content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.cassandra.utils;
  
  import java.util.Collections;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.sun.jna.LastErrorException;
  import com.sun.jna.Native;
  import com.sun.jna.Pointer;
  
  /**
   * A {@code NativeLibraryWrapper} implementation for Linux.
   * <p>
   * When JNA is initialized, all methods that have the 'native' keyword
   * will be attmpted to be linked against. As Java doesn't have the equivalent
   * of a #ifdef, this means if a native method like posix_fadvise is defined in the
   * class but not available on the target operating system (e.g.
   * posix_fadvise is not availble on Darwin/Mac) this will cause the entire
   * initial linking and initialization of JNA to fail. This means other
   * native calls that are supported on that target operating system will be
   * unavailable simply because of one native defined method not supported
   * on the runtime operating system.
   * @see org.apache.cassandra.utils.NativeLibraryWrapper
   * @see NativeLibrary
   */
  @Shared
  public class NativeLibraryLinux implements NativeLibraryWrapper
  {
      private static boolean available;
  
      private static final Logger logger = LoggerFactory.getLogger(NativeLibraryLinux.class);
  
      static
      {
          try
          {
              Native.register(com.sun.jna.NativeLibrary.getInstance("c", Collections.emptyMap()));
              available = true;
          }
          catch (NoClassDefFoundError e)
          {
              logger.warn("JNA not found. Native methods will be disabled.");
          }
          catch (UnsatisfiedLinkError e)
          {
              logger.error("Failed to link the C library against JNA. Native methods will be unavailable.", e);
          }
          catch (NoSuchMethodError e)
          {
              logger.warn("Obsolete version of JNA present; unable to register C library. Upgrade to JNA 3.2.7 or later");
          }
      }
  
      private static native int mlockall(int flags) throws LastErrorException;
      private static native int munlockall() throws LastErrorException;
      private static native int fcntl(int fd, int command, long flags) throws LastErrorException;
      private static native int posix_fadvise(int fd, long offset, int len, int flag) throws LastErrorException;
      private static native int open(String path, int flags) throws LastErrorException;
      private static native int fsync(int fd) throws LastErrorException;
      private static native int close(int fd) throws LastErrorException;
      private static native Pointer strerror(int errnum) throws LastErrorException;
      private static native long getpid() throws LastErrorException;
  
      public int callMlockall(int flags) throws UnsatisfiedLinkError, RuntimeException
      {
          return mlockall(flags);
      }
  
      public int callMunlockall() throws UnsatisfiedLinkError, RuntimeException
      {
          return munlockall();
      }
  
      public int callFcntl(int fd, int command, long flags) throws UnsatisfiedLinkError, RuntimeException
      {
          return fcntl(fd, command, flags);
      }
  
      public int callPosixFadvise(int fd, long offset, int len, int flag) throws UnsatisfiedLinkError, RuntimeException
      {
          return posix_fadvise(fd, offset, len, flag);
      }
  
      public int callOpen(String path, int flags) throws UnsatisfiedLinkError, RuntimeException
      {
          return open(path, flags);
      }
  
      public int callFsync(int fd) throws UnsatisfiedLinkError, RuntimeException
      {
          return fsync(fd);
      }
  
      public int callClose(int fd) throws UnsatisfiedLinkError, RuntimeException
      {
          return close(fd);
      }
  
      public Pointer callStrerror(int errnum) throws UnsatisfiedLinkError, RuntimeException
      {
          return strerror(errnum);
      }
  
      public long callGetpid() throws UnsatisfiedLinkError, RuntimeException
      {
          return getpid();
      }
  
      public boolean isAvailable()
      {
          return available;
      }
  }
  