/*
 * Copyright (c) 1994, 2018, 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
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 */

package java.io;

import java.nio.channels.FileChannel;
import jdk.internal.access.SharedSecrets;
import jdk.internal.access.JavaIOFileDescriptorAccess;
import sun.nio.ch.FileChannelImpl;


/**
 * A file output stream is an output stream for writing data to a
 * <code>File</code> or to a <code>FileDescriptor</code>. Whether or not
 * a file is available or may be created depends upon the underlying
 * platform. Some platforms, in particular, allow a file to be opened
 * for writing by only one {@code FileOutputStream} (or other
 * file-writing object) at a time. In such situations the constructors in
 * this class will fail if the file involved is already open.
 *
 * <p><code>FileOutputStream</code> is meant for writing streams of raw bytes
 * such as image data. For writing streams of characters, consider using
 * <code>FileWriter</code>.
 *
 * @apiNote
 * To release resources used by this stream {@link #close} should be called
 * directly or by try-with-resources. Subclasses are responsible for the cleanup
 * of resources acquired by the subclass.
 * Subclasses that override {@link #finalize} in order to perform cleanup
 * should be modified to use alternative cleanup mechanisms such as
 * {@link java.lang.ref.Cleaner} and remove the overriding {@code finalize} method.
 *
 * @implSpec
 * If this FileOutputStream has been subclassed and the {@link #close}
 * method has been overridden, the {@link #close} method will be
 * called when the FileInputStream is unreachable.
 * Otherwise, it is implementation specific how the resource cleanup described in
 * {@link #close} is performed.
 *
 * @author Arthur van Hoff
 * @see java.io.File
 * @see java.io.FileDescriptor
 * @see java.io.FileInputStream
 * @see java.nio.file.Files#newOutputStream
 * @since 1.0
 */
public
class FileOutputStream extends OutputStream
{
 /**
 * Access to FileDescriptor internals.
 */
 private static final JavaIOFileDescriptorAccess fdAccess =
 SharedSecrets.getJavaIOFileDescriptorAccess();

 /**
 * The system dependent file descriptor.
 */
 private final FileDescriptor fd;

 /**
 * The associated channel, initialized lazily.
 */
 private volatile FileChannel channel;

 /**
 * The path of the referenced file
 * (null if the stream is created with a file descriptor)
 */
 private final String path;

 private final Object closeLock = new Object();

 private volatile boolean closed;

 /**
 * Creates a file output stream to write to the file with the
 * specified name. A new <code>FileDescriptor</code> object is
 * created to represent this file connection.
 * <p>
 * First, if there is a security manager, its <code>checkWrite</code>
 * method is called with <code>name</code> as its argument.
 * <p>
 * If the file exists but is a directory rather than a regular file, does
 * not exist but cannot be created, or cannot be opened for any other
 * reason then a <code>FileNotFoundException</code> is thrown.
 *
 * @implSpec Invoking this constructor with the parameter {@code name} is
 * equivalent to invoking {@link #FileOutputStream(String,boolean)
 * new FileOutputStream(name, false)}.
 *
 * @param name the system-dependent filename
 * @exception FileNotFoundException if the file exists but is a directory
 * rather than a regular file, does not exist but cannot
 * be created, or cannot be opened for any other reason
 * @exception SecurityException if a security manager exists and its
 * <code>checkWrite</code> method denies write access
 * to the file.
 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
 */
 public FileOutputStream(String name) throws FileNotFoundException {
 this(name != null ? new File(name) : null, false);
 }

 /**
 * Creates a file output stream to write to the file with the specified
 * name. If the second argument is <code>true</code>, then
 * bytes will be written to the end of the file rather than the beginning.
 * A new <code>FileDescriptor</code> object is created to represent this
 * file connection.
 * <p>
 * First, if there is a security manager, its <code>checkWrite</code>
 * method is called with <code>name</code> as its argument.
 * <p>
 * If the file exists but is a directory rather than a regular file, does
 * not exist but cannot be created, or cannot be opened for any other
 * reason then a <code>FileNotFoundException</code> is thrown.
 *
 * @param name the system-dependent file name
 * @param append if <code>true</code>, then bytes will be written
 * to the end of the file rather than the beginning
 * @exception FileNotFoundException if the file exists but is a directory
 * rather than a regular file, does not exist but cannot
 * be created, or cannot be opened for any other reason.
 * @exception SecurityException if a security manager exists and its
 * <code>checkWrite</code> method denies write access
 * to the file.
 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
 * @since 1.1
 */
 public FileOutputStream(String name, boolean append)
 throws FileNotFoundException
 {
 this(name != null ? new File(name) : null, append);
 }

 /**
 * Creates a file output stream to write to the file represented by
 * the specified <code>File</code> object. A new
 * <code>FileDescriptor</code> object is created to represent this
 * file connection.
 * <p>
 * First, if there is a security manager, its <code>checkWrite</code>
 * method is called with the path represented by the <code>file</code>
 * argument as its argument.
 * <p>
 * If the file exists but is a directory rather than a regular file, does
 * not exist but cannot be created, or cannot be opened for any other
 * reason then a <code>FileNotFoundException</code> is thrown.
 *
 * @param file the file to be opened for writing.
 * @exception FileNotFoundException if the file exists but is a directory
 * rather than a regular file, does not exist but cannot
 * be created, or cannot be opened for any other reason
 * @exception SecurityException if a security manager exists and its
 * <code>checkWrite</code> method denies write access
 * to the file.
 * @see java.io.File#getPath()
 * @see java.lang.SecurityException
 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
 */
 public FileOutputStream(File file) throws FileNotFoundException {
 this(file, false);
 }

 /**
 * Creates a file output stream to write to the file represented by
 * the specified <code>File</code> object. If the second argument is
 * <code>true</code>, then bytes will be written to the end of the file
 * rather than the beginning. A new <code>FileDescriptor</code> object is
 * created to represent this file connection.
 * <p>
 * First, if there is a security manager, its <code>checkWrite</code>
 * method is called with the path represented by the <code>file</code>
 * argument as its argument.
 * <p>
 * If the file exists but is a directory rather than a regular file, does
 * not exist but cannot be created, or cannot be opened for any other
 * reason then a <code>FileNotFoundException</code> is thrown.
 *
 * @param file the file to be opened for writing.
 * @param append if <code>true</code>, then bytes will be written
 * to the end of the file rather than the beginning
 * @exception FileNotFoundException if the file exists but is a directory
 * rather than a regular file, does not exist but cannot
 * be created, or cannot be opened for any other reason
 * @exception SecurityException if a security manager exists and its
 * <code>checkWrite</code> method denies write access
 * to the file.
 * @see java.io.File#getPath()
 * @see java.lang.SecurityException
 * @see java.lang.SecurityManager#checkWrite(java.lang.String)
 * @since 1.4
 */
 public FileOutputStream(File file, boolean append)
 throws FileNotFoundException
 {
 String name = (file != null ? file.getPath() : null);
 SecurityManager security = System.getSecurityManager();
 if (security != null) {
 security.checkWrite(name);
 }
 if (name == null) {
 throw new NullPointerException();
 }
 if (file.isInvalid()) {
 throw new FileNotFoundException("Invalid file path");
 }
 this.fd = new FileDescriptor();
 fd.attach(this);
 this.path = name;

 open(name, append);
 FileCleanable.register(fd); // open sets the fd, register the cleanup
 }

 /**
 * Creates a file output stream to write to the specified file
 * descriptor, which represents an existing connection to an actual
 * file in the file system.
 * <p>
 * First, if there is a security manager, its <code>checkWrite</code>
 * method is called with the file descriptor <code>fdObj</code>
 * argument as its argument.
 * <p>
 * If <code>fdObj</code> is null then a <code>NullPointerException</code>
 * is thrown.
 * <p>
 * This constructor does not throw an exception if <code>fdObj</code>
 * is {@link java.io.FileDescriptor#valid() invalid}.
 * However, if the methods are invoked on the resulting stream to attempt
 * I/O on the stream, an <code>IOException</code> is thrown.
 *
 * @param fdObj the file descriptor to be opened for writing
 * @exception SecurityException if a security manager exists and its
 * <code>checkWrite</code> method denies
 * write access to the file descriptor
 * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
 */
 public FileOutputStream(FileDescriptor fdObj) {
 SecurityManager security = System.getSecurityManager();
 if (fdObj == null) {
 throw new NullPointerException();
 }
 if (security != null) {
 security.checkWrite(fdObj);
 }
 this.fd = fdObj;
 this.path = null;

 fd.attach(this);
 }

 /**
 * Opens a file, with the specified name, for overwriting or appending.
 * @param name name of file to be opened
 * @param append whether the file is to be opened in append mode
 */
 private native void open0(String name, boolean append)
 throws FileNotFoundException;

 // wrap native call to allow instrumentation
 /**
 * Opens a file, with the specified name, for overwriting or appending.
 * @param name name of file to be opened
 * @param append whether the file is to be opened in append mode
 */
 private void open(String name, boolean append)
 throws FileNotFoundException {
 open0(name, append);
 }

 /**
 * Writes the specified byte to this file output stream.
 *
 * @param b the byte to be written.
 * @param append {@code true} if the write operation first
 * advances the position to the end of file
 */
 private native void write(int b, boolean append) throws IOException;

 /**
 * Writes the specified byte to this file output stream. Implements
 * the <code>write</code> method of <code>OutputStream</code>.
 *
 * @param b the byte to be written.
 * @exception IOException if an I/O error occurs.
 */
 public void write(int b) throws IOException {
 write(b, fdAccess.getAppend(fd));
 }

 /**
 * Writes a sub array as a sequence of bytes.
 * @param b the data to be written
 * @param off the start offset in the data
 * @param len the number of bytes that are written
 * @param append {@code true} to first advance the position to the
 * end of file
 * @exception IOException If an I/O error has occurred.
 */
 private native void writeBytes(byte b[], int off, int len, boolean append)
 throws IOException;

 /**
 * Writes <code>b.length</code> bytes from the specified byte array
 * to this file output stream.
 *
 * @param b the data.
 * @exception IOException if an I/O error occurs.
 */
 public void write(byte b[]) throws IOException {
 writeBytes(b, 0, b.length, fdAccess.getAppend(fd));
 }

 /**
 * Writes <code>len</code> bytes from the specified byte array
 * starting at offset <code>off</code> to this file output stream.
 *
 * @param b the data.
 * @param off the start offset in the data.
 * @param len the number of bytes to write.
 * @exception IOException if an I/O error occurs.
 */
 public void write(byte b[], int off, int len) throws IOException {
 writeBytes(b, off, len, fdAccess.getAppend(fd));
 }

 /**
 * Closes this file output stream and releases any system resources
 * associated with this stream. This file output stream may no longer
 * be used for writing bytes.
 *
 * <p> If this stream has an associated channel then the channel is closed
 * as well.
 *
 * @apiNote
 * Overriding {@link #close} to perform cleanup actions is reliable
 * only when called directly or when called by try-with-resources.
 * Do not depend on finalization to invoke {@code close};
 * finalization is not reliable and is deprecated.
 * If cleanup of native resources is needed, other mechanisms such as
 * {@linkplain java.lang.ref.Cleaner} should be used.
 *
 * @exception IOException if an I/O error occurs.
 *
 * @revised 1.4
 * @spec JSR-51
 */
 public void close() throws IOException {
 if (closed) {
 return;
 }
 synchronized (closeLock) {
 if (closed) {
 return;
 }
 closed = true;
 }

 FileChannel fc = channel;
 if (fc != null) {
 // possible race with getChannel(), benign since
 // FileChannel.close is final and idempotent
 fc.close();
 }

 fd.closeAll(new Closeable() {
 public void close() throws IOException {
 fd.close();
 }
 });
 }

 /**
 * Returns the file descriptor associated with this stream.
 *
 * @return the <code>FileDescriptor</code> object that represents
 * the connection to the file in the file system being used
 * by this <code>FileOutputStream</code> object.
 *
 * @exception IOException if an I/O error occurs.
 * @see java.io.FileDescriptor
 */
 public final FileDescriptor getFD() throws IOException {
 if (fd != null) {
 return fd;
 }
 throw new IOException();
 }

 /**
 * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
 * object associated with this file output stream.
 *
 * <p> The initial {@link java.nio.channels.FileChannel#position()
 * position} of the returned channel will be equal to the
 * number of bytes written to the file so far unless this stream is in
 * append mode, in which case it will be equal to the size of the file.
 * Writing bytes to this stream will increment the channel's position
 * accordingly. Changing the channel's position, either explicitly or by
 * writing, will change this stream's file position.
 *
 * @return the file channel associated with this file output stream
 *
 * @since 1.4
 * @spec JSR-51
 */
 public FileChannel getChannel() {
 FileChannel fc = this.channel;
 if (fc == null) {
 synchronized (this) {
 fc = this.channel;
 if (fc == null) {
 this.channel = fc = FileChannelImpl.open(fd, path, false,
 true, false, this);
 if (closed) {
 try {
 // possible race with close(), benign since
 // FileChannel.close is final and idempotent
 fc.close();
 } catch (IOException ioe) {
 throw new InternalError(ioe); // should not happen
 }
 }
 }
 }
 }
 return fc;
 }

 private static native void initIDs();

 static {
 initIDs();
 }
}