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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * published by the Free Software Foundation.  Oracle designates this

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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

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 */

package java.util.jar;

import java.util.SortedMap;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.File;

import java.io.IOException;

/**

 * Transforms a JAR file to or from a packed stream in Pack200 format.

 * Please refer to Network Transfer Format JSR 200 Specification at

 * <a href=http://jcp.org/aboutJava/communityprocess/review/jsr200/index.html>http://jcp.org/aboutJava/communityprocess/review/jsr200/index.html</a>

 * <p>

 * Typically the packer engine is used by application developers

 * to deploy or host JAR files on a website.

 * The unpacker  engine is used by deployment applications to

 * transform the byte-stream back to JAR format.

 * <p>

 * Here is an example using  packer and unpacker:

 * <pre>{@code

 *    import java.util.jar.Pack200;

 *    import java.util.jar.Pack200.*;

 *    ...

 *    // Create the Packer object

 *    Packer packer = Pack200.newPacker();

 *

 *    // Initialize the state by setting the desired properties

 *    Map p = packer.properties();

 *    // take more time choosing codings for better compression

 *    p.put(Packer.EFFORT, "7");  // default is "5"

 *    // use largest-possible archive segments (>10% better compression).

 *    p.put(Packer.SEGMENT_LIMIT, "-1");

 *    // reorder files for better compression.

 *    p.put(Packer.KEEP_FILE_ORDER, Packer.FALSE);

 *    // smear modification times to a single value.

 *    p.put(Packer.MODIFICATION_TIME, Packer.LATEST);

 *    // ignore all JAR deflation requests,

 *    // transmitting a single request to use "store" mode.

 *    p.put(Packer.DEFLATE_HINT, Packer.FALSE);

 *    // discard debug attributes

 *    p.put(Packer.CODE_ATTRIBUTE_PFX+"LineNumberTable", Packer.STRIP);

 *    // throw an error if an attribute is unrecognized

 *    p.put(Packer.UNKNOWN_ATTRIBUTE, Packer.ERROR);

 *    // pass one class file uncompressed:

 *    p.put(Packer.PASS_FILE_PFX+0, "mutants/Rogue.class");

 *    try {

 *        JarFile jarFile = new JarFile("/tmp/testref.jar");

 *        FileOutputStream fos = new FileOutputStream("/tmp/test.pack");

 *        // Call the packer

 *        packer.pack(jarFile, fos);

 *        jarFile.close();

 *        fos.close();

 *

 *        File f = new File("/tmp/test.pack");

 *        FileOutputStream fostream = new FileOutputStream("/tmp/test.jar");

 *        JarOutputStream jostream = new JarOutputStream(fostream);

 *        Unpacker unpacker = Pack200.newUnpacker();

 *        // Call the unpacker

 *        unpacker.unpack(f, jostream);

 *        // Must explicitly close the output.

 *        jostream.close();

 *    } catch (IOException ioe) {

 *        ioe.printStackTrace();

 *    }

 * }</pre>

 * <p>

 * A Pack200 file compressed with gzip can be hosted on HTTP/1.1 web servers.

 * The deployment applications can use "Accept-Encoding=pack200-gzip". This

 * indicates to the server that the client application desires a version of

 * the file encoded with Pack200 and further compressed with gzip. Please

 * refer to the Java Deployment Guide for techniques and details.

 * <p>

 * method in this class will cause a {@link NullPointerException} to be thrown.

 *

 * @author John Rose

 * @author Kumar Srinivasan

 * @since 1.5

 */

public abstract class Pack200 {

    private Pack200() {} //prevent instantiation

    // Static methods of the Pack200 class.

    /**

     * Obtain new instance of a class that implements Packer.

     * <ul>

     * is defined, then the value is taken to be the fully-qualified name

     * of a concrete implementation class, which must implement Packer.

     * This class is loaded and instantiated.  If this process fails

     * then an unspecified error is thrown.</p></li>

     *

     * <li><p>If an implementation has not been specified with the system

     * property, then the system-default implementation class is instantiated,

     * and the result is returned.</p></li>

     * </ul>

     *

     * <p>Note:  The returned object is not guaranteed to operate

     * correctly if multiple threads use it at the same time.

     * A multi-threaded application should either allocate multiple

     * packer engines, or else serialize use of one engine with a lock.

     *

     * @return  A newly allocated Packer engine.

     */

    public synchronized static Packer newPacker() {

        return (Packer) newInstance(PACK_PROVIDER);

    }

    /**

     * Obtain new instance of a class that implements Unpacker.

     * <ul>

     * is defined, then the value is taken to be the fully-qualified

     * name of a concrete implementation class, which must implement Unpacker.

     * The class is loaded and instantiated.  If this process fails

     * then an unspecified error is thrown.</p></li>

     *

     * <li><p>If an implementation has not been specified with the

     * system property, then the system-default implementation class

     * is instantiated, and the result is returned.</p></li>

     * </ul>

     *

     * <p>Note:  The returned object is not guaranteed to operate

     * correctly if multiple threads use it at the same time.

     * A multi-threaded application should either allocate multiple

     * unpacker engines, or else serialize use of one engine with a lock.

     *

     * @return  A newly allocated Unpacker engine.

     */

    public static Unpacker newUnpacker() {

        return (Unpacker) newInstance(UNPACK_PROVIDER);

    }

    // Interfaces

    /**

     * The packer engine applies various transformations to the input JAR file,

     * making the pack stream highly compressible by a compressor such as

     * gzip or zip. An instance of the engine can be obtained

     * using {@link #newPacker}.

     * The high degree of compression is achieved

     * by using a number of techniques described in the JSR 200 specification.

     * Some of the techniques are sorting, re-ordering and co-location of the

     * constant pool.

     * <p>

     * The pack engine is initialized to an initial state as described

     * by their properties below.

     * The initial state can be manipulated by getting the

     * engine properties (using {@link #properties}) and storing

     * the modified properties on the map.

     * The resource files will be passed through with no changes at all.

     * The class files will not contain identical bytes, since the unpacker

     * is free to change minor class file features such as constant pool order.

     * However, the class files will be semantically identical,

     * as specified in

     * <cite>The Java&trade; Virtual Machine Specification</cite>.

     * <p>

     * By default, the packer does not change the order of JAR elements.

     * Also, the modification time and deflation hint of each

     * JAR element is passed unchanged.

     * (Any other ZIP-archive information, such as extra attributes

     * giving Unix file permissions, are lost.)

     * <p>

     * Note that packing and unpacking a JAR will in general alter the

     * bytewise contents of classfiles in the JAR.  This means that packing

     * and unpacking will in general invalidate any digital signatures

     * which rely on bytewise images of JAR elements.  In order both to sign

     * and to pack a JAR, you must first pack and unpack the JAR to

     * "normalize" it, then compute signatures on the unpacked JAR elements,

     * and finally repack the signed JAR.

     * Both packing steps should

     * use precisely the same options, and the segment limit may also

     * need to be set to "-1", to prevent accidental variation of segment

     * boundaries as class file sizes change slightly.

     * <p>

     * (Here's why this works:  Any reordering the packer does

     * of any classfile structures is idempotent, so the second packing

     * does not change the orderings produced by the first packing.

     * Also, the unpacker is guaranteed by the JSR 200 specification

     * to produce a specific bytewise image for any given transmission

     * ordering of archive elements.)

     * <p>

     * In order to maintain backward compatibility, the pack file's version is

     * set to accommodate the class files present in the input JAR file. In

     * other words, the pack file version will be the latest, if the class files

     * are the latest and conversely the pack file version will be the oldest

     * if the class file versions are also the oldest. For intermediate class

     * file versions the corresponding pack file version will be used.

     * For example:

     *    If the input JAR-files are solely comprised of 1.5  (or  lesser)

     * class files, a 1.5 compatible pack file is  produced. This will also be

     * the case for archives that have no class files.

     *    If the input JAR-files contains a 1.6 class file, then the pack file

     * version will be set to 1.6.

     * <p>

     * constructor or method in this class will cause a {@link NullPointerException}

     * to be thrown.

     *

     * @since 1.5

     */

    public interface Packer {

        /**

         * This property is a numeral giving the estimated target size N

         * (in bytes) of each archive segment.

         * If a single input file requires more than N bytes,

         * it will be given its own archive segment.

         * <p>

         * As a special case, a value of -1 will produce a single large

         * segment with all input files, while a value of 0 will

         * produce one segment for each class.

         * Larger archive segments result in less fragmentation and

         * better compression, but processing them requires more memory.

         * <p>

         * The size of each segment is estimated by counting the size of each

         * input file to be transmitted in the segment, along with the size

         * of its name and other transmitted properties.

         * <p>

         * The default is -1, which means the packer will always create a single

         * segment output file. In cases where extremely large output files are

         * generated, users are strongly encouraged to use segmenting or break

         * up the input file into smaller JARs.

         * <p>

         * A 10Mb JAR packed without this limit will

         * typically pack about 10% smaller, but the packer may require

         * a larger Java heap (about ten times the segment limit).

         */

        String SEGMENT_LIMIT    = "pack.segment.limit";

        /**

         * If this property is set to {@link #TRUE}, the packer will transmit

         * all elements in their original order within the source archive.

         * <p>

         * If it is set to {@link #FALSE}, the packer may reorder elements,

         * and also remove JAR directory entries, which carry no useful

         * information for Java applications.

         * (Typically this enables better compression.)

         * <p>

         * The default is {@link #TRUE}, which preserves the input information,

         * but may cause the transmitted archive to be larger than necessary.

         */

        String KEEP_FILE_ORDER = "pack.keep.file.order";

        /**

         * If this property is set to a single decimal digit, the packer will

         * use the indicated amount of effort in compressing the archive.

         * Level 1 may produce somewhat larger size and faster compression speed,

         * while level 9 will take much longer but may produce better compression.

         * <p>

         * The special value 0 instructs the packer to copy through the

         * original JAR file directly, with no compression.  The JSR 200

         * standard requires any unpacker to understand this special case

         * as a pass-through of the entire archive.

         * <p>

         * The default is 5, investing a modest amount of time to

         * produce reasonable compression.

         */

        String EFFORT           = "pack.effort";

        /**

         * If this property is set to {@link #TRUE} or {@link #FALSE}, the packer

         * will set the deflation hint accordingly in the output archive, and

         * will not transmit the individual deflation hints of archive elements.

         * <p>

         * If this property is set to the special string {@link #KEEP}, the packer

         * will attempt to determine an independent deflation hint for each

         * available element of the input archive, and transmit this hint separately.

         * <p>

         * The default is {@link #KEEP}, which preserves the input information,

         * but may cause the transmitted archive to be larger than necessary.

         * <p>

         * It is up to the unpacker implementation

         * to take action upon the hint to suitably compress the elements of

         * the resulting unpacked jar.

         * <p>

         * The deflation hint of a ZIP or JAR element indicates

         * whether the element was deflated or stored directly.

         */

        String DEFLATE_HINT     = "pack.deflate.hint";

        /**

         * If this property is set to the special string {@link #LATEST},

         * the packer will attempt to determine the latest modification time,

         * among all the available entries in the original archive or the latest

         * modification time of all the available entries in each segment.

         * This single value will be transmitted as part of the segment and applied

         * to all the entries in each segment, {@link #SEGMENT_LIMIT}.

         * <p>

         * This can marginally decrease the transmitted size of the

         * archive, at the expense of setting all installed files to a single

         * date.

         * <p>

         * If this property is set to the special string {@link #KEEP},

         * the packer transmits a separate modification time for each input

         * element.

         * <p>

         * The default is {@link #KEEP}, which preserves the input information,

         * but may cause the transmitted archive to be larger than necessary.

         * <p>

         * It is up to the unpacker implementation to take action to suitably

         * set the modification time of each element of its output file.

         * @see #SEGMENT_LIMIT

         */

        String MODIFICATION_TIME        = "pack.modification.time";

        /**

         * Indicates that a file should be passed through bytewise, with no

         * compression.  Multiple files may be specified by specifying

         * additional properties with distinct strings appended, to

         * make a family of properties with the common prefix.

         * <p>

         * There is no pathname transformation, except

         * that the system file separator is replaced by the JAR file

         * separator '/'.

         * <p>

         * The resulting file names must match exactly as strings with their

         * occurrences in the JAR file.

         * <p>

         * If a property value is a directory name, all files under that

         * directory will be passed also.

         * <p>

         * Examples:

         * <pre>{@code

         *     Map p = packer.properties();

         *     p.put(PASS_FILE_PFX+0, "mutants/Rogue.class");

         *     p.put(PASS_FILE_PFX+1, "mutants/Wolverine.class");

         *     p.put(PASS_FILE_PFX+2, "mutants/Storm.class");

         *     # Pass all files in an entire directory hierarchy:

         *     p.put(PASS_FILE_PFX+3, "police/");

         * }</pre>

         */

        String PASS_FILE_PFX            = "pack.pass.file.";

        /// Attribute control.

        /**

         * Indicates the action to take when a class-file containing an unknown

         * attribute is encountered.  Possible values are the strings {@link #ERROR},

         * {@link #STRIP}, and {@link #PASS}.

         * <p>

         * The string {@link #ERROR} means that the pack operation

         * The string

         * {@link #STRIP} means that the attribute will be dropped.

         * The string

         * {@link #PASS} means that the whole class-file will be passed through

         * (as if it were a resource file) without compression, with  a suitable warning.

         * This is the default value for this property.

         * <p>

         * Examples:

         * <pre>{@code

         *     Map p = pack200.getProperties();

         *     p.put(UNKNOWN_ATTRIBUTE, ERROR);

         *     p.put(UNKNOWN_ATTRIBUTE, STRIP);

         *     p.put(UNKNOWN_ATTRIBUTE, PASS);

         * }</pre>

         */

        String UNKNOWN_ATTRIBUTE        = "pack.unknown.attribute";

        /**

         * When concatenated with a class attribute name,

         * indicates the format of that attribute,

         * using the layout language specified in the JSR 200 specification.

         * <p>

         * For example, the effect of this option is built in:

         * <p>

         * The special strings {@link #ERROR}, {@link #STRIP}, and {@link #PASS} are

         * also allowed, with the same meaning as {@link #UNKNOWN_ATTRIBUTE}.

         * This provides a way for users to request that specific attributes be

         * refused, stripped, or passed bitwise (with no class compression).

         * <p>

         * Code like this might be used to support attributes for JCOV:

         *     Map p = packer.properties();

         *     p.put(CODE_ATTRIBUTE_PFX+"CoverageTable",       "NH[PHHII]");

         *     p.put(CODE_ATTRIBUTE_PFX+"CharacterRangeTable", "NH[PHPOHIIH]");

         *     p.put(CLASS_ATTRIBUTE_PFX+"SourceID",           "RUH");

         *     p.put(CLASS_ATTRIBUTE_PFX+"CompilationID",      "RUH");

         * <p>

         * Code like this might be used to strip debugging attributes:

         *     Map p = packer.properties();

         *     p.put(CODE_ATTRIBUTE_PFX+"LineNumberTable",    STRIP);

         *     p.put(CODE_ATTRIBUTE_PFX+"LocalVariableTable", STRIP);

         *     p.put(CLASS_ATTRIBUTE_PFX+"SourceFile",        STRIP);

         */

        String CLASS_ATTRIBUTE_PFX      = "pack.class.attribute.";

        /**

         * When concatenated with a field attribute name,

         * indicates the format of that attribute.

         * For example, the effect of this option is built in:

         * The special strings {@link #ERROR}, {@link #STRIP}, and

         * {@link #PASS} are also allowed.

         * @see #CLASS_ATTRIBUTE_PFX

         */

        String FIELD_ATTRIBUTE_PFX      = "pack.field.attribute.";

        /**

         * When concatenated with a method attribute name,

         * indicates the format of that attribute.

         * For example, the effect of this option is built in:

         * The special strings {@link #ERROR}, {@link #STRIP}, and {@link #PASS}

         * are also allowed.

         * @see #CLASS_ATTRIBUTE_PFX

         */

        String METHOD_ATTRIBUTE_PFX     = "pack.method.attribute.";

        /**

         * When concatenated with a code attribute name,

         * indicates the format of that attribute.

         * For example, the effect of this option is built in:

         * The special strings {@link #ERROR}, {@link #STRIP}, and {@link #PASS}

         * are also allowed.

         * @see #CLASS_ATTRIBUTE_PFX

         */

        String CODE_ATTRIBUTE_PFX       = "pack.code.attribute.";

        /**

         * The unpacker's progress as a percentage, as periodically

         * updated by the unpacker.

         * Values of 0 - 100 are normal, and -1 indicates a stall.

         * Progress can be monitored by polling the value of this

         * property.

         * <p>

         * At a minimum, the unpacker must set progress to 0

         * at the beginning of a packing operation, and to 100

         * at the end.

         */

        String PROGRESS                 = "pack.progress";

        /** The string "keep", a possible value for certain properties.

         * @see #DEFLATE_HINT

         * @see #MODIFICATION_TIME

         */

        String KEEP  = "keep";

        /** The string "pass", a possible value for certain properties.

         * @see #UNKNOWN_ATTRIBUTE

         * @see #CLASS_ATTRIBUTE_PFX

         * @see #FIELD_ATTRIBUTE_PFX

         * @see #METHOD_ATTRIBUTE_PFX

         * @see #CODE_ATTRIBUTE_PFX

         */

        String PASS  = "pass";

        /** The string "strip", a possible value for certain properties.

         * @see #UNKNOWN_ATTRIBUTE

         * @see #CLASS_ATTRIBUTE_PFX

         * @see #FIELD_ATTRIBUTE_PFX

         * @see #METHOD_ATTRIBUTE_PFX

         * @see #CODE_ATTRIBUTE_PFX

         */

        String STRIP = "strip";

        /** The string "error", a possible value for certain properties.

         * @see #UNKNOWN_ATTRIBUTE

         * @see #CLASS_ATTRIBUTE_PFX

         * @see #FIELD_ATTRIBUTE_PFX

         * @see #METHOD_ATTRIBUTE_PFX

         * @see #CODE_ATTRIBUTE_PFX

         */

        String ERROR = "error";

        /** The string "true", a possible value for certain properties.

         * @see #KEEP_FILE_ORDER

         * @see #DEFLATE_HINT

         */

        String TRUE = "true";

        /** The string "false", a possible value for certain properties.

         * @see #KEEP_FILE_ORDER

         * @see #DEFLATE_HINT

         */

        String FALSE = "false";

        /** The string "latest", a possible value for certain properties.

         * @see #MODIFICATION_TIME

         */

        String LATEST = "latest";

        /**

         * Get the set of this engine's properties.

         * This set is a "live view", so that changing its

         * contents immediately affects the Packer engine, and

         * changes from the engine (such as progress indications)

         * are immediately visible in the map.