HFSPlusFSFile.java

/*-
 * Copyright (C) 2014 Erik Larsson
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.catacombae.storage.fs.hfsplus;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import org.catacombae.hfs.types.decmpfs.DecmpfsHeader;
import org.catacombae.hfs.types.hfscommon.CommonHFSCatalogFile;
import org.catacombae.hfs.types.hfscommon.CommonHFSCatalogFileRecord;
import org.catacombae.hfs.types.hfscommon.CommonHFSCatalogLeafRecord;
import org.catacombae.io.ReadableRandomAccessStream;
import org.catacombae.storage.fs.FSFork;
import org.catacombae.storage.fs.hfscommon.HFSCommonFSFile;
import org.catacombae.storage.fs.hfscommon.HFSCommonFileSystemHandler;
import org.catacombae.util.Util;

/**
 * @author <a href="http://www.catacombae.org/" target="_top">Erik Larsson</a>
 */
public class HFSPlusFSFile extends HFSCommonFSFile {
    private static final boolean DEBUG = Util.booleanEnabledByProperties(false,
            "org.catacombae.debug",
            "org.catacombae.storage.debug",
            "org.catacombae.storage.fs.debug",
            "org.catacombae.storage.fs.hfsplus.debug",
            "org.catacombae.storage.fs.hfsplus." +
            HFSPlusFSFile.class.getSimpleName() + ".debug");

    private FSFork dataFork = null;

    HFSPlusFSFile(HFSCommonFileSystemHandler parentHandler,
            CommonHFSCatalogFileRecord fileRecord)
    {
        super(parentHandler, fileRecord);
    }

    HFSPlusFSFile(HFSCommonFileSystemHandler parentHandler,
            CommonHFSCatalogLeafRecord hardLinkRecord,
            CommonHFSCatalogFileRecord fileRecord)
    {
        super(parentHandler, hardLinkRecord, fileRecord);
    }

    @Override
    protected void fillAttributeForks(List<FSFork> forkList) {
        LinkedList<FSFork> attributeForkList = new LinkedList<FSFork>();
        super.fillAttributeForks(attributeForkList);

        final boolean isCompressed =
                getDataFork() instanceof HFSPlusCompressedDataFork;

        Iterator<FSFork> it = attributeForkList.iterator();
        while(it.hasNext()) {
            FSFork curFork = it.next();
            if(isCompressed && curFork.hasXattrName() &&
                    curFork.getXattrName().equals("com.apple.decmpfs"))
            {
                it.remove();
            }
        }

        forkList.addAll(attributeForkList);
    }

    @Override
    protected FSFork getDataFork() {
        if(DEBUG) {
            System.err.println("getDataFork(): Entering...");
        }

        if(dataFork == null) {
            final CommonHFSCatalogFile catalogFile = fileRecord.getData();
            if(!catalogFile.getPermissions().getOwnerCompressedFlag()) {
                /* Definitely not compressed since the compressed flag is not
                 * set. */
                dataFork = super.getDataFork();
            }
            else {
                LinkedList<FSFork> attributeForkList = new LinkedList<FSFork>();

                /* Note: Need to call super's implementation because this class
                 *       overrides fillAttributeForks to call back into
                 *       getDataFork() in order to determine if we should filter
                 *       out the "com.apple.decmpfs" attribute fork. */
                super.fillAttributeForks(attributeForkList);

                for(FSFork f : attributeForkList) {
                    if(DEBUG) {
                        System.err.println("getDataFork: Checking out " +
                                "attribute fork " + f + (f.hasXattrName() ?
                                " with xattr name \"" + f.getXattrName() +
                                "\"" : "") + ".");
                    }

                    if(f.hasXattrName() &&
                            f.getXattrName().equals("com.apple.decmpfs"))
                    {
                        byte[] headerData = new byte[DecmpfsHeader.STRUCTSIZE];

                        ReadableRandomAccessStream forkStream =
                                f.getReadableRandomAccessStream();
                        try {
                            forkStream.readFully(headerData);
                        } finally {
                            forkStream.close();
                        }

                        DecmpfsHeader header = new DecmpfsHeader(headerData, 0);
                        if(header.getMagic() != DecmpfsHeader.MAGIC) {
                            /* If magic doesn't match, the decmpfs fork is
                             * broken and we treat this attribute fork as a
                             * normal extended attribute for data recovery
                             * purposes. */
                            continue;
                        }

                        switch(header.getRawCompressionType()) {
                            case DecmpfsHeader.COMPRESSION_TYPE_INLINE:
                            case DecmpfsHeader.COMPRESSION_TYPE_RESOURCE:
                                break;
                            default:
                                /* No support for other compression types than
                                 * type "inline" (3) and "resource" (4) at this
                                 * point.
                                 * All other compression types will lead to the
                                 * attribute being exposed as-is for recovery
                                 * purposes. */
                                continue;
                        }

                        /* We override getResourceFork() in this class in order
                         * to hide it if the file is compressed, so call super's
                         * implementation to get it unconditionally (and without
                         * infinite recursion for that matter). */
                        dataFork = new HFSPlusCompressedDataFork(f,
                                super.getResourceFork());
                        break;
                    }
                }

                if(dataFork == null) {
                    /* We haven't created any compressed data fork when going
                     * through the attributes, so this is a regular data fork.
                     * Just call super. */
                    dataFork = super.getDataFork();
                }
            }
        }

        return dataFork;
    }

    @Override
    protected FSFork getResourceFork() {
        final FSFork f = getDataFork();

        if(f instanceof HFSPlusCompressedDataFork) {
            final HFSPlusCompressedDataFork compressedFork =
                    (HFSPlusCompressedDataFork) f;

            if(compressedFork.isUsingResourceFork()) {
                /* Hide compressed data in resource fork. If there are other
                 * resources they will be hidden too.
                 *
                 * TODO: Virtualize the resource fork data if there are other
                 *       resources, so that the caller gets a virtual resource
                 *       fork back with the 'cmpf' resource removed. */
                return null;
            }
        }

        return super.getResourceFork();
    }
}