 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.util.SortedMap;
+import java.io.InputStream;
+
+/**
+ * A common interface for different multipart HttpServletRequest 
+ * implementations. The interface is simple enough to be used by the
+ * upload server.
+ */
+
+public interface MultipartRequest {
+  /**
+   * Returns a sorted map of name to values of an HTTP request.
+   */
+  public SortedMap<String, String> getParameters();
+
+  /**
+   * Returns an input stream of uploading file. 
+   */
+  public InputStream getInputStream();
+}
diff --git a/java/common/src/com/google/airbag/common/NameConstants.java b/java/common/src/com/google/airbag/common/NameConstants.java
new file mode 100644
index 00000000..6ea80692
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/NameConstants.java
@@ -0,0 +1,42 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+/** A class defines URL parameter names. */
+
+public class NameConstants {
+  // URL parameter names
+  // product name
+  public static final String PRODUCT_PNAME = "prod";
+  // version 
+  public static final String VERSION_PNAME = "ver";
+  // application or module
+  public static final String APPLICATION_PNAME = "app";
+  // platform, e.g., win32, linux, mac
+  public static final String PLATFORM_PNAME = "plat";
+  // report format, e.g., dump, xml
+  public static final String FORMAT_PNAME = "fmt";
+  // process uptime
+  public static final String PROCESSUPTIME_PNAME = "procup";
+  // cumulative process uptime
+  public static final String CUMULATIVEUPTIME_PNAME = "cumup";
+  // time when report is created
+  public static final String REPORTTIME_PNAME = "rept";
+  // a random number
+  public static final String RANDOMNUM_PNAME  = "rand";
+  // report checksum
+  public static final String CHECKSUM_PNAME = "sum";
+}
diff --git a/java/common/src/com/google/airbag/common/ReportQueue.java b/java/common/src/com/google/airbag/common/ReportQueue.java
new file mode 100644
index 00000000..c92f385e
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportQueue.java
@@ -0,0 +1,60 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.util.LinkedList;
+
+/**
+ * A queue interface for unprocessed report ids. The interface is intended
+ * for inter-process usage. A report uploading server enqueues new report
+ * ids, and a processor dequeues ids. 
+ * 
+ * The interface is much simpler than <b>java.util.Queue</b>. An implementation
+ * should provide a persistent storage of queued ids even when a process 
+ * is killed.
+ */
+
+public interface ReportQueue {
+  /**
+   * Enqueue a record id.
+   * 
+   * @param rid
+   * @return true if success
+   */
+  public boolean enqueue(String rid);
+  
+  /**
+   * Enqueue a list of ids
+   * 
+   * @param ids
+   * @return true if success
+   */
+  public boolean enqueue(LinkedList<String> ids);
+  
+  /**
+   * Checks if a queue is empty
+   * @return true if the queue is empty
+   */
+  public boolean empty();
+  
+  /**
+   * Removes several ids from the queue. An implementation decides how 
+   * many ids to be removed.
+   * 
+   * @return a list of queue
+   */
+  public LinkedList<String> dequeue();
+}
diff --git a/java/common/src/com/google/airbag/common/ReportQueueDirImpl.java b/java/common/src/com/google/airbag/common/ReportQueueDirImpl.java
new file mode 100644
index 00000000..dc7c922a
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportQueueDirImpl.java
@@ -0,0 +1,115 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.util.LinkedList;
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Implements ReportQueue using directories. Some restrictions:
+ * <ul>
+ *   <li>Ids must be valid file names;</li>
+ *   <li>Ids cannot be duplicated, a duplicated id is ignored;</li>
+ *   <li>No guarantees on ordering, in other words, this is not really 
+ *       a queue (with FIFO order);</li>
+ * </ul>
+ */
+
+public class ReportQueueDirImpl implements ReportQueue {
+  // maximum number of ids returned by dequque method.
+  private static final int MAX_DEQUEUED_IDS = 100;
+  
+  // the directory name for storing files
+  private String queueDir;
+  
+  /**
+   * Creates an instance of ReportQueueDirImpl with a directory name.
+   * @param dirname
+   */
+  public ReportQueueDirImpl(String dirname) 
+    throws IOException
+  {
+    this.queueDir = dirname;
+    File q = new File(dirname);
+    if (!q.exists())
+      q.mkdirs();
+   
+    if (!q.isDirectory())
+      throw new IOException("name "+dirname
+                            +" exits already, but not a directory.");
+  }
+
+  /** Enqueue a report id. */
+  public boolean enqueue(String rid) {
+    //lock on the directory
+    // add a file named by id
+    File f = new File(this.queueDir, rid);
+    try {
+      return f.createNewFile();
+    } catch (IOException e) {
+      // TODO Auto-generated catch block
+      e.printStackTrace();
+      return false;
+    }
+  }
+  
+  /** Enqueue a list of ids. */
+  public boolean enqueue(LinkedList<String> ids) {
+    //lock on the directory
+    // add a file named by id
+    for (String rid : ids) {
+      File f = new File(this.queueDir, rid);
+      try {
+        if (!f.createNewFile())
+          return false;
+      } catch (IOException e) {
+        // TODO Auto-generated catch block
+        e.printStackTrace();
+        return false;
+      }
+    }
+    return true;
+  }
+  
+  /** Checks if the queue is empty. */
+  public boolean empty() {
+    File f = new File(this.queueDir);
+    String[] ids = f.list();
+    if (ids == null)
+      return true;
+    else
+      return ids.length == 0;
+  }
+  
+  /** Remove ids from the queue. */
+  public LinkedList<String> dequeue() {
+    // lock on the directory
+    LinkedList<String> rids = new LinkedList<String>();
+    File d = new File(this.queueDir);
+    String[] ids = d.list();
+    if (ids == null)
+      return rids;
+
+    for (int i =0; i < Math.min(ids.length, MAX_DEQUEUED_IDS); i++) {
+      File f = new File(this.queueDir, ids[i]);
+      f.delete();
+      rids.add(ids[i]);
+    }
+    
+    return rids;
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/ReportQueueFileImpl.java b/java/common/src/com/google/airbag/common/ReportQueueFileImpl.java
new file mode 100644
index 00000000..8d858664
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportQueueFileImpl.java
@@ -0,0 +1,126 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.channels.FileChannel;
+import java.nio.channels.FileLock;
+import java.util.LinkedList;
+import java.util.logging.Logger;
+
+/**
+ * Implementation of ReportQueue using a shared file. File accesses are 
+ * protected by a file lock. When dequeue, all reports in the file were 
+ * returned and the file is truncated to length zero.
+ */
+
+public class ReportQueueFileImpl implements ReportQueue {
+  private static final Logger logger = 
+    Logger.getLogger(ReportQueueFileImpl.class.getName());
+  private String queueFile;
+  
+  /** Given a file name, creates an instance of ReportQueueFileImpl. */
+  public ReportQueueFileImpl(String fname) {
+    this.queueFile = fname;
+  }
+  
+  /** Enqueues a report id. */
+  public boolean enqueue(String rid) {
+    try {
+      RandomAccessFile raf = new RandomAccessFile(this.queueFile, "rw"); 
+      FileChannel fc = raf.getChannel();
+      // block thread until lock is obtained
+      FileLock lock = fc.lock();
+      raf.seek(raf.length());
+      raf.writeBytes(rid);
+      raf.writeByte('\n');
+      lock.release();
+      fc.close();
+      raf.close();
+      return true;
+    } catch (FileNotFoundException e) {
+      logger.severe("Cannot open file "+this.queueFile+" for write.");
+    } catch (IOException e) {
+      logger.severe("Cannot write to file "+this.queueFile);
+    }
+    return false;
+  }
+  
+  /** Enqueues a list of report ids. */
+  public boolean enqueue(LinkedList<String> ids) {
+    try {
+      RandomAccessFile raf = new RandomAccessFile(this.queueFile, "rw"); 
+      FileChannel fc = raf.getChannel();
+      // block thread until lock is obtained
+      FileLock lock = fc.lock();
+      raf.seek(raf.length());
+      for (String rid : ids) {
+        raf.writeBytes(rid);
+        raf.writeByte('\n');
+      }
+      lock.release();
+      fc.close();
+      raf.close();
+      return true;
+    } catch (FileNotFoundException e) {
+      logger.severe("Cannot open file "+this.queueFile+" for write.");
+    } catch (IOException e) {
+      logger.severe("Cannot write to file "+this.queueFile);
+    }
+    return false;
+  }
+
+  public boolean empty() {
+    // check the length of the file
+    File f = new File(this.queueFile);
+    return f.length() == 0L;
+  }
+
+  public LinkedList<String> dequeue() {
+    LinkedList<String> ids = new LinkedList<String>();
+    
+    try {
+      RandomAccessFile raf = new RandomAccessFile(this.queueFile, "rw");
+      FileChannel fc = raf.getChannel();
+      FileLock flock = fc.lock();
+       
+      while (true) {
+        String s = raf.readLine();
+        if (s == null)
+          break;
+        s = s.trim();
+        if (s.equals(""))
+          continue;
+        
+        ids.add(s);
+      }
+    
+      fc.truncate(0L);
+    
+      // release the lock
+      flock.release();
+      fc.close();
+      raf.close();
+    } catch (FileNotFoundException e) {
+      logger.severe("Cannot open file "+this.queueFile+" for write.");
+    } catch (IOException e) {
+      logger.severe("Cannot write to file "+this.queueFile);
+    }
+    return ids;
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/ReportQueueTest.java b/java/common/src/com/google/airbag/common/ReportQueueTest.java
new file mode 100644
index 00000000..62f156ea
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportQueueTest.java
@@ -0,0 +1,62 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.IOException;
+import java.util.LinkedList;
+
+/**
+ * A test class for ReportQueue implementations, currently tests
+ * ReportQueueDirImpl and ReportQueueFileImpl.
+ */
+public class ReportQueueTest {
+
+  public static void main(String[] args) {
+    ReportQueue rq = new ReportQueueFileImpl("/tmp/rqtest");
+    runTest(rq);
+    
+    try {
+      rq = new ReportQueueDirImpl("/tmp/rqdir");
+    } catch (IOException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+    runTest(rq);
+    
+    System.out.println("OK");
+  }
+  
+  private static void runTest(ReportQueue rq) {
+    rq.enqueue("hello");
+    rq.enqueue("world");
+    
+    LinkedList<String> v = rq.dequeue();
+    assert v.size() == 2;
+    
+    assert v.get(0).equals("hello");
+    assert v.get(1).equals("world");
+    assert rq.empty();
+    
+    v.remove();
+    
+    rq.enqueue(v);
+    assert !rq.empty();
+    
+    v = rq.dequeue();
+    assert v.size() == 1;
+    assert v.get(0).equals("world");
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/ReportStorage.java b/java/common/src/com/google/airbag/common/ReportStorage.java
new file mode 100644
index 00000000..0c01281c
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportStorage.java
@@ -0,0 +1,134 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.InputStream;
+import java.io.IOException;
+import java.io.FileNotFoundException;
+
+import java.util.SortedMap;
+
+/**
+ * ReportStorage.java
+ * 
+ * <p>
+ * Provide an abstract layer for storing crash reports and associated meta 
+ * data.
+ * </p>
+ * 
+ * <p>
+ * The interface is intended to be used by a client in the following way:
+ * 
+ * <pre>
+ *     ReportStorage rs = new ReportStorageImpl(...);
+ *     // Write an uploading file to a storage
+ *     try {
+ *        String rid = rs.getUniqueId(attributes); // params from URL
+ *        rs.saveAttributes(id, attributes);
+ *        if (!rs.reportExists(rid) || allowOverwrite)
+ *           rs.writeStreamToReport(rid, input, 0);
+ *        else
+ *           rs.appendStreamToReport(rid, input, 0);
+ *     } catch (...)
+ *  
+ *     // Read a file from the storage
+ *     try {
+ *        OutputStream os = fs.openReportForRead(fid);
+ *        os.read(...);
+ *        os.close();
+ *     } catch (...)
+ * </pre>
+ */
+
+public interface ReportStorage {
+  /**
+   * Given a sorted map of attributes (name and value), returns a unique id
+   * of the crash report.
+   * 
+   * @param params a sorted map from name to value
+   * @return a string as the file id
+   */
+  public String getUniqueId(SortedMap<String, String> params);
+
+  /**
+   * Given a report id, checks if the report data AND attributes identified
+   * by this id exists on the storage.
+   * 
+   * @param id a report id
+   * @return true if the id represents an existing file
+   */
+  public boolean reportExists(String id);
+
+  /**
+   * Given a report id and a sorted map of attributes, saves attributes on
+   * the storage.
+   * 
+   * @param id a report id
+   * @param attrs attributes associated with this id
+   * @return true if attributes are saved successfully
+   */
+  public boolean saveAttributes(String id, SortedMap<String, String> attrs);
+
+  /**
+   * Given a report id, returns attributes associated with this report.
+   * 
+   * @param id a report id
+   * @return a sorted map from name to value
+   * @throws FileNotFoundException if fileExists(id) returns false
+   */
+  public SortedMap<String, String> getAttributes(String id)
+      throws FileNotFoundException;
+
+  /**
+   * Writes <i>max</i> bytes from an input stream to a report identified by 
+   * an <i>id</i>.
+   * 
+   * @param id a report id
+   * @param input an input stream
+   * @param max
+   *          maximum bytes to be written, if max is less or equal than 0, it will
+   *          write all bytes from input stream to the file
+   * @return the number of bytes written
+   * @throws FileNotFoundException
+   *           if reportExists(id) returns false
+   * @throws IOException
+   */
+  public int writeStreamToReport(String id, InputStream input, int max)
+      throws FileNotFoundException, IOException;
+
+  /**
+   * Opens a report for read.
+   * 
+   * @param id a report id
+   * @return an output stream for read
+   * @throws FileNotFoundException
+   */
+  public InputStream openReportForRead(String id) throws FileNotFoundException;
+
+  /** 
+   * @param id a report id
+   * @return the checksum of a report.
+   * @throws FileNotFoundException 
+   */
+  public String getChecksum(String id) throws FileNotFoundException;
+  
+  /**
+   * Removes a report.
+   * 
+   * @param id a report id
+   * @return true if the report is removed successfully
+   */
+  public boolean removeReport(String id) throws FileNotFoundException;
+}
diff --git a/java/common/src/com/google/airbag/common/ReportStorageLocalFileImpl.java b/java/common/src/com/google/airbag/common/ReportStorageLocalFileImpl.java
new file mode 100644
index 00000000..9a6cf91f
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportStorageLocalFileImpl.java
@@ -0,0 +1,197 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.util.SortedMap;
+import java.util.logging.Logger;
+
+import java.io.File;
+import java.io.InputStream;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.FileNotFoundException;
+
+/**
+ * <p>Implement FileStorage using a local file system.</p>
+ * 
+ * <p>Given a sorted map of attributes, create a checksum as unique file 
+ * id.</p>
+ * 
+ * <p>Each file id is associated with two files in the storage:
+ *   <ol>
+ *    <li>an attribute file named as <id>.attr;</li>
+ *    <li>a data file named as <id>.data;</li>
+ *   </ol>
+ * </p>
+ */
+
+public class ReportStorageLocalFileImpl implements ReportStorage {
+
+  // Name extension of attribute file
+  private static final String ATTR_FILE_EXT = ".attr";
+
+  // Name extension of data file
+  private static final String DATA_FILE_EXT = ".data";
+
+  // Set the maximum file length at 1M
+  private static final long MAX_ATTR_FILE_LENGTH = 1 << 10; 
+
+  // Logging
+  private static final Logger logger = 
+    Logger.getLogger(ReportStorageLocalFileImpl.class.getName());
+  
+  // Directory name for storing files.
+  private String directoryName;
+
+  /** 
+   * Creates an instance of ReportStorageLocalFileImpl by providing a 
+   * directory name.
+   * 
+   * @param dirname a directory for storing files
+   * @throws IOException
+   * @throws NullPointerException if dirname is null
+   */
+  public ReportStorageLocalFileImpl(String dirname) throws IOException {
+    this.directoryName = dirname;
+    // new File can throw NullPointerException if dirname is null
+    File dir = new File(dirname);
+    if (!dir.exists() && !dir.mkdirs())
+      throw new IOException("Cannot make dirs for "+dirname);
+    
+    if (!dir.canWrite())
+      throw new IOException("Cannot write to "+dirname
+                            +", check your permissions.");
+  }
+  
+  /**
+   * Returns a hashed string of attributes. Attributes are saved 
+   * in the file storage if not exists.
+   */
+  public String getUniqueId(SortedMap<String, String> attributes) 
+  {
+    String attr = CrashUtils.attributesToString(attributes);
+    return CrashUtils.dataSignature(attr.getBytes());
+  }
+  
+  /**
+   * Saves attributes associated with a given id. if attributes does not 
+   * match the id (comparing results of getUniqueId(attributes)
+   * with id), it returns false. Otherwise, attributes are saved.
+   */
+  public boolean saveAttributes(String id, SortedMap<String, String> attributes)
+  {
+    String attr = CrashUtils.attributesToString(attributes);
+    String digest = CrashUtils.dataSignature(attr.getBytes());
+    
+    if (!digest.equals(id))
+      return false;
+    
+    try {
+      File attrFile = new File(this.directoryName, digest+ATTR_FILE_EXT);
+
+      // check if attr file exists
+      if (!attrFile.exists()) {
+        FileOutputStream fos = new FileOutputStream(attrFile);
+        fos.write(attr.getBytes());
+        fos.close();
+      }
+
+      return true;
+    } catch (IOException e) {
+      e.printStackTrace();
+      logger.warning(e.toString());
+      return false;
+    }    
+  }
+
+  /** Checks if a report id exists. */
+  public boolean reportExists(String id) {
+    File datafile = new File(this.directoryName, id+DATA_FILE_EXT);
+    File attrfile = new File(this.directoryName, id+ATTR_FILE_EXT);
+    return datafile.isFile() && attrfile.isFile();
+  }
+
+  /** Returns attributes in a map associated with an id. */
+  public SortedMap<String, String> getAttributes(String id) 
+    throws FileNotFoundException
+  {
+    if (!this.reportExists(id))
+      throw new FileNotFoundException("no file is identified by "+id);
+    
+    File attrfile = new File(this.directoryName, id+ATTR_FILE_EXT);
+    if (!attrfile.isFile())
+      throw new FileNotFoundException("no file is identified by "+id);
+    
+    int length = (int) attrfile.length();
+    if (length >= MAX_ATTR_FILE_LENGTH)
+      throw new FileNotFoundException("no file is identified by "+id);
+
+    byte[] content = new byte[length];
+
+    try {
+      FileInputStream fis = new FileInputStream(attrfile);
+      fis.read(content);
+      fis.close();
+
+      // verify checksum
+      String sig = CrashUtils.dataSignature(content);
+      if (!sig.equals(id)) {
+        logger.warning("illegal access to "+attrfile);
+        return null;
+      }
+
+      // parse contents
+      return CrashUtils.stringToAttributes(new String(content));
+
+    } catch (IOException e) {
+      logger.warning(e.toString());
+      return null;
+    }
+  }
+
+  public int writeStreamToReport(String id, InputStream input, int max) 
+    throws FileNotFoundException, IOException {
+    File datafile = new File(this.directoryName, id + DATA_FILE_EXT);
+    FileOutputStream fos = new FileOutputStream(datafile);
+
+    int bytesCopied = CrashUtils.copyStream(input, fos, max);
+
+    fos.close();
+    
+    return bytesCopied;
+  }
+
+  public InputStream openReportForRead(String id) throws FileNotFoundException {
+    File datafile = new File(this.directoryName, id + DATA_FILE_EXT);
+    return new FileInputStream(datafile);
+  }
+
+  public String getChecksum(String id) throws FileNotFoundException {
+    File datafile = new File(this.directoryName, id + DATA_FILE_EXT);
+    return CrashUtils.fileSignature(datafile);
+  }
+
+
+  public boolean removeReport(String id) {
+    File datafile = new File(this.directoryName, id + DATA_FILE_EXT);
+    File attrfile = new File(this.directoryName, id + ATTR_FILE_EXT);
+    
+    datafile.delete();
+    attrfile.delete();
+    
+    return true;
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/ReportStorageTest.java b/java/common/src/com/google/airbag/common/ReportStorageTest.java
new file mode 100644
index 00000000..dc17f56a
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/ReportStorageTest.java
@@ -0,0 +1,89 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.ByteArrayInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.TreeMap;
+
+/** A simple regression test of ReportStorage.java and implementations.
+ */
+
+public class ReportStorageTest {
+  public static void main(String[] args) {   
+    // use /tmp/test as testing directory
+    ReportStorage rs = null;
+    try {
+      rs = new ReportStorageLocalFileImpl("/tmp/test");
+    } catch (IOException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+    
+    runTest(rs);
+    
+    // test passed
+    System.out.println("OK.");
+  }
+  
+  private static void runTest(ReportStorage rs) {
+    // test CrashUtil.bytesToHexString
+    byte[] ba = new byte[4];
+    ba[0] = (byte)0xFF;
+    ba[1] = (byte)0x00;
+    ba[2] = (byte)0x0F;
+    ba[3] = (byte)0xF0;
+    String s = CrashUtils.bytesToHexString(ba);
+    assert s.equals("FF000FF0");
+  
+    // construct a simple map of attributes
+    TreeMap<String, String> params = 
+      new TreeMap<String, String>();
+    params.put("Hello", "World");
+    String rid = rs.getUniqueId(params);
+    assert rid != null;
+    
+    boolean b = rs.saveAttributes(rid, params);
+    assert b;
+    ba = "hellow, world!".getBytes();
+    InputStream in = new ByteArrayInputStream(ba);
+    
+    assert rs.reportExists(rid);
+    
+    // save contents to storage
+    try {
+      rs.writeStreamToReport(rid, in, 0);
+    } catch (FileNotFoundException e) {
+      e.printStackTrace();
+      System.exit(1);
+    } catch (IOException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+    
+    // read contents out
+    try {
+      InputStream in1 = rs.openReportForRead(rid);
+      assert in1.available() == ba.length;
+      in1.read(ba);
+      assert(new String(ba).equals("hellow, world!"));
+    } catch (IOException e) { 
+      e.printStackTrace();
+      System.exit(1);
+    }
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/SymbolStorage.java b/java/common/src/com/google/airbag/common/SymbolStorage.java
new file mode 100644
index 00000000..5f0a3508
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/SymbolStorage.java
@@ -0,0 +1,86 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.SortedMap;
+
+/**
+ * <p>SymbolStorage provides a simple interface for storing and retrieving 
+ * symbol files. Symbol files are indexed by a set of attributes:
+ * <ul>
+ *   <li>product name</li>
+ *   <li>version (build id)</li>
+ *   <li>platform</li>
+ *   <li>application/module name</li>
+ * </ul>
+ * </p>
+ * 
+ * <p>
+ * The interface is designed for a symbol server supports upload, getid, 
+ * download operations.
+ * </p>
+ */
+
+public interface SymbolStorage {
+  /**
+   * Saves a symbol file indexed by a set of attributes. Attributes include
+   * product, version, platform, application/module, plus a checksum of
+   * the symbol file.
+   * 
+   * If a symbol file whose checksum matches the attribute, the input stream 
+   * can be NULL. No contents will be written. This can save some workloads
+   * of uploading symbols.
+   * 
+   * @param attrs a map of attributes, it must have 'prod', 'ver', 'plat', 
+   *        'app', and 'sum', values of the first four attributes are used 
+   *        as index, and the value of the last attribute is the MD5 checksum 
+   *        of the symbol file for verification.
+   * @param contents symbol file contents.
+   * @return true if checksum matches 
+   * @throws IOException 
+   */
+  public boolean saveSymbolFile(SortedMap<String, String> attrs, 
+      InputStream contents) throws IOException;
+  
+  /**
+   * Gets the checksum of a symbol file indexed by a set of attributes.
+   * @param attrs a map of attributes, must include 'prod', 'ver', 'plat', 
+   *        and 'app'.
+   * @return MD5 checksum as a string
+   * @throws IOException 
+   */
+  public String getFileChecksum(SortedMap<String, String> attrs)
+     throws IOException;
+  
+  /**
+   * Checks if a file exists already (identified by its checksum).
+   * @param checksum the file checksum
+   * @return true if a file with the same checksum exists
+   */
+  public boolean fileExists(String checksum);
+  
+  /**
+   * Gets an input stream of a symbol server indexed by a set of attributes.
+   * @param attrs a map of attributes, must include 'prod', 'ver', 'plat', 
+   *        and 'app'.
+   * @return an input stream of the symbol file
+   * @throws IOException 
+   */
+  public InputStream openFileForRead(SortedMap<String, String> attrs) 
+    throws IOException;
+}
diff --git a/java/common/src/com/google/airbag/common/SymbolStorageLocalFileImpl.java b/java/common/src/com/google/airbag/common/SymbolStorageLocalFileImpl.java
new file mode 100644
index 00000000..ed4e0e63
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/SymbolStorageLocalFileImpl.java
@@ -0,0 +1,203 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+/**
+ * Implementation of SymbolStorage interface using a local file system.
+ * 
+ * Given a set of parameters, prod, ver, app, plat, computes its MD5 digest.
+ * Digest + .attr contains attributes and checksum of the symbol file.
+ * Symbol file content is stored in a file named by its checksum + .data.
+ * 
+ * To upload a symbol file, a client can send a query:
+ * <pre>
+ *   /symexists?sum=<checksum>, the server checks if a symbol file identified by checksum exists;
+ *   /upload?prod=<product>&ver=<version>&plat=<platform>&app=<module>&sum=<checksum> use POST
+ *   method with or without uploading a file.
+ *   
+ *   A client can always call /upload to upload a symbol file. 
+ *   However, a more efficient way is to check whether a file is on the server by calling /symexists.
+ *   If so, the client can just POST the request without actually upload the file content,
+ *   checksum is sufficient.
+ * 
+ *   /getchecksum?prod=<product>&ver=<version>&plat=<platform>&app=<module>, returns the checksum
+ *   of the symbol file on the server.
+ *   /download?prod=<product>&ver=<version>&plat=<platform>&app=<module>, downloads the symbol file
+ *   on the server.
+ *   
+ *   A client can always use /download to download a symbol file.
+ *   However, if the client maintins its own cache of symbol files, it can call /getchecksum,
+ *   and look up the cache using the checksum. If the cache does not have the file, then it 
+ *   calls /download.
+ * </pre>
+ */
+
+public class SymbolStorageLocalFileImpl implements SymbolStorage {
+
+  // Name extension of attribute file
+  private static final String ATTR_FILE_EXT = ".attr";
+
+  // Name extension of data file
+  private static final String DATA_FILE_EXT = ".data";
+
+  private static final int MAX_ATTR_FILE_LENGTH = 1 << 10;
+  
+  // Directory name for storing files.
+  private String directoryName;
+
+  /** 
+   * Creates an instance of ReportStorageLocalFileImpl by providing a 
+   * directory name.
+   * 
+   * @param dirname
+   * @throws IOException
+   */
+  public SymbolStorageLocalFileImpl(String dirname) throws IOException {
+    this.directoryName = dirname;
+    // new File can throw NullPointerException if dirname is null
+    File dir = new File(dirname);
+    if (!dir.exists() && !dir.mkdirs())
+      throw new IOException("Cannot make dirs for "+dirname);
+    
+    if (!dir.canWrite())
+      throw new IOException("Cannot write to "+dirname
+                            +", check your permissions.");
+  }
+  
+  /**
+   * Save a symbol file.
+   */
+  public boolean saveSymbolFile(SortedMap<String, String> attrs, InputStream contents) 
+    throws IOException {
+    String digest = getAttributesSignature(attrs);
+      
+    // get 'sum' value
+    String checksum = attrs.get(NameConstants.CHECKSUM_PNAME);
+    if (checksum == null)
+      return false;
+ 
+    // attribute file name and data file name
+    File attrFile = new File(this.directoryName, digest+ATTR_FILE_EXT);
+    
+    // use passed in checksum as file name
+    File dataFile = new File(this.directoryName, checksum+DATA_FILE_EXT);
+    
+    // write data to file
+    FileOutputStream outs = new FileOutputStream(dataFile);
+    CrashUtils.copyStream(contents, outs, 0);
+    outs.close();
+     
+    // get signature of input stream
+    String filesig = CrashUtils.fileSignature(dataFile);
+    
+    if (!checksum.equals(filesig)) {
+      dataFile.delete();
+      return false;
+    }
+    
+    // save all attributes with checksum
+    String fullAttrs = CrashUtils.attributesToString(attrs);
+    
+    FileOutputStream fos = new FileOutputStream(attrFile);
+    fos.write(fullAttrs.getBytes());
+    fos.close();
+    
+    return true;
+  }
+  
+  
+  public String getFileChecksum(SortedMap<String, String> attrs) throws IOException {
+    String digest = getAttributesSignature(attrs);
+    File attrFile = new File(this.directoryName, digest+ATTR_FILE_EXT);
+    
+    if (!attrFile.isFile())
+      throw new FileNotFoundException();
+    
+    int length = (int) attrFile.length();
+    if (length >= MAX_ATTR_FILE_LENGTH)
+      throw new FileNotFoundException();
+
+    byte[] content = new byte[length];
+
+    FileInputStream fis = new FileInputStream(attrFile);
+    fis.read(content);
+    fis.close();
+
+    // parse contents
+    SortedMap<String, String> savedAttrs = 
+        CrashUtils.stringToAttributes(new String(content));
+    
+    return savedAttrs.get(NameConstants.CHECKSUM_PNAME);
+  }
+  
+  public boolean fileExists(String checksum) {
+    File dataFile = new File(this.directoryName, checksum+DATA_FILE_EXT); 
+    return dataFile.isFile();
+  }
+  
+  public InputStream openFileForRead(SortedMap<String, String> attrs) 
+    throws IOException {
+    String checksum = getFileChecksum(attrs);
+    if (checksum == null)
+      throw new FileNotFoundException();
+    
+    File dataFile = new File(this.directoryName, checksum + DATA_FILE_EXT);
+    if (!dataFile.isFile())
+      throw new FileNotFoundException();
+    
+    return new FileInputStream(dataFile);
+  }
+  
+  private static final String[] requiredParameters = {
+    NameConstants.PRODUCT_PNAME,
+    NameConstants.APPLICATION_PNAME,
+    NameConstants.PLATFORM_PNAME,
+    NameConstants.VERSION_PNAME
+  };
+  
+  private String getAttributesSignature(SortedMap<String, String> attrs) {
+    // canonize parameters
+    SortedMap<String, String> params = canonizeAttributes(attrs);
+    String attrString = CrashUtils.attributesToString(params);
+    return CrashUtils.dataSignature(attrString.getBytes());
+  }
+  /* Canonize attributes, get 'prod', 'ver', 'plat', and 'app' values,
+   * and put them in a new sorted map. If one of value is missing, 
+   * returns null.
+   */
+  private SortedMap<String, String> 
+    canonizeAttributes(SortedMap<String, String> attrs) {
+    SortedMap<String, String> params = new TreeMap<String, String>();
+    for (String s : requiredParameters) {
+      String v = attrs.get(s);
+      if (v == null)
+        return null;
+      else 
+        params.put(s, v);
+    }
+    return params; 
+  }
+
+}
diff --git a/java/common/src/com/google/airbag/common/TestReportStorageConsumer.java b/java/common/src/com/google/airbag/common/TestReportStorageConsumer.java
new file mode 100644
index 00000000..6b40dee2
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/TestReportStorageConsumer.java
@@ -0,0 +1,87 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.TreeMap;
+
+/**
+ * Test ReportStorage and its implementation by simulating two pocesses
+ * as producer and consuer.
+ * 
+ * To use this test with TestReportStorageProducer:
+ * > java TestReportStorageProducer /tmp/testdir
+ * 
+ * In another console,
+ * > java TestReportStorageConsumer /tmp/testdir
+ * 
+ * Then watch output on both console.
+ */
+public class TestReportStorageConsumer {
+
+  /**
+   * @param args
+   */
+  public static void main(String[] args) {
+    String testdir = args[0];
+    ReportStorage rs = null;
+    try {
+      rs = new ReportStorageLocalFileImpl(testdir);
+    } catch (IOException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+    
+    consume(rs);
+  }
+  
+  private static void consume(ReportStorage rs) {
+    int i = 0;
+    TreeMap<String, String> params = 
+      new TreeMap<String, String>();
+    String v = "hello";
+    byte[] buf = new byte[1024];
+    while (true) {
+      params.put(Integer.toString(i), v);
+      String id = rs.getUniqueId(params);
+      rs.saveAttributes(id, params);
+      if (rs.reportExists(id)) {
+        InputStream is = null;
+        try {
+          is = rs.openReportForRead(id);
+          while (is.read(buf) != -1) {
+            System.out.print(new String(buf));
+          }
+        } catch (FileNotFoundException e) {
+          e.printStackTrace();
+          break;
+        } catch (IOException e) {
+          e.printStackTrace();
+          break;
+        }
+      } 
+      i++;
+      try {
+        Thread.sleep(1000);
+      } catch (InterruptedException e) {
+        e.printStackTrace();
+        break;
+      }
+    }
+  }
+}
diff --git a/java/common/src/com/google/airbag/common/TestReportStorageProducer.java b/java/common/src/com/google/airbag/common/TestReportStorageProducer.java
new file mode 100644
index 00000000..b52296b6
--- /dev/null
+++ b/java/common/src/com/google/airbag/common/TestReportStorageProducer.java
@@ -0,0 +1,86 @@
+/* Copyright (C) 2006 Google Inc.
+
+Licensed 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 com.google.airbag.common;
+
+import java.io.ByteArrayInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.TreeMap;
+
+/**
+ * Test ReportStorage and its implementation by simulating two pocesses
+ * as producer and consuer.
+ * 
+ * To use this test with TestReportStorageConsumer:
+ * > java TestReportStorageProducer /tmp/testdir
+ * 
+ * In another console,
+ * > java TestReportStorageConsumer /tmp/testdir
+ * 
+ * Then watch output on both console.
+ */
+
+public class TestReportStorageProducer {
+
+  /**
+   * @param args
+   */
+  public static void main(String[] args) {
+    String testdir = args[0];
+    ReportStorage rs = null;
+    try {
+      rs = new ReportStorageLocalFileImpl(testdir);
+    } catch (IOException e) {
+      e.printStackTrace();
+      System.exit(1);
+    }
+    
+    produce(rs);
+  }
+  
+  private static void produce(ReportStorage rs) {
+    int i = 0;
+    TreeMap<String, String> params = 
+      new TreeMap<String, String>();
+    String v = "hello";
+    ByteArrayInputStream ba = new ByteArrayInputStream("hello world!".getBytes());
+    while (true) {
+      ba.reset();
+      params.put(Integer.toString(i), v);
+      String id = rs.getUniqueId(params);
+      rs.saveAttributes(id, params);
+      if (id == null) {
+        System.exit(1);
+      }
+      try {
+        rs.writeStreamToReport(id, ba, 0);
+      } catch (FileNotFoundException e) {
+        e.printStackTrace();
+        break;
+      } catch (IOException e) {
+        e.printStackTrace();
+        break;
+      }
+      i++;
+      try {
+        Thread.sleep(1000);
+      } catch (InterruptedException e) {
+        e.printStackTrace();
+        break;
+      }
+    }
+  }
+}