content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code 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 General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.util.logging;
  
  import static java.nio.file.StandardOpenOption.APPEND;
  import static java.nio.file.StandardOpenOption.CREATE_NEW;
  import static java.nio.file.StandardOpenOption.WRITE;
  
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.channels.FileChannel;
  import java.nio.channels.OverlappingFileLockException;
  import java.nio.file.FileAlreadyExistsException;
  import java.nio.file.Files;
  import java.nio.file.LinkOption;
  import java.nio.file.NoSuchFileException;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.util.HashSet;
  import java.util.Set;
  
  /**
   * Simple file logging <tt>Handler</tt>.
   * <p>
   * The <tt>FileHandler</tt> can either write to a specified file,
   * or it can write to a rotating set of files.
   * <p>
   * For a rotating set of files, as each file reaches a given size
   * limit, it is closed, rotated out, and a new file opened.
   * Successively older files are named by adding "0", "1", "2",
   * etc. into the base filename.
   * <p>
   * By default buffering is enabled in the IO libraries but each log
   * record is flushed out when it is complete.
   * <p>
   * By default the <tt>XMLFormatter</tt> class is used for formatting.
   * <p>
   * <b>Configuration:</b>
   * By default each <tt>FileHandler</tt> is initialized using the following
   * <tt>LogManager</tt> configuration properties where <tt>&lt;handler-name&gt;</tt>
   * refers to the fully-qualified class name of the handler.
   * If properties are not defined
   * (or have invalid values) then the specified default values are used.
   * <ul>
   * <li>   &lt;handler-name&gt;.level
   *        specifies the default level for the <tt>Handler</tt>
   *        (defaults to <tt>Level.ALL</tt>). </li>
   * <li>   &lt;handler-name&gt;.filter
   *        specifies the name of a <tt>Filter</tt> class to use
   *        (defaults to no <tt>Filter</tt>). </li>
   * <li>   &lt;handler-name&gt;.formatter
   *        specifies the name of a <tt>Formatter</tt> class to use
   *        (defaults to <tt>java.util.logging.XMLFormatter</tt>) </li>
   * <li>   &lt;handler-name&gt;.encoding
   *        the name of the character set encoding to use (defaults to
   *        the default platform encoding). </li>
   * <li>   &lt;handler-name&gt;.limit
   *        specifies an approximate maximum amount to write (in bytes)
   *        to any one file.  If this is zero, then there is no limit.
   *        (Defaults to no limit). </li>
   * <li>   &lt;handler-name&gt;.count
   *        specifies how many output files to cycle through (defaults to 1). </li>
   * <li>   &lt;handler-name&gt;.pattern
   *        specifies a pattern for generating the output file name.  See
   *        below for details. (Defaults to "%h/java%u.log"). </li>
   * <li>   &lt;handler-name&gt;.append
   *        specifies whether the FileHandler should append onto
   *        any existing files (defaults to false). </li>
   * </ul>
   * <p>
   * For example, the properties for {@code FileHandler} would be:
   * <ul>
   * <li>   java.util.logging.FileHandler.level=INFO </li>
   * <li>   java.util.logging.FileHandler.formatter=java.util.logging.SimpleFormatter </li>
   * </ul>
   * <p>
   * For a custom handler, e.g. com.foo.MyHandler, the properties would be:
   * <ul>
   * <li>   com.foo.MyHandler.level=INFO </li>
   * <li>   com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li>
   * </ul>
   * <p>
   * A pattern consists of a string that includes the following special
   * components that will be replaced at runtime:
   * <ul>
   * <li>    "/"    the local pathname separator </li>
   * <li>     "%t"   the system temporary directory </li>
   * <li>     "%h"   the value of the "user.home" system property </li>
   * <li>     "%g"   the generation number to distinguish rotated logs </li>
   * <li>     "%u"   a unique number to resolve conflicts </li>
   * <li>     "%%"   translates to a single percent sign "%" </li>
   * </ul>
   * If no "%g" field has been specified and the file count is greater
   * than one, then the generation number will be added to the end of
   * the generated filename, after a dot.
   * <p>
   * Thus for example a pattern of "%t/java%g.log" with a count of 2
   * would typically cause log files to be written on Solaris to
   * /var/tmp/java0.log and /var/tmp/java1.log whereas on Windows 95 they
   * would be typically written to C:\TEMP\java0.log and C:\TEMP\java1.log
   * <p>
   * Generation numbers follow the sequence 0, 1, 2, etc.
   * <p>
   * Normally the "%u" unique field is set to 0.  However, if the <tt>FileHandler</tt>
   * tries to open the filename and finds the file is currently in use by
   * another process it will increment the unique number field and try
   * again.  This will be repeated until <tt>FileHandler</tt> finds a file name that
   * is  not currently in use. If there is a conflict and no "%u" field has
   * been specified, it will be added at the end of the filename after a dot.
   * (This will be after any automatically added generation number.)
   * <p>
   * Thus if three processes were all trying to log to fred%u.%g.txt then
   * they  might end up using fred0.0.txt, fred1.0.txt, fred2.0.txt as
   * the first file in their rotating sequences.
   * <p>
   * Note that the use of unique ids to avoid conflicts is only guaranteed
   * to work reliably when using a local disk file system.
   *
   * @since 1.4
   */
  
  public class FileHandler extends StreamHandler {
      private MeteredStream meter;
      private boolean append;
      private int limit;       // zero => no limit.
      private int count;
      private String pattern;
      private String lockFileName;
      private FileChannel lockFileChannel;
      private File files[];
      private static final int MAX_LOCKS = 100;
      private static final Set<String> locks = new HashSet<>();
  
      /**
       * A metered stream is a subclass of OutputStream that
       * (a) forwards all its output to a target stream
       * (b) keeps track of how many bytes have been written
       */
      private class MeteredStream extends OutputStream {
          final OutputStream out;
          int written;
  
          MeteredStream(OutputStream out, int written) {
              this.out = out;
              this.written = written;
          }
  
          @Override
          public void write(int b) throws IOException {
              out.write(b);
              written++;
          }
  
          @Override
          public void write(byte buff[]) throws IOException {
              out.write(buff);
              written += buff.length;
          }
  
          @Override
          public void write(byte buff[], int off, int len) throws IOException {
              out.write(buff,off,len);
              written += len;
          }
  
          @Override
          public void flush() throws IOException {
              out.flush();
          }
  
          @Override
          public void close() throws IOException {
              out.close();
          }
      }
  
      private void open(File fname, boolean append) throws IOException {
          int len = 0;
          if (append) {
              len = (int)fname.length();
          }
          FileOutputStream fout = new FileOutputStream(fname.toString(), append);
          BufferedOutputStream bout = new BufferedOutputStream(fout);
          meter = new MeteredStream(bout, len);
          setOutputStream(meter);
      }
  
      /**
       * Configure a FileHandler from LogManager properties and/or default values
       * as specified in the class javadoc.
       */
      private void configure() {
          LogManager manager = LogManager.getLogManager();
  
          String cname = getClass().getName();
  
          pattern = manager.getStringProperty(cname + ".pattern", "%h/java%u.log");
          limit = manager.getIntProperty(cname + ".limit", 0);
          if (limit < 0) {
              limit = 0;
          }
          count = manager.getIntProperty(cname + ".count", 1);
          if (count <= 0) {
              count = 1;
          }
          append = manager.getBooleanProperty(cname + ".append", false);
          setLevel(manager.getLevelProperty(cname + ".level", Level.ALL));
          setFilter(manager.getFilterProperty(cname + ".filter", null));
          setFormatter(manager.getFormatterProperty(cname + ".formatter", new XMLFormatter()));
          try {
              setEncoding(manager.getStringProperty(cname +".encoding", null));
          } catch (Exception ex) {
              try {
                  setEncoding(null);
              } catch (Exception ex2) {
                  // doing a setEncoding with null should always work.
                  // assert false;
              }
          }
      }
  
  
      /**
       * Construct a default <tt>FileHandler</tt>.  This will be configured
       * entirely from <tt>LogManager</tt> properties (or their default values).
       * <p>
       * @exception  IOException if there are IO problems opening the files.
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control"))</tt>.
       * @exception  NullPointerException if pattern property is an empty String.
       */
      public FileHandler() throws IOException, SecurityException {
          checkPermission();
          configure();
          openFiles();
      }
  
      /**
       * Initialize a <tt>FileHandler</tt> to write to the given filename.
       * <p>
       * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
       * properties (or their default values) except that the given pattern
       * argument is used as the filename pattern, the file limit is
       * set to no limit, and the file count is set to one.
       * <p>
       * There is no limit on the amount of data that may be written,
       * so use this with care.
       *
       * @param pattern  the name of the output file
       * @exception  IOException if there are IO problems opening the files.
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       * @exception  IllegalArgumentException if pattern is an empty string
       */
      public FileHandler(String pattern) throws IOException, SecurityException {
          if (pattern.length() < 1 ) {
              throw new IllegalArgumentException();
          }
          checkPermission();
          configure();
          this.pattern = pattern;
          this.limit = 0;
          this.count = 1;
          openFiles();
      }
  
      /**
       * Initialize a <tt>FileHandler</tt> to write to the given filename,
       * with optional append.
       * <p>
       * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
       * properties (or their default values) except that the given pattern
       * argument is used as the filename pattern, the file limit is
       * set to no limit, the file count is set to one, and the append
       * mode is set to the given <tt>append</tt> argument.
       * <p>
       * There is no limit on the amount of data that may be written,
       * so use this with care.
       *
       * @param pattern  the name of the output file
       * @param append  specifies append mode
       * @exception  IOException if there are IO problems opening the files.
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       * @exception  IllegalArgumentException if pattern is an empty string
       */
      public FileHandler(String pattern, boolean append) throws IOException,
              SecurityException {
          if (pattern.length() < 1 ) {
              throw new IllegalArgumentException();
          }
          checkPermission();
          configure();
          this.pattern = pattern;
          this.limit = 0;
          this.count = 1;
          this.append = append;
          openFiles();
      }
  
      /**
       * Initialize a <tt>FileHandler</tt> to write to a set of files.  When
       * (approximately) the given limit has been written to one file,
       * another file will be opened.  The output will cycle through a set
       * of count files.
       * <p>
       * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
       * properties (or their default values) except that the given pattern
       * argument is used as the filename pattern, the file limit is
       * set to the limit argument, and the file count is set to the
       * given count argument.
       * <p>
       * The count must be at least 1.
       *
       * @param pattern  the pattern for naming the output file
       * @param limit  the maximum number of bytes to write to any one file
       * @param count  the number of files to use
       * @exception  IOException if there are IO problems opening the files.
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       * @exception  IllegalArgumentException if {@code limit < 0}, or {@code count < 1}.
       * @exception  IllegalArgumentException if pattern is an empty string
       */
      public FileHandler(String pattern, int limit, int count)
                                          throws IOException, SecurityException {
          if (limit < 0 || count < 1 || pattern.length() < 1) {
              throw new IllegalArgumentException();
          }
          checkPermission();
          configure();
          this.pattern = pattern;
          this.limit = limit;
          this.count = count;
          openFiles();
      }
  
      /**
       * Initialize a <tt>FileHandler</tt> to write to a set of files
       * with optional append.  When (approximately) the given limit has
       * been written to one file, another file will be opened.  The
       * output will cycle through a set of count files.
       * <p>
       * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
       * properties (or their default values) except that the given pattern
       * argument is used as the filename pattern, the file limit is
       * set to the limit argument, and the file count is set to the
       * given count argument, and the append mode is set to the given
       * <tt>append</tt> argument.
       * <p>
       * The count must be at least 1.
       *
       * @param pattern  the pattern for naming the output file
       * @param limit  the maximum number of bytes to write to any one file
       * @param count  the number of files to use
       * @param append  specifies append mode
       * @exception  IOException if there are IO problems opening the files.
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       * @exception  IllegalArgumentException if {@code limit < 0}, or {@code count < 1}.
       * @exception  IllegalArgumentException if pattern is an empty string
       *
       */
      public FileHandler(String pattern, int limit, int count, boolean append)
                                          throws IOException, SecurityException {
          if (limit < 0 || count < 1 || pattern.length() < 1) {
              throw new IllegalArgumentException();
          }
          checkPermission();
          configure();
          this.pattern = pattern;
          this.limit = limit;
          this.count = count;
          this.append = append;
          openFiles();
      }
  
      private  boolean isParentWritable(Path path) {
          Path parent = path.getParent();
          if (parent == null) {
              parent = path.toAbsolutePath().getParent();
          }
          return parent != null && Files.isWritable(parent);
      }
  
      /**
       * Open the set of output files, based on the configured
       * instance variables.
       */
      private void openFiles() throws IOException {
          LogManager manager = LogManager.getLogManager();
          manager.checkPermission();
          if (count < 1) {
             throw new IllegalArgumentException("file count = " + count);
          }
          if (limit < 0) {
              limit = 0;
          }
  
          // We register our own ErrorManager during initialization
          // so we can record exceptions.
          InitializationErrorManager em = new InitializationErrorManager();
          setErrorManager(em);
  
          // Create a lock file.  This grants us exclusive access
          // to our set of output files, as long as we are alive.
          int unique = -1;
          for (;;) {
              unique++;
              if (unique > MAX_LOCKS) {
                  throw new IOException("Couldn't get lock for " + pattern);
              }
              // Generate a lock file name from the "unique" int.
              lockFileName = generate(pattern, 0, unique).toString() + ".lck";
              // Now try to lock that filename.
              // Because some systems (e.g., Solaris) can only do file locks
              // between processes (and not within a process), we first check
              // if we ourself already have the file locked.
              synchronized(locks) {
                  if (locks.contains(lockFileName)) {
                      // We already own this lock, for a different FileHandler
                      // object.  Try again.
                      continue;
                  }
  
                  final Path lockFilePath = Paths.get(lockFileName);
                  FileChannel channel = null;
                  int retries = -1;
                  boolean fileCreated = false;
                  while (channel == null && retries++ < 1) {
                      try {
                          channel = FileChannel.open(lockFilePath,
                                  CREATE_NEW, WRITE);
                          fileCreated = true;
                      } catch (FileAlreadyExistsException ix) {
                          // This may be a zombie file left over by a previous
                          // execution. Reuse it - but only if we can actually
                          // write to its directory.
                          // Note that this is a situation that may happen,
                          // but not too frequently.
                          if (Files.isRegularFile(lockFilePath, LinkOption.NOFOLLOW_LINKS)
                              && isParentWritable(lockFilePath)) {
                              try {
                                  channel = FileChannel.open(lockFilePath,
                                      WRITE, APPEND);
                              } catch (NoSuchFileException x) {
                                  // Race condition - retry once, and if that
                                  // fails again just try the next name in
                                  // the sequence.
                                  continue;
                              } catch(IOException x) {
                                  // the file may not be writable for us.
                                  // try the next name in the sequence
                                  break;
                              }
                          } else {
                              // at this point channel should still be null.
                              // break and try the next name in the sequence.
                              break;
                          }
                      }
                  }
  
                  if (channel == null) continue; // try the next name;
                  lockFileChannel = channel;
  
                  boolean available;
                  try {
                      available = lockFileChannel.tryLock() != null;
                      // We got the lock OK.
                      // At this point we could call File.deleteOnExit().
                      // However, this could have undesirable side effects
                      // as indicated by JDK-4872014. So we will instead
                      // rely on the fact that close() will remove the lock
                      // file and that whoever is creating FileHandlers should
                      // be responsible for closing them.
                  } catch (IOException ix) {
                      // We got an IOException while trying to get the lock.
                      // This normally indicates that locking is not supported
                      // on the target directory.  We have to proceed without
                      // getting a lock.   Drop through, but only if we did
                      // create the file...
                      available = fileCreated;
                  } catch (OverlappingFileLockException x) {
                      // someone already locked this file in this VM, through
                      // some other channel - that is - using something else
                      // than new FileHandler(...);
                      // continue searching for an available lock.
                      available = false;
                  }
                  if (available) {
                      // We got the lock.  Remember it.
                      locks.add(lockFileName);
                      break;
                  }
  
                  // We failed to get the lock.  Try next file.
                  lockFileChannel.close();
              }
          }
  
          files = new File[count];
          for (int i = 0; i < count; i++) {
              files[i] = generate(pattern, i, unique);
          }
  
          // Create the initial log file.
          if (append) {
              open(files[0], true);
          } else {
              rotate();
          }
  
          // Did we detect any exceptions during initialization?
          Exception ex = em.lastException;
          if (ex != null) {
              if (ex instanceof IOException) {
                  throw (IOException) ex;
              } else if (ex instanceof SecurityException) {
                  throw (SecurityException) ex;
              } else {
                  throw new IOException("Exception: " + ex);
              }
          }
  
          // Install the normal default ErrorManager.
          setErrorManager(new ErrorManager());
      }
  
      /**
       * Generate a file based on a user-supplied pattern, generation number,
       * and an integer uniqueness suffix
       * @param pattern the pattern for naming the output file
       * @param generation the generation number to distinguish rotated logs
       * @param unique a unique number to resolve conflicts
       * @return the generated File
       * @throws IOException
       */
      private File generate(String pattern, int generation, int unique)
              throws IOException {
          File file = null;
          String word = "";
          int ix = 0;
          boolean sawg = false;
          boolean sawu = false;
          while (ix < pattern.length()) {
              char ch = pattern.charAt(ix);
              ix++;
              char ch2 = 0;
              if (ix < pattern.length()) {
                  ch2 = Character.toLowerCase(pattern.charAt(ix));
              }
              if (ch == '/') {
                  if (file == null) {
                      file = new File(word);
                  } else {
                      file = new File(file, word);
                  }
                  word = "";
                  continue;
              } else  if (ch == '%') {
                  if (ch2 == 't') {
                      String tmpDir = System.getProperty("java.io.tmpdir");
                      if (tmpDir == null) {
                          tmpDir = System.getProperty("user.home");
                      }
                      file = new File(tmpDir);
                      ix++;
                      word = "";
                      continue;
                  } else if (ch2 == 'h') {
                      file = new File(System.getProperty("user.home"));
                      // Android-removed: Don't prohibit using user.home property in setuid programs.
                      /*
                      if (isSetUID()) {
                          // Ok, we are in a set UID program.  For safety's sake
                          // we disallow attempts to open files relative to %h.
                          throw new IOException("can't use %h in set UID program");
                      }
                      */
                      ix++;
                      word = "";
                      continue;
                  } else if (ch2 == 'g') {
                      word = word + generation;
                      sawg = true;
                      ix++;
                      continue;
                  } else if (ch2 == 'u') {
                      word = word + unique;
                      sawu = true;
                      ix++;
                      continue;
                  } else if (ch2 == '%') {
                      word = word + "%";
                      ix++;
                      continue;
                  }
              }
              word = word + ch;
          }
          if (count > 1 && !sawg) {
              word = word + "." + generation;
          }
          if (unique > 0 && !sawu) {
              word = word + "." + unique;
          }
          if (word.length() > 0) {
              if (file == null) {
                  file = new File(word);
              } else {
                  file = new File(file, word);
              }
          }
          return file;
      }
  
      /**
       * Rotate the set of output files
       */
      private synchronized void rotate() {
          Level oldLevel = getLevel();
          setLevel(Level.OFF);
  
          super.close();
          for (int i = count-2; i >= 0; i--) {
              File f1 = files[i];
              File f2 = files[i+1];
              if (f1.exists()) {
                  if (f2.exists()) {
                      f2.delete();
                  }
                  f1.renameTo(f2);
              }
          }
          try {
              open(files[0], false);
          } catch (IOException ix) {
              // We don't want to throw an exception here, but we
              // report the exception to any registered ErrorManager.
              reportError(null, ix, ErrorManager.OPEN_FAILURE);
  
          }
          setLevel(oldLevel);
      }
  
      /**
       * Format and publish a <tt>LogRecord</tt>.
       *
       * @param  record  description of the log event. A null record is
       *                 silently ignored and is not published
       */
      @Override
      public synchronized void publish(LogRecord record) {
          if (!isLoggable(record)) {
              return;
          }
          super.publish(record);
          flush();
          if (limit > 0 && meter.written >= limit) {
              // We performed access checks in the "init" method to make sure
              // we are only initialized from trusted code.  So we assume
              // it is OK to write the target files, even if we are
              // currently being called from untrusted code.
              // So it is safe to raise privilege here.
              AccessController.doPrivileged(new PrivilegedAction<Object>() {
                  @Override
                  public Object run() {
                      rotate();
                      return null;
                  }
              });
          }
      }
  
      /**
       * Close all the files.
       *
       * @exception  SecurityException  if a security manager exists and if
       *             the caller does not have <tt>LoggingPermission("control")</tt>.
       */
      @Override
      public synchronized void close() throws SecurityException {
          super.close();
          // Unlock any lock file.
          if (lockFileName == null) {
              return;
          }
          try {
              // Close the lock file channel (which also will free any locks)
              lockFileChannel.close();
          } catch (Exception ex) {
              // Problems closing the stream.  Punt.
          }
          synchronized(locks) {
              locks.remove(lockFileName);
          }
          new File(lockFileName).delete();
          lockFileName = null;
          lockFileChannel = null;
      }
  
      private static class InitializationErrorManager extends ErrorManager {
          Exception lastException;
          @Override
          public void error(String msg, Exception ex, int code) {
              lastException = ex;
          }
      }
  
      // Android-removed: isSetUID's only caller is removed.
      /*
      /**
       * check if we are in a set UID program.
       *
      private static native boolean isSetUID();
      */
  }
  