android-35/java/io/FileDescriptor.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * Copyright (c) 1995, 2011, 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.io;

 import android.system.ErrnoException;
 import android.system.Os;
 import android.system.OsConstants;

 import static android.system.OsConstants.F_DUPFD_CLOEXEC;

 import dalvik.annotation.optimization.CriticalNative;

 import libcore.io.Libcore;

 import java.util.concurrent.atomic.AtomicInteger;

 /**
  * Instances of the file descriptor class serve as an opaque handle
  * to the underlying machine-specific structure representing an open
  * file, an open socket, or another source or sink of bytes. The
  * main practical use for a file descriptor is to create a
  * <code>FileInputStream</code> or <code>FileOutputStream</code> to
  * contain it.
  * <p>
  * Applications should not create their own file descriptors.
  *
  * @author  Pavani Diwanji
  * @see     java.io.FileInputStream
  * @see     java.io.FileOutputStream
  * @since   JDK1.0
  */
 public final class FileDescriptor {
     // Android-changed: Removed parent reference counting.
     // The creator is responsible for closing the file descriptor.

     // Android-changed: Renamed fd to descriptor.
     // Renaming is to avoid issues with JNI/reflection fetching the descriptor value.
     private int descriptor;

     // Android-added: Track fd owner to guard against accidental closure. http://b/110100358
     // The owner on the libc side is an pointer-sized value that can be set to an arbitrary
     // value (with 0 meaning 'unowned'). libcore chooses to use System.identityHashCode.
     private long ownerId = NO_OWNER;

     /**
      * true, if file is opened for appending.
      */
     private boolean append;

     // Android-added: value of ownerId indicating that a FileDescriptor is unowned.
     /** @hide */
     public static final long NO_OWNER = 0L;

     // Android-added: lock for release$.
     private final Object releaseLock = new Object();

     /**
      * Constructs an (invalid) FileDescriptor
      * object.
      */
     public /**/ FileDescriptor() {
         descriptor = -1;
     }

     private /* */ FileDescriptor(int fd) {
         this.descriptor = fd;
         this.append = getAppend(fd);
     }

     /**
      * A handle to the standard input stream. Usually, this file
      * descriptor is not used directly, but rather via the input stream
      * known as <code>System.in</code>.
      *
      * @see     java.lang.System#in
      */
     public static final FileDescriptor in = new FileDescriptor(0);

     /**
      * A handle to the standard output stream. Usually, this file
      * descriptor is not used directly, but rather via the output stream
      * known as <code>System.out</code>.
      * @see     java.lang.System#out
      */
     public static final FileDescriptor out = new FileDescriptor(1);

     /**
      * A handle to the standard error stream. Usually, this file
      * descriptor is not used directly, but rather via the output stream
      * known as <code>System.err</code>.
      *
      * @see     java.lang.System#err
      */
     public static final FileDescriptor err = new FileDescriptor(2);

     /**
      * Tests if this file descriptor object is valid.
      *
      * @return  <code>true</code> if the file descriptor object represents a
      *          valid, open file, socket, or other active I/O connection;
      *          <code>false</code> otherwise.
      */
     public boolean valid() {
         return descriptor != -1;
     }

     /**
      * Force all system buffers to synchronize with the underlying
      * device.  This method returns after all modified data and
      * attributes of this FileDescriptor have been written to the
      * relevant device(s).  In particular, if this FileDescriptor
      * refers to a physical storage medium, such as a file in a file
      * system, sync will not return until all in-memory modified copies
      * of buffers associated with this FileDescriptor have been
      * written to the physical medium.
      *
      * sync is meant to be used by code that requires physical
      * storage (such as a file) to be in a known state  For
      * example, a class that provided a simple transaction facility
      * might use sync to ensure that all changes to a file caused
      * by a given transaction were recorded on a storage medium.
      *
      * sync only affects buffers downstream of this FileDescriptor.  If
      * any in-memory buffering is being done by the application (for
      * example, by a BufferedOutputStream object), those buffers must
      * be flushed into the FileDescriptor (for example, by invoking
      * OutputStream.flush) before that data will be affected by sync.
      *
      * @exception SyncFailedException
      *        Thrown when the buffers cannot be flushed,
      *        or because the system cannot guarantee that all the
      *        buffers have been synchronized with physical media.
      * @since     JDK1.1
      */
     public native void sync() throws SyncFailedException;

     // Android-removed: initIDs not used to allow compile-time initialization.
     /* This routine initializes JNI field offsets for the class */
     //private static native void initIDs();

     /**
      * Returns true, if the file was opened for appending.
      */
     @CriticalNative
     private static native boolean getAppend(int fd);

     // Android-added: Needed for framework to access descriptor value.
     /**
      * Returns the int descriptor. It's highly unlikely you should be calling this. Please discuss
      * your needs with a libcore maintainer before using this method.
      * @hide internal use only
      */
     public final int getInt$() {
         return descriptor;
     }

     // Android-added: Needed for framework to access descriptor value.
     /**
      * Sets the int descriptor. It's highly unlikely you should be calling this. Please discuss
      * your needs with a libcore maintainer before using this method.
      *
      * @hide This method is @SystemApi(MODULE_LIBRARIES) and used by AFileDescriptor_setFd.
      */
     public final void setInt$(int fd) {
         this.descriptor = fd;
         if (fd != -1) {
             this.append = getAppend(fd);
         }
     }

     // BEGIN Android-added: Method to clone standard file descriptors.
     // Required as a consequence of RuntimeInit#redirectLogStreams. Cloning is used in
     // ZygoteHooks.onEndPreload().
     /**
      * Clones the current native file descriptor and uses this for this FileDescriptor instance.
      *
      * This method does not close the current native file descriptor.
      *
      * @hide internal use only
      */
     public void cloneForFork() {
         try {
             int newDescriptor = Os.fcntlInt(this, F_DUPFD_CLOEXEC, 0);
             setInt$(newDescriptor);
         } catch (ErrnoException e) {
             throw new RuntimeException(e);
         }
     }
     // END Android-added: Method to clone standard file descriptors.

     // BEGIN Android-added: Methods to enable ownership enforcement of Unix file descriptors.
     /**
      * Returns the owner ID of this FileDescriptor. It's highly unlikely you should be calling this.
      * Please discuss your needs with a libcore maintainer before using this method.
      * @hide internal use only
      */
     public long getOwnerId$() {
         return this.ownerId;
     }

     /**
      * Sets the owner ID of this FileDescriptor. The owner ID does not need to be unique, but it is
      * assumed that clashes are rare. See bionic/include/android/fdsan.h for more details.
      *
      * It's highly unlikely you should be calling this.
      * Please discuss your needs with a libcore maintainer before using this method.
      * @param newOwnerId the owner ID of the Object that is responsible for closing this FileDescriptor
      * @hide internal use only
      */
     public void setOwnerId$(long newOwnerId) {
         this.ownerId = newOwnerId;
     }

     /**
      * Returns a copy of this FileDescriptor, and sets this to an invalid state.
      *
      * The returned instance is not necessarily {@code valid()}, if the original FileDescriptor
      * was invalid, or if another thread concurrently calls {@code release$()}.
      *
      * @hide internal use only
      */
     public FileDescriptor release$() {
       FileDescriptor result = new FileDescriptor();
       synchronized (releaseLock) {
           result.descriptor = this.descriptor;
           result.ownerId = this.ownerId;
           this.descriptor = -1;
           this.ownerId = FileDescriptor.NO_OWNER;
       }

       return result;
     }
     // END Android-added: Methods to enable ownership enforcement of Unix file descriptors.

     // Android-added: Needed for framework to test if it's a socket.
     /**
      * @hide internal use only
      */
     public boolean isSocket$() {
         return isSocket(descriptor);
     }

     @CriticalNative
     private static native boolean isSocket(int descriptor);
     // Set up JavaIOFileDescriptorAccess in SharedSecrets
     static {
         jdk.internal.access.SharedSecrets.setJavaIOFileDescriptorAccess(
             new jdk.internal.access.JavaIOFileDescriptorAccess() {
                 public void set(FileDescriptor obj, int fd) {
                     obj.descriptor = fd;
                 }

                 public int get(FileDescriptor obj) {
                     return obj.descriptor;
                 }

                 @Override
                 public boolean getAppend(FileDescriptor fdo) {
                     return fdo.append;
                 }

                 public void setHandle(FileDescriptor obj, long handle) {
                     throw new UnsupportedOperationException();
                 }

                 public long getHandle(FileDescriptor obj) {
                     throw new UnsupportedOperationException();
                 }
             }
         );
     }
 // Android-removed: Removed method required for parents reference counting.
 }
	/*
	* Copyright (c) 1995, 2011, 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.io;

	import android.system.ErrnoException;
	import android.system.Os;
	import android.system.OsConstants;

	import static android.system.OsConstants.F_DUPFD_CLOEXEC;

	import dalvik.annotation.optimization.CriticalNative;

	import libcore.io.Libcore;

	import java.util.concurrent.atomic.AtomicInteger;

	/**
	* Instances of the file descriptor class serve as an opaque handle
	* to the underlying machine-specific structure representing an open
	* file, an open socket, or another source or sink of bytes. The
	* main practical use for a file descriptor is to create a
	* <code>FileInputStream</code> or <code>FileOutputStream</code> to
	* contain it.
	* <p>
	* Applications should not create their own file descriptors.
	*
	* @author Pavani Diwanji
	* @see java.io.FileInputStream
	* @see java.io.FileOutputStream
	* @since JDK1.0
	*/
	public final class FileDescriptor {
	// Android-changed: Removed parent reference counting.
	// The creator is responsible for closing the file descriptor.

	// Android-changed: Renamed fd to descriptor.
	// Renaming is to avoid issues with JNI/reflection fetching the descriptor value.
	private int descriptor;

	// Android-added: Track fd owner to guard against accidental closure. http://b/110100358
	// The owner on the libc side is an pointer-sized value that can be set to an arbitrary
	// value (with 0 meaning 'unowned'). libcore chooses to use System.identityHashCode.
	private long ownerId = NO_OWNER;

	/**
	* true, if file is opened for appending.
	*/
	private boolean append;

	// Android-added: value of ownerId indicating that a FileDescriptor is unowned.
	/** @hide */
	public static final long NO_OWNER = 0L;

	// Android-added: lock for release$.
	private final Object releaseLock = new Object();

	/**
	* Constructs an (invalid) FileDescriptor
	* object.
	*/
	public /**/ FileDescriptor() {
	descriptor = -1;
	}

	private /* */ FileDescriptor(int fd) {
	this.descriptor = fd;
	this.append = getAppend(fd);
	}

	/**
	* A handle to the standard input stream. Usually, this file
	* descriptor is not used directly, but rather via the input stream
	* known as <code>System.in</code>.
	*
	* @see java.lang.System#in
	*/
	public static final FileDescriptor in = new FileDescriptor(0);

	/**
	* A handle to the standard output stream. Usually, this file
	* descriptor is not used directly, but rather via the output stream
	* known as <code>System.out</code>.
	* @see java.lang.System#out
	*/
	public static final FileDescriptor out = new FileDescriptor(1);

	/**
	* A handle to the standard error stream. Usually, this file
	* descriptor is not used directly, but rather via the output stream
	* known as <code>System.err</code>.
	*
	* @see java.lang.System#err
	*/
	public static final FileDescriptor err = new FileDescriptor(2);

	/**
	* Tests if this file descriptor object is valid.
	*
	* @return <code>true</code> if the file descriptor object represents a
	* valid, open file, socket, or other active I/O connection;
	* <code>false</code> otherwise.
	*/
	public boolean valid() {
	return descriptor != -1;
	}

	/**
	* Force all system buffers to synchronize with the underlying
	* device. This method returns after all modified data and
	* attributes of this FileDescriptor have been written to the
	* relevant device(s). In particular, if this FileDescriptor
	* refers to a physical storage medium, such as a file in a file
	* system, sync will not return until all in-memory modified copies
	* of buffers associated with this FileDescriptor have been
	* written to the physical medium.
	*
	* sync is meant to be used by code that requires physical
	* storage (such as a file) to be in a known state For
	* example, a class that provided a simple transaction facility
	* might use sync to ensure that all changes to a file caused
	* by a given transaction were recorded on a storage medium.
	*
	* sync only affects buffers downstream of this FileDescriptor. If
	* any in-memory buffering is being done by the application (for
	* example, by a BufferedOutputStream object), those buffers must
	* be flushed into the FileDescriptor (for example, by invoking
	* OutputStream.flush) before that data will be affected by sync.
	*
	* @exception SyncFailedException
	* Thrown when the buffers cannot be flushed,
	* or because the system cannot guarantee that all the
	* buffers have been synchronized with physical media.
	* @since JDK1.1
	*/
	public native void sync() throws SyncFailedException;

	// Android-removed: initIDs not used to allow compile-time initialization.
	/* This routine initializes JNI field offsets for the class */
	//private static native void initIDs();

	/**
	* Returns true, if the file was opened for appending.
	*/
	@CriticalNative
	private static native boolean getAppend(int fd);

	// Android-added: Needed for framework to access descriptor value.
	/**
	* Returns the int descriptor. It's highly unlikely you should be calling this. Please discuss
	* your needs with a libcore maintainer before using this method.
	* @hide internal use only
	*/
	public final int getInt$() {
	return descriptor;
	}

	// Android-added: Needed for framework to access descriptor value.
	/**
	* Sets the int descriptor. It's highly unlikely you should be calling this. Please discuss
	* your needs with a libcore maintainer before using this method.
	*
	* @hide This method is @SystemApi(MODULE_LIBRARIES) and used by AFileDescriptor_setFd.
	*/
	public final void setInt$(int fd) {
	this.descriptor = fd;
	if (fd != -1) {
	this.append = getAppend(fd);
	}
	}

	// BEGIN Android-added: Method to clone standard file descriptors.
	// Required as a consequence of RuntimeInit#redirectLogStreams. Cloning is used in
	// ZygoteHooks.onEndPreload().
	/**
	* Clones the current native file descriptor and uses this for this FileDescriptor instance.
	*
	* This method does not close the current native file descriptor.
	*
	* @hide internal use only
	*/
	public void cloneForFork() {
	try {
	int newDescriptor = Os.fcntlInt(this, F_DUPFD_CLOEXEC, 0);
	setInt$(newDescriptor);
	} catch (ErrnoException e) {
	throw new RuntimeException(e);
	}
	}
	// END Android-added: Method to clone standard file descriptors.

	// BEGIN Android-added: Methods to enable ownership enforcement of Unix file descriptors.
	/**
	* Returns the owner ID of this FileDescriptor. It's highly unlikely you should be calling this.
	* Please discuss your needs with a libcore maintainer before using this method.
	* @hide internal use only
	*/
	public long getOwnerId$() {
	return this.ownerId;
	}

	/**
	* Sets the owner ID of this FileDescriptor. The owner ID does not need to be unique, but it is
	* assumed that clashes are rare. See bionic/include/android/fdsan.h for more details.
	*
	* It's highly unlikely you should be calling this.
	* Please discuss your needs with a libcore maintainer before using this method.
	* @param newOwnerId the owner ID of the Object that is responsible for closing this FileDescriptor
	* @hide internal use only
	*/
	public void setOwnerId$(long newOwnerId) {
	this.ownerId = newOwnerId;
	}

	/**
	* Returns a copy of this FileDescriptor, and sets this to an invalid state.
	*
	* The returned instance is not necessarily {@code valid()}, if the original FileDescriptor
	* was invalid, or if another thread concurrently calls {@code release$()}.
	*
	* @hide internal use only
	*/
	public FileDescriptor release$() {
	FileDescriptor result = new FileDescriptor();
	synchronized (releaseLock) {
	result.descriptor = this.descriptor;
	result.ownerId = this.ownerId;
	this.descriptor = -1;
	this.ownerId = FileDescriptor.NO_OWNER;
	}

	return result;
	}
	// END Android-added: Methods to enable ownership enforcement of Unix file descriptors.

	// Android-added: Needed for framework to test if it's a socket.
	/**
	* @hide internal use only
	*/
	public boolean isSocket$() {
	return isSocket(descriptor);
	}

	@CriticalNative
	private static native boolean isSocket(int descriptor);
	// Set up JavaIOFileDescriptorAccess in SharedSecrets
	static {
	jdk.internal.access.SharedSecrets.setJavaIOFileDescriptorAccess(
	new jdk.internal.access.JavaIOFileDescriptorAccess() {
	public void set(FileDescriptor obj, int fd) {
	obj.descriptor = fd;
	}

	public int get(FileDescriptor obj) {
	return obj.descriptor;
	}

	@Override
	public boolean getAppend(FileDescriptor fdo) {
	return fdo.append;
	}

	public void setHandle(FileDescriptor obj, long handle) {
	throw new UnsupportedOperationException();
	}

	public long getHandle(FileDescriptor obj) {
	throw new UnsupportedOperationException();
	}
	}
	);
	}
	// Android-removed: Removed method required for parents reference counting.
	}